411 2003 Chemistry Lecture Slides. well mixed chemically homogeneous except hyporheic environment...

411 2003Chemistry Lecture Slides

well mixed

•chemically homogeneous•except hyporheic environment•thermal stratification rare (occasionally large pools)

generally aerobic environment•favors oxidation•suppresses anaerobic processes•but locally important exceptions (hyporheic, pools, banks, floodplains)

General conditions affecting River Chemistry

River Ecosystems(3):river chemistry

Concentrations of dissolved material [dissolved load]

in general ionic or polar compounds dissolve best in water amount of dissolved material is highly variable in nature

commonly dissolved material includes ions from simple salts: anions drawn to anode (+ electrode) are negatively charged cations drawn to cathode (- electrode) are positively charged

Common gases from the atmosphere

Dissolved constituents reflect "history" of the water in question what kinds of material has the water come in contact with

source materials include solids and overlying gases atm gases dust, cloud seeds and CL

-

landscape surface and subsurface how long the water has been in contact with soluble material concentration by evaporation

evaporation-> "pure" water leaves heavier solutes behind

dilution by addition of less concentrated water gains and loses due to in situ reactions [both physical and biologically mediated]

anions cations Non- ionic CO3

= carbonate Na+ sodium N2 nitrogen

HCO3- bicarbonate Ca++ calcium O2 oxygen

Cl- chloride Mg++ magnesium CO2 Carbon dioxide

SO4= suphate K+ pottasium DOC Diss org carbon

OH- hydroxide Fe++ iron

Principal dissolved material in freshwater ecosystems

TDS: a complete but general accounting Gravimetric Methods

Total dissolved solids [TDS] Total suspended solids [TSS] : an analog for suspended material

Conductivity a common but nonspecific measure of dissolved content quick and easy basically determined from electrical resistance micrmho=microsiemen are the units doesn't give indication of non-ionic constituents e.g. dissolved organic matter not nec proportion to weight of ionic species

relationships between conductivity and TDS (~2:1)

6 HOH + 6 CO2 <=>C6H12O6 + 6 O2

stoichiometrically useful but too simplified

Photosynthesis and macro-nutrients

a more realistic (but also very simplified) equation for the productionof plant (algae) protoplasm:

106 CO2 + 16 NO 3-+ xPO4 + 122 HOH + 18 H + ENERGY<=> (C106H263O110N16P1) + 138 O2

note molar ratios of 106:16 ( ~12:1) C to N and 16:1 N to P correcting for molar weightsNecessary Inputs atomic wt mg per mole algae wt relative to P

CO2-C ~12 1272 ~41NO3

-N ~14 224 ~7PO4

=-P ~31 31 1Energy

parameter low medium high Conductivity s 5-80 90-800 1000+ TDS ppm <20 40-400 500+ Alkalinity ppm <40 50-150 200+ Ammonia ppb Nitrite ppb Nitrate ppb

<5 <5 <80

20-80 5-20 100-800

100+ 30+ 1000+

SRP (TRP) ppb TP ppb

<5 <10

10-20 15-30

30+ 50+

How much is a lot?

0 . 0 0

0 . 0 4

0 . 0 8

0 . 1 2

0 . 1 6

7 5 1 5 0 2 2 5

O S O HM_ _

E_ _

Alkalin ity (p pm as CaCO3)

SolubleReactivePhos-phate(ppm)

10 ppb

50 ppb

100

Variable Count Mean StdDev pH 131 7.5 0.5 Alkalinity 255 166 62 Conductivity 1130 416 198 NO2 + NO3 (ppm) 947 1.073 2.521 Ammonia (ppm) 833 0.083 0.162 SRP (ppm) 634 0.022 0.031 Total P (ppm) 774 0.059 0.080 Gilvin 242 0.024 0.020 Turbidity (NTU) 247 15.980 15.530

What is average?

parameter continental rain

Maine river

Michigan river

Seawater

Na+ mg/l

0.20 0.90 15.00 11000.00 K+

mg/l 0.15 0.30 3.60 399.00

NH4+

mg/l 0.10 0.08 0.04 0.04

Mg++ mg/l

0.05 0.40 7.70 1290.00 Ca++

mg/l 0.10 1.7 33.00 412.00

Cl- mg/l 0.20 0.55 19.00 19354.00

NO3-N mg/l

0.40 0.06 0.50 5.00 SO4

= mg/l 1.00 6.33 69.00 2712.00

CO3=

mg/l <1.0 7.7 100.0 120.00

PO43+-P

mg/l 0.010 0.010 0.030 0.025

PH -log10 [H+] 4.5 4.9 7 8.1

Cond. s 6 36 496 70000+ TDS mg/l 3 18 249 35292

Examples of some chemically distinct waters

…three ways to look at dissolved materials:

•load or loading [mg/sec or g/day or kg/yr]can standardize loading by area:

yield [e.g. mg/sec/sq mile or g/day/acre or kg/yr/km2]•concentration [mg/liter]

River Ecosystems(3):river chemistry

dominated by input and output

•retention decreases with increasing velocity and decreasing biological activity•longitudinally, incremental uptake/deposition leads to an assimilative capacity for consumable inputs•by a combination of assimilation and dilution abnormally high inputs can be processed longitudinally

nutrient cycling becomes nutrient spiraling

mass balance in a channel segment

River Ecosystems(3):river chemistry

Spiraling length

Sb Sw

dissolved material load•constituents reflect hydrologic source and history of material contacts• concentrations highly variable across landscape (spatial) as well as over time

Concentration

Mass/Volume Mass flux (load)/ water flux (Q)

[C] = L / Q

[C] = a Q b-1

River Ecosystems(3):river chemistry

VdC/dt = QCin – QCout +/- VrC

Mass balanceFor a CompletelyMixed Flow reactor

material transport in rivers: load

flow transportthree categories of material [load]

•dissolved (chemistry)•suspended•bed

L = a Q b

Where a and b are constants

b=1b >1

b< 1

b<< 1

Q

L

All forms of load are highly variable over time (flow effects)

Qd

d

Point Source (PS) and non-Point Source (NPS) loading

•PS loads relatively constant (b<<1, concentration strongly subject to dilution)•NPS loads usually increases with increasing runoff: note options

Q

Loa

d (q

uant

ity/

tim

e)Typical non-point source

Typical point source

hysteresis

Q

Con

cent

rati

on (

quan

tity

/vol

)

Typical non-point source

Typical point source

Nitrate+Nitrite (ppm)

Sol. Reactive Phosphate (ppm)

1 2 3

3

12

Primary productivity of Aquatic ecosystems

A basic model for enzyme mediated reaction rates. Common used to describe the relationship between concentrations of a limiting input and the resulting rate of photosynthesis.

growth or uptake rate = (S * Max) / (S+K)

S=input concentration; Max= maximum rate; K=1/2 saturation constant

Monod’s model

Primary productivity of Aquatic ecosystems

A basic model for enzyme mediated reaction rates. Common used to describe the relationship between concentrations of a limiting input and the resulting rate of photosynthesis.

growth or uptake rate = (S * Max) / (S+K)

S=input concentration; Max= maximum rate; K=1/2 saturation constant

Monod’s model

Max

concentration of limiting input [S]

photosyntheticrate

1/2 max

K value

Ecological implications:photosynthesis responds in a non-linear fashion to changes in all essential inputs

Max

concentration of limiting input [S]

photosyntheticrate

1/2 max

K value

Monod’s model

Ecological implications:photosynthesis responds in a non-linear fashion to changes in all essential inputs

small changes in rare inputs can induce large responses, but large changes in common inputs can have relatively small

consequences

Max

concentration of limiting input [S]

photosyntheticrate

1/2 max

K value

Monod’s model

Some typical uptake constants for phosphate taxon division K (g l-1 P) Max (-15 g

per m-2cell

surface day -1) Cyclotella nana bacillariophyceae 0.6 2.0 Thalassiosira fluviatilis bacillariophyceae 1.7 7.3 Scenedesmus sp. chlorophyceae 19 30 Psudomonas aeruginosa

cyanophyta 12.2 18

Physiological richness

yield or growth of an organisms is determined by the abundance of that substance which, in relationship to the needs of the organism, is least abundant in the environment [i.e.,at a minimum]

Liebig’s Law of the minimum

Liebig’s Law of the minimum

TABLE: Proportions of Essential Elements for Growth in Living Tissues of Freshwater Plants(Requirements), in the Mean World River Water (Supply), and the Approximate Ratio ofConcentrations Required to Those Available

ELEMENT AVERAGE PLANT CONTENT/REQUIREMENT (% by

weight)

AVERAGE SUPPLY INSURFACE WATERS

(% by weight)

RATIO of NEED to SUPPLY[RELATIVE DEMAND]

Oxygen 80.5 89 1Hydrogen 9.7 11 1Carbon 6.5 0.0012 5000Silicon 1.3 0 .00065 2000Nitrogen 0.7 0.000023 30,000Calcium 0.4 0.0015 <1000Potassium 0.3 0.00023 1300Phosphorus 0.08 0.000001 80,000Magnesium 0.07 0.0004 <1000Sulfur 0.06 0.0004 <1000Chlorine 0.06 0.0008 <1000Sodium 0.04 0.0006 < 1000Iron 0.02 0.00007 <1000Boron 0.001 0.00001 <1000Manganese 0.0007 0.0000015 <1000Zinc 0.0003 0.000001 < 1000Copper 0.0001 0.000001 <1000Molybdenum 0.00005 0.0000003 <1000Cobalt 0.000002 0.000000005 <1000

After Vallentyne, J.R.: The Algal Bowl--Lakes and Man. Miscellaneous Special Publication 22, Ottawa,Dept. of the Environment, 1974

Liebig’s Law of the minimum

there is always some input which is least abundant and limits primary production

ELEMENT AVERAGE PLANT CONTENT/REQUIREMENT (% by

weight)

AVERAGE SUPPLY INSURFACE WATERS

(% by weight)

RATIO of NEED to SUPPLY[RELATIVE DEMAND]

Oxygen 80.5 89 1Hydrogen 9.7 11 1Carbon 6.5 0.0012 5000Silicon 1.3 0 .00065 2000Nitrogen 0.7 0.000023 30,000Calcium 0.4 0.0015 <1000Potassium 0.3 0.00023 1300Phosphorus 0.08 0.000001 80,000Magnesium 0.07 0.0004 <1000Sulfur 0.06 0.0004 <1000Chlorine 0.06 0.0008 <1000Sodium 0.04 0.0006 < 1000Iron 0.02 0.00007 <1000Boron 0.001 0.00001 <1000Manganese 0.0007 0.0000015 <1000Zinc 0.0003 0.000001 < 1000Copper 0.0001 0.000001 <1000Molybdenum 0.00005 0.0000003 <1000Cobalt 0.000002 0.000000005 <1000

essential input indicator examples of systems withphotosynthetic ratelimited by this input

inorganic carbon <40 ppm total alkalinity soft water lakesPhosphorus <10 ppb TRP or N:P>>16 eastern and midwestern rivers, most N.A. lakesNitrogen <40 ppb NO3 or N:P<<16 southwest and northwest rivers, oceansMicro-nutrients Poor growth with high CNP Some tropical streamsradiant energy high turbidity/ gilvin/ depth

the 1% ruleReservoirs, turbid rivers

•limiting factors may change over time and across space•co-limitations are important

[Si] : [TP] <160

RCC: does it work?

decomposers

allocthonous

autochthonous

DETRITALPOOL

[algae+ macrophytes]

invertivorous fish /birds

grazersshredderscollector-gathersfilter-feeders

invertpredators

[terrestrial

leaves, wood, DOC]

piscivorous fish

piscivorous birds /mammals

Bacteria & fungi

Ripariancondition

Veloc

Light

Nutrients

Invert.biomass

Algal Biomass

Nutrients

Grazerbiomass

Algal Biomass

Nutrients

FISH?INSECTPREDATORS?

FLOODS?

DROUGHTS? POLLUTION?

DISEASE?

Top-down community controls and high disturbance regimes can obscure

simple responses to nutrient inputs

SRP [ug/l -1] SRP [ug/l -1]

4030201098765

400000300000200000

100000

50000400003000020000

10000

5000400030002000

1000

500400300200

40302010987654

400000300000200000

100000

50000400003000020000

10000

5000400030002000

1000

500400300200

Bio

mas

s [m

g d.

w. m

-2]

Periphyton

Invertebrates

Drift Bedrock

Figure 3. Hypothetical (A) and fitted (B) path diagram illustrating results of CSA of the effects of hydrologic disturbance on benthic algal and primary consumer biomass in Knobs and glacial drift streams. Rectangles are observed exogenous and

endogenous variables, ovals are unmeasured, latent variables, and small circles are error variances. Numbers give the magnitude of direct effects, and numbers in italics are squared multiple correlations. Bold indicates significant effects at p <

0.05 based on bootstrapped error estimates (n = 133).

Nutrients

High FlowDisturbance

Low FlowDisturbance

PhosphorusInorganicNitrogen

Frequency ofSubstrate Movement

.14

Algal BiomassBenthic Chlorophyll a

Q90 &Summer Temp

.51

GrazerBiomass

.59

Filter FeederBiomass

e10

.87 .27

.37

e3

e4

BankfullPower

.45

.17

.24

- .12

-.20

.87

-.24

- .92

.05

.43

.45

.55

- .52

- .48 - .51

.56

.74

.37

.14

.51

.59

.87 .27

.37

e3

e4

.45

1.00

.24

- .12

-.20

-.24

- .92

.05

.43

.45

.55

- .52

- .48 - .51

.56

.74

.37

(B)

Nutrients

High FlowDisturbance

Low FlowDisturbance

PhosphorusInorganicNitrogen

Frequency ofSubstrate Movement

.14

Algal BiomassBenthic Chlorophyll a

Q90 &Summer Temp

.51

GrazerBiomass

.59

Filter FeederBiomass

e10

.87 .27

.37

e3

e4

BankfullPower

.45

.17

.24

- .12

-.20

.87

-.24

- .92

.05

.43

.45

.55

- .52

- .48 - .51

.56

.74

.37

.14

.51

.59

.87 .27

.37

e3

e4

.45

1.00

.24

- .12

-.20

-.24

- .92

.05

.43

.45

.55

- .52

- .48 - .51

.56

.74

.37

(B)

Oxy

gen

cons

umed

Bio

logi

cal O

xyen

Dem

and

BO

D p

pm

Oxy

gen

ppm

time