Geochemical Assessment of Surface Water-Groundwater

University of Calgary

PRISM: University of Calgary's Digital Repository

Graduate Studies The Vault: Electronic Theses and Dissertations

2014-09-04

Geochemical Assessment of Surface

Water-Groundwater Interaction in the Englishman

River Watershed, British Columbia

Provencher, Shannon

Provencher, S. (2014). Geochemical Assessment of Surface Water-Groundwater Interaction in the

Englishman River Watershed, British Columbia (Unpublished master's thesis). University of

Calgary, Calgary, AB. doi:10.11575/PRISM/26278

http://hdl.handle.net/11023/1724

master thesis

University of Calgary graduate students retain copyright ownership and moral rights for their

thesis. You may use this material in any way that is permitted by the Copyright Act or through

licensing that has been assigned to the document. For uses that are not allowable under

copyright legislation or licensing, you are required to seek permission.

Downloaded from PRISM: https://prism.ucalgary.ca

UNIVERSITY OF CALGARY

Geochemical Assessment of Surface Water-Groundwater Interaction in the

Englishman River Watershed, British Columbia

by

Shannon Kathleen Provencher

A THESIS

SUBMITTED TO THE FACULTY OF GRADUATE STUDIES

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE

DEGREE OF MASTER OF SCIENCE

DEPARTMENT OF GEOSCIENCE

CALGARY, ALBERTA

AUGUST, 2014

© Shannon Kathleen Provencher 2014

ii

Abstract

A geochemical and stable isotopic approach was used to aid in assessment of surface

water-groundwater interactions within the Englishman River Watershed, British

Columbia. Groundwater contribution to surface water is highest in late summer, early

fall, and winter months. Groundwater discharge to surface water constitutes the majority

of surface water discharge in the Englishman River during this period. In fall,

precipitation rates increase, which in conjunction with low discharge rates in late

summer, cause a loss of the groundwater signature in surface water. In spring,

precipitation and meltwater sourced from the snowpack on Mt. Arrowsmith are the

primary contributors to surface water. Shallow aquifers in surficial sediments influence

surface waters to a higher degree than deeper bedrock aquifers. However, groundwater

from deeper, more saline aquifers contributes to surface water and is measurable during

late summer; although the influence is likely minor.

iii

Acknowledgements

I would first like to thank my supervisors Bernhard Mayer and Stephen Grasby for their

ongoing guidance, support, and patience. I would like to thank everyone in the Applied

Geoscience Group, especially Michael Nightingale and Maurice Shevalier for their

advice, assistance, and for always being there to help. Without the help of Jesusa and

Nenita in the Isotope Science Laboratory, I’m not sure I would have ever gotten through

all of my samples, thank you. To everyone who helped me in the field, Krista

Williscroft, Laura Collins, Anita Gue, and Bernadette Proemse, if water sampling wasn’t

already fun, it was more fun with you there. Finally, I would like to thank all my friends

and family, and most importantly Lee for your amazing support, humour, and love, thank

you so much; I could not have accomplished this without you.

iv

Table of Contents

ABSTRACT ................................................................................................................................... II

ACKNOWLEDGEMENTS ....................................................................................................... III

TABLE OF CONTENTS ............................................................................................................ IV

LIST OF FIGURES ..................................................................................................................... VI

LIST OF TABLES ........................................................................................................................ X

1 INTRODUCTION ................................................................................................................. 11.1 PROJECT RATIONALE ...................................................................................................... 11.2 PREVIOUS WORK ............................................................................................................ 21.3 OBJECTIVES .................................................................................................................... 3

2 STUDY AREA ....................................................................................................................... 42.1 LOCATION AND BASIN PROFILE ..................................................................................... 42.2 CLIMATE ......................................................................................................................... 72.3 BEDROCK GEOLOGY ..................................................................................................... 102.4 SURFICIAL GEOLOGY .................................................................................................... 132.5 HYDROGEOLOGY .......................................................................................................... 132.6 HYDROLOGY ................................................................................................................. 18

3 SAMPLE COLLECTION AND METHODOLOGY ...................................................... 223.1 DATA COLLECTION ....................................................................................................... 22

3.1.1 Precipitation ............................................................................................................. 223.1.2 Groundwater ............................................................................................................ 223.1.3 Surface Water ........................................................................................................... 23

3.2 FIELD METHODS ........................................................................................................... 263.3 LABORATORY METHODS AND TECHNIQUES.................................................................. 28

3.3.1 Geochemical Analyses ............................................................................................. 283.3.2 Stable Isotope Analyses ............................................................................................ 29

4 RESULTS............................................................................................................................. 344.1 TOTAL DISSOLVED SOLIDS ........................................................................................... 34

4.1.1 Surface Water ........................................................................................................... 344.1.2 Groundwater ............................................................................................................ 36

4.2 MAJOR ION CHEMISTRY ............................................................................................... 374.2.1 Major Cations .......................................................................................................... 374.2.2 Major Anions ............................................................................................................ 414.2.3 Combined Cations and Anions ................................................................................. 45

4.3 STABLE ISOTOPES ......................................................................................................... 474.3.1 Isotopic Composition of Water (δ18OH2O and δ2HH2O) .............................................. 474.3.2 Isotopic Composition of Dissolved Inorganic Carbon (δ13CDIC) .............................. 514.3.3 Isotopic Composition of Sulphate (δ34SSO4 and δ18OSO4) ........................................... 534.3.4 Isotopic Composition of Nitrate (δ15NNO3 and δ18ONO3) ............................................ 55

5 ISOTOPE GEOCHEMISTRY ........................................................................................... 595.1 INTRODUCTION ............................................................................................................. 595.2 ISOTOPIC COMPOSITION OF WATER ............................................................................. 60

5.2.1 Precipitation ............................................................................................................. 605.2.2 Surface Water ........................................................................................................... 62

v

5.2.3 Groundwater ............................................................................................................ 715.3 DISSOLVED INORGANIC CARBON ................................................................................. 74

5.3.1 Dissolved Inorganic Carbon (13CDIC) ..................................................................... 775.3.2 Surface Water ........................................................................................................... 795.3.3 Groundwater ............................................................................................................ 84

5.4 SULPHATE ..................................................................................................................... 865.4.1 Sulphate concentrations ........................................................................................... 865.4.2 Isotopic Composition of Sulphate (34SSO4 and 18OSO4) .......................................... 885.4.3 Discussion of Sulphate Sources................................................................................ 93

5.5 NITRATE........................................................................................................................ 995.5.1 Nitrate Concentrations ........................................................................................... 1005.5.2 Isotopic Composition of Nitrate (15NNO3 and 18ONO3) ......................................... 1015.5.3 Discussion of Nitrate Sources ................................................................................ 102

5.6 SUMMARY ................................................................................................................... 105

6 MAJOR ION GEOCHEMISTRY ................................................................................... 1076.1 INTRODUCTION ........................................................................................................... 1076.2 PRECIPITATION ........................................................................................................... 108

6.2.1 Marine Contribution to Precipitation .................................................................... 1086.2.2 Non-Marine Contribution to Precipitation ............................................................ 112

6.3 GROUNDWATER AND SURFACE WATER ..................................................................... 1146.3.1 Cation Exchange .................................................................................................... 1146.3.2 Possible Weathering Reactions .............................................................................. 1186.3.3 Saturation Indices .................................................................................................. 123

6.4 SUMMARY ................................................................................................................... 126

7 GROUNDWATER-SURFACE WATER INTERACTION .......................................... 1287.1 STABLE ISOTOPIC EVIDENCE ...................................................................................... 128

7.1.1 Isotopic Composition of Water (δ18OH2O and δ2HH2O) ............................................ 1287.1.2 Dissolved Inorganic Carbon (δ13CDIC) ................................................................... 1367.1.3 Sulphate (δ34SSO4 and δ18OSO4) ................................................................................ 138

7.2 GEOCHEMICAL EVIDENCE .......................................................................................... 1407.3 SUMMARY ................................................................................................................... 146

8 CONCLUSIONS AND FUTURE WORK ...................................................................... 1498.1 CONCLUSIONS ............................................................................................................. 149

8.1.1 Determination of Solute Sources ............................................................................ 1498.1.2 Controlling Processes on Solute Concentrations ................................................... 1508.1.3 Surface Water-Groundwater Interaction ............................................................... 151

8.2 FUTURE WORK ........................................................................................................... 152

BIBLIOGRAPHY ...................................................................................................................... 154

APPENDIX A ............................................................................................................................. 160

APPENDIX B ............................................................................................................................. 178

vi

List of Figures

Figure 2.1 Location of the study area in context of Vancouver Island and Canada. ........... 5

Figure 2.2 Extent of the Englishman River Watershed in reference to the Englishman River and Mt. Arrowsmith. Map was created using ArcGIS with data obtained from Natural Resources Canada (2011), and Ministry of Environment British Columbia (2013a,b). .............................................................................................. 6

Figure 2.3 Locations of climate stations near the Englishman River Watershed. ............... 8

Figure 2.4 Historical mean monthly precipitation values for Coombs (1961-2006), Nanaimo (1946-2006), Nanoose (1912-1939), Parksville (1916-1960), Qualicum (1963-2006), and Parksville South (1967-1993) stations (Figure 2.3; Environment Canada, 2012a). ............................................................................... 9

Figure 2.5 Historical mean monthly temperature values for Coombs (1961-2006), Nanaimo (1946-2006), Nanoose (1912-1939), Parksville (1916-1960), Qualicum (1963-2006), and Parksville South (1967-1993) stations (Figure 2.3; Environment Canada, 2012a). ............................................................................... 9

Figure 2.6 Englishman River Watershed with underlying bedrock geology. Map was created using ArcGIS with data obtained from Natural Resources Canada (2011), BC Geological Survey (2005). ................................................................ 12

Figure 2.7 Surficial aquifers within the Englishman River Watershed. Map was created using ArcGIS with data obtained from Natural Resources Canada (2011), and the Ministry of Environment British Columbia (2013a,b). ................................. 16

Figure 2.8 Bedrock aquifers within the Englishman River Watershed. Map was created using ArcGIS with data obtained from Natural Resources Canada (2011), and the Ministry of Environment British Columbia (2013a,b). ................................. 17

Figure 2.9 Location of hydrometric station in relation to the Englishman River Watershed, the Englishman River, its tributaries, and seven lakes. Map was created using ArcGIS with data obtained from Natural Resources Canada (2011), Environment Canada (2012c), and Ministry of Environment British Columbia (2013a,b). ............................................................................................ 20

Figure 2.10 Minimum, maximum and average monthly discharge data for Englishman River near Parksville (Water Survey Canada Station 08HB002) between 1980 and 2011 (Environment Canada, 2012b). ............................................................ 21

Figure 2.11 Average daily discharge data for Englishman River near Parksville (Water Survey Canada Station 08HB002) for 2011 (Environment Canada, 2012c). ...... 21

Figure 3.1 Locations of groundwater wells from which samples were obtained in July 2011. Map was created using ArcGIS with data obtained from Natural Resources Canada (2011), and the Ministry of Environment British Columbia (2013a,b). ............................................................................................................. 24

vii

Figure 3.2 Locations of surface water sampling sites. Map was created using ArcGIS with data obtained from Natural Resources Canada (2011), and the Ministry of Environment British Columbia (2013a,b). .......................................................... 25

Figure 4.1 Average TDS and average monthly discharge during August 2010, October 2010, February 2011, May 2011, July 2011, and September 2011 sampling periods from all sampling locations. .................................................................... 35

Figure 4.2 a) Temporal variation of TDS versus distance from headwaters for surface water samples, excluding estuary samples b) Expanded view of TDS versus distance from headwaters for surface water samples, including estuary samples.35

Figure 4.3 TDS versus depth for groundwater samples. .................................................... 36

Figure 4.4 Piper diagram of surface water, groundwater, and precipitation samples. ....... 46

Figure 5.1 a) Temporal variation in δ18O and δ2H values of surface water samples in comparison to the GMWL, CMWL, SMWL, and SWL. b) Close-up of the δ2H-δ18O diagram. ....................................................................................................... 66

Figure 5.2 Amount of daily precipitation in relation to mean daily temperature for February 2011 (Environment Canada, 2012). ..................................................... 67

Figure 5.3 Total daily precipitation in relation to daily temperature over the entire study period from August 2010 to September 2011. ..................................................... 68

Figure 5.4 Mean daily discharge and mean daily precipitation reported monthly over the entire study period from August 2010 to September 2011. ................................. 69

Figure 5.5 Spatial and temporal variation of δ18O and δ2H values of surface water samples in relation to increasing distance from the headwaters of the Englishman River in relation to δ18O and δ2H ranges in groundwater samples. . 70

Figure 5.6 δ18O and δ2H values of groundwater samples in relation to the GMWL, CMWL, and the SMWL. ..................................................................................... 72

Figure 5.7 a) 2H values of groundwater samples versus depth. b) 18O values of groundwater samples versus depth. ..................................................................... 73

Figure 5.8 δ18O and δ2H values of surface water samples and groundwater samples in relation to the GMWL, CMWL, and the SMWL. ............................................... 74

Figure 5.9 Downstream trend of 13CDIC values of surface water samples over six sampling periods in relation to range of groundwater 13CDIC values and 13CDIC

values of various DIC sources. ............................................................................ 82

Figure 5.10 May, July, and September 2011 sampling periods with 25 and 50% mixing lines of DIC sourced from soil CO2 with atmospheric CO2. ............................... 83

Figure 5.11 13CDIC versus DIC concentration as expressed in HCO3 for surface water samples. ............................................................................................................... 83

Figure 5.12 Well depth versus 13CDIC values of groundwater samples. .......................... 85

Figure 5.13 13CDIC versus DIC as expressed in HCO3- for groundwater samples. ........... 86

viii

Figure 5.14 a) Downstream trend of SO4 concentrations of surface water samples over six

sampling periods. b) Close-up view of SO4 versus distance from headwaters diagram. ............................................................................................................... 87

Figure 5.15 a) Spatial and temporal variation of δ34SSO4 values of surface water samples in relation to increasing distance from the headwaters of the Englishman River. b) Spatial and temporal variation of δ18OSO4values of surface water samples with increasing distance from headwaters of the Englishman River. c) Expanded view of δ18OSO4 vs. distance from headwaters for surface waters collected in May 2011. .................................................................................................................... 91

Figure 5.16 Depth vs. 34SSO4 and 18OSO4 values for groundwater samples. ................... 93

Figure 5.17 a) Temporal variation in δ34S and δ18O values of surface water samples in relation to typical ranges of 34S and 18O values of various sulphate sources (modified from Mayer, 2005). b) Close-up of the δ18O - δ34S diagram. ............. 94

Figure 5.18 34S and 18O values of sulphate for groundwater samples in relation to typical ranges of 34S and 18O values of various sulphate sources (modified from Mayer, 2005). .............................................................................................. 95

Figure 5.19 34S and 18O values of groundwater against sulphate concentrations. ......... 97

Figure 5.20 Trend of 34S and 18O values against sulphate concentrations during a) admixture of sulphate from sulfide oxidation b) bacterial (dissimilatory) sulphate reduction (modified from Mayer, 2005). ............................................................. 98

Figure 5.21 Dual isotope plot of 34S and 18O values depicting the isotopic evolution of sulphate in groundwater during bacterial (dissimilatory) sulphate reduction in relation to surface water samples. ........................................................................ 99

Figure 5.22 15N and 18O values of surface water and groundwater samples with typical ranges of 15N and 18O values for various nitrate sources (modified from Mayer, 2005). ..................................................................................................... 104

Figure 5.23 15N and 18O values of surface water and groundwater samples against nitrate concentrations. ........................................................................................ 104

Figure 6.1 Concentrations of solutes against chloride in Saturna precipitation monthly averages (1989-2007). ....................................................................................... 111

Figure 6.2 Temporal variation of major ions in precipitation (eq/L). ........................... 112

Figure 6.3 Na/(Ca+Mg) (molar ion ratio) versus TDS (mg/L) for groundwater and surface water samples. .................................................................................................... 115

Figure 6.4 Activity-activity diagram of Ca2+ versus Mg2+ of groundwater and surface water samples with respect to reaction boundaries which were calculated at 1 bar and 5 C, and are independent of activity data. ................................................. 116

Figure 6.5 Activity-activity diagram of K+ versus Na+ for groundwater and surface water samples. Reaction boundaries are calculated at 1 bar and 5C. ......................... 118

ix

Figure 6.6 log a [Ca2+/(H+)2] versus log a [H4SiO4] for groundwater and surface water samples. ............................................................................................................. 121

Figure 6.7 log a [Mg2+/(H+)2] versus log a [H4SiO4] for groundwater and surface water samples. ............................................................................................................. 121

Figure 6.8 log a [Na+/H+] versus log a [H4SiO4] for groundwater and surface water samples. ............................................................................................................. 122

Figure 6.9 log a [K+/H+] versus log a [H4SiO4] for groundwater and surface water samples. ............................................................................................................. 122

Figure 6.10 Relative proportions of mineral saturation states of groundwater samples. . 125

Figure 6.11 Relative proportions of mineral saturation states of surface water samples. 126

Figure 7.1 Temporal variation in δ18O and δ2H values of surface water samples with respect to the overall range of groundwater samples. ........................................ 131

Figure 7.2 Spatial and temporal variation of δ18O and δ2H values of surface water samples with respect to overall range of groundwater samples. ....................... 132

Figure 7.3 Temporal variation of average surface water δ18O values with respect to average groundwater δ18O values, mean daily discharge, and volume weighted precipitation δ18O values with interpreted major contributors to surface water.133

Figure 7.4 Temporal variation of average surface water δ18O values with respect to average groundwater δ18O values, mean daily precipitation, and volume weighted precipitation δ18O values with interpreted major contributors to surface water. ................................................................................................................. 134

Figure 7.5 δ13CDIC values of surface water samples versus distance from headwaters with respect to δ13C value range of groundwater samples. ........................................ 137

Figure 7.6 δ13CDIC values of surface water and groundwater samples versus HCO3

concentrations in reference to δ13C values of typical DIC sources. .................. 138

Figure 7.7 Temporal variation in δ34S and δ18O values of surface water and groundwater samples in relation to typical ranges of 34S and 18O values of various sulphate sources (modified from Mayer, 2005). .............................................................. 139

Figure 7.8 Locations of groundwater samples with δ34S and δ18O values within the range of those in surface water samples with corresponding well depths. .................. 140

Figure 7.9 Piper diagram depicting surface water, groundwater, and precipitation samples. ............................................................................................................. 142

Figure 7.10 a) HCO3 versus Ca + Mg for surface water samples. b) Close-up view of

HCO3 versus Ca + Mg for surface water samples. c) HCO3 versus Ca + Mg for

groundwater samples. ........................................................................................ 143

Figure 7.11 Major cations and anions versus TDS for surface water and groundwater samples. ............................................................................................................. 145

x

List of Tables

Table 2.1 Historical climate data displaying mean annual temperatures and precipitation from various climate stations within or near the Englishman River Watershed (Environment Canada, 2012a). .............................................................................. 7

Table 2.2 Characteristics of mapped aquifers in the Englishman River Watershed (Ministry of Environment BC, 2012). ................................................................. 15

Table 4.1 Statistical summary of average monthly (from 1989 to 2007) cation concentrations of precipitation samples (n=6542, Saturna Island Station). ........ 39

Table 4.2 Statistical summary of cation concentrations of surface water samples (n=85).40

Table 4.3 Statistical summary of cation concentrations of groundwater samples (n=50). 41

Table 4.4 Statistical summary of anion concentrations of precipitation samples (1989-2007). ................................................................................................................... 43

Table 4.5 Statistical summary of anion concentrations of surface water samples. ............ 44

Table 4.6 Statistical summary of anion concentrations of groundwater samples. ............. 45

Table 4.7 Statistical summary of δ2H and δ18O values for precipitation samples (1989-2007). ................................................................................................................... 49

Table 4.8 Statistical summary of δ2H and δ18O values for surface water samples . .......... 50

Table 4.9 Statistical summary of δ2H and δ18O values for groundwater samples. ............ 51

Table 4.10 Statistical summary of δ13CDIC for surface water samples. .............................. 52

Table 4.11 Statistical Summary of δ13CDIC for groundwater samples. .............................. 52

Table 4.12 Statistical summary δ34S and δ18O values of sulphate for surface water samples (n=39)..................................................................................................... 54

Table 4.13 Statistical Summary of δ34S and δ18O values of sulphate for groundwater samples (n=4)....................................................................................................... 55

Table 4.14 Statistical summary of δ15N and δ18O values of nitrate for surface water samples (n=6)....................................................................................................... 57

Table 4.15 Statistical summary of δ15N and δ18O values of nitrate for groundwater samples (n=4)....................................................................................................... 58

Table 6.1 Correlation coefficients of ionic species in precipitation. ............................... 108

Table 6.2 Equivalent ratios of various species to Na in precipitation and seawater (Keene et al., 1986). ....................................................................................................... 110

Table 6.3 Percent sea salt (ss) and non sea salt (nss) fraction of Saturna precipitation, estimated using Na as a reference species for seawater. .................................... 110

xi

Table A - 1 Surface water sample locations (NAD 83). .................................................. 161

Table A - 2 Groundwater sample locations (NAD 83). ................................................... 163

Table A - 3 Surface water field parameters. .................................................................... 164

Table A - 4 Groundwater field parameters. ..................................................................... 166

Table A - 5 Chemical analyses for Saturna Island precipitation samples averaged monthly (1989-2007). ...................................................................................................... 167

Table A - 6 Chemical analyses including Charge Balance (CB) of surface water samples over six sampling periods in the Englishman River Watershed. ....................... 168

Table A - 7 Chemical analyses including Charge Balance (CB) of groundwater samples within the Englishman River Watershed. .......................................................... 170

Table A - 8 Stable isotope abundance ratios of precipitation samples from Saturna Island.

………………….............................................................................................................. 172

Table A - 9 Stable isotope abundance ratios of surface water samples. .......................... 174

Table A - 10 Stable isotope abundance ratios of groundwater samples within the ERW.176

Table B - 1 Saturation indices of groundwater samples. ................................................. 179

Table B - 2 Saturation indices of surface water samples. ................................................ 181

1

1 Introduction

1.1 Project Rationale

Parksville, British Columbia, and surrounding communities located within the

Englishman River Watershed (ERW) are over 50% reliant on groundwater. Increasing

development pressures have raised local, provincial and federal government concerns

over sustainability of water resources. The Englishman River is a significant water source

to support future growth and economic development.

Increasing population, development, existing industrial and commercial land use

practices, combined with the impacts of changing climate puts sustainable water resource

supplies at risk. The ERW provides a significant source of drinking water to the local

community and has immense value to fisheries, with chinook, chum, coho, sockeye and

pink salmon; cutthroat, rainbow, and steelhead trout all present at some point during the

year (FISS, 2006). The Englishman River is an important fisheries river and is identified

as a sensitive stream according to the Fish Protection Act (FPA), due to inadequate water

flow, which affects fish populations (FISS, 2006; Barlak et al., 2010).

Managing long-term sustainable use of this resource is imperative for both

ecologic health and economic prosperity. As water demand pressures grow, it has been

recognized that surface water and groundwater are not two independent water sources

that can be managed separately. Sustainable water management requires new knowledge

of the degree of surface water-groundwater interaction within a watershed. New methods

to assess this seasonal interaction are required. Developing geochemical tools that can

2

place constraints on these complex systems will aid development of hydrogeological

models, which can be used to support decision makers in water allocation.

1.2 Previous Work

Currently there are no peer-reviewed publications on the geochemistry or

hydrogeology of the ERW. There have been groundwater geochemical studies conducted

in the Gulf Islands off the eastern coast of Vancouver Island, southeast of the study area.

Dakin et al. (1981) studied the origin of dissolved solids in groundwaters on Mayne

Island. Geochemical and isotopic techniques were used to determine the origin of saline

groundwaters on Mayne Island. Allen (2004) studied sources of water salinity on Hornby

Island and Saturna Island (15 km northwest and 97 km southeast of the ERW

respectively) using 18O, 2H, and 34S. Both studies suggest that saline groundwater found at

depths on the Gulf Islands is late Pleistocene in age and was recharged when the island

was submerged below sea level and prior to rebound at the end of the last glaciation.

Allen and Suchy (2001) conducted a detailed geochemical and isotopic study of surface

waters, spring waters, and groundwaters to analyze the geochemical evolution of

groundwater on Saturna Island. Major ion chemistry demonstrated that groundwater was

recharged locally but is mixed with saline waters at depth or near the coast. Cation

exchange results in a spatially variable geochemical groundwater composition dependant

on geology.

Initiatives from the Ministry of Environment BC were undertaken to assess

surface water quality within the ERW (Barlak et al., 2010). The purpose of the study was

to accumulate baseline data necessary to assess both the current state of water quality,

establish ambient water quality objectives, and provide future monitoring

3

recommendations (Barlak et al., 2010). The Mid Vancouver Island Habitat Enhancement

Society (MVIHES) is a community organization, which worked in conjunction with GW

Solutions Consulting to assess the extent of surface water-groundwater interaction within

the ERW. The report revealed that interaction between surficial aquifers and the

Englishman River first occurs 16 km upstream of the estuary. With increasing

downstream distance, groundwater-surface water interaction increases. This is due to the

increased number and thickness of aquifers. In the lower portion of the watershed, the

surficial aquifers were estimated to contribute ~30 % of the summer low flow. It was also

shown that bedrock aquifers within the watershed could provide up to 30 to 40 % of the

baseflow in dry summer months (Wendling, 2012).

1.3 Objectives

The objective of this study was to provide a comprehensive geochemical and

isotopic analysis of surface water from the Englishman River and nearby groundwater

within the developed portion of the ERW. The objectives include: determination of the

sources of solutes in both surface waters and groundwaters, identification of possible

rock-water interactions, and providing valuable geochemical and isotopic information

that can aid in current attempts to assess the extent and nature of surface water-

groundwater interaction within the watershed.

4

2 Study Area

2.1 Location and Basin Profile

The Englishman River Watershed is located south west of the City of Parksville

on Vancouver Island, British Columbia, Canada (Figure 2.1). The Englishman River is 39

km in length and flows in an easterly direction from its headwaters on Mount Arrowsmith

(elevation 1819 m), and discharges in the Strait of Georgia (Figure 2.2). The total

drainage area of the watershed is approximately 324 km2. Most licensed water demand

occurs in the lower part of the Englishman River and its tributary Morrison Creek

(Environment Canada, 1994). Other tributaries within the watershed include: Pollard

Creek, Dayton Brook, and Connell Creek tributaries of Swane Creek. Swayne Creek

and Digby Creek are tributaries of Morison Creek. The watershed of Morison Creek

comprises 15% of the area of the total Englishman River Watershed. The largest tributary

to the Englishman River is the South Englishman River and its sub-watershed contributes

48.60 km2, or 15% to the total watershed (Barlak et al., 2010; Figure 2.2).

5

Figure 2.1 Location of the study area in context of Vancouver Island and Canada.

6

Figure 2.2 Extent of the Englishman River Watershed in reference to the Englishman River and Mt. Arrowsmith. Map was created using ArcGIS with data obtained from Natural Resources Canada (2011), and Ministry of Environment British Columbia (2013a,b).

7

2.2 Climate

The ecozone of Vancouver Island is part of the temperate rainforest of Cascadia, a

bioregion defined by the watersheds of the rivers flowing into the Pacific Ocean through

North America’s temperate rain forests (Environment Canada, 2012a). The climate of the

ERW is characterized by mild, wet winters; and warm, dry summers. The mountain

ranges to the west create a rain shadow affecting the eastern slopes of the central

Vancouver Island. Unfortunately there are no active climate stations within the ERW, so

data from historical and nearby active stations were used to delineate climatic conditions.

There are six climate stations located within or near the study area, which were either

historically active or are still actively recording temperature and precipitation data (Table

2.1; Figure 2.3, Figure 2.4, Figure 2.5).

Table 2.1 Historical climate data displaying mean annual temperatures and precipitation from various climate stations within or near the Englishman River Watershed (Environment Canada, 2012a).

Hudson (2000) revealed through studies on the south coast of BC that between 0-

300, 300-800, and above 800 masl correspond to the rain dominated, rain on snow, and

snow dominated zones respectively. Approximately 30% of the ERW lies within the

rainfall dominated zone, whereas 60% is located in the rain on snow zone, and only 10%

in a snow dominated zone. Therefore, the ERW is a rain driven hydrologic system,

influenced by heavy rainfall in fall and winter months. This results in peak flows in

Climate Station Observation Period Mean Annual Temperature Mean Annual Precipitation(°C) (mm)

Parksville 1916-1960 8.5 818.7Parksville South 1967-1993 10.0 845.6

Nanaimo 1946-2006 9.6 1132.1Nanoose 1912-1939 9.2 785.8Qualicum 1963-2006 9.4 1305.3Coombs 1961-2006 9.1 1139.8

8

winter months and a dry summer season, correlating with low discharge rates (Figure 2.3,

Figure 2.4, Figure 2.5; Wade et al., 2001; Environment Canada, 2012a).

Figure 2.3 Locations of climate stations near the Englishman River Watershed.

9

Figure 2.4 Historical mean monthly precipitation values for Coombs (1961-2006), Nanaimo (1946-2006), Nanoose (1912-1939), Parksville (1916-1960), Qualicum (1963-2006), and Parksville South (1967-1993) stations (Figure 2.3; Environment Canada, 2012a).

Figure 2.5 Historical mean monthly temperature values for Coombs (1961-2006), Nanaimo (1946-2006), Nanoose (1912-1939), Parksville (1916-1960), Qualicum (1963-2006), and Parksville South (1967-1993) stations (Figure 2.3; Environment Canada, 2012a).

10

2.3 Bedrock Geology

The east-central coast of Vancouver Island is underlain predominately by the

Nanaimo Group, which is Upper Cretaceous in age with a total thickness close to 5000 m

(Fyles, 1963; Mustard, 1994; Figure 2.6). The Nanaimo group is characterized by a series

of alternating layers of conglomerate, sandstone, siltstone, and mudstone sediments

deposited mostly under marine conditions, largely as submarine fans, offshore from

coastal shelf deposits (Mustard, 1994). The remaining bedrock within the study area is

from the Wrangellia Terrane, which is most commonly characterized by widespread

exposures of Triassic flood basalts and complementary intrusive rocks (Jones et al., 1977;

Figure 2.6).

The Upper Triassic Vancouver Group of the Wrangellia Terrane underlies much

of the headwaters region of the study area, and outcrops on Mt. Arrowsmith. The Group

is subdivided into a thick basaltic volcanic package called the Karmutsen Formation and

an upper sedimentary package designated as the Quatsino Formation. The Karmutsen

Formation forms pillowed basalt flows, pillow breccias, and breccias interbedded with

massive flows and sills (Massey et al., 1995; Figure 2.6). These sequences are

predominantly extrusive, marine sequences locally exceeding 6000 m in thickness. The

Quatsino Formation is characterized by massive, thickly bedded, black micritic

limestone. Northeast of the Karmutsen and Quatsino outcrops, outcrops of Jurassic Island

Intrusions and Westcoast Crystalline Complex (WCC) are observed. The WCC includes

granitic rocks that are intrusive equivalents of the Bonanza Formation (which does not

outcrop in the study area), and form intrusions, which are dominantly equigranular quartz

diorite to granodiorite, rich in mafic inclusions (Massey et al. 1995; Massey and Friday,

11

1987; Figure 2.6).

The Sicker and Buttle Lake Groups of the Wrangellia Terrane underlie the study

area to the Southeast and outcrop in areas of Mt. Arrowsmith. The Sicker and Buttle Lake

Groups are the oldest rocks of Vancouver Island and range from Middle Devonian to

Lower Permian in age. The Devonian Sicker Group is a thick package of lower

greenschist facies, metavolcanic and volcaniclastic rocks that formed in an oceanic island

environment (Massey et al., 1995). The Buttle Lake Group is characterized by epiclastic

and bioclastic limestone sedimentary sequences ranging from Mississippian to Early

Permian in age (Greene et al., 2004; Massey et al., 1995; Massey and Friday, 1987;

Figure 2.6).

12

Figure 2.6 Englishman River Watershed with underlying bedrock geology. Map was created using ArcGIS with data obtained from Natural Resources Canada (2011), BC Geological Survey (2005).

Nanaimo Group undivided sedimentary rocks Vancouver Group undivided sedimentary rocks, marine sedimentary volcanic rocks, baslatic volcanic rocks Island Plutonic Suite granodiorite and feldspar porphyritic intrusive rocks Sicker Group basaltic volcanic rocks, undivided volcanic rocks, calc-alkaline volcanic rocks Buttle Lake Group undivided sedimentary rocks, chert, siliceous argillite, siliciclastic rocks, limestone reef Mount Washington Plutonic Suite quartz dioritic intrusive rocks Mount Hall Gabbro and Buttle Lake Group granodioritic to gabbroic intrusive rocks

Legend

Fault

13

2.4 Surficial Geology

The glacial history of Vancouver Island was affected by at least three glaciations.

Surficial deposits from the Pleistocene include the Quadra Sands, which are described as

glacio-fluvial sands, and the Vashon Drift, characterized as glacial tills (Clague, 1977;

Fyles, 1963). The Holocene deposits are comprised of marine, fluvial, and lacustrine

deposits relating to prior sea levels called the Capilano Sediments and Salish sediments

relating to deposition during present sea level (Fyle, 1963; Howes, 1983). Salish

sediments make up the surficial sediments of the easternmost coast, where the

Englishman River discharges into the Strait of Georgia. The Quadra Sands crop out in

small areas North and South of the Englishman River, but are a dominant lithology of the

aquifers within the study area (Fyles, 1963; Howes, 1983). The Quadra Sands are

described as well sorted, distinctive white sands that can exceed 75 m in thickness. The

sands are characterized as remarkably uniform, with horizontal stratification and

extensive cross bedding (Fyles, 1963; Clague 1977).

2.5 Hydrogeology

There are six aquifers within the ERW, which have been mapped with the BC

Aquifer Classification System (Kreye et al., 2001). Bedrock and surficial geology

mapping, well lithology records, and hydrogeological reports were used to delineate

aquifer boundaries. The aquifers are further classified based on their level of

development and vulnerability to contamination (Kreye et al., 2001).

Four of the six aquifers within the ERW consist of unconsolidated, surficial

sediments; three consisting of Quadra Sand and one of Salish Sediments, and two

aquifers consist of fractured bedrock from the Nanaimo Group (Table 2.2; Figure 2.7,

14

Figure 2.8; Ministry of Environment BC, 2012) The highest yielding wells are those

completed within sand, and gravel glacial outwash, and post-glacial fluvial deposits as

well as those completed in major faults or fractures in bedrock (Yorath, 2005).

Information on well completion depth and lithology were obtained from drilling records

recorded by water well drilling companies and voluntarily submitted to the MOE BC.

These records were used only as an estimate of probable depth and lithology for this

study. Based on this information, wells completed in surficial aquifers ranged in depths

from 2 to 60 m with an average well completion of ~18 m. Wells in bedrock aquifers

ranged from depths of 17 to 125 m, with average depths of ~70 m (Ministry of

Environment BC, 2012).

Unconfined aquifers consisting of coarse surficial sediments are those with the

highest vulnerability to contamination (Denny et al., 2006; Table 2.2; Figure 2.7).

Aquifer 221 is highly susceptible to localized contamination, while aquifers 214, 216,

and 220 are moderately vulnerable (Kreye et al., 2001; Ministry of Environment BC,

2012). Aquifers 216 and 220 are shown to be at risk due to dropping water levels due to

unsustainable demand from domestic, industrial, and agricultural use.

15

Table 2.2 Characteristics of mapped aquifers in the Englishman River Watershed (Ministry of Environment BC, 2012).

Size Km2

0209 Sand and Gravel Low Moderate Low 10.7 Quadra Sand Multiple0216 Sand and Gravel Moderate Moderate Moderate 25.5 Quadra Sand Multiple0219 Sand and Gravel Moderate Moderate Low 37.8 Quadra Sand Domestic0221 Sand and Gravel Moderate High High 4 Salish Sediments Domestic0220 Bedrock Low Low Moderate 59.2 Nanaimo Group Multiple0214 Bedrock Low Low Moderate 30.4 Nanaimo Group Domestic

Aquifer Water UseStratigraphic UnitVulnerabilityProductivityDemandAquifer Materials

16

Figure 2.7 Surficial aquifers within the Englishman River Watershed. Map was created using ArcGIS with data obtained from Natural Resources Canada (2011), and the Ministry of Environment British Columbia (2013a,b).

Legend

Aquifer 209: Quadra Sand - Sand/Gravel

Aquifer 221: Salish Sediments - Sand/Gravel



17

Figure 2.8 Bedrock aquifers within the Englishman River Watershed. Map was created using ArcGIS with data obtained from Natural Resources Canada (2011), and the Ministry of Environment British Columbia (2013a,b).

Aquifer 220: Nanaimo Group - Bedrock

Aquifer 214: Nanaimo Group - Bedrock

Legend

18

The Ministry of Environment of British Columbia (MOE BC) has a voluntary

program for water well drillers to submit a well report, which is available on the WELLS

database (Denny et al., 2006). There are nearly 300 wells in the WELLS database that are

located within the ERW, although the total number of wells is likely much higher. Well

reports outline details such as well location, depth, lithology, and an estimate of flow rate.

As this is a voluntary program, accurate aquifer demand estimates prove to be difficult

(Kreye et al., 2001).

2.6 Hydrology

There are five major tributaries that drain into the Englishman River: South

Englishman River, Swane Creek, Morrison Creek, Shelley Creek, and Centre Creek. The

Englishman River discharges into the Strait of Georgia and the entire watershed has a

drainage area of 324 km2 (Barlak et al. 2010; Boom and Bryden, 1994). There are seven

lakes in the watershed: Arrowsmith, Fishtail, Rowbotham, Healy, Shelton, Marshall, and

Hidden lakes. The Englishman River originates from Arrowsmith Lake on Mt.

Arrowsmith, and the Arrowsmith Dam moderates flow into the Englishman River. The

dam has a live storage volume of 9,000,000 m3 that stores heavy winter rain and melting

snow. During the dry season (summer and early fall), 50% of the storage volume is

available for release into the river (Boom and Bryden, 1994).

There is one hydrometric station located on the Englishman River, approximately

200 m upstream of the estuary (Figure 2.9). Historical hydrometric data is available from

1913 to 2010 and real-time hydrometric data from 2011 to present (Environment Canada,

2012 b, c). Historical data includes monthly maximum, minimum and mean discharge

19

values and real-time data is recorded hourly throughout the day. The mean annual

discharge of the Englishman River, based on data from 1915 to 2011, is 13.6 m3/s.

(Figure 2.10, Figure 2.11; Environment Canada, 2012b).

Maximum discharge rates exceeding 50 m3/s occur during November to February

when precipitation is typically greatest. Minimum discharge rates less that 1 m3/s

typically occur during late August and September when precipitation is minimal (Figure

2.10, Figure 2.11; Environment Canada, 2012a, b, and c).

20

Figure 2.9 Location of hydrometric station in relation to the Englishman River Watershed, the Englishman River, its tributaries, and seven lakes. Map was created using ArcGIS with data obtained from Natural Resources Canada (2011), Environment Canada (2012c), and Ministry of Environment British Columbia (2013a,b).

21

Figure 2.10 Minimum, maximum and average monthly discharge data for Englishman River near Parksville (Water Survey Canada Station 08HB002) between 1980 and 2011 (Environment Canada, 2012b).

Figure 2.11 Average daily discharge data for Englishman River near Parksville (Water Survey Canada Station 08HB002) for 2011 (Environment Canada, 2012c).

22

3 Sample Collection and Methodology

3.1 Data Collection

3.1.1 Precipitation

Geochemical analyses of precipitation and corresponding sample volumes from

Saturna Island (~97 km southeast of the ERW) were obtained from the Canadian Air and

Precipitation Monitoring Network (CAPMoN, 2012), along with precipitation volumes.

Data were collected daily from 1989 to 2007 and a total of 6542 samples were obtained.

Monthly averages were determined using daily precipitation samples collected from 1989

to 2007. Monthly averages were averaged over the entire sampling period (1989-2007) to

obtain overall monthly averages, these values were used for the purposes of this study

(CAPMoN, 2012).

Stable isotope abundance ratios of hydrogen (δ2HH2O) and oxygen (δ18OH2O) of

precipitation from Saturna Island were obtained from the Canadian Network for Isotopes

in Precipitation (CNIP). Data were collected daily from 1993 to 2003, and amount

weighted monthly averages were calculated – overall, 122 values were obtained. Amount

weighted monthly averages were averaged over the entire sampling period (1993 to 2003)

to obtain overall monthly averages, these values were used for the purposes of this study

(CNIP, 2012).

3.1.2 Groundwater

Fifty groundwater samples were collected from the ERW in July 2011 from

residential, commercial, and municipal wells. The locations of the groundwater wells

were focused near the Englishman River, but sampling locations were limited to

23

previously drilled wells. The locations of groundwater sampling sites are illustrated in

Figure 3.1.

3.1.3 Surface Water

Surface water samples were collected from the Englishman River from the

estuary draining into the Strait of Georgia, upstream to the Englishman River Regional

Park (Figure 3.2). The sampling sites were focused on the lower portion of the river

where higher water demands exist and where groundwater wells are located. In August

2010, 14 surface water samples were collected and in October 2010, two more sample

sites were added between Englishman River Falls Provincial Park and Englishman River

Regional Park, for a total of 16 sites. These new sites were accessed from private logging

roads managed by Island Timberlands (Barlak et al, 2010). In February 2011, May 2011,

and September 2011, only 14 sites were sampled, since the logging roads were no longer

accessible. Figure 3.2 depicts the 14 sites that were sampled during all 6 sampling

campaigns.

24

Figure 3.1 Locations of groundwater wells from which samples were obtained in July 2011. Map was created using ArcGIS with data obtained from Natural Resources Canada (2011), and the Ministry of Environment British Columbia (2013a,b).

25

Figure 3.2 Locations of surface water sampling sites. Map was created using ArcGIS with data obtained from Natural Resources Canada (2011), and the Ministry of Environment British Columbia (2013a,b).

26

3.2 Field Methods

Surface water samples were collected from the middle of the river, with sufficient

water depth (0.5 to 2.5 m) in well-mixed areas of high flow, to ensure a representative

sample. When possible, samples were collected with a bucket, by wading into the river;

when flows were too high, samples were collected from the side of the river in high

flowing, well mixed areas. The sampling bucket was rinsed three times with the sample

water before collection. Groundwater samples were collected, when possible, directly

from the wellhead, otherwise they were collected from an outside tap connected to

untreated well water.

A Thermo Scientific Orion 5 Star multiprobe electrode was used to measure in

situ parameters: temperature, pH, electrical conductivity (EC), and dissolved oxygen

(DO). During surface water sample collection, the probes were placed in the river in high

flowing, well mixed areas, and readings were recorded once all parameters stabilized. For

groundwater sampling, to ensure representative aquifer readings, the probe was placed in

a flow through cell and water was pumped from the well until parameters stabilized. The

reported accuracy of temperature, pH, EC, and DO is: ± 0.1°C, ± 0.05, 0.01 µS/cm, and ±

0.1 mg/L up to 8 mg/L and ± 0.2 mg/L from 8 to 20 mg/L respectively (Fisher Scientific,

2013).

All surface water and groundwater samples were collected and analyzed for the

following geochemical parameters: major cations, major anions, and select trace metals

(total iron (Fe2+ and Fe3+), and manganese (Mn)). Major cations measured include:

calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K). Major anions include:

chloride (Cl), sulphate (SO4), nitrate (NO3), and alkalinity (reported as bicarbonate

27

(HCO3)). Stable isotope measurements include: water (δ2HH2O and δ18OH2O), nitrate

(δ15NNO3 and δ18ONO3), sulphate (δ34SSO4 and δ18OSO4), and dissolved inorganic carbon

(δ13CDIC).

All samples, with exception of nitrate and sulphate isotope samples were vacuum

filtered in the field through a 0.45 μm cellulose acetate filter. Samples for sulphate and

nitrate stable isotope analysis were filtered in the laboratory due to the large sample

quantities. Sample containers were first triple rinsed with filtered sample water, then

filled to overflowing, creating a positive meniscus, ensuring minimal exposure to

atmospheric oxygen. Treatment of the samples and the volume of the containers used for

collection depend on the analysis. Cation (and trace metal), anion, and alkalinity samples

were collected in 125 ml HDPE bottles. The cation samples were acidified using

concentrated nitric acid to a pH of < 2. Water isotope (δ2H and δ18O) samples were

collected in 30 ml HDPE bottles. Samples for stable isotope analysis of nitrate (δ15N and

δ18O) and sulphate (δ34S and δ18O) were collected in four, 1litre HDPE bottles. Dissolved

inorganic carbon (DIC) isotope (δ13C) samples were collected in a 60 ml amber glass

bottle; minimizing degassing of CO2 and biological activity, which can lead to altered

δ13CDIC values. Additionally, zinc acetate was added as a biocide. All samples were

quickly sealed and refrigerated at 4 °C until analyzed.

In August, October 2010, and February 2011 samples for stable isotope analysis

of nitrate (δ15N and δ18O) and sulphate (δ34S and δ18O) were collected in 1litre HDPE

bottles, however, sulphate and nitrate concentrations were insufficient for isotope

analysis. Therefore in subsequent sampling trips, four 1litre HDPE bottles were used to

collect sufficient amounts of each sample.

28

3.3 Laboratory methods and techniques

3.3.1 Geochemical Analyses

3.3.1.1 Alkalinity

Alkalinity measurements were conducted at the Applied Geochemistry Group

Laboratory at the University of Calgary. Alkalinity was measured by acid titration

analysis with 0.01M sulfuric acid, using an automated titrator (Orion 960), which has a

detection limit of ~10 mg/L. The inflection point in the titration curve was used to obtain

the alkalinity of the sample. Standards were titrated before, and in between sample

titrations and triplicate analyses were conducted every 15 samples. The average

discrepancy between triplicate samples was < 5 % of the measured value. Alkalinity

measures all titratable species including HCO3, CO3, ionized silicic acid, bisulfide,

borate, and organic acids (Drever, 1997). In natural waters, HCO3- and CO3 are the main

contributors to the overall neutralizing capacity, while all other species are assumed to be

insignificant in comparison (Drever, 1997). In waters of neutral pH, HCO3 is the

dominant species contributing to alkalinity, although there are very minor contributions

from CO3. All study samples are within a neutral pH range; therefore all alkalinity

measurements are reported as HCO3.

3.3.1.2 Cations and Anions

All cation and trace metal analyses were conducted at the Geological Survey of

Canada Laboratories in Ottawa. Trace metal analyses were conducted using Inductively

Coupled Plasma emission spectrometry/mass spectrometry (ICP-ES/MS). Major cations

(Ca, Mg, Na, and K) were analyzed using ICP-ES. A duplicate analysis of major cations

29

of all samples was conducted at the Applied Geochemistry Group Laboratory at the

University of Calgary. Samples were measured using a Perkin Elmer AAnalyst 100

atomic absorption spectrometer. Duplicate sample results from the two laboratories

agreed within < 5 % of the measured values.

Major anion (Cl, SO4, and NO3) analysis was conducted at the Geological Survey

of Canada Laboratories in Ottawa using Ion Chromatography (IC-110). A duplicate

analysis of major anions of all samples was conducted at the Applied Geochemistry

Group Laboratory at the University of Calgary using a Dionex ICS 2000 Column

Suppression Ion Liquid Chromatograph. Duplicate samples between the two laboratories

agreed within < 5 % of the measured values.

For all analyses, three standards were analyzed before each sample set, and one

standard after every ten samples. Triplicate analyses were conducted every 15 samples.

The average discrepancy between triplicate runs was < 5 % of the measured value. When

parameters were measured more than once, the average of all the measurements was

reported. Accuracy of the analytical analyses was tested using a charge balance equation

where reliable measurements yield a < ± 5 % charge balance. All samples had a charge

balance within ± 5 %, with the exception of six samples; which had alkalinity values

below the detection limit of 10 mg/L (Appendix A).

3.3.2 Stable Isotope Analyses

All stable isotope analyses were completed at the Isotope Science Laboratory of

the University of Calgary. Laboratory standards were used at the beginning and end of

each sample set to correct for instrument drift and to normalize data to international

30

reference materials. All measurements are reported in delta (δ) notation. The δ notation is

described by:

δ (‰) = [(Rsample - Rstandard) / Rstandard] ·1000 (3.1)

Where R is the ratio of the less abundant isotope to the most abundant isotope (i.e.

18O/16O) and the value is reported in parts per thousand (‰) (Appelo and Postma, 2005).

The standards are Vienna Standard Mean Ocean Water (VSMOW) for water, and oxygen

in nitrate and sulphate, PeeDee Belemnite (PDB) for carbon, Canyon Diablo Troilite

(CDT) for sulphur, and air N2 for nitrogen.

3.3.2.1 Water Isotopes (δ18OH2O and δ2HH2O)

Water isotope measurements were conducted using laser absorption spectroscopy

with a Los Gatos Research (LGR) DLT-100 instrument. 18O/16O and 2H/1H ratios were

obtained by injecting a 750 nL sample of water, which is vapourized then expanded into a

laser chamber. These vapourized water molecules are measured by Off-Axis Integrated-

Cavity Output Spectroscopy (Off-Axis ICOS). δ18O and δ2H values were reported in ‰

relative to VSMOW (Wassenaar and Hendry, 2008). Accuracy and precision of the δ18O

and δ2H measurements were ± 0.2 and 1.0‰ respectively.

3.3.2.2 Dissolved Inorganic Carbon (δ13CDIC)

Dissolved inorganic carbon (DIC) was isolated from the water sample by first

adding anhydrous phosphoric acid, producing CO2 gas which was then cryogenically

purified and captured in a 6 mm Pyrex break seal (Atekwana and Krishnamurthy, 2004).

The 13C/12C ratio of the CO2 gas was determined using an isotope ratio mass spectrometer

31

(VG-903). The δ13C value was reported in ‰ relative to the PDB standard (Coplen et al.,

2006). Accuracy and precision of the δ13C measurements were ± 0.2 ‰.

3.3.2.3 Sulphate (δ34SSO4 and δ18OSO4)

The stable isotope ratios of sulphate (34S/32S and 18O/16O) were analyzed from

dissolved sulphate that was converted to barium sulphate (BaSO4) precipitate. To obtain

BaSO4, samples were acidified to a pH < 4 and pumped through anion exchange

columns, where sulphate (SO42-) and nitrate (NO3

-) substituted for Cl- and were retained

within the column. The columns were eluted with 3.0 M potassium chloride (KCl), and

then flushed with deionized water; the resulting eluent contained all of the SO42- and

NO3- that was originally present in the sample. Sulphate concentrations for each sample

were used to delineate the appropriate volume of eluent needed to precipitate enough

BaSO4 to allow for stable isotope analysis of δ34S and δ18O of sulphate, the remaining

eluent was reserved for stable isotope analysis of nitrate. Barium chloride (BaCl2)

crystals were added to the eluent in excess, and a BaSO4 precipitate formed (Lico et al.

1982). The sample was then acidified to a pH of 2 using 10% hydrochloric acid (HCl), to

prevent barium carbonate (BaCO3) from precipitating. The remaining BaSO4 precipitate

was filtered through a 0.45μm cellulose acetate filter, washed with deionized water to

remove any excess Cl-, and dried. The 34S/32S ratios were obtained via Continuous Flow-

Isotope Ratio Mass Spectrometry (CF-EA-IRMS) using a Carlo Erba NA 1500 elemental

analyzer coupled to a VG PRISM II mass spectrometer. The δ34S values were reported in

‰ relative to the CDT standard (Mayer and Krouse, 2004). 18O/16O ratios of sulfate were

obtained using a Finnigan MAT TC/EA pyrolysis reactor interfaced to a Finnigan Mat

Delta+XL mass spectrometer via a Conflow III open split/interface (Kornexl et al.,

32

1999). The δ18O values of sulphate were reported in ‰ relative to the VSMOW.

Precision of δ34S and δ18O values of sulphate are ± 0.3 and ± 0.5‰ respectively.

3.3.2.4 Nitrate (δ15N and δ18O)

The stable isotope ratios of dissolved nitrate (15N/15N and 18O/16O) were

determined using the denitrifier method on nitrate obtained from the eluent remaining

from elution of the ion exchange columns (Sigman et al., 2001; Casciotti et al., 2002).

The denitrifying method involves reducing NO3- to nitrous oxide (N2O) using

denitrifying bacteria. There is isotope fractionation that occurs during the reduction of

NO3- to N2O, although when done in a sealed, airtight container with no access to

atmosphere, no fractionation will occur and the nitrogen isotope composition of the N2O

will remain the same as the original NO3- (Sigman et al., 2001). When NO3

- is reduced to

N2O, only one oxygen molecule is transferred, and oxygen isotope fractionation occurs,

while the remaining oxygen exchanges with water. The fractionation that occurs is

deemed to be small, and correction factors as well as standards with known δ18ONO3

values are used to correct for these shifts (Casciotti et al., 2002).

The preparation of the denitrifying bacteria begins by altering a tryptic soy broth

by adding 10 mM potassium nitrate, 1 mM ammonium sulphate, and 1 ml/L of an

antifoaming agent. The medium is dispensed into 500 ml media bottles and is then

autoclaved. A starter tube of the tryptic soy broth mixture is inoculated with an individual

colony, and is grown overnight. Using the starter tube, the media bottles are inoculated

and are incubated for seven days. The seven day incubation period allows for sufficient

time for complete consumption of O2 within the headspace (Sigman et al., 2001). The

bacteria were then divided into 40 ml aliquots and centrifuged. The concentrated cells are

33

resuspended and then are further divided into separate vials for each sample, which are

flushed with inert N2. This is done to ensure anaerobic conditions and to remove any N2O.

The sample water is then injected into each vial using a syringe and needle. For samples

greater than 9 ml, a venting needle is placed through the septum of the vial into the

headspace, to prevent pressurization of the vial and loss of N2O gas. After the sample

water has been injected into the vials, the vials are inverted and allowed to incubate

overnight for complete conversion of NO3- to N2O (Sigman et al., 2001). After

incubation, sodium hydroxide (NaOH) was injected into each vial to lyse the bacteria,

stop the reaction, and immobilize the CO2 gas into DIC. The sample vials were then

loaded into an autosampler which is interfaced to an HP 6890 gas chromatogram with

PreCon® device connected to a Finnigan Mat Delta+XL mass spectrometer. After

samples are loaded, the headspace of each vial is flushed with helium acting as a carrier

gas. The N2O along with the carrier gas, are passed through a series of traps to remove

any excess H2O or CO2. The N2O is then cyrofocussed by the PreCon device and then

passes through a gas chromatogram to separate out any remaining CO2. The isolated N2O

is then transferred to the mass spectrometer and the δ15N and δ18O values are calculated

by the instrument software (ISODAT 2.63). Raw data is corrected using reference

materials analyzed alongside the samples and the δ15N and δ18O values of nitrate were

reported in ‰ relative to N2 air and VSMOW respectively (Werner and Brand, 2001).

Precision of δ15N and δ18O values of nitrate are reported as ± 0.3 and ± 0.7‰

respectively.

34

4 Results

4.1 Total Dissolved Solids

4.1.1 Surface Water

Total dissolved solids (TDS) concentrations of surface water samples ranged from

21 to 308 mg/L with an overall mean value of 43 33 mg/L. The high standard deviation

is due to the high TDS values of samples taken from the estuary sampling location. These

increased TDS values are due to an influx of seawater. The influence of seawater on the

sample TDS value is dependent on the time of day when the samples were taken, and the

level of the tide (i.e. the higher the tide, the greater the influence). When discharge is

high, TDS concentrations do not respond by decreasing at the same rate; TDS

concentrations do decrease but not until May, indicating a time lag (Figure 4.1). The

relatively high average TDS concentration in February could be due to a higher

proportion of discharge being sourced from stormflow. Stormflow can increase TDS

concentrations in rivers through increased runoff containing higher concentrations of

solutes from fertilizers, soils, and sewer and septic systems (Schoonover et al., 2005). In

August 2010, October 2010, and February 2011, TDS concentrations increased with

downstream distance to maximum values of 62.5, 308.2, and 165.0 mg/L respectively

(Figure 4.2). In May 2011, July 2011, and September 2011, TDS concentrations

remained relatively constant moving downstream with mean values of 36.2 1.6, 34.6

3.3, and 42.3 4.7 mg/L respectively.

35

Figure 4.1 Average TDS and average monthly discharge during August 2010, October 2010, February 2011, May 2011, July 2011, and September 2011 sampling periods from all sampling locations.

Figure 4.2 a) Temporal variation of TDS versus distance from headwaters for surface water samples, excluding estuary samples b) Expanded view of TDS versus distance from headwaters for surface water samples, including estuary samples.

36

4.1.2 Groundwater

The TDS of groundwater samples are typically greater than surface water due to the

increased residence time, which allows for a higher degree of rock-water interaction

(Appelo & Postma, 2005). TDS of groundwater samples ranged from 48 to 665 mg/L,

with an average value of 156 122 mg/L. TDS values of groundwater samples were

plotted against depths for wells with available depth data (Figure 4.3). Samples taken

from wells with depths <15 m had TDS values <200 mg/L. In contrast groundwater

samples taken from wells with depths >80 m had TDS values ranging from 119 to 665

mg/L. Samples taken from shallower wells (<80 m) are much less variable with an

average TDS value of 109 67 mg/L, whereas samples taken from deeper wells (>80 m)

have an average TDS value of 356 220 mg/L (Figure 4.3).

Figure 4.3 TDS versus depth for groundwater samples.

37

4.2 Major Ion Chemistry

4.2.1 Major Cations

4.2.1.1 Precipitation

Ca, Mg, Na, K, and NH4 concentrations of precipitation samples had overall

average values of 0.11, 0.11, 0.80, 0.07, and 0.20 mg/L respectively. Maximum

concentrations of Na and Mg were measured in samples collected in February, where

maximum concentrations of Ca, K, and NH4 were sampled in April, March, and

November respectively. Minimum concentrations of all cations, were below detection

and occurred in nearly every month. Precipitation samples had relatively low variability

in cation concentrations with standard deviations of 0.17, 1.25, 0.16, 0.10, and 0.26 mg/L

for Ca, Na, Mg, K, and NH4 respectively (Table 4.1).

4.2.1.2 Surface Water

Based on all 6 sampling events between August 2010 and September 2011, Ca,

Mg, Na, K concentrations of surface water samples had overall average values of 6.89,

0.88, 3.32, and 0.15 mg/L respectively. Maximum concentrations of Ca occurred in

August 2010, with a value of 12.11 mg/L, where maximum concentrations of Mg, Na,

and K occurred in October 2010 with values of 8.25, 66.48, and 2.66 mg/L respectively.

Minimum concentrations of Ca, Mg, and Na occurred in October 2010 with values of

4.84, 0.48, and 1.07 mg/L respectively. Minimum potassium concentrations of 0.02 mg/L

were measured for samples collected in September 2011. Surface water samples had low

overall variability in Ca, Mg, and K concentrations with low standard deviations of 1.49,

0.91, and 0.30 mg/L respectively. Na concentrations varied the most with a high standard

38

deviation of 7.34 mg/L (Table 4.2).

4.2.1.3 Groundwater

Based on all 6 sampling events between August 2010 and September 2011, Ca,

Mg, Na, and K concentrations of groundwater samples had average values of 18.11, 6.10,

16.10, and 0.58 mg/L respectively. Ca, Mg, Na, and K had maximum concentrations of

69.39, 25.45, 168.67 and 1.68 mg/L; and minimum values of 0.32, 0.05, 1.76, and 0.10

mg/L respectively. Cation concentrations are much more variable in groundwater

samples as compared to surface water samples with the exception of potassium, which

has a standard deviation of 0.39 mg/L. Ca, Mg, and Na display much higher standard

deviations with values of 14.19, 6.00, and 33.42 mg/L respectively (Table 4.3).

39

Table 4.1 Statistical summary of average monthly (from 1989 to 2007) cation concentrations of precipitation samples (n=6542, Saturna Island Station).

Ca Na Mg K NH4 Ca Na Mg K NH4

mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/LMean 0.089 1.059 0.132 0.056 0.147 Mean 0.073 0.200 0.033 0.035 0.189Min 0.001 0.028 0.007 0.005 0.003 Min 0.010 0.020 0.004 0.004 0.001Max 1.029 7.780 0.926 0.750 1.642 Max 0.530 1.401 0.182 0.310 0.978σ 0.103 1.152 0.148 0.070 0.195 σ 0.093 0.248 0.035 0.046 0.208

Mean 0.110 1.315 0.161 0.069 0.169 Mean 0.075 0.301 0.045 0.046 0.202Min 0.001 0.014 0.002 0.003 0.005 Min 0.005 0.015 0.003 0.003 0.006Max 1.643 45.760 5.150 1.615 1.637 Max 0.805 2.380 0.305 0.770 2.576σ 0.153 3.292 0.378 0.121 0.213 σ 0.116 0.371 0.048 0.095 0.324





February August

March September

Sampling Period

StatisticSampling

PeriodStatistic

January July

May November

June December

April October

40

Table 4.2 Statistical summary of cation concentrations of surface water samples (n=85).

Sampling Statistic Ca Mg Na K Period mg/L mg/L mg/L mg/L

August 2010

Mean 9.78 1.205 4.78 0.19 Min 8.99 0.787 4.51 0.09 Max 12.11 3.195 6.79 0.39 σ 0.79 0.601 0.59 0.09

October 2010

Mean 6.45 1.152 5.89 0.28 Min 4.84 0.485 1.07 0.09 Max 10.26 8.250 66.48 2.66 σ 1.41 1.898 16.17 0.64

February 2011

Mean 6.36 1.043 4.31 0.18 Min 5.88 0.674 2.66 0.08 Max 7.11 3.411 23.19 0.99 σ 0.47 0.689 5.44 0.24

May 2011

Mean 5.85 0.601 1.51 0.09 Min 5.52 0.527 1.35 0.07 Max 6.36 0.673 1.67 0.13 σ 0.21 0.051 0.11 0.02

August 2011

Mean 6.55 0.615 1.72 0.07 Min 6.29 0.513 1.53 0.05 Max 6.95 0.718 1.99 0.09 σ 0.24 0.076 0.15 0.01

September 2011

Mean 6.33 0.681 1.71 0.08 Min 5.98 0.612 1.32 0.02 Max 6.65 0.750 1.96 0.21 σ 0.21 0.043 0.20 0.06

Overall

Mean 6.89 0.883 3.32 0.15 Min 4.84 0.485 1.07 0.02 Max 12.11 8.250 66.48 2.66 σ 1.49 0.912 7.34 0.30

41

Table 4.3 Statistical summary of cation concentrations of groundwater samples (n=50).

Statistic Ca Mg Na K mg/L mg/L mg/L mg/L

Mean 18.11 6.097 16.10 0.58 Min 0.32 0.054 1.76 0.10 Max 69.39 25.449 168.67 1.68 σ 14.19 6.002 33.42 0.39

4.2.2 Major Anions


Cl, SO4, and NO3 concentrations of precipitation samples had overall average

values of 1.43, 1.26, and 1.43 mg/L, respectively (Table 4.4). HCO3 concentrations were

not measured, and therefore are not included in this study (CAPMoN, 2012). All

calculated Ion charge balance (ICB) were < 10 %, with no significant surplus of

cations, therefore HCO3 concentrations are likely negligible in this area. Maximum

concentrations of Cl, SO4, and NO3 were measured in February, August, and January

with values of 1.43, 1.26, and 1.43 mg/L respectively. Minimum values were near

detection limits and were observed in May, January, and November for Cl, SO4, and

NO3, with values of 0.01, 0.13, and 0.04 mg/L, respectively. Precipitation samples had

relatively low variability in anion concentrations with low standard deviations of 2.17,

1.14, and 1.66 mg/L respectively for Cl, SO4, and NO3 (Table 4.4).


Cl, HCO3, SO4, and NO3 concentrations of surface water samples had overall

average values of 6.31, 20, 1.77 and 0.27 mg/L, respectively (Table 4.5). Maximum

concentrations of Cl and SO4 occurred in October 2010, with values of 111.21 and 16.45

42

mg/L respectively. However, maximum concentrations of HCO3, and NO3 occurred in

August 2010, and May 2011, with values of 16.45 and 4.65 mg/L respectively. Minimum

values of Cl and HCO3 were measured in samples collected in October 2010, with values

of 1.48 and 13 mg/L respectively. Minimum SO4 concentrations were measured in

samples collected in August 2011, with a minimum value of 0.80 mg/L. Minimum

concentrations of NO3 were below the detection limit of 0.02 mg/L in all sampling trips

except May 2011 which had a minimum measured concentration of 0.23 mg/L. Surface

water samples had large variations in Cl concentrations, with a high standard deviation of

12.5 mg/L. HCO3 concentrations exhibited moderate variability with a standard deviation

of 4.00 mg/L. Surface waters had very low ranges of both sulphate and nitrate with low

standard deviations of 1.78 and 0.70 mg/L respectively, due to low overall concentrations

of both ions in surface water (Table 4.5).

4.2.2.3 Groundwater

Cl, HCO3, SO4, and NO3 concentrations of groundwater samples had average

values of 14.4, 96, 4.37 and 1.28 mg/L respectively (Table 4.6). Cl and HCO3 had much

higher concentrations than SO4 and NO3, with maximum values of 197.31 and 391 mg/L

respectively. Maximum concentrations of SO4, and NO3 were 20.1 and 25.7 mg/L.

Minimum concentrations of Cl, HCO3, and SO4 were 1.56, 19, and 0.28 respectively;

minimum NO3 concentrations were below detection limit. Cl and HCO3 were the most

variable, with high standard deviations of 28.8 and 78 mg/L respectively, whereas SO4

and NO3 were the least variable, with low standard deviations of 3.78 and 3.98 mg/L

respectively (Table 4.6).

43

Table 4.4 Statistical summary of anion concentrations of precipitation samples (1989-2007).

Cl SO4 NO3 Cl SO4 NO3

mg/L mg/L mg/L mg/L mg/L mg/LMean 1.90 0.96 1.24 Mean 0.43 1.24 1.64Min 0.07 0.13 0.09 Min 0.04 0.16 0.16Max 13.58 7.86 18.24 Max 2.52 4.75 6.86σ 2.09 0.78 1.63 σ 0.47 0.96 1.54

Mean 2.30 1.06 1.28 Mean 0.57 1.48 1.50Min 0.04 0.16 0.04 Min 0.03 0.21 0.13Max 72.91 11.42 12.69 Max 4.23 12.84 10.88σ 5.33 1.02 1.48 σ 0.64 1.73 1.81





September

April October

Statistic

May November

June December

Sampling Period

January July

February August

StatisticSampling

Period

March

44

Table 4.5 Statistical summary of anion concentrations of surface water samples.

Sampling Statistic Cl HCO3 SO4 NO3 Period mg/L mg/L mg/L mg/L

August 2010

Mean 11.24 26 2.09 0.19 Min 10.88 21 1.34 0.00 Max 13.17 42 3.43 1.12 σ 0.58 5 0.71 0.28

October 2010

Mean 9.92 18 2.61 0.05 Min 1.48 13 1.10 0.00 Max 111.21 21 16.45 0.09 σ 27.05 3 3.71 0.03

February 2011

Mean 7.74 18 2.26 0.10 Min 4.50 17 1.75 0.00 Max 40.70 20 6.77 0.20 σ 9.51 1 1.30 0.06

May 2011

Mean 2.61 17 1.56 0.97 Min 2.33 16 1.35 0.23 Max 2.89 18 3.18 4.65 σ 0.20 1 0.47 1.45

August 2011

Mean 3.30 20 0.99 0.01 Min 2.81 18 0.80 0.00 Max 3.83 21 1.13 0.03 σ 0.37 1 0.11 0.01

September 2011

Mean 3.03 20 1.10 0.29 Min 2.20 18 0.87 0.01 Max 3.91 22 1.23 2.26 σ 0.54 1 0.12 0.59

Overall

Mean 6.31 20 1.77 0.27 Min 1.48 13 0.80 0.00 Max 111.21 42 16.45 4.65 σ 12.46 4 1.78 0.70

45

Table 4.6 Statistical summary of anion concentrations of groundwater samples.

Statistic Cl HCO3 SO4 NO3 mg/L mg/L mg/L mg/L

Mean 14.40 96 4.37 1.28 Min 1.56 19 0.28 0.00 Max 197.31 391 20.09 25.71 σ 28.81 78 3.78 3.94

4.2.3 Combined Cations and Anions


All precipitation data lie along the right side of the Piper diagram (Figure 4.4).

This is due to the lack of HCO3 in precipitation. Precipitation ranges from a Na-Cl-NO3,

Na-Cl-SO4 or a Na-Cl-SO4-NO3 water type. Na is the dominant cation, whereas Cl is

typically the dominant anion, with varying concentrations of NO3 and SO4 (Figure 4.4).


Data from 98% of the surface water samples depict water types ranging from Ca-

HCO3-Cl to Ca-HCO3, whereas 2% are Na-Cl water type (Figure 4.4). Temporal

variation in the surface water type is observed; August 2010 and February 2011 samples

have (28 samples) a water type of Ca-HCO3-Cl, whereas in October 2010, May 2011,

August 2011, and September 2011 (61 samples) a Ca-HCO3 water type was observed.

October 2010 depicted the highest water chemistry variability showing a downstream

trend from Ca-HCO3 to Ca-HCO3-Cl to Na-Cl water types (Figure 4.4).

46

4.2.3.3 Groundwater

The groundwater data plot within a smaller area of the piper diagram relative to

surface water, therefore displaying lower variability in water chemistry (Figure 4.4). Of

the groundwater samples, 86% have a Ca-Mg-HCO3-Cl water type, whereas 10% and 4%

have a Na-HCO3 and Ca-Na-HCO3-Cl water type respectively (Figure 4.4).

Figure 4.4 Piper diagram of surface water, groundwater, and precipitation samples.

47

4.3 Stable Isotopes

4.3.1 Isotopic Composition of Water (δ18OH2O and δ2HH2O)


The amount-weighted average δ2H and δ18O values of precipitation samples from 1989 to

2007 were -72.0 and -9.5 ‰ respectively. Maximum monthly values of δ2H and δ18O

were measured in April and had values of -22.8 and +1.7 ‰ respectively. Minimum

monthly average values of δ2H and δ18O were sampled in February and were -108.8 and

-14.6 ‰ respectively (Table 4.7).


The overall mean from all surface water samples had δ2H and δ18O values of -87 and -

12.3 ‰. The highest δ2H and δ18O values in surface waters were measured in September

2011 with values of -73 and -10.3 ‰ respectively. The lowest δ2H and δ18O values were

measured in May 2011 with values of -96 and -13.6 ‰ respectively. Seasonally, δ2H and

δ18O values varied the most between sampling locations in September 2011 with

corresponding standard deviations of 2 and 0.3 ‰. In contrast, there was little to no

variability in δ2H and δ18O values in May 2011 with standard deviations of 1 and 0.1 ‰

respectively, which is within the measurement uncertainty (Table 4.8).

4.3.1.3 Groundwater

Groundwater had mean values of -86 3 and -12.1 0.6 ‰ respectively for δ2H and

δ18O, which were comparable to overall mean values for surface water (Table 4.8, Table

4.9). The highest δ2H and δ18O values were -81 and -11.2 ‰ respectively; whereas the

lowest δ2H and δ18O values were -95 and -13.4 ‰ respectively (Table 4.8, Table 4.9).

48

Overall, groundwater samples were less variable than surface water samples with respect

to δ2H and δ18O values. Groundwater samples were also more depleted with respect to 2H

and 18O since the maximum values of δ2H and δ18O were much lower than surface water

maxima, even though minima were comparable (Table 4.8, Table 4.9).

49

Table 4.7 Statistical summary of δ2H and δ18O values for precipitation samples (1989-2007).

Month Statistic 18OH2O 2HH2O Month Statistic 18OH2O 2HH2O

‰ ‰ ‰ ‰Mean -10.0 -67 Mean -4.1 -38Min -12.1 -90 Min -7.8 -64Max -14.4 -108 Max -12.1 -93σ 1.5 12 σ 2.7 19

Mean -10.1 -73 Mean -2.1 -35Min -12.3 -92 Min -7.1 -59Max -14.6 -109 Max -11.4 -84σ 1.6 12 σ 2.7 15


Mean 1.7 -23 Mean -5.7 -35Min -8.5 -66 Min -8.0 -57Max -12.2 -87 Max -10.4 -75σ 3.9 18 σ 1.5 11



October

November

December

January

February

March

April

May

June

July

August

September

50

Table 4.8 Statistical summary of δ2H and δ18O values for surface water samples.

Sampling Statistic δ2HH20 δ18OH2O Period ‰ ‰

August 2010

Mean -87 -12.3 Min -89 -12.5 Max -86 -12.1 σ 1 0.1

October 2010

Mean -82 -11.6 Min -84 -12.1 Max -79 -11.3 σ 2 0.2

February 2011

Mean -92 -12.9 Min -94 -13.1 Max -91 -12.7 σ 1 0.1

May 2011

Mean -95 -13.4 Min -96 -13.6 Max -93 -13.3 σ 1 0.3

July 2011

Mean -92 -13.2 Min -94 -13.5 Max -90 -12.8 σ 1 0.3

September 2011

Mean -75 -10.7 Min -79 -11.1 Max -73 -10.3 σ 2 0.3

Overall

Mean -87 -12.3 Min -96 -13.6 Max -73 -10.3 σ 7 1.0

51

Table 4.9 Statistical summary of δ2H and δ18O values for groundwater samples.

Statistic δ2HH20 δ18OH2O ‰ ‰

Mean -86 -12.1 Min -95 -13.4 Max -81 -11.2 σ 3 0.6

4.3.2 Isotopic Composition of Dissolved Inorganic Carbon (δ13CDIC)


The highest and lowest δ13CDIC values were measured in September 2011 and

August 2010 with values of +0.6 and -32.2 ‰ respectively (Table 4.10). The overall

mean δ13CDIC value of for all surface water samples was -16.9 ‰, with a standard

deviation of +12.5 ‰. This large variability is due to temporally variable sources

contributing to DIC within surface water samples. August 2010 was the most variable

sample set, where October 2010 was the least variable, with standard deviations for

δ13CDIC of 3.0 and 1.2 ‰ respectively (Table 4.10).

4.3.2.2 Groundwater

The highest and lowest δ13CDIC values were -9.4 and -34.6 ‰ respectively (Table

4.11). The groundwater samples had a mean δ13CDIC value of -21.0 ‰ and a standard

deviation of +5.0 ‰. Overall groundwater samples were less variable in δ13CDIC than

surface water samples, and were more depleted with respect to 13C; groundwater samples

had a standard deviation of 5.0 ‰, whereas surface water samples had a standard

deviation of 12.5 ‰ (Table 4.10, Table 4.11).

52

Table 4.10 Statistical summary of δ13CDIC for surface water samples.

Sampling Statistic δ13CDIC Period ‰

August 2010

Mean -29.2 Min -32.2 Max -19.9 σ 3.0

October 2010

Mean -28.4 Min -29.8 Max -24.7 σ 1.2

February 2011

Mean -28.3 Min -29.9 Max -20.7 σ 2.5

May 2011

Mean -4.2 Min -7.9 Max -2.7 σ 2.1

July 2011

Mean -6.1 Min -10.8 Max -3.1 σ 2.1

September 2011

Mean -2.1 Min -5.3 Max 0.6 σ 1.7

Overall

Mean -16.9 Min -32.2 Max 0.6 σ 12.5

Table 4.11 Statistical Summary of δ13CDIC for groundwater samples.

Statistic δ13CDIC ‰

Mean -21.0 Min -34.6 Max -9.4 σ 5.0

53

4.3.3 Isotopic Composition of Sulphate (δ34SSO4 and δ18OSO4)


Overall, mean values of sulphate were -2.0 and -2.6 ‰ respectively for δ34S and

δ18O (39 samples). The highest mean values were observed in samples taken in August

2011 for δ34S, and May 2011 for δ18O, where the lowest mean values occurred in May

2011 and September 2011 for δ34S and δ18O respectively (Table 4.11). The highest δ34S

and δ18O values of sulphate were measured for samples taken in September 2011 and

May 2011 with values of +1.0 and +13.5 ‰ respectively. The lowest δ34S and δ18O

values were measured in samples taken in May 2011 and August 2011 with values of -5.5

and -4.2 ‰ respectively (Table 4.11). δ18O values of sulphate for surface water samples

were overall more variable than δ34S values with standard deviations of 1.8 and 2.6 ‰

respectively (Table 4.11). δ34S values were the most variable between sampling sites in

September 2011 and the least variable in August 2011, with corresponding standard

deviations of 1.0 and 0.6 ‰. δ18O values had the highest variability in May 2011 and the

smallest variability in September 2011, with standard deviations of 4.4 and +.5 ‰

respectively (Table 4.12).

4.3.3.2 Groundwater

Overall the groundwater samples had much more variable δ34S values than the

surface water samples, and slightly more variable δ18O values (Table 4.12, Table 4.13).

The highest and lowest δ34S values were +15.6 and -17.4 ‰ respectively, where +7.3 and

-5.4 ‰ correspond to the highest and lowest values of δ18O. The overall mean value of

δ34S and δ18O for sulphate in groundwater was +2.0 and +0.2 ‰ respectively. δ34S values

54

were more variable than δ18O values with corresponding standard deviations of 5.9 and

3.3 ‰ (Table 4.13).

Table 4.12 Statistical summary δ34S and δ18O values of sulphate for surface water samples (n=39).

Sampling Statistic δ34SSO4 δ18OSO4 Period ‰ ‰

August 2010

Mean - ‐

Min - - Max - - σ - -

October 2010

Mean - - Min - - Max - - σ - -

February 2011

Mean - - Min - - Max - - σ - -

May 2011 Mean -3.2 -1.6 Min -5.5 -3.5 Max -2.5 13.5

σ 0.6 0.6

July 2011

Mean 0.2 -2.4 Min -0.7 -4.2 Max 1.0 -1.6 σ 0.6 0.6

September 2011

Mean -2.7 -2.6 Min -4.6 -3.0 Max -1.3 -1.7 σ 1.0 0.5

Overall

Mean -2.0 -2.2 Min -5.5 -4.2 Max 1.0 13.5 σ 1.8 2.6

55

Table 4.13 Statistical Summary of δ34S and δ18O values of sulphate for groundwater samples (n=4).

Statistic δ34SSO4 δ18OSO4 ‰ ‰

Mean 2.0 0.2 Min -17.4 -5.4 Max 15.6 7.3 σ 5.9 3.3

4.3.4 Isotopic Composition of Nitrate (δ15NNO3 and δ18ONO3)


The highest δ15N and δ18O values were measured in August 2011 and September

2011, with values of 18.6 and 13.1 ‰ respectively. The lowest δ15N and δ18O values

were measured in September 2011 with values of 0.7 and 10.4 ‰ respectively (Table

4.14). The overall mean values for all surface water samples (6 samples) were 5.9 and

11.7 ‰ respectively for δ15N and δ18O. The highest mean values for a given sampling

event were observed in August 2011 for δ15N, and May 2011 for δ18O, where the lowest

mean values were observed in September 2011 (Table 4.14). δ15N values of nitrate for

surface water samples were overall more variable than δ18O values with standard

deviations of 5.1 and 1.0 ‰ respectively (Table 4.14). δ15N values were the most variable

between sampling sites in August 2011 and the least variable in September 2011, with

corresponding standard deviations of 4.9 and 2.1 ‰. δ18O values had the highest

variability between sampling sites in September 2011 with a standard deviation of 1.4 ‰,

whereas there was little to no variability in May 2011 with a standard deviation of 0.5 ‰,

which is within the measurement uncertainty of 0.5 ‰ (Table 4.14).

56

4.3.4.2 Groundwater

The highest and lowest δ15N values were 14.8 and 3.8 ‰ respectively, whereas

4.2 and -0.4 ‰ correspond to the highest and lowest values of δ18O. The overall mean

value of δ15N and δ18O was 8.6 and 1.2 ‰ respectively. δ15N values were more variable

than δ18O values with corresponding standard deviations of 3.5 and 2.1 ‰ (Table 4.15).

Overall the surface water samples had a higher variability in δ15N values than the

groundwater samples. In contrast, the groundwater samples had a higher variability in

δ18O values, although, most likely due to the very small sample set (Table 4.14, Table

4.15).

57

Table 4.14 Statistical summary of δ15N and δ18O values of nitrate for surface water samples (n=6).

Sampling Statistic δ15NNO3 δ18ONO3 Period ‰ ‰

August 2010

Mean ‐ ‐

Min ‐ ‐

Max ‐ ‐

σ - -

October 2010

Mean - - Min - - Max - - σ - -

February 2011

Mean - - Min - - Max - - σ - -

May 2011

Mean 4.0 11.9 Min 1.3 11.5 Max 15.7 12.2 σ 4.9 -

July 2011

Mean 10.4 - Min 3.5 - Max 18.6 - σ 4.9 -

September 2011

Mean 2.5 11.6 Min 0.7 10.4 Max 6.4 13.1 σ 2.1 1.4

Overall

Mean 5.9 11.7 Min 0.7 10.4 Max 18.6 13.1 σ 5.1 1.0

58

Table 4.15 Statistical summary of δ15N and δ18O values of nitrate for groundwater samples (n=4).

Statistic δ15NNO3 δ18ONO3 ‰ ‰

Mean 8.6 1.2 Min 3.8 -0.4 Max 14.8 4.2 σ 3.5 2.1

59

5 Isotope Geochemistry

5.1 Introduction

Stable isotope abundance ratios can provide information about the sources of

water and its dissolved compounds, as well as processes, and pathways the water and its

dissolved constituents may have undergone. Different sources of water, DIC, sulphate,

and nitrate often have distinct isotopic signatures, potentially revealing the source of

these compounds in water. Every isotope has a distinct mass, therefore affecting the rate

of reaction in physical, chemical, and biological processes (Appelo & Postma, 2005).

This mass dependent preferential reaction of different isotopes during various

environmental processes is the basis of mass dependent isotope fractionation. As

elements cycle through various physical, chemical and biological pathways, predictable

isotope fractionation occurs (Friedman & O’Neil, 1977). Determining the isotopic

composition of water and dissolved solutes can aid in understanding the biogeochemical

processes and reactions that may have occurred (Appelo & Postma, 2005; Clark & Fritz,

1997; Friedman & O’Neil, 1977).

The notation is used, which expresses the deviation of the isotopic ratio in the

sample with respect to the ratio in a standard. For example oxygen isotope ratios are

noted as follows (Equation 5.1; Appelo & Postma, 2005):

18Osample (‰) = [(18O/16O)sample – (18O/16O)standard)/(

18O/16O)standard] x 1000 (5.1)

Delta units are not SI units; they are relative units and are not a measure of absolute

isotope concentration. However, they have become the conventional units for measuring

60

natural abundance isotope variations (Appelo & Postma, 2005; Slater et al., 2001). Stable

isotope abundances for water (δ18O and δ2H), DIC (δ13C), sulphate (δ34S and δ18O), and

nitrate (δ15N and δ18O) in surface water and groundwater samples from the ERW are

studied and interpreted in this chapter to delineate the possible sources and processes

affecting these compounds within the watershed.

5.2 Isotopic Composition of Water (δ18OH2O and δ2HH2O)

Stable isotope abundances of hydrogen and oxygen in water can be used to

evaluate the possible sources of water contributing to both surface water and

groundwater. Analysis of spatial and temporal variations of δ2H and δ18O values of

surface water and groundwater samples can aid in understanding these isotopic

variations. Source of moisture, evaporation, elevation, and climate affect the natural

variations in water isotope ratios (Appelo & Postma, 2005; Drever, 1997); their influence

on δ2H and δ18O are discussed in this section.

5.2.1 Precipitation

There are various processes and effects that alter the isotopic composition of

water in precipitation through isotopic fractionation of hydrogen and oxygen in the water

molecule (Dansgaard, 1964). During evaporation, the lighter isotope is preferentially

evaporated, leaving the residual water enriched, and the resulting atmospheric water

vapour depleted with respect to the heavy isotopes 2H and 18O (Craig & Gordon, 1965).

During this process, both equilibrium and non-equilibrium isotope fractionation occur

(Craig & Gordon, 1965). The extent of equilibrium isotope fractionation that occurs is

dependent on temperature, whereas the extent of additional non-equilibrium isotope

fractionation is in part dependent on relative humidity. In order for equilibrium isotope

61

fractionation to occur, relative humidity must be 100 %; which occurs in the boundary

layer – near the ocean surface. Above the boundary layer relative humidity decreases and

non-equilibrium isotope fractionation occurs (Craig & Gordon, 1965; Dansgaard, 1964).

The rain out effect occurs as atmospheric vapour moves from the coast over continental

regions; condensation occurs resulting in equilibrium isotope fractionation of water. The

heavier isotopes 2H and 18O are preferentially rained out, resulting in higher levels of 1H

and 16O in the remaining water vapour. During subsequent rainout events, the resulting

precipitation is further depleted with respect to 2H and 18O in comparison to previous

rainout events (Clark & Fritz, 1997; Craig & Gordon, 1965; Dansgaard, 1964). The

temperature effect leads to seasonal fluctuations of the isotopic composition of

precipitation, as temperature is a driving force in cooling and condensing atmospheric

water vapour. Lower temperatures cause increased isotope fractionation and more

rainout, leading to relatively low δ2H and δ18O values in winter precipitation, and relative

enrichment of 2H and 18O in summer precipitation (Clark & Fritz, 1997; Kendall &

MacDonnell, 1998).

In this study, no precipitation samples were collected, but the global meteoric

water line (GMWL), Canadian meteoric water line (CMWL), and Saturna meteoric water

line (SMWL) were used as isotopic references for precipitation. The GMWL was

determined by plotting δ2H versus δ18O values for global precipitation samples (Equation

5.2; Rozanski et al., 1993). The CMWL was identified based on precipitation values from

five stations across Canada, over the course of 7 years (Equation 5.3; Clark and Fritz,

1997). The SMWL was determined using precipitation data accessed from CNIP, using

data from over 10 years (1993 to 2003) (Equation 5.4).

62

GMWL: δ2H = 8 x δ18O + 10 (5.2)

CMWL: δ2H = 7.75 x δ18O + 9.83 (5.3)

SMWL: δ2H = 7.11 x δ18O – 0.23 (5.4)

δ2H values are plotted against δ18O, where the slope of the linear regression line will vary

based on relative humidity above the oceanic water source. Low relative humidity

maximizes the effects of evaporation, producing a shallower slope, whereas high relative

humidity produces steeper slopes, closer to the GMWL (Clark and Fritz, 1997;

Gonfiantini, 1986). Continental stations have slopes similar to the GMWL due to strong

seasonal variations in temperature, which cause wide ranges in δ18O and δ2H values, and

result in well-defined slopes. Marine locations like Saturna Island have narrower ranges

of data than continental stations due to the moderating maritime effect on temperature,

which result in less well-defined, lower slopes than the GMWL (Clark & Fritz, 1997).

5.2.2 Surface Water

The isotopic compositions of surface water samples in relation to he GMWL,

CMWL, and SMWL is presented in Figure 5.1. The overall average δ2H and δ18O values

in surface water samples are -87 ± 7 and -12.3 ± 1.0 ‰ respectively. δ2H values range

from -96 to -73 ‰, whereas δ18O values range from -13.6 to -10.3 ‰. In Figure 5.1, the

slope of the linear regression line of surface water samples (SWL) lies almost coincident

with the SMWL. The SWL has a slightly lower slope of 6.99 compared to the SMWL

with a slope of 7.11. This is an indication that the SMWL is a good approximation of

precipitation in the Englishman River Watershed. The slightly lower slope of the surface

water δ2H and δ18O values suggests surface water is affected by evaporation (Figure 5.1).

Ninety-two percent of surface water samples lie between the CMWL and the GMWL

63

(Figure 5.1). The remaining 8 % of samples, all from July 2011 lie slightly above the

CMWL, showing a relative enrichment in 2H in comparison to 18O. This could be due to a

more arid vapour source, resulting in enrichment of 2H and 18O in the source precipitation

(McGuire et al., 2007). Alternatively, this could be due to natural data variation since the

maximum deviation of δ2H values from the CMWL is only 1.2 ‰, which is only slightly

higher than the measurement uncertainty of δ2H, and the standard deviation of 1.0 ‰ for

all surface water samples (Figure 5.1; Table 4.7). Six percent of samples, all from

September 2011, lie below the GMWL and are likely influenced by evaporation, leading

to an overall enrichment in 2H and 18O and a deviation from the GMWL.

Although all surface water samples lie within a fairly narrow field, there is

temporal variability (Figure 5.1). Surface water samples collected in September 2011 had

the highest δ2H and δ18O values, suggesting that summer precipitation is a major water

source. Surface water samples collected in February, May, and July 2011 had the lowest

δ2H and δ18O values. Values ranged from -96 to -90 and -14.0 to -10.3 ‰ for δ2H and

δ18O respectively; indicating that winter precipitation and/or contribution from snowmelt

is the major contributor of water to the river during late winter to early summer. During

the February 2011 sampling trip, there was a major snowfall event; this in conjunction

with low δ2H and δ18O values suggests winter precipitation is a major source of water to

the river during this period (Figure 5.2). Surface water samples from May and July 2011

also had low δ2H and δ18O values, however the average daily temperatures during these

sampling events ranged from 7.1 to 12.8 and 13.4 to 18.4 ºC respectively. Therefore the

major contributor of water to the river during these periods is likely snowmelt (Figure

5.1, 5.3 and 5.4). Samples taken during August 2010 and October 2010 had average δ2H

64

and δ18O values; ranging from -89 to -79 and -12.5 to -11.3 ‰ for δ2H and δ18O

respectively. This could be due to water being sourced from two end member water

sources (snowmelt and summer precipitation), or an increased influence from

groundwater. δ2H and δ18O values of groundwater samples lie within the same range,

and discharge within the river is lowest (< 0.5 m3/s) from August to mid September,

which correlates with low precipitation rates (average daily values < 3 mm), suggesting

that in August 2010, the majority of water within the river was derived from baseflow,

which is in agreement with previous work in the area (Figure 5.3 and 5.4; Barlak et al.,

2010; Wendling, 2012). Conversely, during October 2010 average daily discharge rates

rose to 15 m3/day from 5 m3/day in September 2010, correlating with an increase in

precipitation from mid September to the end of October 2010, therefore suggesting that

late summer, early fall precipitation is likely a major source of water during this period

(Figure 5.3 and 5.4). Samples collected in September 2011 had the highest δ2H and δ18O

values, ranging from -79 to -73 and -11.1 to -10.3 ‰ respectively; suggesting summer

precipitation is a significant supplier of water to the river during this period (Figure 5.1).

This is further supported by the increased amount of precipitation in mid September 2011

from 0 to ~10 mm, with mean daily temperature ranging from 10 to 20 C (Figure 5.3

and 5.4).

There is little spatial variation in δ2H and δ18O values of surface water samples

between sampling sites, with maximum standard deviations of +2 and +0.3 ‰

respectively, (observed in September 2011). Although, in samples collected in October

2010 and September 2011, there is an apparent increasing trend in δ2H and δ18O values

with increasing downstream distance. In October 2010, δ2H and δ18O values increased

65

from -84 to -79 and -12.1 to -11.3 ‰ respectively. In September 2011, δ2H and δ18O

values increased from -79 to -73 and -11.1 to -10.3 ‰ moving downstream. This, in

conjunction with low precipitation during late summer and early fall as previously

discussed, suggests that evaporation along the length of the river could be the cause of the

slight enrichment in 2H and 18O observed in samples taken in October 2010 and

September 2011 (Figure 5.1 and 5.2). Figure 5.4 illustrates a hydrograph depicting mean

daily discharge and mean daily precipitation reported monthly over the study period.

There is no time lag between precipitation and discharge peaks; therefore residence time

of water within the ERW is short; likely on the order of weeks to months. Samples from

August 2010, February 2011, and May 2011 do not show any obvious trends downstream

in δ2H and δ18O values. This implies that evaporation does not play a significant role

during these sampling events. In July 2011, the samples show a decreasing trend in δ2H

and δ18O values along the flow path, with values ranging from -90 to -94 and -12.8 to

-13.5 ‰ respectively (Figure 5.5). This could be due to an introduction of another water

source that is depleted with respect to 18O and 2H in the lower portion of the river. The

South Englishman River coalesces with the Englishman River approximately 35 km

downstream of the headwaters, which could be the additional water source causing a

slight depletion in 18O and 2H, moving downstream.

66

Figure 5.1 a) Temporal variation in δ18O and δ2H values of surface water samples in comparison to the GMWL, CMWL, SMWL, and SWL. b) Close-up of the δ2H-δ18O diagram.

67

Figure 5.2 Amount of daily precipitation in relation to mean daily temperature for February 2011 (Environment Canada, 2012).

68

Figure 5.3 Total daily precipitation in relation to daily temperature over the entire study period from August 2010 to September 2011.

69

Figure 5.4 Mean daily discharge and mean daily precipitation reported monthly over the entire study period from August 2010 to

September 2011.

70

Figure 5.5 Spatial and temporal variation of δ18O and δ2H values of surface water samples in relation to increasing distance from the headwaters of the Englishman River in relation to δ18O and δ2H ranges in groundwater samples.

71

5.2.3 Groundwater

All groundwater samples lie near the SMWL. Forty percent of all groundwater

samples lie between the CMWL and the GMWL and 4 % of samples plot above the

CMWL. The remaining 51 % of samples plot below the GMWL. However, these samples

plot only 0.5 to 0.6 ‰ (for both δ18O and δ2H) from the CMWL, which is within the

standard deviation of all groundwater samples (+3 and +0.6 ‰ for δ2H and δ18O

respectively). Therefore statistically, there is no difference between these samples and the

CMWL, or the SMWL (Figure 5.6). Unlike the surface water samples, the groundwater

samples plot closer to the GMWL, suggesting minimal evaporation effects during

recharge. There are five samples that have δ18O and δ2H values of less than -13 and -90

‰ respectively. All of these samples were from relatively shallow wells < 25 m. There is

no direct correlation between the isotopic composition of groundwater samples and

depth, as all shallow samples have a wide range of water isotope compositions, ranging

from -86 to -95 ‰ and -12.1 to -13.4 ‰ for δ2H and δ18O values respectively. However,

the deepest wells > 100 m, have δ18O and δ2H within +0.6 and +3 ‰ respectively of each

other, which is equal to the variability of all groundwater samples. This can be explained

by the proximity of the wells, which are all within 750 m (Figure 5.7, Figure 3.1). Figure

5.8 depicts surface water samples and groundwater samples in relation to the CMWL,

GMWL, and the SMWL. The groundwater samples and surface water samples plot in

very close proximity to each other. However, 14 % of groundwater samples plot near the

lower δ18O and δ2H values of surface water suggesting that snowmelt and/or winter

precipitation preferentially recharges groundwater. This is further supported by increased

precipitation and discharge rates from November to April, when snowmelt contributes to

72

the river (Figure 5.3, 5.4, 5.8). The remaining 86 % of groundwater samples plot near the

average δ2H and δ18O values (-87 7 and -12.3 1.0 ‰ respectively) of surface water

samples, suggesting there is a higher degree of mixing of water within the aquifer, due a

longer residence time.

Figure 5.6 δ18O and δ2H values of groundwater samples in relation to the GMWL, CMWL, and the SMWL.

73

Figure 5.7 a) 2H values of groundwater samples versus depth. b) 18O values of

groundwater samples versus depth.

74

Figure 5.8 δ18O and δ2H values of surface water samples and groundwater samples in relation to the GMWL, CMWL, and the SMWL.

5.3 Dissolved Inorganic Carbon

Dissolved inorganic carbon (DIC) is the sum of all inorganic carbon species in

solution: carbonic acid (H2CO3), carbonate (CO32-), and bicarbonate (HCO3

-) (Appelo

and Postma, 2005). DIC found in surface water and groundwater can be sourced from the

atmosphere, biosphere, pedosphere, and lithosphere. Each source has a distinct carbon

isotope signature, which can be used to determine the source of DIC in surface water and

groundwater (Telmer and Veizer, 1999; Spence and Telmer, 2005).

75

DIC can be sourced from atmospheric CO2 by the following reactions:

CO2(g) + H2O H2CO3 (5.5)

H2CO3 HCO3- + H+ (5.6)

HCO3- CO3

2- + H+ (5.7)

The relative role of the above reactions is dependent on pH. At 25 °C reaction 5.5 is

dominant at pH values below 6.3, reaction 5.6 is dominant at pH values ranging from 6.3

to 10.3, and equation 5.7 is the dominant reaction at pH values > 10.3 (Clark and Fritz,

1997).

Atmospheric CO2 is dissolved in water, until equilibrium is reached between the

partial pressure of atmospheric CO2(g) and the CO2 in solution (Drever, 1997). Aqueous

CO2 reacts with H2O and forms carbonic acid (H2CO3) (Appelo and Postma, 2005).

H2CO3 readily dissociates to form HCO3- and H+, and if the pH is > 10.3 CO3

2- and H+

subsequently form (Eq. 5.7; Appelo and Postma, 2005).

DIC can be sourced from CO2 produced within the soil zone. CO2 gas is produced

via aerobic respiration within the soil zone as organic matter decays and is oxidized

(Drever, 1997). As water infiltrates into the soil zone, the atmospheric CO2(aq)

equilibrates with the CO2(g) in the soil zone. The CO2(aq) then reacts to form H2CO3,

which further reacts to form HCO3- and CO3

2- dependant on pH (Kendall & MacDonnell,

1998).

Lithospheric sources of DIC include dissolution of carbonate minerals (Dubois et

al., 2010). There is minimal carbonate bedrock present in the ERW; limestone is present

in the Quatsino Formation and in sections of the Buttle Lake Group outcropping in the

headwaters and eastern portions of the study area. Additional sources of minor calcite

have been identified in volcanic bedrock and in veins within intrusive volcanics. Calcite

76

veins can form when hydrothermal fluids are supersaturated with respect to Ca2+ and

HCO3- (Appelo and Postma, 2005). The saturation index (SI) is the ratio of the Ion

Activity Product (IAP) in a water sample and the solubility product (K) of activities in

equilibrium, on a logarithmic scale (Appelo and Postma, 2005). A SI between -0.3 and

0.3, is considered saturated, SI > 0.3 is supersaturated, and SI < -0.3 is subsaturated with

respect to the mineral in question. The program “The Geochemist’s Workbench” was

used to determine the saturation states of water samples with respect to calcite in surface

water and groundwater samples and results are presented in Appendix B. There are no

surface water samples with SI between -0.3 and 0.3, or above 0.3, indicating all surface

water samples are subsaturated with respect to calcite. Eighteen percent of groundwater

samples have SIcalcite values > 0.3, indicating supersaturation, 12% have values between

-0.3 and 0.3, indicating saturation, and the remaining 70% are subsaturated with respect

to calcite. Of the groundwater samples that are supersaturated, the average SIcalcite is 0.67

0.31, ranging from 0.30 to 1.23. SIcalcite values indicating saturation or supersaturation,

suggest the possibility of calcareous cement and/or veins within the ERW aquifers,

dissolution of carbonate bedrock, and the potential for precipitation of CaCO3 within

these groundwater samples. Supersaturation with respect to calcite indicates the

likelihood of precipitation of calcite (CaCO3) in order to reestablish equilibrium.

There can be losses of DIC as groundwater flows towards the surface, feeding

surface water. The CO2(aq) within the groundwater usually has a higher partial pressure

in comparison to atmospheric CO2(g), which causes degassing of CO2 (Grasby, 1997;

Telmer and Veizer, 1999). Photosynthesis occurring within surface water can also cause

losses of CO2, and DIC (Telmer and Veizer, 1999).

77

Determination of the dominant species comprising DIC in surface water and

groundwater samples can be achieved using measured alkalinity concentrations and pH

values. In surface water samples (n=86), HCO3- comprised nearly 100 % of DIC. In

groundwater (n=50), only 76 9.2 % of DIC was comprised of HCO3-, whereas 24

3.2 % can be attributed to H2CO3. According to pH and alkalinity results, CO32- is not a

significant constituent of DIC within the watershed.

5.3.1 Dissolved Inorganic Carbon (13CDIC)

The average atmospheric 13CCO2 value is -8 ‰ (Pawellek and Veizer, 1994;

Dubois et al. 2010). As atmospheric CO2 equilibrates with aqueous CO2, and dissociates

to HCO3, carbon isotope fractionation occurs (Appelo and Postma, 2005). Therefore, an

enrichment factor must be used as expressed by:

(HCO3- – CO2) = 9.483 * 103/T – 23.89 (5.8)

where T is expressed in kelvin (Mook et al. 1974). The historical average annual air

temperature based on weather stations within and near the ERW is 9.3 C (Table 2.1).

Based on observed temperatures, the enrichment factor for carbon isotope fractionation

between CO2 and HCO3 was calculated to be +9.7 ‰; this value was used for further

isotope fractionation calculations. The resulting 13CDIC value for HCO3 derived from

atmospheric CO2 is +1.7 ‰.

Marine carbonates have an average 13C value of ~0 ‰ (Appelo and Postma,

2005). On Vancouver Island, calcite originating from hydrothermal fluids; precipitating

in fractures or veins of igneous rocks have more negative 13C values than marine

carbonates, ranging from -5 to +2 ‰ (Al-Aasm et al., 1995). H2CO3 from soil CO2 can

react with calcite veins during subsurface weathering, the 13CDIC can be calculated from

78

the relative proportions of soil and carbonate-derived DIC. DIC sourced from soil CO2

produced from the decay and oxidation of organic matter has an average value of -27 ‰

(Clark & Fritz, 1997; Dubois et al., 2010). DIC derived from carbonate dissolution by

soil CO2 has an isotopic value that is an intermediate between the two sources of carbon

(soil CO2 and calcite). Hence, the above 1:1 mixture of C derived from soil CO2 + the

enrichment factor and C derived from carbonates should theoretically have a 13CHCO3

between -6.3 and -2.8 ‰, with an average value of -4.6 ‰ (Dubois et al., 2010).

In surface water, respiration, photosynthesis, and atmospheric exchange can also

effect the isotopic composition of DIC. Aquatic photosynthesis preferentially consumes

12C, causing a relative enrichment of 13C in the remaining DIC, with the extent of

enrichment being dependent on the amount of CO2 available (Baird et al., 2001). The

resulting organic matter produced by aquatic photosynthesis is depleted with respect to

13C. Respiration consumes the 13C depleted organic matter and produces CO2 with a

similar 13C value, typically near -27 ‰ (Keough et al., 1998). Degassing of CO2 occurs

when the system is oversaturated with respect to CO2; this can lead to higher 13C values

in the remaining DIC (Dubois et al., 2010). Exchange with atmospheric CO2 (13C = -8

‰) can alter the isotopic composition of surface water to 13C values of ~ 0 ‰ for DIC

that is in equilibrium with atmospheric CO2 (Mook et al., 1974).

79

5.3.2 Surface Water

Figure 5.9 depicts the downstream trend of 13C values of DIC for surface water

samples over six sampling periods. In August 2010, October 2010, and February 2011,

13CDIC values were very low, with values ranging from -19.9 to -32.2 ‰. There are two

elevated values within these 3 sampling periods (-19.9 and -20.7 ‰); otherwise there is

little variation in 13CDIC values with downstream distance, with a standard deviation of

1.4 ‰ (Figure 5.9). In September 2011, May 2011, and July 2011, 13CDIC values of

surface water samples were much higher, ranging from -10.8 to +0.4 ‰ in September

2011, and July 2011 respectively (Figure 5.9). In September 2011, there was a slight

trend of decreasing 13CDIC values with downstream distance (+0.4 to -3.3 ‰). In May

2011 and September 2011, 13CDIC values were rather constant with increasing

downstream distance (Figure 5.9).

There is minimal spatial variation, however there is a marked variation

temporally: in May 2011, July 2011, and September 2011 there was an average 13CDIC

value of -4.1 2.4 ‰ observed, while in August 2010, October 2010, and February 2011

there was an average 13CDIC value of -28.5 2.3 ‰ (Figure 5.9). While there is temporal

variation, it is not seasonal, instead the first 3 sampling periods (August 2010, October

2010, and February 2011) exhibit values heavily depleted with respect to 13C, where the

last 3 sampling periods (May 2011, July 2011, and September 2011) present much higher

13CDIC values. This could be due to an analytical flaw during the first three sampling

campaigns, however sampling and laboratory methodology did not change throughout the

study. Interestingly, groundwater samples also had very low 13CDIC values.

80

Groundwater samples were collected during July 2011, and were analyzed in

conjunction with July 2011 surface water samples, which had much higher 13CDIC

values. Therefore without resampling, or further testing of possible sampling or

laboratory errors, the very low 13CDIC values observed in August 2010, October 2010,

February 2011, and in sampled groundwater cannot be discounted. The first three

sampling periods had 13CDIC values well within the range of groundwater samples;

therefore, the temporal variability observed could likely be due to increased precipitation

and exchange with atmospheric CO2, causing an enrichment in 13C as seen in the last 3

sampling periods.

5.3.2.1 Sources of DIC

The primary sources of DIC in surface water samples are either from lithospheric,

pedospheric, or atmospheric origin: DIC sourced from weathering and dissolution of

bedrock, CO2 enriched soil water via respiration of organic material within the soil zone,

and direct input and exchange with atmospheric CO2. DIC sourced from carbonate

dissolution is likely minimal due to the small amount carbonate rocks within the basin

(Massey and Friday, 1987; Mustard, 1994; Yorath, 2005). CO2 sourced from oxidation

and decay of organic matter occurring in the soil zone has an average value of -27‰, the

resulting CO2 derived DIC has a 13CDIC value of -17.3 ‰. DIC sourced from

atmospheric CO2 has a 13CDIC value of +1.7 ‰ (Pawellek and Veizer, 1994). In August

2010, October 2010, and February 2011 the average 13CDIC value is ~ -29 ‰. These low

observed 13C values are even lower than typical of DIC sourced from CO2 via

respiration of organic matter (-27 ‰), where HCO3- would have a value of ~ -17.3 ‰.

Since all pH values of surface water are above 6.3, the majority of DIC should be in the

81

form of HCO3-. The very low 13C values could be due to increased respiration of organic

matter within the riverine system, or influx of low 13C groundwater (Figure 5.9; Dubois

et al., 2010; Telmer & Veizer, 1999). There are 3 small peaks of higher 13C values in

August 2010, October 2010, and February 2010, with values of -19.9, -24.7, and -20.7 ‰

respectively. There are numerous factors that could lead to increased values of 13CDIC,

degassing of CO2 exchange of surface water CO2 with atmospheric CO2, direct input of

atmospheric CO2 from precipitation, and aquatic photosynthesis (Dubois et al., 2010;

Telmer and Veizer, 1999). All sampling of surface water was conducted within 3 days for

each sampling period, atmospheric exchange of CO2 is unlikely in explaining the small

peaks seen in these 3 sampling periods.

In May 2011, July 2011, and September 2011, the main source of DIC in surface

waters was from atmospheric CO2, although the average 13CDIC value is -4.1 2.4 ‰

which is lower than atmospheric CO2 (+1.7 ‰). The lower values observed in surface

water are likely due to an additional source of DIC from 12C depleted soil CO2 and/or

calcite dissolution (Figure 5.9). Figure 5.10 depicts the relative 13CDIC values based on

mixing between atmospheric CO2 and soil DIC end member sources. Eighty percent of

samples lie within the 25 and 50% soil CO2 mixing lines. Therefore the main DIC source

was likely from atmospheric CO2, with minor to significant contributions from soil CO2

with possible small contributions from carbonate dissolution (Figure 5.10). Fourteen

percent lie above the 25% mixing line, all samples are from September 2011, suggesting

the majority of DIC in this sampling period was from atmospheric sources. Only 5% of

samples, all from July 2011 lie below the 50% mixing line, suggesting in this sampling

82

period more DIC is contributed from soil CO2 than in February or September 2011

(Figure 5.10).

13C of DIC were plotted against DIC concentration, expressed in HCO3-

concentrations (Figure 5.11). 13CDIC is not dependant on DIC concentration, therefore

there is no trend between alkalinity and 13CDIC values for surface water. This could be

due to the low variation in HCO3 concentrations with an average value of 20 4 mg/L.

Figure 5.9 Downstream trend of 13CDIC values of surface water samples over six sampling periods in relation to range of groundwater 13CDIC values and 13CDIC values of various DIC sources.

83

Figure 5.10 May, July, and September 2011 sampling periods with 25 and 50% mixing lines of DIC sourced from soil CO2 with atmospheric CO2.

Figure 5.11 13CDIC versus DIC concentration as expressed in HCO3 for surface water samples.

-40.0

-35.0

-30.0

-25.0

-20.0

-15.0

-10.0

-5.0

0.0

5.0

10.0

15.00 17.00 19.00 21.00 23.00 25.00

δ 13

CD

IC(‰

) (V

-PD

B)

HCO3 (mg/L)

August 2010

October 2010

February 2011

May 2011

July 2011

September 2011

84

5.3.3 Groundwater

5.3.3.1 Sources of DIC

The 13C values of DIC for groundwater ranged from -34.6 to -9.4 ‰ with an

average of -21.0 5.0 ‰ (n=50). The majority of groundwater samples (86%) have

lower than expected (-17.3 ‰) 13CDIC value for DIC sourced from soil CO2. This

suggests that respiration of organic matter in addition to soil CO2 derived DIC is the

dominant source of DIC for the majority of groundwater samples (Figure 5.12). Also,

24% of groundwater samples have a pH <6.3, therefore DIC is dominantly comprised of

H2CO3 or CO2. Therefore for these samples, it would be expected that if DIC was

sourced primarily from soil CO2, the 13C value could be as low as -32 ‰. Of

groundwater samples, 14 % lie between the expected values of DIC sourced from soil

CO2 and the dissolution of calcite (Figure 5.12). Therefore, in 14 % of groundwater

samples, DIC is sourced from primarily soil CO2, with a secondary contribution from

dissolution of calcite (Figure 5.12). There is not a clear correlation between 13C values

and depth, but the lowest 13C values correspond to the shallowest wells (<20 m). All

wells with depths >20 m (with the exception of one), have 13CDIC values between -25

and -9 ‰, suggesting DIC is sourced from soil CO2 and possible calcite dissolution

(Figure 5.12).

13C values of groundwater samples were plotted against DIC concentration,

expressed as HCO3 (Figure 5.13). At low alkalinity (<50 mg/L HCO3) there is no

correlation with 13CDIC. The 13C values range from -34.6 to -9.4 ‰ over a change in

DIC concentration of only ~30 mg/L (Figure 5.13). Whereas, groundwater samples with

85

higher DIC concentrations (>100 mg/L) had more consistent 13CDIC values ranging from

-23.3 to -11.2 ‰. These values were close to the average groundwater 13CDIC value of

-16.9 ‰ and within the standard deviation of 12.5 ‰. This suggests that groundwater

samples with high DIC concentrations are likely sourced from soil CO2. Additionally,

more consistent 13CDIC values imply there is a higher degree of mixing of water within

the aquifer, and therefore a longer residence time.

Figure 5.12 Well depth versus 13CDIC values of groundwater samples.

86

Figure 5.13 13CDIC versus DIC as expressed in HCO3- for groundwater samples.

5.4 Sulphate

Sulphate can be derived from natural sources such as the dissolution of sulphate

minerals, and the oxidation of pyrite. Anthropogenic activities can contribute sulphate

from industrial emissions from sour gas processing, burning of fossil fuels, fertilizers,

soaps and detergents, or municipal effluent (Clark & Fritz, 1997; Krouse & Grinenko,

1991; Mayer, 2005). These sulphate sources may have distinct δ34S values and therefore,

the isotopic composition of sulphate may assist in tracing sources of sulphur.

5.4.1 Sulphate concentrations

Surface water samples had an average SO4 concentration of 1.90 1.92 mg/L,

ranging from 0.80 to 16.45 mg/L. Groundwater samples had an average SO4

concentration of 4.37 3.78 mg/L, ranging from 0.28 to 20.09 mg/L. Figure 5.14

illustrates the relationship between SO4 concentrations of surface water samples with

87

increasing distance downstream. Samples from July 2011 and September 2010 show little

variation with increasing flow distance, whereas August 2010, February 2011, and May

2011 show small increases in SO4 concentration in the direction of flow, particularly 35

to 40 km downstream. The largest variation in SO4 concentrations moving downstream

occurred in October 2010, with a maximum concentration of 16.45 mg/L near the estuary

(Figure 5.14). Depending on the level of the tide, an influx of seawater could explain the

elevated SO4 concentrations. SO4

concentration in seawater can be >1000 mg/L; therefore

even limited mixing with seawater could greatly influence SO4 concentrations in surface

water samples at the mouth of the river (Manzano, 2005).

Figure 5.14 a) Downstream trend of SO4 concentrations of surface water samples over

six sampling periods. b) Close-up view of SO4 versus distance from headwaters diagram.

88

5.4.2 Isotopic Composition of Sulphate (34SSO4 and 18OSO4)

The source of sulphate in surface water and groundwater can be traced by

applying a dual isotope approach using 34S and 18O values of sulphate. Sulphate can be

sourced from the atmosphere, pedosphere, and lithosphere. Sulphate sourced from

atmospheric deposition in industrialized countries ranges from -1 to +6 ‰ (Mayer, 2005).

In coastal regions like Vancouver Island, seaspray is often the dominant source of

atmospheric sulphate and 34S values can be as high as +21 ‰ (Wadleigh et al., 1996).

18O values of sulphate in atmospheric deposition typically range between +5 and +17 ‰

in temperate climates, with lower values observed in winter and high values in summer

precipitation (Mayer, 2005).

Lithospheric sources of sulphate include sulfide minerals that oxidize to form

sulphate, evaporites, and mantle and igneous sources. The oxidative weathering of sulfide

minerals to form aqueous sulphate is associated with a negligible sulphur isotope

fractionation. Therefore, the resulting aqueous sulphate has a similar 34S value as the

reduced parent sulfide mineral (Seal, 2006). Sulphate derived from oxidation of sulfide

minerals typically has negative 34S values with oxygen isotope ratios lower than those of

sulphate from evaporitic or atmospheric sources (Mayer, 2005; Seal, 2006). Sulphate

derived from the dissolution of evaporites can have 34S values that range between +8

and +35 ‰ and 18O values that range from +7 to +20 ‰ (Claypool et al., 1980; Mayer,

2005). Sulphate resulting from the weathering of igneous compounds has characteristic

34S and 18O values near 0 ‰ (Mayer, 2005).

Sulphate in surface water and groundwater can also be contributed from

anthropogenic sources that can produce a wide range of isotopic compositions. Municipal

89

effluent is an anthropogenic source of sulphate that may be derived from soaps,

detergents, and additives used in water treatment (Mayer, 2005). Additional sources of

sulphate include landfills, and fertilizers (Mayer, 2005). Anthropogenic sources have 34S

and 18O values ranging from 0 and +5 ‰, and +5 and +15 ‰ respectively, which makes

it difficult to differentiate this sulphate from atmospheric deposition (Figure 5.15; Mayer,

2005).

Processes such as mixing of sulphate from different sources and bacterial

(dissimilatory) sulphate reduction can make sulphate source deduction difficult. During

bacterial (dissimilatory) sulphate reduction, bacteria preferentially metabolize the lighter

32S and 16O isotopes, leaving the remaining sulphate enriched with respect to 34S and 18O

(Strebel et al., 1990).


The overall average 34S value of sulphate for all surface water samples was

-2.0 ± 1.9 ‰ (42 samples; Figure 5.15). The average 18O values of sulphate in May

2011 and September 2011 were -3.2 ± 0.6 ‰ and -2.7 ± 1.0 ‰ respectively. The

difference between the mean values in May and September 2011, are within the range of

both standard deviations, indicating there is no significant variation between these two

sampling periods. In July 2011 the average 34S value of sulphate was +0.2 ± 0.6 ‰,

which is 3.4 and 2.9 ‰ higher than the mean value in May and September 2011

respectively. These differences are beyond the statistical variation in all sampling

periods, signifying there is small temporal variation in 34S of sulphate in July 2011

(Figure 5.15).

90

The overall average 18O value of sulphate in surface water samples was -2.2 ±

2.6 ‰. Although there was one sample in May of 2011 with a 18O value of +13.5 ‰

(Figure 5.15). This sample was taken near the estuary during high tide, and corresponds

with a high TDS value of 249 mg/L indicating an influx of seawater, and is not included

in further statistical calculations. The overall average 18O value of the remaining

samples is -2.6 ± 0.5 ‰. The average 18O value of sulphate in May, July, and September

2011 was -2.7 ± 0.5, -2.4 ± 0.6, and -2.6 ± 0.5 ‰ respectively. There is only a variation

of 0.2 ‰ for 18O between all sampling periods, which is within the statistical variation

seen within each sampling period, and within the measurement uncertainty of ± 0.5 ‰,

indicating there is no temporal variation in 18O values of sulphate (Figure 5.15).

91

Figure 5.15 a) Spatial and temporal variation of δ34SSO4 values of surface water samples in relation to increasing distance from the headwaters of the Englishman River. b) Spatial and temporal variation of δ18OSO4values of surface water samples with increasing distance from headwaters of the Englishman River. c) Expanded view of δ18OSO4 vs. distance from headwaters for surface waters collected in May 2011.

92

5.4.2.2 Groundwater

Groundwater samples have average 34S and 18O values of sulphate of +2.0 ± 5.9

and +0.2 ± 3.3 ‰ respectively. Overall, groundwater samples are more variable in 34S

and 18O values of sulphate than surface water samples. 34S values of groundwater

sulphate are highly variable at shallower depths (< 50 m) with values ranging from -3.0 to

+15.0 ‰, whereas at greater depths 34S values range from -2.0 to +7.5 ‰. 18O values

of sulphate are variable at all depths, although 80 % of samples from shallow depths (>

20 m) lie within a range of -3.2 and +2.2 ‰, which is within the standard deviation of all

groundwater samples. At depths > 20 m, 18O values range from -5.4 to +7.1 ‰ and are

much more variable (Figure 5.16). Therefore, there is no distinct trend in 34S and 18O

values of groundwater samples and depth.

93

Figure 5.16 Depth vs. 34SSO4 and 18OSO4 values for groundwater samples.

5.4.3 Discussion of Sulphate Sources


Surface water samples are plotted on a dual 34S and 18O isotope diagram to aid

in interpretation of possible sulphate sources (Figure 5.17). Ninety-seven percent of

surface water samples had 34S and 18O values within the typical range of sulphate

sourced from sulfide oxidation (Figure 5.17). One sample from May 2011 had a similar

34S value to all other surface water samples, however the sample was enriched with

respect to 18O with a value of +13.5 ‰, indicating atmospheric deposition as the

dominant source of sulphate (Figure 5.17; Mayer, 2005).

94

Figure 5.17 a) Temporal variation in δ34S and δ18O values of surface water samples in relation to typical ranges of 34S and 18O values of various sulphate sources (modified from Mayer, 2005). b) Close-up of the δ18O - δ34S diagram.

5.4.3.2 Groundwater

Groundwater samples are presented on a dual 34S and 18O isotope figure to aid

in interpretation of possible sulphate sources (Figure 5.18). Fifty-five percent of

groundwater samples lie in the typical range of sulphate sourced from sulfide oxidation.

Thirty percent of samples had similar 34S and 18O values to sulphate sourced from the

soil zone (Figure 5.18; Mayer 2005). Atmospheric deposition appeared to be the source

of sulphate for 11 % of groundwater samples. However, four of those samples overlapped

with additional sulphate sources: two with anthropogenic sulphate, and two with sulphate

sourced from evaporite dissolution (Figure 5.18; Mayer, 2005). There are, however no

95

major evaporite deposits within the study area, therefore it is unlikely that groundwater

sulphate is derived from evaporite dissolution (Massey et al., 1995). The two samples

overlapping with typical anthropogenic sources of sulphate do not have elevated sulphate

concentrations (2.15 to 3.36 mg/L) therefore input from anthropogenic sources is likely

minimal.

Figure 5.18 34S and 18O values of sulphate for groundwater samples in relation to typical ranges of 34S and 18O values of various sulphate sources (modified from Mayer, 2005).

34S and 18O values were plotted against sulphate concentrations for

groundwater samples (Figure 5.19). High 34S and 18O values correlate with lower

sulphate concentrations (< 10 mg/L), whereas the few samples with high sulphate

concentrations are relatively depleted with respect to 34S and 18O (Figure 5.19). Typical

trends relating the isotopic composition of sulphate to its concentration is depicted in

96

Figure 5.20 (Mayer, 2005). Comparing Figure 5.19 with 5.20, an admixture of sulphate

from sulfide oxidation, or bacterial (dissimilatory) sulphate reduction could explain the

trend seen in the groundwater samples. However, all surface water samples (with the

exception of one) had 34S and 18O values similar to typical values of sulphate sourced

from sulfide oxidation. If an admixture of sulphate from sulfide oxidation were affecting

the trend seen within groundwater samples, one would expect to see surface water

samples with elevated sulphate concentrations, as observed in groundwater. It is more

plausible that waters recharging groundwater are similar to that of surface water, and

through bacterial (dissimilatory) sulphate reduction, groundwater sulphate becomes

increasingly enriched with respect to 34S and 18O (Figure 5.21).

97

Figure 5.19 34S and 18O values of groundwater against sulphate concentrations.

-15.0

-10.0

-5.0

0.0

5.0

10.0

15.0

20.0

25.0

δ34 S

‰(V

-CD

T)

-15.0

-10.0

-5.0

0.0

5.0

10.0

15.0

20.0

25.0

0.0 5.0 10.0 15.0 20.0 25.0

δ18 O

‰ (

VS

MO

W)

SO42- (mg/L)

98

Figure 5.20 Trend of 34S and 18O values against sulphate concentrations during a) admixture of sulphate from sulfide oxidation b) bacterial (dissimilatory) sulphate reduction (modified from Mayer, 2005).

99

Figure 5.21 Dual isotope plot of 34S and 18O values depicting the isotopic evolution of

sulphate in groundwater during bacterial (dissimilatory) sulphate reduction in relation to surface water samples.

5.5 Nitrate

A variety of natural and anthropogenic processes can influence nitrate in aqueous

systems. Natural processes include the oxidation of ammonium (NH4+) to ammonia

(NH3), and nitrification of soil organic matter mediated by bacteria (Kendall et al., 2007).

Lightning and biogenic soil emissions result in nitrate formation in the atmosphere via

nitric and nitrous oxide pathways (N2O and NO respectively). N2O and NO are released

into the atmosphere, which oxidize to HNO3, and then readily dissociate to form NO3

(Kendall et al., 2007). Atmospheric nitrate can be introduced to aquatic systems either by

wet or dry deposition, the latter is deposited as particulate NO3- (Kendall et al., 2007).

Anthropogenic sources of nitrate include: biogenic biomass burning, fossil fuel burning

100

(both from industrial processes and vehicles), manure, septic systems, waste water

treatment plants, and synthetic fertilizers (Kendall et al., 2007).

Elevated levels of NO3- in aquatic systems can negatively impact both

environmental and human health. High NO3- concentrations in surface water and

groundwater can lead to an overall loss of biodiversity through acidification, hypoxia,

and/or eutrophication especially in coastal marine waters (Camargo & Alonso, 2006;

Galloway et al., 2003). Ingestion of water polluted with NO3- levels exceeding the

Maximum Allowable Concentration (MAC) of 45 mg/L NO3, can have negative health

effects (Health Canada, 2012). One particularly serious condition is methemoglobinemia

- a condition particularly affecting infants, where the oxygen-carrying capacity of

hemoglobin is blocked (Camargo & Alonso, 2006).

Natural attenuation of NO3- in groundwater can occur through denitrification.

During denitrification, bacteria metabolize NO3-, which is reduced to N2, N2O, or NO

gases (Kendall et al., 2007). The role of denitrification in the reduction of NO3- in

riverine waters is somewhat unclear, but considered very important (Burgin & Hamilton,

2007; Mayer et al., 2002; Seitzinger et al., 2002).

5.5.1 Nitrate Concentrations

Concentrations of NO3- for surface water and groundwater samples were

discussed in detail in Chapter 4. Overall surface concentrations were low and no samples

approached or exceeded the MAC. NO3- concentrations ranged from below detection

limit (0.02 mg/L) to 4.65 mg/L with an average value of 0.26 0.73 mg/L. Nitrate

concentrations in groundwater samples ranged from below detection limit to 25.71 mg/L

with an average value of 1.28 3.94 mg/L.

101

5.5.2 Isotopic Composition of Nitrate (15NNO3 and 18ONO3)

The source of nitrate in surface water and groundwater can be traced by applying

a dual isotope approach using 15N and 18O values of nitrate. Nitrate source

determination is possible because different sources often have distinctive combinations of

δ15N and δ18O values (Mayer, 2005). Nitrate sourced from atmospheric deposition

typically has δ15N values ranging from -10 to +8 ‰ with δ18O values as high as +80 ‰.

Synthetic nitrogen-containing fertilizers have δ15N values near 0 ‰, and δ18O values

ranging from +19 to +25 ‰ (Kendall & MacDonnell, 1998; Wassenaar, 1995). Nitrate

input sourced from manure and sewage has δ15N values from +7 to +20 ‰ or higher,

with corresponding δ18O values typically less than 10 ‰ (Mayer, 2005). Nitrate within

the soil zone, which is produced through nitrification processes is difficult to differentiate

because the δ15N value alone is not distinct from other nitrate sources. However, δ18O

values are typically less than 15 ‰, making distinction possible (Kendall & MacDonnell,

1998; Mayer, 2005; Mayer et al., 2001).

Various isotope fractionating processes affect the isotopic composition of

nitrogen throughout the nitrogen cycle, ultimately affecting the resulting nitrate isotopic

composition. Processes such as nitrification – the conversion of ammonium (NH4+) to

nitrate preferentially convert the lighter isotope 14N into nitrate, where the remaining

NH4+ becomes enriched in 15N (Kendall et al., 2007). Conversion to nitrate also

incorporates three new oxygen atoms, resulting in δ18O values of nitrate ranging from 0

to + 15 ‰ (Mayer, 2005; Mayer et al., 2001). Volatilization is the transformation of NH4+

to ammonia (NH3), where 14N is incorporated into NH3, leaving the remaining NH4+

enriched with respect to 15N (Hübner, 1986). An additional process affecting the isotopic

102

composition of nitrate is microbial denitrification; microorganisms preferentially

metabolize the 14N and 16O, leaving the remaining nitrate enriched in 15N and 18O, as

nitration concentrations decrease (Böttcher et al., 1990).


Due to low NO3- concentrations, it was only possible to determine δ15N and δ18O

values from six surface water samples. Surface water samples had δ15N values ranging

from +1.3 to +12.2 ‰, with an average value of +4 4 ‰. δ18O values ranged from +1.0

to +13.1 ‰, with an average value of +10 4 ‰.

5.5.2.2 Groundwater

Like surface water samples the majority of groundwater samples had low

concentrations of nitrate making isotopic analysis difficult. Therefore δ15N and δ18O

values were only determined for four samples. Groundwater samples had δ15N values

ranging from +3.8 to +14.8 ‰, with an average value of +9 3 ‰. δ18O values ranged

from -0.4 to +4.2 ‰, with an average value of +1 2 ‰.

5.5.3 Discussion of Nitrate Sources


Surface water samples are presented on a dual 15N and 18O isotope figure to aid

in interpretation of possible nitrate sources (Figure 5.22). Eighty-three percent of surface

water samples had 15N and 18O values within the typical range of nitrate sourced from

soil nitrification (Figure 5.22). One sample had 15N and 18O values characteristic of

nitrate sourced from sewage or manure (Figure 5.22; Chang et al., 2002; Mayer, 2005;

Mayer et al., 2002). There was no correlation in surface water samples between nitrate

103

concentration and nitrate source, as samples with the highest and lowest nitrate

concentrations were sourced from soil nitrification (Figure 5.23).

5.5.3.2 Groundwater

15N and 18O values of groundwater samples were plotted together with surface

water samples on a dual isotope diagram of 18O versus 15N (Figure 5.22). Half of

groundwater samples had similar 15N and 18O values typical of nitrate sourced from

soil nitrification, while the remaining 2 samples had values characteristic of nitrate

sourced from sewage and manure. However, one sample had a 15N value near the upper

limit of values normally associated with nitrate from soil nitrification, therefore possible

mixing of nitrate from soil nitrification, and sewage and manure could be occurring

(Chang et al., 2002; Mayer, 2005). It should be noted that the two samples with the

highest nitrate concentrations (7.45 and 25.71 mg/L) were the most enriched with respect

to 15N (Figure 5.23). These two samples were taken from wells located near small-scale

agricultural farms in a rural area; therefore contamination from manure application,

and/or septic systems is likely.

104

Figure 5.22 15N and 18O values of surface water and groundwater samples with typical ranges of 15N and 18O values for various nitrate sources (modified from Mayer, 2005).

Figure 5.23 15N and 18O values of surface water and groundwater samples against

nitrate concentrations.

105

5.6 Summary

Groundwater and surface water samples have very similar δ2H and δ18O values.

However, the mean value of δ18O and δ2H values of groundwater samples are lower than

surface water samples, suggesting groundwater is more highly influenced by winter

precipitation and/or meltwater sourced from Mt. Arrowsmith where winter snowfall often

exceeds 15 m annually (Clermont, 2011). This winter contribution results in lower δ18O

and δ2H isotope values. Groundwater samples are also less variable than surface water

samples, due to higher the greater residence time of groundwater, which allows for a

higher degree of mixing. Surface water samples show little spatial variation, however,

δ2H and δ18O values do vary with increasing flow distance downstream. In July 2011

there was a slight decrease in δ2H and δ18O values indicating an introduction of a water

source with lower δ2H and δ18O values, possibly due to a converging stream or

groundwater discharge. In October 2010 and September 2011, there was a shift to higher

δ2H and δ18O values. In the fall this could be due to increased precipitation from

temperate to warm rains with higher δ2H and δ18O values, or evaporation. In May 2011,

this could be attributed to snow melt and winter precipitation contributions in the

headwaters, and then influence from relatively 2H and 18O depleted rains compared to

downstream sections of the river.

DIC in surface water was derived from a variety of sources depending on the

sampling period. In August 2010, October 2010, and February 2011 surface water

samples had DIC sourced from CO2 enriched soil water via respiration of organic

material within the soil zone. In contrast, for samples taken in May 2011, July 2011, and

September 2011, DIC is sourced mainly from atmospheric CO2 with minor contributions

106

from calcite dissolution and soil CO2. Dissolution of calcite contributes DIC to 14 % of

groundwater samples. Soil CO2 is the dominant source of DIC for the 86 % of

groundwater samples, with a significant influence from respiration of organic matter.

The majority of surface water samples and 55 % of groundwater samples

contained sulphate sourced from sulfide oxidation. The remaining 30 and 11 % of

groundwater samples have sulphate sourced from soil and atmospheric sources

respectively. Surface water and waters recharging groundwater likely have similar

sulphate sources, therefore through bacterial (dissimilatory) sulphate reduction,

groundwater samples become increasingly enriched with respect to 34S and 18O.

Nitrate in surface waters is primarily sourced from soil nitrification. Half of the

groundwater samples with measurable nitrate concentrations, contained nitrate sourced

from soil nitrification. The other half was sourced from sewage and manure. The latter

samples had the highest nitrate concentrations, and were sampled from wells near small-

scale agricultural farms in rural areas, indicating contamination from manure application

and/or septic systems.

107

6 Major Ion Geochemistry

6.1 Introduction

There are many factors controlling the concentrations of solutes in aquatic

systems. Weathering of bedrock has been shown to be a dominant source of solutes in

surface water and groundwater (Drever, 1997). As meteoric water filters through the soil

and the unsaturated zone, chemical evolution takes place as infiltrating water reacts with

the soil and aquifer materials (Drever, 1997). Rock-water interactions liberate ions into

the aqueous phase, which are then taken up and transported into the groundwater. Longer

groundwater residence times often result in increased solute concentrations due to

increased rock-water interactions (Frape et al., 1984; Grasby et al., 1999). Other mineral

related controls, including ion exchange, and dissolution and precipitation of minerals,

show that bedrock mineralogy is a controlling factor in resulting water chemistry (Frape

et al., 1984).

Atmospheric, biological, and anthropogenic inputs can also affect the

geochemistry of surface water and groundwater. Atmospheric inputs include both wet

and dry deposition, which contribute solutes to aqueous systems. Biological processes

include respiration, decay of organic matter, and the uptake and release of nutrients from

plants or microorganisms (Drever, 1997). Production of CO2(g) in the soil zone through

decay of organic matter decreases the pH, which promotes mineral weathering (Drever,

1997). Anthropogenic inputs of solutes to aqueous systems within the study area include

timber harvesting, agriculture, rural residential, urban residential, and light industrial

development (Barlak et al., 2010).

108

In this chapter, major water types of surface water and groundwaters were

distinguished. Solute sources of groundwater and surface water samples were determined

by assessing inputs from atmospheric, biologic, and anthropogenic sources; possible

rock-water interactions were explored through the use of geochemical modeling.

6.2 Precipitation

Atmospheric deposition via precipitation can influence solute concentrations in

surface water and groundwater. Understanding the chemical composition and solute

sources of precipitation can aid in understanding the overall evolution of the surface

water and groundwater geochemistry. Precipitation is an efficient pathway for removing

gases and particles from the atmosphere (Junge & Werby, 1958; Salve et al., 2008).

Atmospheric aerosols (sea salt, crustal dust, and biogenic aerosols) are the primary source

of dissolved species in rainwater (Négrel & Roy, 1998). The proportion of dissolved

species sourced from marine and non-marine origins will be outlined in the following

sections. Geochemical data of Saturna Island precipitation obtained from CAPMoN was

used in this chapter to assess sources of solute concentrations in precipitation. Molar

concentrations were used in calculation of ion ratios.

6.2.1 Marine Contribution to Precipitation

Geochemical data of Saturna Island precipitation obtained from CAPMoN was

used to calculate ion ratios used in assessment of marine contribution to precipitation. To

estimate the marine contribution of ions to precipitation, equivalent ratios were calculated

using a reference element. The reference element must not undergo fractionation during

aerosol formation and must be of exclusively of marine origin (Keene, Pszenny,

Galloway, & Hawley, 1986; Négrel & Roy, 1998). Na is commonly used as a reference

109

element for calculation of the marine contribution to precipitation due to its conservative

behaviour (Berner & Berner, 1987), and therefore was also used in this study. The

correlation coefficients of precipitation between Na and Mg, and Cl were calculated to be

0.99 and 1.00 respectively (Table 6.1). Also the temporal trends of Na, Mg, and Cl

concentrations are similar with high concentrations in the winter months, and low

concentrations in the summer months (Figure 6.2). Using equivalent ratios found in sea

water and comparing them to ratios observed in precipitation samples, the sea salt (ss)

contribution to precipitation for Mg and Cl was calculated to be 91.2 and 100%

respectively (Keene et al., 1986; Table 6.2 and 6.3). Therefore essentially all of the Mg,

Cl, and Na in the precipitation samples are sourced from sea salt. In contrast Ca, K, and

SO4 have percent ss fractions of 30.7, 50.2, and 19.4 respectively (Table 6.3). Therefore

only portions of these ions are of marine origin, with additional lithospheric and

anthropogenic sources contributing these ions to precipitation.

Table 6.1 Correlation coefficients of ionic species in precipitation.

Ion H K Na Ca Mg Cl NO3 SO4

H 1 K -0.37 1 Na -0.89 0.43 1 Ca -0.14 0.90 0.15 1 Mg -0.87 0.57 0.99 0.30 1 Cl -0.88 0.42 1.00 0.13 0.98 1

NO3 0.61 0.44 -0.49 0.64 -0.37 -0.50 1

SO4 0.61 0.38 -0.50 0.59 -0.38 -0.51 0.80 1

110

Table 6.2 Equivalent ratios of various species to Na in precipitation and seawater (Keene et al., 1986).

Table 6.3 Percent sea salt (ss) and non sea salt (nss) fraction of Saturna precipitation, estimated using Na as a reference species for seawater.

Ion Ratio Saturna SeawaterCa/Na 0.143 0.0439 Mg/Na 0.249 0.227 K/Na 0.0434 0.0218 Cl/Na 1.16 1.16

SO4/Na 0.624 0.121

Ion SS NSS% %

Ca 30.7 69.3 Mg 91.2 8.76 K 50.2 49.8

Cl 100 0

SO4 19.4 80.6

111

Figure 6.1 Concentrations of solutes against chloride in Saturna precipitation monthly averages (1989-2007).

112

Figure 6.2 Temporal variation of major ions in precipitation (eq/L).

6.2.2 Non-Marine Contribution to Precipitation

Non-marine contributions to dissolved solutes in precipitation can be sourced

from anthropogenic activities, biological emissions and crustal dust. Excess SO4 over

land commonly ranges from 10 to more than 100 mol/L; the average SO4 in the Saturna

Island precipitation samples is 12.7 2.0 mol/L (Négrel & Roy, 1998). The non-sea salt

0

5

10

15

20

25

30

35

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0

20

40

60

80

100


0

5

10

15

20

25

30


02468

10121416


0

10

20

30

40

50

60

70

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0

2

4

6

8

10

12


0

5

10

15

20

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0

1

2

3

4


a) SO42-

c) Cl- d) NH4+

e) Na+

b) NO3-

f) Ca2+

g) Mg2+ h) K+

113

(nss) fraction of SO4 is estimated to be 80.6%, therefore the majority of SO4 and likely all

of NO3 are sourced from anthropogenic emissions mainly due to burning of fossil fuels

(Berner & Berner, 1987; Bertrand et al., 2009). SO4 and NO3 have a correlation

coefficient of 0.80, and a similar temporal trend to NH3, with concentration peaks in the

spring and lows in the winter. This suggests that the majority of SO4, NO3 and NH3 come

from the same origin (Table 6.1, Figure 6.2). NO3 and NH3 in rain comes from both

human activities (like fuel combustion) and chemical reactions in the atmosphere,

however the largest source of NO3 and NH3 to the atmosphere is combustion of fossil

fuels (Berner & Berner, 1987). Therefore, all NO3 and NH3 in the precipitation samples

are likely sourced from anthropogenic sources like the majority of SO4. Ca and K have

nss fractions estimated at 69.3 and 49.8% respectively and have a correlation coefficient

of 0.90 (Table 6.1, Table 6.3). Therefore, it is likely that the majority of Ca and K in

Saturna precipitation are from the same source. The majority of Ca and half of K in

Saturna precipitation is from terrestrial origin, such as crustal dust (Négrel & Roy, 1998).

However, the majority of Ca is likely sourced from CaCO3 dust, whereas 50% of K was

of marine origin, and the other 50 % from various possible terrestrial sources such as soil

dust from silicate and calcareous soils, agricultural soil dust with fertilizer, and biogenic

aerosols (Berner & Berner, 1987; Négrel & Roy, 1998). Overall NO3 and SO4

concentrations in precipitation are influenced by anthropogenic sources, whereas Na, Cl,

and Mg are almost exclusively of marine origin. K is equally sourced from marine and

terrestrial sources, however the exact terrestrial sources influencing K concentrations in

precipitation are unclear.

114

6.3 Groundwater and Surface Water

Groundwater solute concentrations can be influenced by rock-water interactions,

cation exchange, anthropogenic activities, and recharge. In the ERW, groundwater

samples are more variable in chemical composition than surface water samples, which is

due to the increased residence time and therefore a higher degree of rock-water

interactions and possible cation exchange. As presented in Chapter 4, 86% of

groundwater samples have a Ca-Mg-HCO3-Cl water type, whereas 10% and 4% have a

Na-HCO3 and Ca-Na-HCO3-Cl water type respectively. Overall cation concentrations in

groundwater samples rank as Ca > Na > Mg > K, and anion concentrations rank as HCO3

> Cl > SO4 > NO3.

Surface water solute concentrations can be influenced by atmospheric inputs,

anthropogenic sources, cation exchange, and rock-water interactions. In the ERW, solute

concentrations of surface water samples do not significantly vary spatially, however they

do vary temporally. Ninety-eight percent of surface water samples have a water type

ranging from Ca-HCO3-Cl to Ca-HCO3 (Chapter 4). Overall cation concentrations in

surface water samples rank as Ca>Na>Mg>K, and anion concentrations rank as

HCO3>Cl>SO4>NO3. In this section, geochemical processes that influence or contribute

to solute concentrations in groundwater and surface water will be explored. Molar

concentrations were used to calculate ion ratios for groundwater and surface water

samples.

6.3.1 Cation Exchange

It is commonly assumed that the main influence of groundwater and surface water

composition are rock-water interactions. However, it has been suggested that equilibrium

115

cation exchange reactions between Na/K-smectite and Ca/Mg-smectite may play a

significant role in controlling surface water and groundwater composition (Allen, 2004;

Bluth & Kump, 1994; Drever, 1997; Grasby et al., 1999). This is especially evident in

basins draining sedimentary rocks and basaltic terrains, like the Englishman River

Watershed (Allen, 2004; Drever, 1997).

Figure 6.3 Na/(Ca+Mg) (molar ion ratio) versus TDS (mg/L) for groundwater and surface water samples.

116

Figure 6.4 Activity-activity diagram of Ca2+ versus Mg2+ of groundwater and surface water samples with respect to reaction boundaries which were calculated at 1 bar and 5 C, and are independent of activity data.

The role of cation exchange reactions was investigated using the cation molar ratio

(CMR) defined as Na/(Ca+Mg), and by construction of activity-activity diagrams.

Activities of major ions were calculated using the geochemical modelling software

Aquachem and PHREEQC. Mineral stability boundaries were calculated using

Geochemist’s Workbench at 1 bar and 5 C.

There is no clear trend between the CMR and TDS, which suggests that cation

exchange is likely independent of salinity increases in most samples. However, samples

with a high CMR have dominantly Na-HCO3 water types (Figure 6.3). The activity-

activity diagram of Ca versus Mg is presented in Figure 6.4. Groundwater and surface

water have a linear regression line slope of 0.96 and an R2 value of 0.99. All groundwater

and surface water samples lie within the stability fields of calcite-dolomite and Mg-

smectite-Ca-smectite (Eq. 6.1 and 6.2). However, groundwater samples lie slightly closer

117

to the Ca/Mg-smectite boundary, whereas surface water samples lie closer to the calcite-

dolomite stability boundary (Figure 6.4).

Calcite Dolomite

2 CaCO3 + Mg2+ + 2H+ CaMgCO3+ Ca2+ + 2H+ (6.1)

Mg-smectite Ca-smectite

Ca2+ + 20 [Mg0.167Al2.33Si3.67O10(OH)2]

20 [Ca0.167Al2.33Si3.67O10(OH)2] 3 Mg2+ (6.2)

Both reactions are reasonable based on the mineralogy of the study area, however, the

rocks in the region are dominantly sedimentary and volcanic rocks, therefore dissolution

of carbonate and dolomite is likely occurring, but cation exchange on smectite is likely a

more dominant control on cation ratios in groundwater.

Na and K activity ratios were plotted against each other and are presented in

Figure 6.5. Ninety-eight percent of groundwater samples lie within the Na-smectite and

K-feldpar stability fields, while the remaining one sample lies within the K-smectite zone

(Figure 6.5). Therefore this suggests not only is smectite a controlling factor of Ca-Mg

ratios, but possibly also on Na-K ratios (Equation 6.3).

Ninety-eight percent of surface water samples lie within the Na-smectite stability

field, whereas the remaining 2 samples lie within the K-feldspar and K-smectite stability

fields (Figure 6.5). Groundwater samples have a greater range of Na+ and K+ activity

values and are more variable than surface water samples, which lie predominantly in the

Na-smectite stability field. This suggests that cation exchange on smectite does not

control Na/K ratios in surface water samples (Figure 6.5).

118

Na-smectite K-smectite

3 Na+ + 10 [K0.33Al2.33Si3.67O10(OH)2] 10 [Na0.33Al2.33Si3.67O10(OH)2] + 3 K+ (6.3)

Figure 6.5 Activity-activity diagram of K+ versus Na+ for groundwater and surface water samples. Reaction boundaries are calculated at 1 bar and 5C.

6.3.2 Possible Weathering Reactions

Weathering of bedrock is a major contributor of solutes to surface water and

groundwater. As discussed in Chapter 2, the ERW is underlain primarily by igneous

basalt and granite, and siliciclastic and carbonate sedimentary rocks (Massey & Friday,

1987; Mustard, 1994).

Mineral stability boundaries were calculated using Geochemist’s Workbench

using a reaction temperature of 5 C and 1 atm for pressure. These mineral interactions

are presented to reflect possible minerals found within the regional and local geology that

may be controlling the chemical composition of groundwater and surface water. The

119

observed bedrock compositions are shale, sandstone, siltstone, mudstone, conglomerate,

limestone, basalt, and granite (Mustard, 1994; Yorath, 2005). Only reactions among

minerals stable at low temperature are considered as part of this study, as this setting is

representative of the aquifer conditions in the ERW.

In addition to cation exchange on smectite, groundwater samples lie within the

Na-smectite, K-smectite, K-feldspar, and albite stability fields, whereas surface water

samples lie within Na-smectite, K-smectite, and K-feldspar stability fields (Figure 6.5).

Equations 6.2 to 6.7 represent weathering reactions of these minerals:

K-feldspar + Illite K-smectite

59 KAlSi3O8 + 34 [K0.6Mg0.25Al2.3Si3.5O10(OH)2] + 8 H2O (6.4)

64 K+ + 74 [K0.33Al2.33Si3.67O10(OH)2] K-feldspar Albite

KAlSi3O8 + Na+ K+ + NaAlSi3O8 + Na+ (6.5)

Illite + Albite Na-smectite

40 H2O + 170 [K0.6Mg0.5Al2.3Si3.5O10(OH)2] + 295 [NaAlSi3O8] (6.6)

370 [Na0.33Al2.33Si3.67O10(OH)2] + 184 Na+ + 136 K+

Illite + K-feldspar Na-smectite

111 Na+ + 40 H2O + 170 [K0.6Mg0.25Al2.3Si3.5O10(OH)2] + 295 KAlSi3O8 (6.7)

370 [Na0.33Al2.33Si3.67O10(OH)2] + 431 K+

Figure 6.6 to Figure 6.9 are stability diagrams depicting activities of major cations

against SiO2(aq) represented as H4SiO4. All groundwater samples in activity-activity

diagrams of Ca2+, Mg2+, and Na+ against H4SiO4 fall within the stability boundaries of

kaolinite. However in Figure 6.9, 32 % of groundwater samples fall within or on the

stability boundary of k-feldspar, with the remaining 68 % within the kaolinite stability

boundary. All surface water samples lie within the kaolinite stability or on the boundary

120

between gibbsite and kaolinite (Figure 6.6 to 6.9; Equation 6.14). This suggests that

silicate dissolution reactions, presented in Equations 6.8 to 6.11 are possible sources of

Ca2+, Mg2+, Na+, and K+ ions. Basalts, which are rich in MgO, underlay the western

portions of the study area. Therefore, weathering of basalt is likely a contributor of Mg2+

to groundwater. Weathering of pyroxene, a common mineral in basaltic rocks, can be an

additional important reaction in contributing Mg2+ to groundwater in the study area

(Equation 6.12 and 6.13).

Anorthite Kaolinite CaAl2Si2O8 + 2CO2 + 3H2O Al2Si2O5(OH)4 + 2HCO3

- + Ca2+ (6.8)

Albite Kaolinite 2NaAlSi3O8 + 2CO2 + 11H2O Al2Si2O5(OH)4 + 4H4SiO4 + 2HCO3

- + 2Na+ (6.9)

K-feldspar Kaolinite 2KAlSi3O8 + 2CO2 + 11H2O Al2Si2O5(OH)4 + 4H4SiO4 + HCO3

- + 2K+ (6.10)

Kaolinite Gibbsite Al2Si2O5(OH)4 + 5 H2O 2 Al(OH)3 + 2 H4SiO4 (6.11)

Enstatite (Pyroxene)

MgSiO3 + 2CO2 + 3H2O H4CO3 + Mg2+ (6.12)

Diopside (Pyroxene) MgCaSi2O6 + 4CO2 + 6H2O 2H4SiO4 + 4HCO3

- + Mg2+ + Ca2+ (6.13)

121

Figure 6.6 log a [Ca2+/(H+)2] versus log a [H4SiO4] for groundwater and surface water samples.

Figure 6.7 log a [Mg2+/(H+)2] versus log a [H4SiO4] for groundwater and surface water samples.

122

Figure 6.8 log a [Na+/H+] versus log a [H4SiO4] for groundwater and surface water samples.

Figure 6.9 log a [K+/H+] versus log a [H4SiO4] for groundwater and surface water samples.

In Figure 6.6 and Figure 6.7 groundwater samples with higher ion activity ratios

and H4SiO4 activities plotted closer to the smectite stability field. Equations 6.7 to 6.9

indicate Ca2+, Mg2+, and H4SiO4 are released during weathering of anorthite, albite, and

123

K-feldpar to kaolinite, and kaolinite to gibbsite. The increase in these products causes a

shift towards the smectite stability line. This suggests that with increased residence time,

allowing for increased weathering of silicate minerals, will result in a greater shift

towards the smectite stability field. As the solution reaches the equilibrium boundary

between kaolinite and smectite, the reaction is:

Kaolinite Ca-smectite

1.17 Al2Si2O5(OH)4 + 0.17 Ca2+ + 1.33 H4SiO4

Ca0.165Al2.33Si3.67O10(OH)2 + 0.33 H+ + 3.83 H2O (6.14)

Overall, silicate dissolution reactions are a main contributor of major cations to

groundwaters and surface waters. However groundwater samples are more strongly

influenced by weathering and cation exchange reactions involving smectite, in

comparison to surface water samples.

6.3.3 Saturation Indices

The saturation index (SI) is the ratio of the ion activity product (IAP) and the

solubility product (K) on a logarithmic scale (Appelo & Postma, 2005). Saturation

indices can provide information about the saturation state of a particular mineral and its

likelihood of precipitation or dissolution. When a water sample is saturated or

supersaturated with respect to a mineral, it may indicate dissolution and/or precipitation

of that particular mineral. Saturation indices of groundwater and surface water samples

are summarized in Appendix B. SI values from -0.3 to 0.3 are considered saturated

whereas values > 0.3 and < -0.3 are supersaturated and subsaturated respectively (Appelo

& Postma, 2005). Figure 6.10 and 6.12 summarize the percentage of groundwater and

124

surface water samples that are subsaturated, saturated, and supersaturated for common

minerals.

Fifty percent of groundwater samples were saturated or supersaturated with respect

to quartz (SiO2) and 40 % with respect to chalcedony − a quartz polymorph. Similarly, in

surface water 48 % of samples were saturated with respect to quartz, although 100 % of

samples were sub saturated with respect to chalcedony. Saturation of quartz can result

from weathering of primary silicate minerals which release SiO2(aq). Precipitation of

quartz has a very slow reaction rate at low temperatures, typical for groundwater samples

(Rimstidt, 1997). The slow rate of quartz precipitation explains the high percentage of

groundwater and surface water samples that are saturated and supersaturated with respect

to quartz and chalcedony.

Fifty percent of groundwater samples were saturated or supersaturated with respect

to kaolinite and gibbsite. In contrast, 85 % of surface water samples were supersaturated

with respect to gibbsite and kaolinite. Gibbsite is a weathering product of kaolinite

(Equation 6.11). This suggests that Al3+ and H4SiO4 are sourced from the weathering of

alkali rich minerals such as K-feldpar and albite found in clastic sedimentary rocks, like

those of the Nanaimo Group, and concentrations in surface water and groundwater are

controlled by the formation of clay minerals (Eq. 6.8 and 6.9).

Eight and sixteen percent of groundwater samples were saturated or supersaturated

with respect to calcite and dolomite, whereas 100 % of surface water samples were

subsaturated with respect to calcite and dolomite (Figure 6.10 and Figure 6.11).

Degassing of CO2 as groundwater flows to surface while sampling can cause samples to

appear surpersaturated until sufficient time is allowed for equilibration. However,

125

samples that were saturated or supersaturated with respect to calcite or dolomite were

taken from wells that ranged in depths from 6 to 115 m. Degassing of CO2 is unlikely to

be a factor in samples taken from shallow wells. This suggests that dissolution of calcite

and dolomite found within calcareous or dolomitic cements or limestone of the Quatsino

Formation may be influencing groundwater (Massey & Friday, 1987). Interestingly,

samples that are supersaturated with respect to calcite and dolomite are not typically

supersaturated with respect to quartz. This suggests there is variability in rock-water

interactions, which can be attributed to the mineralogical composition of the aquifer,

bedrock, cement, or residence time. Dissolution of calcite and dolomite liberates HCO3,

which has a neutralizing capacity. Samples that were saturated or supersaturated with

respect to calcite and dolomite correlate to samples with elevated pH values (7.82 to

9.20) in comparison to other samples and the overall average pH of 7.03.

Figure 6.10 Relative proportions of mineral saturation states of groundwater samples.

126

Figure 6.11 Relative proportions of mineral saturation states of surface water samples.

6.4 Summary

In groundwater samples, cation exchange on smectite is a controlling factor of

Ca/Mg, Na/K, and Ca/Na ratios. Weathering of sedimentary and intrusive and extrusive

volcanic rocks result in aluminosilicate-rich and/or clay minerals such as feldspar,

kaolinite, and gibbsite. Weathering of these minerals and cation exchange on smectite are

the dominant contributors and controls of solutes to surface water and groundwater in the

ERW. Therefore the bedrock geology, whether via cation exchange or weathering

reactions is a major factor controlling major ion concentrations within groundwater.

In all stability diagrams, surface water samples plot slightly offset from

groundwater samples. This suggests that water sources other than groundwaters, such as

precipitation are influencing the composition of surface water. If precipitation were

influencing surface water, it would be expected that the effect of precipitation would be

127

highest during the wet season, which coincides with winter months. However samples

from May 2011 have the lowest ion activity levels, therefore snowmelt, as well as

precipitation must be influencing surface water composition. Yet samples from May 2011

still plot within the same field as samples taken during the dry season (summer-fall). This

suggests that ion exchange reactions influence surface water compositions regardless of

variable precipitation inputs throughout the year. Differences between surface water and

groundwater samples may be due to varying extents of ion exchange and rock-water

interactions, which influence groundwater samples to a higher degree.

128

7 Groundwater-Surface Water Interaction

Increasing development pressures within the study area have raised local, provincial,

and federal government concerns over the sustainability of water resources in the ERW.

As water demand pressures grow, it has been recognized that surface water and

groundwater are not two independent water sources that can be managed separately.

Understanding the extent and nature of groundwater-surface water interaction, can aid in

sustainable management of both resources. In previous chapters, solute source

contributions from precipitation, groundwater, and surface water have been assessed

using stable isotope geochemistry and major ion geochemistry analyses. Using isotopic

and geochemical information for precipitation, groundwater, and surface water, the

contribution of precipitation and groundwater to surface water is assessed in this chapter

and the extent and nature of surface water-groundwater interaction is explored.

7.1 Stable Isotopic Evidence

7.1.1 Isotopic Composition of Water (δ18OH2O and δ2HH2O)

In this section δ18O and δ2H values of groundwater, surface water, and precipitation

were used to aid in delineation of source contribution from these two end members to

surface water. However, groundwater and precipitation do not have distinct δ18O and δ2H

values from each other. Therefore, a qualitative approach was taken to demonstrate

possible temporal and spatial trends of surface water-groundwater interaction. Though

quantitative delineation of groundwater contribution to surface water was not possible,

understanding both low and high estimates of groundwater contribution to surface water

will aid in a greater understanding of this relationship within the watershed.

129

Figure 7.1 and Figure 7.2 depict δ18O and δ2H values of surface water samples

compared to the range of groundwater samples and precipitation. Groundwater has a

narrower range of δ18O and δ2H values in comparison to precipitation and surface water

samples due to longer residence times, leading to a higher degree of water mixing.

Precipitation samples with higher δ18O and δ2H represent summer precipitation, while

lower δ18O and δ2H values represent winter precipitation and/or snowmelt. Figure 7.1 and

Figure 7.2 display the range of groundwater δ18O and δ2H values with only the maximum

and minimum precipitation ranges, therefore this depicts an optimistic estimate of

groundwater contribution to surface water.

On Vancouver Island, spring is characterized by moderate temperatures (average

monthly temperature of 12 C), however significant snowmelt occurs during late spring

and early summer. In Figure 7.1 three surface water samples from May 2011 have low

δ18O and δ2H values, therefore snowmelt is likely contributing to surface water during

this period. The remaining samples from May 2011, which are slightly more elevated

with respect to δ18O and δ2H values were likely sourced from a mixture of groundwater

and snowmelt, or spring precipitation (Figure 7.1). Surface water samples taken in

August 2010, October 2010, February 2011, and July 2011 are all within the range of

groundwater δ18O and δ2H values. Therefore, groundwater likely contributes to surface

water during these periods. Samples taken in September 2011 are enriched with respect to

18O and 2H. This indicates that summer precipitation contributed to surface water during

this sampling period. There is no clear seasonal trend in δ18O and δ2H values indicating

source contribution to surface water. However, during the fall, surface waters are sourced

from a mixture of groundwater and summer precipitation. In contrast, spring and winter

130

surface waters are sourced from a combination of groundwater, snowmelt and winter

precipitation. There is higher variability of δ18O and δ2H values in summer months,

however spring and winter surface waters appear to be mainly sourced from groundwater.

The higher variability could be due to weather fluctuations that can influence

precipitation and timing of snow melt, which may have influenced samples from July

2011. The period between July and August could represent a shift from snowmelt, to

groundwater as a main source water contributor to surface water. However, further

sampling would have to be conducted to determine if the variability exits from yearly

fluctuations or the proposed snow melt to groundwater shift (Figure 7.1).

Figure 7.2 illustrates the spatial variations of δ18O and δ2H values of surface water

samples in relation to overall δ18O and δ2H ranges of groundwater samples. In October

2010, May 2011, July 2011, and September 2011, there is a slight increasing or

decreasing trend in δ18O and δ2H values of surface water with downstream distance. In

fall months (October 2010, and September 2011), δ18O and δ2H values increase with

increasing downstream distance. This suggests that there is increased contribution from

summer precipitation, ~34 km downstream of the headwaters. In May 2011, there is also

a slight increase in δ18O and δ2H values with increasing downstream distance, suggesting

contribution from precipitation with elevated δ18O and δ2H values. This suggests that

while snowmelt likely contributes to surface water in the headwaters, additional

contribution from spring precipitation with elevated δ18O and δ2H values occurs

downstream. Conversely, in July 2011 there is a decrease in δ18O and δ2H values with

increasing downstream distance. This indicates that an introduction of a water source that

is relatively depleted with respect to 18O and 2H. This could be due to a converging

131

stream with lower δ18O and δ2H values from snowmelt and/or groundwater discharge. In

August 2010, and February 2011, there is no clear decreasing or increasing trend in δ18O

and δ2H values with increasing downstream distance. In August 2010, this can be

attributed to low rates of precipitation. In February 2011, there was a significant snowfall

event, therefore rather than increasing δ18O and δ2H values from contribution of

precipitation with elevated δ18O and δ2H values, there was no significant change.

Figure 7.1 Temporal variation in δ18O and δ2H values of surface water samples with respect to the overall range of groundwater samples.

132

Figure 7.2 Spatial and temporal variation of δ18O and δ2H values of surface water samples with respect to overall range of groundwater samples.

133

Figure 7.3 Temporal variation of average surface water δ18O values with respect to average groundwater δ18O values, mean daily discharge, and volume weighted precipitation δ18O values with interpreted major contributors to surface water.

134

Figure 7.4 Temporal variation of average surface water δ18O values with respect to average groundwater δ18O values, mean daily

precipitation, and volume weighted precipitation δ18O values with interpreted major contributors to surface water.

.

135

Figure 7.3 and Figure 7.4 illustrate the relationship between temporal variation of

surface water δ18O values and average groundwater and precipitation δ18O values.

Precipitation δ18O ranges were used in these figures, whereas only the average δ18O value

for groundwater was used, therefore this represents a higher estimate of precipitation

contribution to surface water and a conservative estimate of groundwater contribution to

surface water. Precipitation averages were volume weighted to ensure precipitation

amounts were properly represented with respect to δ18O values. It is important to

understand the range of possible groundwater contribution to properly assess the extent of

surface water-groundwater interaction. Assuming that baseflow represents groundwater

discharge into rivers during times of low precipitation and discharge rates, periods of

groundwater discharge to the Englishman River can be delineated (Kalbus et al., 2006).

Between August 2010 and October 2010, and during August 2011, discharge and

precipitation rates were at their lowest and these periods also coincide with surface water

δ18O values near -12.1 ‰, the average δ18O value of groundwater samples (Figure 7.3,

Figure 7.4). In October 2010, surface water samples had an average δ18O value higher

than that of groundwater samples; with an increase in the amount of precipitation this

suggests that groundwater and precipitation are both contributing to surface water during

the fall months. In February 2011, δ18O values of surface water decreased to -12.9 ‰,

which corresponds to an average precipitation δ18O of -12.3 ‰. This indicates that winter

precipitation is likely a major contributor to the Englishman River during winter months.

In May 2011, the average δ18O value of surface water was -13.4 ‰, suggesting snow

pack melt water was influencing surface water, and causing a decrease in δ18O values in

spring months. Therefore in summer months, groundwater contribution to surface water

136

was highest at times when precipitation rates were low. During fall months, a mixture of

groundwater and precipitation are contributing to surface water discharge. Meltwater is a

dominant source of surface water during spring and likely into early summer months,

whereas during the wet season in winter, meltwater is likely a minor contributor in

comparison to winter precipitation based on hydrogen and oxygen isotope data

interpreted in concert with discharge.

7.1.2 Dissolved Inorganic Carbon (δ13CDIC)

In Chapter 5, sources of DIC in surface water and groundwater samples were

discussed in detail. In this section periods and locations where groundwater and surface

water samples have similar DIC sources were investigated as possible sites of

groundwater contribution to surface water. Figure 7.5 depicts δ13CDIC values of surface

water samples with respect to the range of δ13CDIC values of groundwater samples. In

August 2010, October 2010, and February 2011, surface water samples have similar δ13C

values to groundwater samples; suggesting DIC is likely sourced from both soil sources

via groundwater influx (Figure 7.5). In contrast, δ13C values of surface water samples

taken in May 2011, July 2011, and September 2011 are not within the range of

groundwater samples, suggesting contribution of DIC from atmospheric sources.

However, in the headwaters of the Englishman River, δ13CDIC values in July 2011 are

within the upper range of δ13CDIC values of groundwater samples. There are also

decreases in δ13C values with increasing downstream distance in May 2011, July 2011,

and September 2011 samples. This could signify an additional DIC source with lower

δ13C values - possible sites of groundwater discharge into the river. Figure 7.6 depicts

δ13C values of DIC in surface water and groundwater samples versus alkalinity.

137

Groundwater samples have variable alkalinity concentrations in comparison to surface

water samples, ranging from 19 to 391 mg/L, compared to 13 to 42 mg/L respectively.

The majority of groundwater samples with δ13C values similar to those of surface water

have alkalinity concentrations < 100 mg/L. Therefore, an increase in alkalinity is not

necessarily an indication of groundwater discharge to surface water.

In summary, samples taken in August 2010, October 2010, and February 2011

have low δ13C values, within the range of groundwater samples; suggesting that

groundwater discharge is influencing surface water DIC concentrations during these

periods.

Figure 7.5 δ13CDIC values of surface water samples versus distance from headwaters with respect to δ13C value range of groundwater samples.

138

Figure 7.6 δ13CDIC values of surface water and groundwater samples versus HCO3

concentrations in reference to δ13C values of typical DIC sources.

7.1.3 Sulphate (δ34SSO4 and δ18OSO4)

Determination of solute sources in surface water and groundwater can aid in

identification of possible locations where surface water-groundwater interaction is

occurring. If an ion is contributed by similar sources in both surface water and

groundwater, it may be attributed to potential sites of interaction. In Figure 7.7, δ34S and

δ18O values of sulphate of groundwater and surface water samples are plotted with

reference to typical ranges of δ34S and δ18O of various sulphate sources (Mayer, 2005).

Ninety-eight percent of surface water samples have sulphate sourced from sulfide

oxidation. There are nine groundwater samples that lie in the range of surface water

samples. These groundwater samples were sampled from wells with depths ranging from

4.6 to 113.7 m and completed in both bedrock and surficial aquifers. Locations of

groundwater samples with sulphate sourced from sulfide oxidation are presented in

139

Figure 7.8. The groundwater samples depicted in Figure 7.8 are from both surficial and

bedrock aquifers. All groundwater samples with similar δ34S and δ18O to surface water

are all within 1 km of the river and in moderately shallow wells. Other than the proximity

of sampled wells to the river, there are no other trends associated with groundwater and

surface water samples with similar δ34S and δ18O values. This suggests that surface

water-groundwater interaction is rapid and occurs mainly in the vicinity of the

Englishman River.

Figure 7.7 Temporal variation in δ34S and δ18O values of surface water and groundwater samples in relation to typical ranges of 34S and 18O values of various sulphate sources (modified from Mayer, 2005).

140

Figure 7.8 Locations of groundwater samples with δ34S and δ18O values within the range of those in surface water samples with corresponding well depths.

7.2 Geochemical Evidence

Understanding the geochemistry of precipitation, surface water, and groundwater

can aid in delineating source contributions of precipitation and groundwater to the

Englishman River. Figure 7.9 illustrates concentrations of major cations and anions of

precipitation, surface water, and groundwater samples. Alkalinity concentrations are

below detection limit in precipitation samples, and therefore, all precipitation samples

plot to the right of the diagram indicating 0 % alkalinity, exhibiting a Na-K-SO4-Cl water

type. Eighty-six % of groundwater samples and 98 % of surface water samples have a

141

Ca-HCO3 dominated water type. Surface water samples taken in October 2010, February

2011, May 2011, July 2011, and September 2011 all plot within the same region as 86 %

of groundwater samples. However, surface water samples have lower percentages of Mg

and slightly higher percentages of SO4 and Cl. This is likely due to contribution of

precipitation, which has low concentrations of Mg and relatively high concentrations of

Cl and SO4. Samples from August 2010 plot outside the general range of surface water

samples, with a shift towards Ca-HCO3-Cl type groundwaters. These groundwater

samples have TDS values > 400 mg/L and are from wells with depths > 125 m. This

indicates a possibility that groundwater from deeper units may be in connection with

surface water.

142

Figure 7.9 Piper diagram depicting surface water, groundwater, and precipitation

samples.

Eighty-six percent of groundwater samples and 98 % of surface water samples

plot on or near the 1:1 ratio line of HCO3:(Ca + Mg) (Figure 7.10). This implies that

calcite and/or dolomite contribute to Ca, Mg, and HCO3 concentrations within the

majority of surface water and groundwater samples, which was discussed in detail in

Chapter 6. This also, suggests that surface water is chemically very similar to the

majority of groundwater samples, indicating the likelihood of surface water-groundwater

interaction. Rock-water interactions occur to a greater extent in groundwater due to

longer residence times than in surface water.

143

Figure 7.10 a) HCO3 versus Ca + Mg for surface water samples. b) Close-up view of

HCO3 versus Ca + Mg for surface water samples. c) HCO3 versus Ca + Mg

for groundwater samples.

144

Figure 7.11 illustrates the relationship between major cations and anions and TDS

of surface water and groundwater samples. All surface water samples plot within the

range of groundwater samples, with the exception of two samples from October 2010 and

February 2011, which were taken from the estuary and reflect an influx of seawater. All

groundwater samples with TDS concentrations < 100 mg/L plot within the same region

as surface water samples. This corresponds to 40 % of groundwater samples which were

sampled from wells ranging in depth from 6.5 to 205 m with an average depth of 45 m.

Therefore, with the exception of one well at 205 m depth, the majority of groundwater

samples that indicate interaction with surface water are relatively shallow with an average

we ll depth of 50 m.

145

Figure 7.11 Major cations and anions versus TDS for surface water and groundwater

samples.

146

7.3 Summary

In this chapter indication of surface water-groundwater interaction was explored

using evidence provided by stable isotopic and geochemical analyses. A qualitative

assessment of surface water-groundwater interaction was obtained using δ18O and δ2H

values of water to provide a range of seasonal periods in which groundwater is

discharging to surface water. Understanding the range of possible estimates of

groundwater-surface water interaction, allows an understanding of the uncertainty

associated with the assessment. Conservatively, groundwater is discharging to surface

water during peak summer months with contributions from groundwater and precipitation

in the fall and early winter. However, groundwater is likely contributing to surface water

year round, but percent contribution of surface water is greatest during low flow periods.

δ13C values of DIC in surface water revealed temporal trends of groundwater

contributions to surface water that coincide with trends observed in δ18O and δ2H values.

During late summer, late fall, and winter groundwater is likely the major contributor to

surface water. The majority of groundwater samples with low to moderate DIC

concentrations (< 100 mg/L), had δ13C values within the range of surface water samples.

Therefore, an increase in DIC concentrations in surface water is not necessarily an

indication of groundwater contribution to surface water.

δ34S and δ18O values of sulphate in surface water and groundwater samples

indicated that 18 % of groundwater samples have similar δ34S and δ18O values to surface

water. These corresponded to wells with depths ranging from 4.6 to 113.7 m, with the

majority < 60 m depth. Therefore, groundwater from relatively shallow wells are most

likely to discharge to surface water, with only minor contributions from deeper sources. It

147

was also shown that proximity to the river may play a role in likelihood of interaction

with surface water, where all groundwater samples with similar sulphate sources to

surface water were within 2 km of the river.

Ninety-eight and eighty-six percent of surface water and groundwater samples

respectively had Ca-HCO3 dominant water types. Surface water samples had slightly

higher proportions of SO4 and Cl and lower proportions of Mg when compared to

groundwater samples, which is an indication of influence from precipitation. Therefore,

groundwater is likely a major source of dissolved solutes to surface water with minor

contributions from precipitation. Samples from August 2010 appeared to be influenced

by Ca-Na-HCO3-Cl groundwaters which account for only 4 % of groundwater samples

are associated with high TDS values (>400 mg/L) and wells with depths exceeding 250

m. However, influences from deeper, more saline wells could be present year round, yet

only observable when discharge rates in the river are low.

Ninety-eight and eighty-five percent of groundwater and surface water samples

respectively are influenced by carbonate dissolution. Since rock-water interactions are

more likely to occur in groundwater samples due to longer residence times, this indicates

that groundwater discharge to surface water is more probable than surface water recharge

to groundwater. When major cations and anions were plotted against TDS concentrations

for surface water and groundwater samples, the majority of surface water samples plotted

within the same range as groundwater samples with low TDS (< 100 mg/L) and from

wells with relatively shallow depths.

Overall, increased groundwater discharge to surface water occurs during late

summer, late fall, and winter. Discharge and precipitation rates are lowest in August,

148

therefore small contributions from deeper, more saline groundwater can cause observable

changes in surface water chemistry. This also is reflected in early fall, where discharge

rates are low from summer months, and precipitation rate increase, this causes a loss of

the groundwater signature in surface water due to the large contribution from

precipitation.

149

8 Conclusions and Future Work

8.1 Conclusions

Sources and processes affecting surface water and groundwater within the

Englishman River Watershed were investigated using geochemical, and stable isotopic

analyses. Isotopic tracers were used to identify sources of water, DIC, sulphate and

nitrate to surface water and groundwater. Sources of dissolved solutes in precipitation

were evaluated using ion ratios. Delineation of possible weathering and cation-exchange

reactions controlling major ion concentrations in surface water and groundwater were

investigated using ion activity diagrams, stability diagrams, and geochemical modelling.

Indications of surface water-groundwater interaction were derived using geochemical and

isotopic tracers identified in previous chapters to outline groundwater contribution to

surface water both spatially and temporally.

8.1.1 Determination of Solute Sources

Solute sources in surface waters and groundwaters are of a variety of origins,

including the pedosphere, lithosphere, atmosphere, and anthropogenic origins. Isotopic

analyses aided in qualitative and quantitative delineation of these solute sources.

DIC in surface water samples was derived from a variety of sources. In late

summer, fall, and winter DIC is sourced from CO2 enriched soil water via respiration of

organic matter in the soil zone. In spring, early summer, and fall DIC is derived from

sources including atmospheric CO2, calcite dissolution, and soil CO2. Groundwater DIC

was sourced primarily from soil CO2, with a strong influence from respiration of organic

matter with minor contributions from calcite dissolution.

150

Sulphate from sulfide oxidation, most likely contained in the soil zone, as no

known sulfide deposits are present within the study area, is the main contributor of

sulphate to surface water and to 55 % of groundwater. Groundwater sulphate

concentrations are also influenced by atmospheric and soil sulphate sources. There is a

trend of increasing δ34S and δ18O values which is likely attributed to bacterial

(dissimilatory) bacterial reduction in groundwater within the study area.

Soil nitrification is the primary source of nitrate in surface waters and 50% of

groundwater with detectable nitrate concentrations. Elevated concentrations of nitrate in

groundwater samples can be attributed to anthropogenic contributions of nitrate from

sewage and manure.

Solute sources in precipitation are influenced by marine and non-marine sources.

Na, Mg, Cl, and 50 % of K are primarily of marine origin, whereas Ca, and the remaining

50 % of K are attributed to terrestrial sources such as soil dust. Anthropogenic sources

influence SO4, NO3, and NH4 concentrations and contribute up to 81 % of SO4 in

precipitation.

8.1.2 Controlling Processes on Solute Concentrations

Bedrock geology is a controlling factor on solute ratios and concentrations of

major cation and anions in groundwater and surface water through weathering and cation

exchange reactions. Weathering of sedimentary and volcanic rocks result in

aluminosilicate-rich clay weathering products, which contribute Si, Al, Ca, Na, K, Mg,

and HCO3 to surface water and groundwater. Cation exchange between Ca-smectite and

Mg-smectite and K-smectite and Na-smectite control Ca/Mg and Na/K ratios in

groundwater and surface water samples, however groundwater is more highly influenced.

151

Groundwater is more highly influenced by geochemical reactions in comparison

to surface water due to longer water residence times, which allows for a higher degree of

rock water interactions. Precipitation, and groundwater contribute to surface water.

However, regardless of precipitation input, weathering and exchange reactions maintain

relatively constant ion ratios in surface water year round. Geochemical variations

between surface water and groundwater can be attributed to varying extents of ion

exchange and rock-water interactions.

8.1.3 Surface Water-Groundwater Interaction

Percent groundwater contribution to surface water flow is highest in late summer,

late fall, and winter months. Minimum discharge and precipitation rates occur during late

summer. Therefore groundwater discharge to surface water constitutes the majority of

surface water discharge during this period. In early fall, precipitation rates increase,

which in conjunction with low discharge rates in late summer, cause a loss of the

groundwater signature in surface water. Surface water during this period is largely

influenced by precipitation. In spring, precipitation and meltwater sourced from snow on

Mt. Arrowsmith are the primary contributors to surface water during this period.

Proximity of groundwater to the river increases the likelihood of interaction with surface

water. Shallow surficial aquifers influence surface waters to a higher degree than deeper

bedrock aquifers. However, groundwater from deeper, more saline aquifers contributes to

surface water and is measurable during late summer; however the influence is likely

minor.

152

8.2 Future Work

A comprehensive compilation of geochemical and isotopic data was achieved during

this study. However, measurement of additional parameters could provide useful

information to further assess surface water-groundwater interaction in the study area.

There are no mapped aquifers or groundwater wells within the headwaters of the

Englishman River, therefore surface water and groundwater samples were only sampled

within the populated (downstream) portion of the ERW. A campaign including sampling

of surface water and springs within this area could be valuable in understanding possible

surface water-groundwater interaction in the headwaters region of the ERW.

A physical hydrogeological approach could be taken, by measuring water levels in

the river, and groundwater seasonally. This would allow determination of groundwater

flow directions, a quantitative assessment of groundwater contribution to surface water,

and determination of where surface water may recharge groundwater.

Mineralogy of bedrock geology, aquifer lithology, and weathering products would

provide valuable information for further characterization of rock-water and cation

exchange reactions occurring within the watershed. Precipitation samples were not

sampled in the study area, therefore to obtain a more accurate LMWL, and geochemical

reference of precipitation within the study area, a comprehensive geochemical and

isotopic sampling campaign of local precipitation would be beneficial.

87Sr is a radiogenic product from the decay of 87Rb. The ratio of 87Sr to the stable,

non-radiogenic 86Sr can be used to deduce the source of strontium in water.

Determination of Sr sources can reveal information of calcium sources as Sr behaves

geochemically very similar to Ca. 87Sr/86Sr can also provide a method to delineate

153

between atmospheric and bedrock weathering contributions of ions to surface water and

groundwater (Appelo & Postma, 2005; Drever, 1997; Négrel & Roy, 1998; White &

Blum, 1995). 3H (tritium) is produced naturally in the atmosphere by interaction of

cosmic rays with nitrogen and oxygen in the atmosphere, however the largest

contribution of tritium is from the testing of thermonuclear weapons between 1952 and

1969 (Appelo & Postma, 2005; Drever, 1997). 3H radioactively decays to 3He and 3H/3He

ratios can be used to date groundwaters up to 50 years old (Appelo & Postma, 2005).

Dating of groundwater can be useful in assessing mixing of groundwater, as well as

delineating different groundwater flow regimes. This information can aid in the

assessment of surface water-groundwater interaction.

154

Bibliography

Al-Aasm, I. S., Coniglio, M., & Desrochers, A. (1995) Formation of complex fibrous calcite veins in Upper Triassic strata of Wrangellia Terrain, British Columbia, Canada. Sedimentary Geology, 100(1), 83–95.

Allen, D. M. (2004) Sources of Ground Water Salinity on Islands Using 18O, 2H, and 34S. Ground Water, 42(1), 15.

Allen, D. M., & Suchy, M. (2001) Geochemical evolution of groundwater on Saturna Island, British Columbia. Canadian Journal of Earth Sciences, 38(7), 1059–1080.

Appelo, C. A. J., & Postma, D. (2005) Geochemistry, groundwater and pollution. CRC

Press.

Barlak, R., Epps, D., & Phippen, B. (2010) Water Quality Assessment and Objectives for the Englishman River Community Watershed (Technical Report). British Columbia Ministry of Environment.

BC Geological Survey (2005) Digital Geology Maps. http://www.empr.gov.bc.ca/Mining/Geoscience/PublicationsCatalogue/DigitalGeologyMaps/Pages/default.aspx [accessed 21 January 2014].

BC Ministry of Environment (2013a) BC Water Resource Atlas, http://webmaps.gov.bc.ca/imf5/imf.jsp?site=wrbc [accessed 15 November 2013].

BC Ministry of Environment (2013b) iMap BC

http://webmaps.gov.bc.ca/imfx/imf.jsp?site=imapbc [accessed 2 October 2013].

Berner, E. K., & Berner, R. A. (1987) Global water cycle: geochemistry and environment. Prentice-Hall.

Bertrand, G., Celle-Jeanton, H., Laj, P., Rangognio, J., & Chazot, G. (2009) Rainfall chemistry: long range transport versus below cloud scavenging. A two-year study at an inland station (Opme, France). Journal of Atmospheric Chemistry, 60(3), 253–271.

Bluth, G. J., & Kump, L. R. (1994) Lithologic and climatologic controls of river chemistry. Geochimica et Cosmochimica Acta, 58(10), 2341–2359.

Boom, A., and G. Bryden (1994) Englishman River Water Allocation Plan. Ministry of Environment British Columbia.

155

Burgin, A. J., & Hamilton, S. K. (2007) Have we overemphasized the role of denitrification in aquatic ecosystems? A review of nitrate removal pathways. Frontiers in Ecology and the Environment, 5(2), 89–96.

Camargo, J. A., & Alonso, Á. (2006) Ecological and toxicological effects of inorganic nitrogen pollution in aquatic ecosystems: A global assessment. Environment International, 32(6), 831–849.

Canadian Air and Precipitation Monitoring Network (CAPMoN) Saturna Island Precipitation Geochemistry Data. https://www.ec.gc.ca/rsmn/default.asp?lang=En&n=752CE271-1 [accessed 12 January 2012].

Canadian Network for Isotopes in Precipitation (CNIP) Saturna Island Precipitation

Isotope Data. http://www.science.uwaterloo.ca/~twdedwar/cnip/cniphome.html [accessed 18

January 2012].

Carlisle, Donald, and Takeo Susuki. (1974) Emergent Basalt and Submergent Carbonate-clastic Sequences Including the Upper Triassic Dilleri and Welleri Zones on Vancouver Island.” Canadian Journal of Earth Sciences 11, no. 2: 254–279.

Chang, C. C., Kendall, C., Silva, S. R., Battaglin, W. A., & Campbell, D. H. (2002) Nitrate stable isotopes: tools for determining nitrate sources among different land uses in the Mississippi River Basin. Canadian Journal of Fisheries and Aquatic Sciences, 59(12), 1874–1885.

Clague, John Joseph. (1977) Quadra Sand: a Study of the Late Pleistocene Geology and Geomorphic History of Coastal Southwest British Columbia. Energy, Mines, and Resources Canada: available from Print. and Pub. Supply and Services Canada, 1977.

Clark, I., & Fritz, P. (1997) Environmental isotopes in hydrology. Lewis Publishers, Boca Raton, Fla.

Claypool, G. E., Holser, W. T., Kaplan, I. R., Sakai, H., & Zak, I. (1980) The age curves of sulfur and oxygen isotopes in marine sulfate and their mutual interpretation. Chemical Geology, 28, 199–260.

Clermont, H., (2011). The State of Mount Arrowsmith Biosphere Reserve: Global and Climate Change in Mountain Sites (GLOCHAMOST) Report 2011.

Craig, H., & Gordon, L. I. (1965) Deuterium and oxygen 18 variations in the ocean and the marine atmosphere. Consiglio nazionale delle richerche, Laboratorio de geologia nucleare.

Dansgaard, W. (1964) Stable isotopes in precipitation. Tellus, 16(4), 436–468.

156

Denny, S. C., D. M. Allen, and J. M. Journeay. (2006) DRASTIC-Fm: a Modified Vulnerability Mapping Method for Structurally Controlled Aquifers in the Southern Gulf Islands, British Columbia, Canada. Hydrogeology Journal 15, no. 3: 483–493.

Drever, J. I. (1997) The geochemistry of natural waters: surface and groundwater environments. Prentice Hall PTR. Retrieved from http://books.google.ca/books?id=mbYPAQAAIAAJ

Dubois, K. D., Lee, D., & Veizer, J. (2010) Isotopic constraints on alkalinity, dissolved organic carbon, and atmospheric carbon dioxide fluxes in the Mississippi River. Journal of Geophysical Research, 115(G2).

Environment Canada. (2012a) Canada’s National Climate Archive. http://climate.weatheroffice.gc.ca/climateData/canada_e.html [accessed 15 September 2012].

Environment Canada (2012b) Archived Hydrometric Data. Water Survey of Canada. http://www.wsc.ec.gc.ca/applications/H2O/index-eng.cfm [accessed 2 August 2012].

Environment Canada (2012c) Real-time Hydrometric data. http://www.wateroffice.ec.gc.ca/index_e.html [accessed 2 August 2012].

FISS (Fisheries Information Summary System) Database (2006) Ministry of Environment and Department of Fisheries and Oceans. Available online at: http://www.bcfisheries.gov.bc.ca/fishinv/fiss.html [accessed 15 March 2011].

Frape, S. K., Fritz, P., & McNutt, R. t. (1984) Water-rock interaction and chemistry of groundwaters from the Canadian Shield. Geochimica et Cosmochimica Acta, 48(8), 1617–1627.

Friedman, I., & O’Neil, J. R. (1977) Compilation of stable isotope fractionation factors of geochemical interest (Vol. 440). USGPO.

Galloway, J. N., Aber, J. D., Erisman, J. W., Seitzinger, S. P., Howarth, R. W., Cowling, E. B., & Cosby, B. J. (2003) The Nitrogen Cascade. BioScience, 53(4), 341.

Gonfiantini, R. (1986) Environmental isotopes in lake studies. Handbook of Environmental Isotope Geochemistry, 2, 113–168.

Grasby, S. E., Hutcheon, I., & McFarland, L. (1999) Surface-water–groundwater interaction and the influence of ion exchange reactions on river chemistry. Geology, 27(3), 223.

157

Greene, A.R., J. S. Scoates, and D. Weis (2004) “Wrangellia Terrane on Vancouver Island, British Columbia: Distribution of Flood Basalts with Implications for Potential Ni-Cu-PGE Mineralization in Southwestern British Columbia.” Terrane Map of Western Canada and Alaska (modified After Wheeler Et Al.[1991]) Showing the Distribution of the Wrangellia Terrane (WR) in British Columbia, the Yukon and Alaska fttp://fttp.eos.ubc.ca/pub/jscoates/publications/Greene_BCGF_2005.pdf.

Holland, S. (1976) Landforms of British Columbia: A Physiographic Outline. Bulletin 48. Victoria, Canada: British Columbia Department of Mines and Petroleum Resources.

Howes, D. E. (1983) Late Quaternary Sediments and Geomorphic History of Northern Vancouver Island, British Columbia. Canadian Journal of Earth Sciences 20, no. 1: 57–65.

Hudson, R. (1977) “Snowpack Recovery in Regenerating Coastal British Columbia Clearcuts. Canadian Journal of Forest Research 30, no. 4 (2000): 548–556.

Jones, D.L., N. J. Silberling, and John Hillhouse. (1977) “Wrangellia-A Displaced Terrane in Northwestern North America. Canadian Journal of Earth Sciences 14, no. 11: 2565–2577.

Junge, C. E., & Werby, R. T. (1958) Concentration of chloride, sodium, potassium, calcium, and sulfate in rain water over the United States. J. Meteorol.;(United States), 15.

Kalbus, E., Reinstorf, F., & Schirmer, M. (2006) Measuring methods for groundwater? surface water interactions: a review. Hydrology and Earth System Sciences Discussions, 10(6), 873–887.

Keene, W. C., Pszenny, A. A., Galloway, J. N., & Hawley, M. E. (1986) Sea-salt corrections and interpretation of constituent ratios in marine precipitation. Journal of Geophysical Research: Atmospheres (1984–2012), 91(D6), 6647–6658.

Kendall, C., Elliott, E. M., & Wankel, S. D. (2007) Tracing anthropogenic inputs of nitrogen to ecosystems. Stable Isotopes in Ecology and Environmental Science, 2, 375–449.

Kendall, C., & McDonnell, J. J. (1998) Isotope tracers in catchment hydrology. Access Online via Elsevier.

Keough, J. R., Hagley, C. A., Ruzycki, E., & Sierszen, M. (1998) δ13C composition of primary producers and role of detritus in a freshwater coastal ecosystem. Limnology and Oceanography, 43(4), 734–740.

158

Kreye, R., K. Ronneseth, and M. Wei. (2001) An Aquifer Classification System for Groundwater Management in British Columbia. Ministry of Environment, Water, Air and Climate Change Branch.

Liggett, J., A. Gilchrist, S. Denny, R. Purdy, L. Munro, P. Lapcevic, V. Carmichael, S. Earle, S. Talwar, and J. M. Journeay. (2010) Technical Summary of Intrinsic Vulnerability Mapping Methods in the Regional Districts of Nanaimo and Cowichan Valley. Geological Survey of Canada, Open File 6168: 64.

Manzano, M. (2005). Groundwater and saline intrusion. IGME.

Massey, N. W. D., & Friday, S. J. (1987) Geology of the Alberni-Nanaimo Lakes Area, Vancouver Island (91F/1W, 92F/2E and part of 92F/7). Geological Fieldwork, 1989–1.

Massey, N. W. D., Friday, S. J., Tercier, P. E., & Rublee, V. J. (1995) Geology of the Cowichan Lake Area. Ministry of Energy, Mines and Petroleum Resources.

Mayer, B. (2005) Assessing sources and transformations of sulphate and nitrate in the hydrosphere using isotope techniques. Isotopes in the Water Cycle, 67–89.

Mayer, B., Boyer, E. W., Goodale, C., Jaworski, N. A., Van Breemen, N., Howarth, R. W., Nadelhoffer, K. (2002) Sources of nitrate in rivers draining sixteen watersheds in the northeastern US: Isotopic constraints. Biogeochemistry, 57(1), 171–197.

McGuire, K., McDonnell, J., Michener, R., & Lajtha, K. (2007) Stable isotope tracers in watershed hydrology. Blackwell Publishing: Oxford.

Mustard, P. (1994) The Upper Cretaceous Nanaimo Group, Georgia Basin. Geological Survey of Canada Bulletin, (481), 27–95.

Natural Resouces Canada (2011) Geogratis. http://geogratis.gc.ca/geogratis/search?lang=en [accessed 12 Feb 2011].

Négrel, P., & Roy, S. (1998) Chemistry of rainwater in the Massif Central (France): a strontium isotope and major element study. Applied Geochemistry, 13(8), 941–952.

Rimstidt, J. D. (1997) Quartz solubility at low temperatures. Geochimica et Cosmochimica Acta, 61(13), 2553–2558.

Rozanksi, K., Araguas-Araguas, L., & Gonfiantini, R. (1993) Isotopic Patterns in Modern Global Precipitation. Gephysical Monograph Series, 78(1), 1-36.

159

Salve, P. R., Maurya, A., Wate, S. R., & Devotta, S. (2008) Chemical Composition of Major Ions in Rainwater. Bulletin of Environmental Contamination and Toxicology, 80(3), 242–246.

Schoonover, J. E., Lockaby, B. G., & Pan, S. (2005) Changes in chemical and physical propertiesof stream water across an urban-rural gradient in western Georgia. Urban Ecosystems, 8(1), 107–124.

Seal, R. R. (2006) Sulfur Isotope Geochemistry of Sulfide Minerals. Reviews in Mineralogy and Geochemistry, 61(1), 633–677.

Slater, C., Preston, T., & Weaver, L. T. (2001) Stable isotopes and the international system of units. Rapid Communications in Mass Spectrometry, 15(15), 1270–1273.

Strebel, O., Böttcher, J., & Fritz, P. (1990) Use of isotope fractionation of sulfate-sulfur and sulfate-oxygen to assess bacterial desulfurication in a sandy aquifer. Journal of Hydrology, 121(1), 155–172.

Telmer, K., & Veizer, J. (1999) Carbon fluxes, pCO2 and substrate weathering in a large northern river basin, Canada: carbon isotope perspectives. Chemical Geology, 159(1–4), 61 – 86.

Wade, Norman L., Jillian Martin, and Paul H. Whitfield (2001) Hydrologic and Climatic Zonation of Georgia Basin, British Columbia. Canadian Water Resources Journal 26, no. 1: 43–70.

Wadleigh, M. A., Schwarcz, H. P., & Kramer, J. R. (1996) Isotopic evidence for the origin of sulphate in coastal rain. Tellus B, 48(1), 44–59.

Wassenaar, L. I., Hendry, M. J., Chostner, V. L., & Lis, G. P. (2008). High resolution pore water δ2H and δ18O measurements by H2O (liquid)− H2O (vapor) equilibration laser spectroscopy. Environmental science & technology, 42(24), 9262-9267.

Wendling, G. (2012) Lower Englishman River Watershed Groundwater and Surface

Water Interaction (p. 35). Nanaimo, Canada: GW Solutions. White, A. F., & Blum, A. E. (1995) Effects of climate on chemical_ weathering in

watersheds. Geochimica et Cosmochimica Acta, 59(9), 1729–1747. Yorath, C. J. (2005) The geology of southern Vancouver Island. Harbour Pub Co.

160

Appendix A

161

Table A - 1 Surface water sample locations (NAD 83).

Sample ID Sampling Period Latitude Longitude10SKP-01 August 2010 49.3162 -124.284610SKP-02 August 2010 49.3211 -124.286410SKP-03 August 2010 49.3243 -124.288810SKP-04 August 2010 49.3104 -124.283510SKP-05 August 2010 49.3089 -124.284210SKP-06 August 2010 49.3015 -124.276810SKP-07 August 2010 49.2994 -124.267810SKP-08 August 2010 49.2782 -124.310710SKP-09 August 2010 49.2665 -124.331010SKP-10 August 2010 49.2570 -124.343710SKP-11 August 2010 49.2436 -124.348210SKP-13 August 2010 49.2962 -124.268310SKP-14 August 2010 49.2889 -124.278810SKP-15 October 2010 49.2807 -124.299710SKP-16 October 2010 49.3162 -124.284910SKP-17 October 2010 49.3210 -124.286510SKP-18 October 2010 49.3244 -124.288910SKP-19 October 2010 49.3100 -124.283710SKP-20 October 2010 49.3085 -124.284410SKP-21 October 2010 49.3028 -124.279810SKP-22 October 2010 49.2965 -124.267610SKP-23 October 2010 49.2891 -124.278810SKP-24 October 2010 49.2806 -124.299810SKP-25 October 2010 49.2797 -124.290610SKP-26 October 2010 49.2437 -124.349810SKP-27 October 2010 49.2574 -124.343610SKP-28 October 2010 49.2669 -124.331610SKP-29 October 2010 49.2790 -124.295710SKP-30 October 2010 49.2267 -124.373010SKP-31 October 2010 49.2778 -124.310010SKP-32 February 2011 49.3162 -124.284410SKP-33 February 2011 49.3210 -124.286610SKP-34 February 2011 49.3241 -124.291610SKP-35 February 2011 49.3105 -124.283510SKP-36 February 2011 49.3086 -124.284310SKP-37 February 2011 49.3028 -124.279810SKP-38 February 2011 49.2961 -124.268210SKP-39 February 2011 49.2881 -124.278610SKP-40 February 2011 49.2805 -124.299810SKP-41 February 2011 49.2796 -124.290610SKP-42 February 2011 49.2437 -124.349810SKP-43 February 2011 49.2667 -124.331510SKP-44 February 2011 49.2779 -124.310310SKP-45 February 2011 49.2571 -124.3437

162

Sample ID Sampling Period Latitude Longitude11SKP-47 May 2011 49.3164 -124.284311SKP-48 May 2011 49.3210 -124.286711SKP-49 May 2011 49.3253 -124.291211SKP-50 May 2011 49.3104 -124.283411SKP-51 May 2011 49.3080 -124.284311SKP-52 May 2011 49.3029 -124.279811SKP-53 May 2011 49.2961 -124.268311SKP-54 May 2011 49.2881 -124.277911SKP-55 May 2011 49.2806 -124.299911SKP-56 May 2011 49.2793 -124.290911SKP-57 May 2011 49.2783 -124.310611SKP-58 May 2011 49.2571 -124.343211SKP-59 May 2011 49.2668 -124.331711SKP-60 May 2011 49.2430 -124.348411SKP-70 July 2011 49.3162 -124.284711SKP-71 July 2011 49.3210 -124.286911SKP-72 July 2011 49.3251 -124.291011SKP-100 July 2011 49.3103 -124.283511SKP-101 July 2011 49.3083 -124.284211SKP-102 July 2011 49.3030 -124.279811SKP-117 July 2011 49.2961 -124.268211SKP-118 July 2011 49.2881 -124.277811SKP-119 July 2011 49.2794 -124.290911SKP-120 July 2011 49.2807 -124.299811SKP-121 July 2011 49.2574 -124.343311SKP-122 July 2011 49.2668 -124.331311SKP-123 July 2011 49.2781 -124.310511SKP-124 July 2011 49.2433 -124.348611SKP-125 September 2011 49.3162 -124.284811SKP-126 September 2011 49.3210 -124.286911SKP-127 September 2011 49.3251 -124.291011SKP-128 September 2011 49.3062 -124.276911SKP-129 September 2011 49.3083 -124.283911SKP-130 September 2011 49.3030 -124.279711SKP-131 September 2011 49.2962 -124.268111SKP-132 September 2011 49.2885 -124.278411SKP-133 September 2011 49.2795 -124.290711SKP-134 September 2011 49.2806 -124.299811SKP-135 September 2011 49.2572 -124.343511SKP-136 September 2011 49.2667 -124.331411SKP-137 September 2011 49.2781 -124.3104

163

Table A - 2 Groundwater sample locations (NAD 83).

Sample ID Latitude Longitude Sample ID Latitude Longitude11SKP-61 49.2535 -124.3506 11SKP-89 49.2840 -124.268511SKP-62 49.3087 -124.3065 11SKP-90 49.3093 -124.264011SKP-63 49.2632 -124.3518 11SKP-91 49.3085 -124.261611SKP-64 49.2629 -124.3551 11SKP-92 49.2691 -124.330711SKP-65 49.3095 -124.3025 11SKP-93 49.2660 -124.338011SKP-66 49.2973 -124.2845 11SKP-94 49.2769 -124.330211SKP-67 49.2983 -124.2733 11SKP-95 49.2729 -124.324311SKP-68 49.2593 -124.3559 11SKP-96 49.2743 -124.322311SKP-69 49.2905 -124.3802 11SKP-97 49.3019 -124.278711SKP-73 49.2589 -124.3586 11SKP-98 49.2788 -124.320411SKP-74 49.2546 -124.3494 11SKP-99 49.2799 -124.312111SKP-75 49.2586 -124.3468 11SKP-103 49.2668 -124.352211SKP-76 49.2659 -124.3421 11SKP-104 49.2690 -124.346411SKP-77 49.3216 -124.2861 11SKP-105 49.2725 -124.349711SKP-78 49.3222 -124.2866 11SKP-106 49.2815 -124.382411SKP-79 49.2813 -124.2725 11SKP-107 49.2664 -124.364311SKP-80 49.2812 -124.2718 11SKP-108 49.2639 -124.361511SKP-81 49.3107 -124.2867 11SKP-109 49.3040 -124.301011SKP-82 49.3140 -124.2872 11SKP-110 49.3035 -124.295911SKP-83 49.3045 -124.2887 11SKP-111 49.3015 -124.291811SKP-84 49.3052 -124.2850 11SKP-112 49.3011 -124.288511SKP-85 49.3021 -124.2813 11SKP-113 49.2993 -124.281711SKP-86 49.3038 -124.2835 11SKP-114 49.2988 -124.300211SKP-87 49.2649 -124.3445 11SKP-115 49.2981 -124.291711SKP-88 49.2861 -124.2692 11SKP-116 49.2954 -124.2973

164

Table A - 3 Surface water field parameters.

Temp pH EC DO°C µS/cm mg/L

10SKP-01 August 2010 12.9 7.93 73.1 9.1810SKP-02 August 2010 13.0 8.04 73.2 10.5010SKP-03 August 2010 15.4 7.76 80.7 9.7710SKP-04 August 2010 16.7 8.19 71.5 12.6610SKP-05 August 2010 14.1 8.00 70.9 11.2010SKP-06 August 2010 16.5 8.19 71.8 10.7110SKP-07 August 2010 13.0 8.20 73.5 13.2810SKP-08 August 2010 13.8 7.82 66.1 16.5010SKP-09 August 2010 12.9 8.04 66.0 14.2510SKP-10 August 2010 11.1 7.91 66.5 12.1310SKP-11 August 2010 11.6 7.72 64.8 11.0810SKP-13 August 2010 14.8 8.06 93.3 9.5510SKP-14 August 2010 15.6 7.37 67.3 9.5710SKP-15 August 2010 13.6 7.20 44.8 10.7010SKP-16 October 2010 8.9 8.23 57.0 10.4910SKP-17 October 2010 8.4 8.15 57.0 9.3910SKP-18 October 2010 8.4 7.68 460.0 10.9810SKP-19 October 2010 8.3 7.82 55.0 10.8710SKP-20 October 2010 8.3 7.78 58.0 10.6910SKP-21 October 2010 7.3 7.86 44.0 11.8010SKP-22 October 2010 7.6 7.76 53.0 10.5010SKP-23 October 2010 7.4 7.65 42.0 10.9710SKP-24 October 2010 7.3 7.96 43.0 10.6810SKP-25 October 2010 7.5 7.73 44.0 10.8010SKP-26 October 2010 7.4 7.89 43.0 11.0210SKP-27 October 2010 7.9 8.12 32.0 9.1710SKP-28 October 2010 8.2 8.34 31.0 8.3010SKP-29 October 2010 7.8 8.17 32.0 10.8210SKP-30 October 2010 7.5 7.72 32.0 10.8210SKP-31 October 2010 8.2 7.89 31.0 12.1111SKP-32 February 2011 -2.1 6.99 114.5 10.3111SKP-33 February 2011 -3.3 7.18 97.2 10.2711SKP-34 February 2011 -3.2 7.01 246.2 11.1211SKP-35 February 2011 -3.7 8.09 58.9 10.3711SKP-36 February 2011 -3.5 7.42 55.8 11.0411SKP-37 February 2011 -2.5 6.75 52.3 11.0711SKP-38 February 2011 -2.8 6.93 53.7 10.7811SKP-39 February 2011 -2.3 7.01 53.3 9.8111SKP-40 February 2011 -1.8 7.19 57.7 9.4111SKP-41 February 2011 -3.8 7.02 57.6 10.9011SKP-42 February 2011 -4.2 7.25 58.5 11.6211SKP-43 February 2011 -3.7 7.22 60.8 11.1611SKP-44 February 2011 -3.6 7.11 61.3 10.9611SKP-45 February 2011 -3.8 7.12 65.8 10.63

Sampling PeriodSample ID

165

Temp pH EC DO°C µS/cm mg/L

11SKP-47 May 2011 7.1 7.66 50.2 10.2111SKP-48 May 2011 7.3 7.44 53.6 10.2411SKP-49 May 2011 7.3 7.29 54.3 10.5411SKP-50 May 2011 8.1 7.40 51.8 10.6211SKP-51 May 2011 7.4 7.50 55.4 10.3011SKP-52 May 2011 7.5 7.38 56.1 10.6511SKP-53 May 2011 7.2 7.27 57.4 10.6611SKP-54 May 2011 8.4 7.19 53.9 10.6411SKP-55 May 2011 6.6 7.43 53.0 10.8711SKP-56 May 2011 7.8 7.35 53.8 10.8111SKP-57 May 2011 7.0 7.21 56.2 10.8911SKP-58 May 2011 5.8 7.51 57.7 10.9811SKP-59 May 2011 6.0 7.65 52.1 11.0111SKP-60 May 2011 5.8 7.76 50.1 11.1211SKP-70 July 2011 10.5 8.37 50.6 9.7811SKP-71 July 2011 11.1 7.60 51.5 7.4811SKP-72 July 2011 10.9 7.41 51.7 6.48

11SKP-100 July 2011 11.2 7.82 52.8 11.0511SKP-101 July 2011 11.0 7.72 53.5 11.0911SKP-102 July 2011 11.5 7.63 58.1 11.0411SKP-117 July 2011 12.9 8.63 36.3 10.7311SKP-118 July 2011 12.5 8.19 56.3 10.7711SKP-119 July 2011 12.4 8.16 55.2 10.2411SKP-120 July 2011 12.7 8.02 53.2 10.1211SKP-121 July 2011 9.3 7.44 50.9 11.0311SKP-122 July 2011 9.7 8.33 51.2 11.2111SKP-123 July 2011 10.4 7.50 51.5 11.0411SKP-124 July 2011 9.8 7.45 50.4 10.6511SKP-125 September 2011 1.5 7.72 62.5 10.3311SKP-126 September 2011 1.5 7.43 62.2 10.2711SKP-127 September 2011 1.6 7.76 64.1 10.7311SKP-128 September 2011 3.4 7.79 60.8 11.0111SKP-129 September 2011 1.7 7.35 63.7 11.5911SKP-130 September 2011 2.0 7.43 63.8 11.8211SKP-131 September 2011 2.1 7.46 53.7 11.7411SKP-132 September 2011 1.4 6.98 54.2 10.0411SKP-133 September 2011 1.0 7.17 56.0 9.6611SKP-134 September 2011 0.9 8.16 59.3 9.9011SKP-135 September 2011 0.6 7.55 71.9 10.6511SKP-136 September 2011 0.4 7.84 74.2 10.3411SKP-137 September 2011 0.0 8.02 74.8 10.27

Sampling PeriodSample ID

166

Table A - 4 Groundwater field parameters.

Temp pH EC DO Temp pH EC DO°C µS/cm mg/L °C µS/cm mg/L

11SKP-61 12.0 6.53 122.9 0.87 11SKP-89 15.5 6.44 250.1 0.1211SKP-62 12.9 6.59 88.6 7.69 11SKP-90 15.5 7.03 84.4 9.2111SKP-63 9.7 6.08 81.1 7.53 11SKP-91 14.2 6.92 87.4 9.2111SKP-64 13.7 6.07 82.2 3.85 11SKP-92 10.0 6.30 142.4 1.3211SKP-65 16.5 7.82 373.0 1.15 11SKP-93 11.0 8.50 248.1 0.0811SKP-66 12.4 7.95 250.0 1.09 11SKP-94 11.9 6.65 202.7 0.1111SKP-67 14.1 6.82 50.6 0.31 11SKP-95 11.2 5.85 138.7 6.3011SKP-68 11.4 7.92 279.1 3.65 11SKP-96 15.4 6.25 47.6 7.3811SKP-69 12.7 7.99 669.2 8.72 11SKP-97 12.6 5.98 200.6 3.6811SKP-73 12.4 5.84 50.6 1.75 11SKP-98 11.4 5.02 180.6 8.8811SKP-74 13.1 6.06 83.8 7.05 11SKP-99 14.2 6.45 177.5 6.7311SKP-75 10.7 7.32 54.3 7.32 11SKP-103 11.6 5.77 67.5 6.4011SKP-76 13.1 8.88 194.8 0.11 11SKP-104 10.4 6.61 124.5 7.0111SKP-77 8.5 6.35 59.1 4.09 11SKP-105 9.6 6.07 106.8 6.1011SKP-78 8.1 6.51 69.1 3.38 11SKP-106 13.8 8.00 726.0 3.6811SKP-79 8.7 8.41 457.1 0.47 11SKP-107 10.8 6.22 122.7 5.1311SKP-80 8.8 8.97 342.0 0.32 11SKP-108 9.7 6.15 173.7 5.1811SKP-81 11.0 6.16 219.5 2.18 11SKP-109 11.4 7.44 248.5 4.4911SKP-82 11.3 6.43 259.5 0.48 11SKP-110 13.8 7.42 371.0 0.0711SKP-83 10.7 6.71 295.2 3.84 11SKP-111 13.7 8.34 341.0 1.3911SKP-84 12.8 6.13 287.0 5.28 11SKP-112 12.8 8.92 304.1 0.7711SKP-85 16.7 9.20 236.2 0.22 11SKP-113 16.5 6.58 992.1 1.6811SKP-86 16.0 7.45 405.2 0.05 11SKP-114 14.4 8.47 327.0 7.4111SKP-87 12.6 7.01 153.0 0.97 11SKP-115 15.5 8.14 250.9 3.2011SKP-88 12.5 6.69 243.2 1.33 11SKP-116 13.3 8.25 292.2 10.06

Sample ID Sample ID

167

Table A - 5 Chemical analyses for Saturna Island precipitation samples averaged monthly (1989-2007).

Month pH Ca Na Mg K NH4 Cl SO4 NO3

mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L Detection limit 0.5 0.005 0.005 0.005 0.005 0.001 0.01 0.01 0.01

January 4.8 0.089 1.059 0.132 0.056 0.147 1.90 0.96 1.24 February 4.8 0.110 1.315 0.161 0.069 0.169 2.30 1.06 1.28 March 4.7 0.171 1.128 0.156 0.111 0.244 1.98 1.41 1.68 April 4.6 0.213 0.779 0.124 0.123 0.270 1.37 1.47 1.76 May 4.6 0.177 0.494 0.081 0.071 0.264 0.89 1.55 1.63 June 4.6 0.104 0.326 0.050 0.045 0.198 0.59 1.21 1.49 July 4.5 0.073 0.200 0.033 0.035 0.189 0.43 1.24 1.64

August 4.5 0.075 0.301 0.045 0.046 0.202 0.57 1.48 1.50 September 4.6 0.086 0.500 0.067 0.049 0.175 0.89 1.28 1.41

October 4.7 0.077 0.788 0.100 0.049 0.187 1.40 1.20 1.26 November 4.8 0.080 1.158 0.143 0.058 0.144 2.06 1.05 1.00 December 4.8 0.112 1.512 0.188 0.070 0.161 2.72 1.16 1.32

168

Table A - 6 Chemical analyses including Charge Balance (CB) of surface water samples over six sampling periods in the Englishman River Watershed.

Sample ID Sampling CB Ca Mg Na K Cl HCO3 SO4 NO3

Period % mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L0.02 0.005 0.05 0.05 0.01 1 0.02 0.02

10SKP-01 Aug-10 -0.5 9.82 1.186 4.54 0.14 10.97 25 3.43 0.0810SKP-02 Aug-10 -0.8 9.84 1.196 4.68 0.22 10.93 27 2.97 0.1210SKP-03 Aug-10 0.0 9.38 1.363 6.79 0.39 13.17 28 2.99 0.0410SKP-04 Aug-10 4.4 10.48 1.230 4.93 0.17 10.88 25 2.30 0.0010SKP-05 Aug-10 0.5 9.79 1.138 4.78 0.23 10.98 25 3.02 0.0410SKP-06 Aug-10 3.1 9.97 1.159 4.74 0.21 10.95 25 1.62 0.1610SKP-07 Aug-10 1.5 10.04 1.164 4.61 0.14 11.31 26 1.68 0.0810SKP-08 Aug-10 1.3 9.52 0.918 4.61 0.15 10.94 24 1.82 0.1010SKP-09 Aug-10 1.3 8.99 0.833 4.51 0.10 10.98 21 1.60 0.1410SKP-10 Aug-10 0.9 9.02 0.787 4.54 0.17 11.09 22 1.40 0.1410SKP-11 Aug-10 2.9 9.26 0.808 4.56 0.09 11.25 21 1.34 0.3510SKP-13 Aug-10 0.3 12.11 3.195 4.57 0.39 11.14 42 1.94 1.1210SKP-14 Aug-10 1.2 9.51 1.030 4.56 0.15 11.38 24 1.63 0.0710SKP-15 Aug-10 0.4 9.17 0.867 4.58 0.14 11.45 22 1.55 0.2010SKP-16 Oct-10 3.9 7.67 0.857 2.76 0.14 5.16 21 2.14 0.0710SKP-17 Oct-10 4.8 7.21 0.841 2.64 0.12 5.05 19 1.76 0.0010SKP-18 Oct-10 4.2 10.26 8.250 66.48 2.66 111.21 21 16.45 0.0310SKP-19 Oct-10 0.6 7.08 0.822 2.66 0.12 5.26 21 1.76 0.0310SKP-20 Oct-10 4.0 7.22 0.827 2.67 0.12 5.13 20 1.62 0.0310SKP-21 Oct-10 2.6 6.32 0.677 1.85 0.12 3.18 19 1.70 0.0410SKP-22 Oct-10 3.0 7.16 0.978 2.28 0.15 3.92 21 2.87 0.0710SKP-23 Oct-10 3.1 6.11 0.644 1.83 0.10 3.10 18 1.64 0.0010SKP-24 Oct-10 6.2 6.48 0.620 1.75 0.09 2.87 17 1.55 0.0510SKP-25 Oct-10 4.1 6.23 0.636 1.86 0.09 3.12 18 1.56 0.0510SKP-26 Oct-10 4.8 6.80 0.626 1.87 0.09 3.06 19 1.62 0.0410SKP-27 Oct-10 5.8 4.88 0.562 1.09 0.15 1.48 13 1.93 0.0910SKP-28 Oct-10 9.3 4.84 0.526 1.09 0.15 1.51 13 1.22 0.0410SKP-29 Oct-10 8.8 4.89 0.550 1.13 0.14 1.55 13 1.41 0.0810SKP-30 Oct-10 0.8 5.09 0.485 1.07 0.09 1.52 16 1.10 0.0810SKP-31 Oct-10 8.6 4.98 0.534 1.17 0.11 1.57 13 1.41 0.0811SKP-32 Feb-11 2.6 6.05 0.961 2.66 0.15 4.50 19 1.96 0.0011SKP-33 Feb-11 3.9 6.23 1.005 2.73 0.15 4.51 19 1.89 0.1511SKP-34 Feb-11 1.9 6.83 3.411 23.19 0.99 40.70 19 6.77 0.2011SKP-35 Feb-11 3.5 6.03 0.954 2.66 0.13 4.61 18 1.75 0.0411SKP-36 Feb-11 1.5 5.88 0.938 2.66 0.15 4.67 19 1.94 0.0011SKP-37 Feb-11 3.3 6.02 0.941 2.71 0.12 4.86 18 1.81 0.1311SKP-38 Feb-11 4.8 6.05 0.903 2.74 0.12 4.83 17 1.83 0.1411SKP-39 Feb-11 1.3 5.93 0.874 2.72 0.12 4.83 18 1.87 0.1111SKP-40 Feb-11 1.8 6.37 0.863 2.90 0.12 5.21 19 2.03 0.1611SKP-41 Feb-11 2.6 5.89 0.857 2.74 0.11 4.85 17 1.93 0.1511SKP-42 Feb-11 1.5 6.60 0.674 2.94 0.10 5.62 18 1.86 0.0611SKP-43 Feb-11 1.6 7.02 0.728 3.23 0.09 6.28 19 1.99 0.0811SKP-44 Feb-11 1.1 7.08 0.780 3.19 0.08 6.27 20 2.00 0.09

Detection Limit

169

Sample ID Sampling CB Ca Mg Na K Cl HCO3 SO4 NO3

Period % mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L0.02 0.005 0.05 0.05 0.01 1 0.02 0.02

11SKP-45 Feb-11 1.0 7.11 0.719 3.30 0.09 6.6 20 2.04 0.0711SKP-47 May-11 -2.8 6.36 0.673 1.67 0.11 2.84 18 1.49 4.6511SKP-48 May-11 -2.1 5.88 0.648 1.62 0.08 2.78 18 3.18 0.2911SKP-49 May-11 2.0 5.83 0.654 1.64 0.13 2.84 18 1.47 0.2311SKP-50 May-11 2.7 5.93 0.650 1.61 0.08 2.72 17 1.57 0.2411SKP-51 May-11 3.6 6.07 0.655 1.63 0.10 2.84 17 1.48 0.2511SKP-52 May-11 2.9 5.77 0.642 1.60 0.08 2.89 17 1.41 0.2711SKP-53 May-11 2.4 5.69 0.595 1.46 0.09 2.48 17 1.46 0.3411SKP-54 May-11 4.1 5.59 0.578 1.42 0.08 2.42 16 1.38 0.2711SKP-55 May-11 0.4 5.77 0.555 1.35 0.08 2.37 18 1.37 0.2411SKP-56 May-11 2.3 5.52 0.573 1.41 0.08 2.43 16 1.40 0.2711SKP-57 May-11 3.0 5.89 0.552 1.50 0.12 2.59 17 1.41 0.3111SKP-58 May-11 1.4 5.89 0.527 1.39 0.07 2.57 17 1.35 0.2511SKP-59 May-11 -0.4 5.94 0.538 1.40 0.08 2.46 17 1.42 2.4111SKP-60 May-11 2.0 5.78 0.572 1.45 0.09 2.33 17 1.38 3.5011SKP-70 Jul-11 -1.1 6.32 0.654 1.69 0.08 3.44 20 1.04 0.0011SKP-71 Jul-11 1.6 6.33 0.654 1.67 0.08 3.25 19 1.08 0.0211SKP-72 Jul-11 2.1 6.36 0.657 1.71 0.09 3.11 19 1.12 0.0211SKP-100 Jul-11 1.9 6.89 0.711 1.91 0.08 3.74 21 1.13 0.0211SKP-101 Jul-11 2.5 6.95 0.718 1.99 0.08 3.83 21 1.11 0.0011SKP-102 Jul-11 0.9 6.88 0.712 1.94 0.08 3.75 21 1.10 0.0211SKP-117 Jul-11 0.9 6.70 0.646 1.80 0.07 3.54 21 1.02 0.0211SKP-118 Jul-11 1.2 6.70 0.619 1.80 0.07 3.57 20 0.97 0.0011SKP-119 Jul-11 1.1 6.57 0.602 1.77 0.07 3.52 20 1.01 0.0011SKP-120 Jul-11 1.9 6.56 0.565 1.66 0.06 3.14 20 0.80 0.0311SKP-121 Jul-11 1.6 6.34 0.513 1.53 0.05 2.86 19 0.87 0.0011SKP-122 Jul-11 3.0 6.29 0.516 1.53 0.05 2.81 18 0.89 0.0011SKP-123 Jul-11 1.7 6.41 0.537 1.56 0.06 2.82 20 0.91 0.0011SKP-124 Jul-11 2.9 6.38 0.513 1.55 0.05 2.85 19 0.83 0.0011SKP-125 Sep-11 1.4 6.62 0.750 1.52 0.12 2.30 22 1.02 0.0211SKP-126 Sep-11 1.1 6.65 0.651 1.32 0.05 2.20 21 1.11 0.0911SKP-127 Sep-11 1.1 6.24 0.638 1.87 0.03 2.50 21 1.05 0.4311SKP-128 Sep-11 -0.8 6.10 0.657 1.47 0.11 3.80 18 1.23 0.0111SKP-129 Sep-11 2.4 6.54 0.612 1.95 0.03 3.91 19 1.21 0.1011SKP-130 Sep-11 -1.5 5.98 0.741 1.85 0.03 3.45 18 1.14 2.2611SKP-131 Sep-11 1.0 6.01 0.721 1.65 0.05 3.30 19 1.20 0.0111SKP-132 Sep-11 3.2 6.28 0.736 1.74 0.04 3.28 19 1.06 0.0711SKP-133 Sep-11 1.8 6.33 0.698 1.45 0.07 3.40 19 0.97 0.0711SKP-134 Sep-11 2.8 6.32 0.645 1.62 0.02 3.30 18 0.87 0.3411SKP-135 Sep-11 4.9 6.42 0.687 1.77 0.21 2.90 19 0.92 0.0411SKP-136 Sep-11 3.0 6.56 0.646 1.88 0.04 2.81 20 1.18 0.4611SKP-137 Sep-11 3.0 6.38 0.677 1.84 0.14 2.50 20 1.17 0.0611SKP-138 Sep-11 0.4 6.22 0.670 1.96 0.13 2.80 21 1.20 0.12

Detection Limit

170

Table A - 7 Chemical analyses including Charge Balance (CB) of groundwater samples within the Englishman River Watershed.

Sample ID CB Ca Mg Na K Cl HCO3 SO4 NO3

% mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L0.02 0.005 0.05 0.05 0.01 1 0.02 0.02

11SKP-61 3.1 8.11 1.623 2.65 0.27 2.45 32 1.14 0.0711SKP-62 -0.6 53.59 19.501 10.31 0.60 37.78 210 8.37 7.4511SKP-63 1.8 8.52 1.870 2.45 0.20 4.33 30 2.28 0.0211SKP-64 1.4 8.60 2.112 2.67 0.20 5.05 31 2.20 0.0311SKP-65 -0.7 43.20 14.376 7.28 0.84 10.54 199 7.76 0.0011SKP-66 0.5 22.13 12.394 5.51 0.78 3.90 131 4.79 0.0011SKP-67 1.9 5.45 0.925 1.76 0.16 2.71 19 1.26 0.0511SKP-68 0.5 35.70 6.573 4.48 0.78 9.21 115 17.31 0.0011SKP-69 1.7 8.43 3.125 134.99 0.70 58.26 278 7.06 0.0011SKP-73 0.4 15.48 3.901 8.95 0.27 15.39 52 2.86 7.7511SKP-74 1.0 10.82 1.231 2.65 0.17 1.56 42 0.73 0.0011SKP-75 1.0 5.44 1.135 1.89 0.20 3.87 19 1.01 0.0411SKP-76 0.9 9.17 2.033 28.44 0.50 2.30 105 2.44 0.0011SKP-77 1.5 6.48 0.901 2.68 0.15 2.95 24 1.34 0.0011SKP-78 1.2 7.42 1.121 2.94 0.26 3.08 29 1.35 0.0011SKP-79 -0.6 44.30 15.989 16.71 1.39 53.19 163 8.50 0.0011SKP-80 -0.4 32.99 12.008 12.33 1.21 17.10 158 7.92 0.0011SKP-81 0.9 14.16 4.076 7.69 0.85 9.46 62 3.70 0.3811SKP-82 1.2 17.95 5.984 7.58 0.82 11.22 80 3.52 0.0011SKP-83 0.6 19.49 7.985 6.97 0.92 6.10 102 4.62 0.0011SKP-84 0.1 16.53 5.612 10.38 0.95 11.61 77 4.86 3.9811SKP-85 3.0 0.94 0.310 114.90 0.46 15.43 262 2.49 0.0011SKP-86 0.2 33.92 10.285 5.98 1.02 8.57 152 3.91 0.0011SKP-87 0.6 13.66 1.947 2.67 0.37 2.02 53 1.52 0.0011SKP-88 -0.3 17.45 5.668 4.22 0.33 9.56 70 5.73 0.48

Detection Limit

171

Sample ID CB Ca Mg Na K Cl HCO3 SO4 NO3

% mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L0.02 0.005 0.05 0.05 0.01 1 0.02 0.02

11SKP-89 1.0 18.18 5.376 5.30 0.24 8.93 75 2.69 0.7011SKP-90 1.6 7.14 0.850 2.05 0.12 4.35 22 1.18 0.0611SKP-91 1.5 7.16 0.851 2.06 0.11 4.31 22 1.21 0.0811SKP-92 0.8 11.38 3.389 3.55 0.27 6.76 47 1.48 0.0811SKP-93 -0.5 10.25 1.939 26.54 0.50 2.01 106 3.36 0.0011SKP-94 1.8 0.32 0.054 31.20 0.10 3.15 75 0.28 0.0211SKP-95 0.0 9.40 1.674 3.76 1.56 2.06 35 5.16 4.7211SKP-96 0.3 5.17 1.021 1.89 0.29 1.89 21 1.81 0.0011SKP-97 1.1 15.65 5.706 10.33 0.48 13.00 70 5.54 2.7211SKP-98 0.8 15.45 3.789 6.36 0.86 9.70 38 2.53 25.7111SKP-99 1.2 17.83 4.789 5.66 0.33 8.43 74 2.15 0.00

11SKP-103 1.3 5.92 1.460 2.50 0.20 4.01 21 2.25 1.0811SKP-104 0.7 12.77 3.308 3.35 0.25 6.18 49 2.57 0.9211SKP-105 -0.7 11.31 2.223 2.97 0.26 7.69 38 2.45 0.0011SKP-106 3.6 1.84 0.562 168.67 0.78 16.89 391 3.36 0.0011SKP-107 1.1 11.86 2.976 3.62 0.31 9.60 37 3.07 2.2311SKP-108 0.3 11.01 3.173 10.78 0.50 25.52 29 2.29 2.3911SKP-109 0.2 22.94 12.691 4.95 0.65 8.80 124 6.52 0.0011SKP-110 -0.8 30.48 19.129 5.83 0.79 16.50 155 20.09 0.0011SKP-111 -0.2 34.79 13.190 5.86 1.03 15.75 153 6.19 2.4211SKP-112 -0.6 31.26 12.303 6.71 1.68 13.92 147 7.11 0.0011SKP-113 1.2 69.39 25.449 59.31 0.75 197.31 134 8.73 0.6011SKP-114 -1.1 31.27 14.687 6.66 0.95 18.62 152 6.50 0.1011SKP-115 0.5 24.03 11.049 7.90 0.93 3.94 136 5.34 0.0011SKP-116 -0.6 28.71 10.530 8.31 0.84 3.21 152 6.02 0.00

Detection Limit

172

Table A - 8 Stable isotope abundance ratios of precipitation samples from Saturna Island.

18OH2O 2HH2O 18OH2O 2HH2O

‰ ‰ ‰ ‰0.2 1 0.2 1

Sat-01 Feb-93 -11.3 -82 Sat-32 Sep-95 -4.2 -30Sat-02 Mar-93 -10.9 -84 Sat-33 Oct-95 -9.3 -65Sat-03 Apr-93 -6.9 -59 Sat-34 Nov-95 -11.2 -84Sat-04 May-93 -7.6 -60 Sat-35 Dec-95 -12.4 -89Sat-05 Jun-93 -7.6 -67 Sat-36 Jan-96 -12.8 -92Sat-06 Jul-93 -6.2 -52 Sat-37 Feb-96 -14.6 -109Sat-07 Aug-93 -5.3 -50 Sat-38 Mar-96 -11.5 -81Sat-08 Sep-93 -7.0 -51 Sat-39 Apr-96 -8.4 -67Sat-09 Oct-93 -7.3 -55 Sat-40 May-96 -8.3 -63Sat-10 Nov-93 -9.1 -66 Sat-41 Jun-96 -12.4 -98Sat-11 Dec-93 -9.5 -70 Sat-42 Jul-96 -7.8 -64Sat-12 Jan-94 -10.2 -81 Sat-43 Aug-96 -5.7 -46Sat-13 Feb-94 -10.4 -88 Sat-44 Sep-96 -5.6 -38Sat-14 Mar-94 -8.4 -66 Sat-45 Oct-96 -7.4 -52Sat-15 Apr-94 1.7 -23 Sat-46 Nov-96 -11.0 -76Sat-16 May-94 -11.2 -95 Sat-47 Dec-96 -11.3 -82Sat-17 Jun-94 -6.5 -66 Sat-48 Jan-97 -12.4 -95Sat-18 Jul-94 -4.1 -38 Sat-49 Feb-97 -13.7 -102Sat-19 Aug-94 -4.7 -62 Sat-50 Mar-97 -11.5 -84Sat-20 Sep-94 -1.5 -28 Sat-51 Apr-97 -11.2 -78Sat-21 Oct-94 -6.2 -54 Sat-52 May-97 -10.5 -81Sat-22 Nov-94 -10.6 -78 Sat-53 Jun-97 -12.1 -93Sat-23 Dec-94 -12.9 -96 Sat-54 Jul-97 -12.1 -93Sat-24 Jan-95 -13.4 -98 Sat-55 Aug-97 -7.0 -51Sat-25 Feb-95 -14.4 -109 Sat-56 Sep-97 -7.1 -49Sat-26 Mar-95 -7.4 -79 Sat-57 Oct-97 -9.6 -66Sat-27 Apr-95 -10.3 -76 Sat-58 Nov-97 -13.6 -100Sat-28 May-95 -11.7 -89 Sat-59 Dec-97 -11.8 -88Sat-29 Jun-95 -9.2 -70 Sat-60 Jan-98 -13.4 -100Sat-30 Jul-95 -11.6 -88 Sat-61 Feb-98 -14.2 -102Sat-31 Aug-95 -8.4 -58 Sat-62 Mar-98 -13.6 -96

Masurement Uncertainty Masurement Uncertainty

Sampling Period

Sample ID Sampling Period

Sample ID

173

18OH2O 2HH2O 18OH2O 2HH2O

‰ ‰ ‰ ‰0.2 1 0.2 1

Sat-63 Apr-98 -10.2 -76 Sat-93 Oct-00 -10.4 -75Sat-64 May-98 -8.4 -64 Sat-94 Nov-00 -8.2 -58Sat-65 Jun-98 -8.5 -73 Sat-95 Dec-00 -11.5 -84Sat-66 Jul-98 -10.4 -85 Sat-96 Jan-01 -11.6 -89Sat-67 Aug-98 -11.4 -85 Sat-97 Feb-01 -12.0 -91Sat-68 Sep-98 -6.2 -43 Sat-98 Mar-01 -11.2 -85Sat-69 Oct-98 -5.7 -35 Sat-99 Apr-01 -9.8 -72Sat-70 Nov-98 -8.6 -57 Sat-100 May-01 -8.9 -71Sat-71 Dec-98 -13.2 -95 Sat-101 Jun-01 -9.2 -72Sat-72 Jan-99 -10.6 -77 Sat-102 Jul-01 -7.2 -57Sat-73 Feb-99 -11.8 -85 Sat-103 Aug-01 -7.8 -61Sat-74 Mar-99 -10.0 -73 Sat-104 Sep-01 -6.0 -40Sat-75 Apr-99 -12.2 -88 Sat-105 Oct-01 -7.4 -51Sat-76 May-99 -9.6 -74 Sat-106 Nov-01 -12.5 -87Sat-77 Jun-99 -8.0 -59 Sat-107 Dec-01 -10.6 -81Sat-78 Jul-99 -6.0 -51 Sat-108 Jan-02 -12.0 -89Sat-79 Aug-99 -2.1 -35 Sat-109 Feb-02 -10.8 -83Sat-80 Sep-99 -7.4 -54 Sat-110 Mar-02 -13.1 -96Sat-81 Oct-99 -8.6 -59 Sat-111 Apr-02 -10.0 -74Sat-82 Nov-99 -11.3 -80 Sat-112 May-02 -10.2 -76Sat-83 Dec-99 -12.8 -91 Sat-113 Jun-02 -9.2 -67Sat-84 Jan-00 -14.4 -108 Sat-114 Jul-02 -7.2 -64Sat-85 Feb-00 -12.3 -93 Sat-115 Aug-02 -8.5 -74Sat-86 Mar-00 -10.8 -79 Sat-116 Sep-02 -8.8 -64Sat-87 Apr-00 -8.0 -66 Sat-117 Oct-02 -8.1 -56Sat-88 May-00 -8.6 -67 Sat-118 Nov-02 -12.8 -90Sat-89 Jun-00 -7.1 -56 Sat-119 Dec-02 -12.1 -87Sat-90 Jul-00 -6.0 -47 Sat-120 Jan-03 -10.0 -67Sat-91 Aug-00 -9.8 -72 Sat-121 Feb-03 -10.1 -73Sat-92 Sep-00 -7.4 -53 Sat-122 Mar-03 -9.7 -68


Masurement Uncertainty Masurement Uncertainty


174

Table A - 9 Stable isotope abundance ratios of surface water samples.

Sample ID Sampling δ2HH20 δ18OH2O δ13CDIC δ34SSO4 δ18OSO4 δ15NNO3 δ18ONO3

Period ‰ ‰ ‰ ‰ ‰ ‰ ‰1 0.2 0.2 0.3 0.5 0.3 0.7

10SKP-01 Aug-10 -89 -12.5 -28.5 - - - -10SKP-02 Aug-10 -87 -12.4 -29.4 - - - -10SKP-03 Aug-10 -86 -12.2 -28.4 - - - -10SKP-04 Aug-10 -88 -12.2 -28.7 - - - -10SKP-05 Aug-10 -87 -12.2 -30.1 - - - -10SKP-06 Aug-10 -86 -12.1 -32.2 - - - -10SKP-07 Aug-10 -87 -12.3 -32.1 - - - -10SKP-08 Aug-10 -86 -12.3 -30.6 - - - -10SKP-09 Aug-10 -88 -12.4 -32.0 - - - -10SKP-10 Aug-10 -87 -12.4 -19.9 - - - -10SKP-11 Aug-10 -87 -12.4 -27.9 - - - -10SKP-13 Aug-10 -88 -12.2 -29.4 - - 12.2 1.010SKP-14 Aug-10 -87 -12.3 -29.6 - - - -10SKP-15 Aug-10 -87 -12.2 -29.5 - - - -10SKP-16 Oct-10 -80 -11.3 -28.3 - - - -10SKP-17 Oct-10 -79 -11.3 -24.7 - - - -10SKP-18 Oct-10 -81 -11.5 -28.4 - - - -10SKP-19 Oct-10 -80 -11.5 -27.4 - - - -10SKP-20 Oct-10 -80 -11.5 -29.8 - - - -10SKP-21 Oct-10 -83 -11.7 -29.3 - - - -10SKP-22 Oct-10 -81 -11.7 -28.3 - - - -10SKP-23 Oct-10 -80 -11.5 -28.7 - - - -10SKP-24 Oct-10 -82 -11.7 -29.4 - - - -10SKP-25 Oct-10 -81 -11.6 -28.2 - - - -10SKP-26 Oct-10 -82 -11.6 -28.0 - - - -10SKP-27 Oct-10 -84 -11.9 -29.3 - - - -10SKP-28 Oct-10 -84 -12.1 -29.3 - - - -10SKP-29 Oct-10 -84 -11.4 -28.2 - - - -10SKP-30 Oct-10 -82 -11.5 -28.2 - - - -10SKP-31 Oct-10 -83 -11.6 -28.8 - - - -11SKP-32 Feb-11 -94 -13.1 -29.6 - - - -11SKP-33 Feb-11 -92 -12.7 -29.4 - - - -11SKP-34 Feb-11 -92 -13.1 -29.4 - - - -11SKP-35 Feb-11 -94 -13.1 -29.5 - - - -11SKP-36 Feb-11 -92 -13.0 -20.7 - - - -11SKP-37 Feb-11 -93 -12.9 -27.7 - - - -11SKP-38 Feb-11 -92 -13.0 -29.2 - - - -11SKP-39 Feb-11 -92 -12.9 -29.5 - - - -11SKP-40 Feb-11 -93 -13.0 -28.5 - - - -11SKP-41 Feb-11 -92 -12.9 -29.4 - - - -11SKP-42 Feb-11 -92 -12.9 -25.2 - - - -11SKP-43 Feb-11 -93 -12.9 -28.3 - - - -

Measurement Uncertainty

175

Sample ID Sampling δ2HH20 δ18OH2O δ

13CDIC δ34SSO 4 δ18OSO 4δ

15NNO 3δ18ONO 3

Period ‰ ‰ ‰ ‰ ‰ ‰ ‰1 0.2 0.2 0.3 0.5 0.3 0.7

11SKP-44 Feb-11 -91 -12.9 -29.9 - - - -11SKP-45 Feb-11 -94 -13.0 -29.6 - - - -11SKP-47 May-11 -94 -13.4 -5.0 -5.5 -2.2 1.7 11.511SKP-48 May-11 -93 -13.3 -5.1 -3.6 -3.0 1.8 -11SKP-49 May-11 -95 -13.5 -4.9 -3.6 13.5 15.7 -11SKP-50 May-11 -94 -13.4 -4.3 -3.2 -2.7 7.1 -11SKP-51 May-11 -95 -13.3 -5.5 -2.9 -2.2 1.6 -11SKP-52 May-11 -94 -13.3 -4.4 -3.1 -2.7 4.2 -11SKP-53 May-11 -94 -13.3 -3.0 -2.9 -2.3 2.9 -11SKP-54 May-11 -96 -13.4 -3.9 -2.8 -2.6 2.5 -11SKP-55 May-11 -95 -13.5 -2.7 -3.0 -2.8 3.7 -11SKP-56 May-11 -94 -13.5 -2.7 -2.6 -2.4 1.4 -11SKP-57 May-11 -96 -13.5 -7.9 -3.7 -3.5 3.4 -11SKP-58 May-11 -95 -13.5 -2.7 -3.2 -3.4 5.4 -11SKP-59 May-11 -96 -13.6 -2.8 -2.8 -2.9 - -11SKP-60 May-11 -95 -13.4 -4.5 -2.5 -3.0 1.3 12.211SKP-70 Jul-11 -93 -13.4 -4.3 -0.6 -2.3 13.4 -11SKP-71 Jul-11 -92 -13.2 -5.6 -0.4 -2.6 6.0 -11SKP-72 Jul-11 -94 -13.5 -5.9 0.1 -2.2 8.0 -11SKP-100 Jul-11 -93 -13.5 -6.7 -0.3 -1.8 3.5 -11SKP-101 Jul-11 -93 -13.5 -5.1 - -4.2 - -11SKP-102 Jul-11 -93 -13.4 -6.7 -0.7 -1.6 - -11SKP-117 Jul-11 -90 -13.0 -9.1 0.6 -2.3 10.0 -11SKP-118 Jul-11 -91 -13.0 -7.5 -0.2 -2.4 6.6 -11SKP-119 Jul-11 -90 -12.8 -4.4 0.3 -2.2 18.6 -11SKP-120 Jul-11 -91 -13.0 -3.8 0.7 -2.3 14.7 -11SKP-121 Jul-11 -91 -13.1 -10.8 0.9 -2.6 17.2 -11SKP-122 Jul-11 -90 -13.0 -6.5 0.6 -2.2 5.1 -11SKP-123 Jul-11 -92 -13.0 -3.1 0.7 - 13.1 -11SKP-124 Jul-11 -90 -12.8 -5.7 1.0 -2.9 8.1 -11SKP-125 Sep-11 -74 -10.5 -4.5 -5.1 -2.6 6.5 -11SKP-126 Sep-11 -74 -10.7 -2.1 -2.8 -2.4 1.6 13.111SKP-127 Sep-11 -74 -10.3 -3.3 -1.3 -1.8 - -11SKP-128 Sep-11 -73 -10.6 -2.2 -3.5 -2.8 0.7 -11SKP-129 Sep-11 -75 -10.4 -0.8 -1.3 -2.4 0.9 -11SKP-130 Sep-11 -73 -10.4 -2.1 -4.6 -2.7 1.1 -11SKP-131 Sep-11 -75 -10.5 -5.3 -3.8 -1.7 6.4 -11SKP-132 Sep-11 -76 -10.7 -5.0 -2.8 -2.7 5.6 -11SKP-133 Sep-11 -75 -10.8 -2.6 -2.9 -2.5 - -11SKP-134 Sep-11 -76 -10.9 -0.8 -2.8 -3.0 1.8 -11SKP-135 Sep-11 -79 -11.1 0.6 -2.4 -3.0 - -11SKP-136 Sep-11 -77 -10.9 -0.7 -3.0 -2.9 1.7 10.4

Measurement Uncertainty

176

Table A - 10 Stable isotope abundance ratios of groundwater samples within the ERW.

δ2HH20 δ18OH2O δ


15NNO 3δ18ONO 3

‰ ‰ ‰ ‰ ‰ ‰ ‰Measurement

Uncertainty1 0.2 0.2 0.3 0.5 0.3 0.7

11SKP-61 -88 -11.8 -29.1 2.5 -0.5 - -11SKP-62 -82 -11.2 -17.5 2.9 -0.4 10.6 4.211SKP-63 -83 -11.3 -19.3 - - 6.8 -0.411SKP-64 -88 -12.2 -28.3 - - 4.9 -0.211SKP-65 -83 -11.8 -21.2 - - 9.2 -11SKP-66 -84 -12.0 -20.8 -1.2 -3.1 8.8 -11SKP-67 -92 -13.1 -15.3 -1.2 -4.2 - -11SKP-68 -82 -11.2 -17.1 -6.5 -0.8 - -11SKP-69 -83 -11.3 -17.9 12.1 7.2 - -11SKP-73 -89 -12.1 -22.5 0.3 -2.3 3.8 -11SKP-74 -89 -12.4 -22.3 14.4 7.0 - -11SKP-75 -89 -12.5 -23.0 5.7 -1.7 - -11SKP-76 -88 -12.1 -23.3 -1.4 4.5 - -11SKP-77 -95 -13.4 -15.9 -2.4 -3.2 - -11SKP-78 -93 -13.4 -24.7 -2.3 -1.8 - -11SKP-79 -87 -12.1 -20.7 -0.7 -2.7 - -11SKP-80 -89 -12.3 -22.0 0.2 0.9 9.5 -11SKP-81 -90 -12.8 -27.1 4.0 -0.5 - -11SKP-82 -85 -12.2 -19.4 7.2 3.4 - -11SKP-83 -85 -12.1 -24.9 2.2 -0.6 - -11SKP-84 -87 -12.4 -24.2 4.9 0.9 - -11SKP-85 -88 -12.0 -16.4 15.6 5.3 - -11SKP-86 -84 -11.7 -22.4 3.1 2.2 - -11SKP-87 -84 -11.8 -19.9 2.3 1.3 - -11SKP-88 -83 -11.5 -20.3 2.1 3.1 - -

Sample ID

177

δ2HH20 δ18OH2O δ


15NNO 3δ18ONO 3

‰ ‰ ‰ ‰ ‰ ‰ ‰Measurement

Uncertainty1 0.2 0.2 0.3 0.5 0.3 0.7

11SKP-89 -83 -11.5 -17.7 5.7 -0.4 - -11SKP-90 -93 -13.4 -9.4 -0.6 -2.1 - -11SKP-91 -94 -13.4 -10.8 -0.4 -2.4 - -11SKP-92 -87 -12.3 -18.0 - - - -11SKP-93 -90 -12.0 -17.2 -0.6 7.3 - -11SKP-94 -84 -11.7 -20.1 - - - -11SKP-95 -90 -12.7 -14.0 6.4 -1.7 - -11SKP-96 -90 -12.7 -21.1 10.4 2.2 - -11SKP-97 -89 -12.2 -24.6 5.7 1.0 - -11SKP-98 -88 -12.0 -34.6 7.2 0.4 14.8 1.211SKP-99 -84 -11.4 -22.0 4.8 7.1 - -

11SKP-103 -87 -12.1 -29.6 2.7 0.3 - -11SKP-104 -85 -11.6 -26.8 3.3 -1.2 - -11SKP-105 -84 -11.6 -31.3 0.7 -1.6 - -11SKP-106 -86 -11.9 -11.2 7.9 3.1 - -11SKP-107 -86 -11.8 -24.8 0.2 -1.5 - -11SKP-108 -87 -11.9 -16.0 4.3 0.4 - -11SKP-109 -85 -12.3 -21.6 - -5.0 - -11SKP-110 -84 -12.1 -19.8 -17.4 -4.8 - -11SKP-111 -84 -12.2 -23.5 -11.4 -0.5 - -11SKP-112 -85 -11.9 -20.8 -1.4 -5.4 - -11SKP-113 -81 -11.4 -20.5 4.2 2.8 - -11SKP-114 -85 -12.1 -17.2 -4.4 -1.1 - -11SKP-115 -82 -11.7 -18.0 -0.3 0.9 - -11SKP-116 -81 -11.5 -23.5 -0.7 -2.5 - -

Sample ID

178

Appendix B

179

Table B - 1 Saturation indices of groundwater samples.

11SKP-61 -1.24 -5.70 -12.42 -2.58 -0.28 2.98 7.11 0.1911SKP-62 -0.77 -2.23 -7.85 -0.98 0.00 2.22 6.15 0.4711SKP-63 -2.61 -6.67 -14.74 -3.06 -0.12 1.75 4.97 0.3611SKP-64 -2.64 -6.41 -14.30 -2.99 -0.22 1.97 5.21 0.2511SKP-65 -1.24 0.15 -0.93 0.20 -0.18 0.88 3.11 0.2811SKP-66 -1.28 -0.43 -1.22 -0.17 -0.24 0.97 3.15 0.2311SKP-67 -3.44 -5.84 -12.98 -2.63 -0.77 2.16 4.49 -0.3011SKP-68 -0.24 -0.73 -1.15 -0.07 0.07 1.08 4.03 0.5511SKP-69 -1.37 -0.80 -2.92 -0.27 -0.26 0.92 3.04 0.2111SKP-73 -2.97 -6.03 -14.88 -2.80 -0.14 1.51 4.46 0.3311SKP-74 -3.01 -6.33 -15.47 -2.78 -0.29 1.90 4.94 0.1811SKP-75 -1.88 -4.92 -8.35 -2.19 -0.28 1.69 4.53 0.2011SKP-76 -1.84 0.08 1.72 0.28 -0.36 -0.01 0.98 0.1111SKP-77 -3.13 -6.80 -16.00 -3.02 -0.56 2.39 5.39 -0.0811SKP-78 -2.56 -6.19 -14.59 -2.73 -0.50 2.39 5.50 -0.0111SKP-79 -0.83 0.80 1.20 0.57 -0.22 0.68 2.64 0.2611SKP-80 -0.96 1.59 4.08 0.96 -0.26 0.15 1.51 0.2211SKP-81 -1.99 -5.31 -13.47 -2.46 -0.22 1.94 5.16 0.2511SKP-82 -1.20 -4.29 -11.03 -1.98 -0.15 2.26 5.93 0.3311SKP-83 -0.82 -3.41 -8.97 -1.58 -0.11 2.22 5.92 0.3611SKP-84 -1.74 -4.92 -12.68 -2.31 -0.15 1.96 5.31 0.3211SKP-85 -0.94 -0.43 0.92 -0.11 -0.51 1.05 2.78 -0.0511SKP-86 -0.62 -1.04 -3.18 -0.37 -0.07 1.46 4.49 0.3911SKP-87 -1.03 -3.98 -8.90 -1.65 -0.19 2.31 5.95 0.2811SKP-88 -1.30 -3.86 -8.97 -1.77 -0.06 2.01 5.62 0.41

Gibbsite Kaolinite QuartzChalcedonySample ID K-feldspar Dolomite Talc Calcite

180

11SKP-89 -1.84 -4.16 -10.40 -1.92 -0.15 2.13 5.65 0.3011SKP-90 -3.75 -5.16 -11.85 -2.23 -0.83 1.94 3.92 -0.3711SKP-91 -3.70 -5.44 -12.68 -2.35 -0.82 2.11 4.30 -0.3511SKP-92 -2.56 -5.47 -12.53 -2.53 -0.10 1.38 4.27 0.3811SKP-93 -2.28 -0.69 -0.68 -0.05 -0.28 -0.27 0.60 0.1911SKP-94 -1.41 -7.62 -14.96 -3.50 0.03 2.19 6.15 0.5011SKP-95 -3.17 -6.95 -16.60 -3.17 -0.27 0.94 3.06 0.2111SKP-96 -3.65 -6.81 -14.48 -3.16 -0.38 1.08 3.11 0.0811SKP-97 -2.97 -5.32 -13.70 -2.53 -0.18 1.26 3.86 0.2911SKP-98 -5.48 -8.01 -20.31 -3.77 -0.21 -0.45 0.39 0.2711SKP-99 -1.75 -4.27 -10.37 -1.94 -0.07 1.82 5.21 0.3911SKP-103 -3.76 -7.75 -17.21 -3.64 -0.28 1.37 3.89 0.1911SKP-104 -2.17 -4.76 -10.47 -2.15 -0.06 1.35 4.30 0.4211SKP-105 -2.96 -6.31 -14.71 -2.86 -0.15 1.36 4.15 0.3311SKP-106 -1.71 -1.86 -5.12 -0.77 -0.30 0.66 2.43 0.1611SKP-107 - -5.84 -13.07 -2.69 -0.11 - - 0.3711SKP-108 -2.75 -6.26 -13.85 -2.92 -0.17 1.27 3.92 0.3111SKP-109 -1.67 -1.51 -3.95 -0.70 -0.13 0.82 3.10 0.3511SKP-110 -1.56 -1.00 -3.20 -0.49 -0.13 0.85 3.16 0.3411SKP-111 -1.58 0.71 1.84 0.47 -0.13 -0.20 1.05 0.3411SKP-112 -1.87 1.62 4.48 0.92 -0.27 -0.85 -0.53 0.2011SKP-113 - -2.31 -6.95 -1.05 0.02 - - 0.4711SKP-114 - 0.98 2.29 0.55 -0.28 - - 0.1911SKP-115 - 0.10 0.22 0.11 -0.26 - - 0.2011SKP-116 - 0.35 0.72 0.30 -0.19 - - 0.28

QuartzSample ID K-feldspar Dolomite Talc Calcite Chalcedony Gibbsite Kaolinite

181

Table B - 2 Saturation indices of surface water samples.

Sample ID Sampling Period K-feldspar Dolomite Talc Calcite Chalcedony Gibbsite Kaolinite Quartz

10SKP-01 August 2010 -3.76 -3.11 -6.18 -1.18 -0.75 0.74 1.69 -0.2810SKP-02 August 2010 -2.73 -2.85 -5.48 -1.06 -0.75 1.47 3.16 -0.2810SKP-03 August 2010 -2.79 -3.23 -6.62 -1.30 -0.76 1.45 3.10 -0.3010SKP-04 August 2010 -2.74 -2.43 -4.14 -0.86 -0.81 1.56 3.20 -0.3510SKP-05 August 2010 -2.86 -2.95 -5.70 -1.11 -0.77 1.42 3.01 -0.3110SKP-06 August 2010 -3.15 -2.46 -4.25 -0.88 -0.80 1.06 2.22 -0.3510SKP-07 August 2010 -3.11 -2.57 -4.59 -0.90 -0.76 1.14 2.49 -0.2910SKP-08 August 2010 -2.88 -3.51 -7.47 -1.34 -0.86 2.04 4.06 -0.4010SKP-09 August 2010 -3.55 -3.23 -6.46 -1.19 -0.87 1.37 2.70 -0.4010SKP-10 August 2010 -3.22 -3.58 -7.48 -1.33 -0.84 1.50 3.05 -0.3610SKP-11 August 2010 -3.72 -3.96 -8.56 -1.53 -0.85 1.51 3.03 -0.3810SKP-13 August 2010 -2.08 -1.83 -2.98 -0.73 -0.54 1.22 3.06 -0.0810SKP-14 August 2010 -3.02 -4.25 -9.45 -1.75 -0.80 2.15 4.41 -0.3410SKP-15 August 2010 -3.65 -4.80 -11.33 -1.98 -0.87 1.97 3.90 -0.4110SKP-16 October 2010 -2.67 -3.12 -5.10 -1.13 -0.66 1.30 3.00 -0.1710SKP-17 October 2010 -2.43 -3.44 -5.63 -1.30 -0.64 1.63 3.70 -0.1610SKP-18 October 2010 -1.45 -3.32 -5.72 -1.66 -0.65 1.78 3.98 -0.1610SKP-19 October 2010 -2.75 -4.00 -7.68 -1.57 -0.65 1.68 3.78 -0.1610SKP-20 October 2010 -2.72 -4.12 -7.90 -1.63 -0.64 1.74 3.91 -0.1610SKP-21 October 2010 -2.56 -4.22 -8.04 -1.66 -0.69 1.97 4.29 -0.2010SKP-22 October 2010 -2.49 -4.10 -7.90 -1.66 -0.63 1.87 4.18 -0.1510SKP-23 October 2010 -2.59 -4.71 -9.30 -1.90 -0.68 2.21 4.78 -0.1910SKP-24 October 2010 -2.74 -4.10 -7.58 -1.58 -0.70 1.80 3.94 -0.2110SKP-25 October 2010 -2.75 -4.54 -8.86 -1.81 -0.69 2.02 4.38 -0.2010SKP-26 October 2010 -2.77 -4.14 -7.93 -1.59 -0.69 1.82 3.98 -0.2010SKP-27 October 2010 -2.22 -4.22 -6.80 -1.68 -0.74 2.11 4.45 -0.2610SKP-28 October 2010 -2.42 -3.81 -5.60 -1.47 -0.76 1.74 3.67 -0.2810SKP-29 October 2010 -2.46 -4.12 -6.55 -1.62 -0.74 1.83 3.89 -0.26

182


10SKP-30 October 2010 -2.68 -4.83 -9.46 -1.94 -0.74 2.26 4.77 -0.2510SKP-31 October 2010 -2.62 -4.67 -8.20 -1.89 -0.74 2.06 4.34 -0.2611SKP-32 February 2011 -3.06 -5.21 -10.58 -2.34 -0.68 2.09 4.51 -0.2411SKP-33 February 2011 -3.08 -4.79 -9.38 -2.14 -0.68 1.90 4.13 -0.2411SKP-34 February 2011 -2.27 -4.66 -8.90 -2.32 -0.68 2.05 4.43 -0.2411SKP-35 February 2011 -2.85 -3.07 -3.98 -1.28 -0.68 1.26 2.86 -0.2311SKP-36 February 2011 -2.87 -4.40 -8.03 -1.94 -0.68 1.87 4.06 -0.2411SKP-37 February 2011 -3.21 -5.75 -12.03 -2.61 -0.68 2.29 4.92 -0.2311SKP-38 February 2011 -3.14 -5.45 -11.00 -2.46 -0.68 2.18 4.70 -0.2311SKP-39 February 2011 -2.99 -5.25 -10.58 -2.35 -0.68 2.25 4.82 -0.2411SKP-40 February 2011 -3.12 -4.84 -9.55 -2.13 -0.69 1.95 4.21 -0.2411SKP-41 February 2011 -3.21 -5.29 -10.59 -2.37 -0.69 2.09 4.48 -0.2511SKP-42 February 2011 -3.55 -4.82 -9.74 -2.05 -0.75 1.73 3.66 -0.3011SKP-43 February 2011 -3.83 -4.77 -9.84 -2.04 -0.75 1.54 3.28 -0.3111SKP-44 February 2011 -3.58 -4.94 -10.34 -2.13 -0.73 1.86 3.94 -0.2911SKP-45 February 2011 -3.86 -4.96 -10.47 -2.13 -0.75 1.62 3.42 -0.3111SKP-47 May 2011 -2.72 -4.69 -9.53 -1.89 -0.75 2.22 4.67 -0.2611SKP-48 May 2011 -3.19 -5.14 -10.87 -2.13 -0.75 2.09 4.39 -0.2611SKP-49 May 2011 -3.00 -5.44 -11.74 -2.28 -0.75 2.23 4.69 -0.2611SKP-50 May 2011 -3.14 -5.19 -10.98 -2.15 -0.76 2.20 4.59 -0.2811SKP-51 May 2011 -2.88 -5.02 -10.46 -2.06 -0.75 2.26 4.75 -0.2611SKP-52 May 2011 -3.14 -5.31 -11.20 -2.21 -0.75 2.21 4.62 -0.2711SKP-53 May 2011 -3.11 -5.58 -12.10 -2.33 -0.78 2.37 4.91 -0.2911SKP-54 May 2011 -3.27 -5.75 -12.48 -2.43 -0.80 2.39 4.91 -0.3111SKP-55 May 2011 -3.10 -5.27 -11.41 -2.15 -0.79 2.33 4.79 -0.3011SKP-56 May 2011 -3.23 -5.45 -11.61 -2.27 -0.79 2.24 4.63 -0.3011SKP-57 May 2011 -3.08 -5.73 -12.69 -2.38 -0.80 2.42 4.96 -0.3111SKP-58 May 2011 -3.22 -5.18 -11.15 -2.09 -0.79 2.18 4.50 -0.30

183


11SKP-59 May 2011 -3.18 -4.89 -10.24 -1.94 -0.79 2.07 4.28 -0.3011SKP-60 May 2011 -2.99 -4.70 -9.26 -1.87 -0.72 1.87 4.02 -0.23

11SKP-100 July 2011 -3.81 -3.94 -8.27 -1.55 -0.88 1.45 2.86 -0.4011SKP-101 July 2011 -3.83 -4.14 -8.86 -1.64 -0.87 1.49 2.95 -0.3911SKP-102 July 2011 -3.92 -4.27 -9.35 -1.72 -0.87 1.51 2.99 -0.4011SKP-117 July 2011 -4.27 -2.32 -3.42 -0.74 -0.92 0.33 0.52 -0.4511SKP-118 July 2011 -4.21 -3.22 -6.17 -1.18 -0.92 0.83 1.53 -0.4511SKP-119 July 2011 -4.28 -3.33 -6.44 -1.23 -0.93 0.86 1.58 -0.4611SKP-120 July 2011 -4.31 -3.62 -7.38 -1.36 -0.95 1.04 1.89 -0.4811SKP-121 July 2011 -4.29 -5.02 -11.51 -2.02 -0.93 1.72 3.30 -0.4511SKP-122 July 2011 -4.29 -3.28 -6.14 -1.15 -0.94 0.83 1.50 -0.4611SKP-123 July 2011 -4.32 -4.81 -10.90 -1.93 -0.93 1.59 3.03 -0.4511SKP-124 July 2011 -4.22 -4.99 -11.29 -2.01 -0.91 1.71 3.30 -0.4311SKP-70 July 2011 -3.61 -2.97 -5.24 -1.06 -0.89 1.11 2.15 -0.4111SKP-71 July 2011 -3.71 -4.51 -9.75 -1.83 -0.89 1.81 3.56 -0.4111SKP-72 July 2011 -3.70 -4.89 -10.92 -2.02 -0.89 1.96 3.87 -0.41

11SKP-125 September 2011 - -4.58 - -1.79 - - - -11SKP-126 September 2011 - -5.26 - -2.10 - - - -11SKP-127 September 2011 - -4.63 - -1.79 - - - -11SKP-128 September 2011 - -4.60 - -1.81 - - - -11SKP-129 September 2011 - -5.53 - -2.22 - - - -11SKP-130 September 2011 - -5.36 - -2.20 - - - -11SKP-131 September 2011 - -5.25 - -2.14 - - - -11SKP-132 September 2011 - -6.22 - -2.62 - - - -11SKP-133 September 2011 - -5.88 - -2.43 - - - -11SKP-134 September 2011 - -4.00 - -1.47 - - - -11SKP-135 September 2011 - -5.15 - -2.05 - - - -11SKP-136 September 2011 - -4.56 - -1.74 - - - -11SKP-137 September 2011 - -3.20 - -1.26 - - - -

Documents

Geochemical Assessment of Surface Water-Groundwater