Embed Size (px)
Citation preview
Assessment of physico-chemical qualities and heavy metalconcentrations of Umgeni and Umdloti Rivers in Durban,South Africa
Ademola O. Olaniran & Kovashnee Naicker &
Balakrishna Pillay
Received: 21 December 2012 /Accepted: 26 November 2013 /Published online: 13 December 2013# Springer Science+Business Media Dordrecht 2013
Abstract We assessed the effects of seasonal dynamicson the physico-chemical qualities and heavy metalsconcentrations of the Umgeni and Umdloti Rivers inDurban, South Africa. Water samples were taken fromnine different sampling points and analysed for thefollowing parameters; temperature, pH, turbidity, elec-trical conductivity (EC), biological oxygen demand(BOD5), chemical oxygen demand (COD), phosphate(PO4
2−), nitrate (NO32−), ammonium (NH4
+), sulphate(SO4
2−), lead (Pb2+), mercury (Hg2+), cadmium (Cd2+),aluminium (Al3+), and copper (Cu2+) using standardmethods. The data showed variations it terms of theseasonal fluctuations and sampling regime as follows:temperature 12–26.5 °C; pH 5.96–8.45; turbidity 0.53–18.8 NTU; EC 15.8–5180 mS m−1; BOD5 0.60–7.32 mg L−1; COD 10.5–72.9 mg L−1; PO4
2−<500–2,460 μg L−1; NO3
2− <0.05–4.21 mg L−1; NH4+<0.5–
1.22 mg L−1; SO42− 3.90–2,762 mg L−1; Pb2+ 0.023–
0.135 mg L−1; Hg2+ 0.0122–0.1231 mg L−1 Cd2+
0.068–0.416 mg L−1; Al3+ 0.037–1.875 mg L−1, andCu2+0.006–0.144 mg L−1. The concentrations of mostof the investigated parameters exceeded the recom-mended limit of the South African Guidelines andWorld Health Organization tolerance limits for freshwa-ter quality. We conclude that these water bodies arepotentially hazardous to public health and this highlights
the need for implementation of improved managementstrategies of these river catchments for continuedsustainability.
Keywords Environmental variables . Heavymetals .
Pollution . Seasonal variation .Water quality
Introduction
Pollution, demand and profligate use of water has in-creased pressure on freshwater resources, raising world-wide concern (Prüss-Üstün et al. 2008). A population’sliving standards and well-being is greatly impacted bythe quality and quantity of water that is accessible andavailable, thus global and local efforts are widespread atensuring adequate provision of clean and safe water.Deteriorating water quality is one of the major threatsto South Africa’s capability to provide sufficient waterof appropriate quality to meet its demands and to ensureenvironmental sustainability. As a semi-arid country,South Africa has a peculiar challenge of meeting it’sever increasing water demand, which is also influencedby industrial and population growth. This has inspiredthe government to establish a ‘Strategic Framework forWater Services’ (Department of Water Affairs andForestry (DWAF 2003) aimed at ensuring basic watersupply (at least 25 l of potable water per capita per day)to all South Africans.
The development of industries and urban economiesas well as human settlements has contributed greatlytowards pollution of inland surface water bodies in
Environ Monit Assess (2014) 186:2629–2639DOI 10.1007/s10661-013-3566-8
A. O. Olaniran (*) :K. Naicker :B. PillayDiscipline of Microbiology, School of Life Sciences, Collegeof Agriculture, Engineering and Science, University ofKwaZulu-Natal (Westville Campus),Private Bag X54001, Durban 4000, Republic of South Africae-mail: [email protected]
urban localities (Suthar et al. 2010). The quality ofriver water bodies such as the Umgeni and UmdlotiRivers in Durban, South Africa has been significantlyaffected by various polluting sources including agri-cultural drainage, urban wash-off, effluent return, in-dustries, mining, insufficient sanitation services,leachate from landfills and human settlements(Department of Environmental Affairs and Tourism(DEAT) 2006). Urbanisation (human activities andinfluences) has decreased the water quality of thelower reaches of these river catchments which posesa hazard to users. The consequences of human activ-ities on these freshwater habitats include acidificationby sulphur and nitrogen compounds, mobilization oforganic substances from soils; accelerated erosion andsedimentation in River channels, damming and diver-sion of River flows. In addition, eutrophication bynitrogen and phosphorus compounds, structural alter-ation of Rivers for flood prevention in the interests ofagriculture, fragmentation of habitats and introductionof alien species and selective removal of others, canalso occur (Anderson et al. 2008).
Physico-chemical parameters such as temperature,pH, dissolved oxygen (DO), salinity, and nutrient loadshave been reported to influence biochemical reactionswithin water systems. Variations in the value of theseparameters are indicative of changes in the condition ofthe water system (Hacioglu and Dulger 2009), and couldcompromise the water quality for beneficial uses. Thechemical composition of a water system is based on aninteraction between various factors, including theweathering of rocks, intensity and composition of therainfall in that area, chemical reactions that occur be-tween the water and soil/sediment, and pollution fromvarying sources (Da Silva and Sacomani 2001).Chemical pollutants that enter surface waters throughvarious pathways may pose a significant health hazardeven at extremely low concentrations, especially persis-tent chemicals (McMichael et al. 2001; Yassi et al.2001). The presence of toxic metals such as Pb and Cdin the environment has been a source of fret to environ-mentalists, government agencies and health practi-tioners. This is mainly due to their health implicationssince they are non-essential metals of no benefit tohumans (Fatoki et al. 2002). The presence of thesemetals in the aquatic ecosystem has far-reaching impli-cations directly to the biota and indirectly to man. Theirtoxic effects in man are related to dermal, lung and nasalsinus cancers.
Despite increasing stresses onwater resources in bothdeveloped and developing countries, understanding ofpollutants in these aquatic environments is fairlyscattered. Recent climate change has given rise tochanges in hydrologic patterns in both fresh and marinewaters, whose irregular water regimes have been addi-tionally influenced by anthropogenic factors due to pol-lution and other human interference which gives rise tospecific problems (Pradhan et al. 2009). The need toassess the quality of these freshwater bodies in terms ofphysico-chemical parameters andmetallic load becomesimperative since water from the rivers is used for do-mestic, irrigation and livestock watering activities bypeople living in the catchment area. In this study, weassessed the effects of seasonal fluctuations on thephysico-chemical qualities and heavy metals concentra-tions of two freshwater locales: the Umgeni andUmdloti Rivers, in Durban, KwaZulu-Natal Provinceof South Africa.
Materials and methods
Description of study site and sample collection
Water samples were collected from the designatedpoints of Umgeni (A1–A5) and Umdloti (C1–C4)Rivers located in Durban, KwaZulu-Natal (Fig. 1): andsampling was done from the river mouths (A1 and C1)to the Inanda (A5) and Hazelmere (C4) dam, respective-ly. The Umgeni River is 230 km long with a catchmentarea of approximately 5,000 km2; making it the largestcatchment in the KwaZulu-Natal region. The UmgeniRiver provides water to over 3.5 million people and aidsapproximately 65 % of the total economic production inthe province (Water Research Commission (WRC)2002) by supporting surrounding areas. The InandaDam is 23 km long from the bridge to the dam walland is 1.5 km at the widest point and 50 m deep at itsdeepest point (Inanda Dam Precinct and ResourceManagement Plan (IDPRMP) 2007). From InandaDam, the Umgeni River flows from the ThousandHills with a gentle gradient for 24 km before it flowsout to sea just North of Durban (IDPRMP 2007). Thispart of the Umgeni River is extensively modified, withriparian vegetation and the direction of flow is signifi-cantly altered to accommodate human settlements andactivities. The Umdloti River flows perennially with amean annual average flow of 2m3 s−1 (WRC 2002). The
2630 Environ Monit Assess (2014) 186:2629–2639
Umdloti River estuary mouth is approximately 25 kmNorth East of Durban Central and the length of theUmdloti River is <90 km (WRC 2002). Approximately
20 km upstream of the estuary lies the Hazelmere Dam ina gorge on the Umdloti River, about 5 km upstream(North-West) of the town of Verulam (HDPRMP 2007).
Sample CARDINAL POINTS
Latitude Longitude
A1 29° 48´ 43S 031° 02´ 20EA2 29° 47´ 47S 030° 58´ 03EA3 29° 48´ 13S 030° 53´ 36EA4 29° 46´ 18S 030° 50´ 11EA5 29° 40´ 29S 030° 51´ 19EC1 29° 38´ 53S 031° 07´ 42EC2 29° 38´ 10S 031° 02´ 56EC3 29° 37´ 19S 031° 02’ 41EC4 29° 35´ 38S 031° 02’ 09E
Fig. 1 Map of the study regionwithin Durban and surrounding areas. Shown are the locations of the water resources and nine sampling sitesinvestigated in this study
Environ Monit Assess (2014) 186:2629–2639 2631
The Dam was constructed to supply domestic, industrialand agricultural requirements within the area and in ex-pectation of Durban’s new international airport.
Water samples were taken every 3 months fromOctober 2008 (spring) to July 2009 (winter) allowinginvestigation of effects of seasonal variations on thewater quality at these sampling stations. Water sam-ples were collected 0.5 m below the water surfacefrom the rivers in pre-sterilised [70 % (v/v) alcohol]5 L plastic containers, protected from direct sunlightand transported on gel ice packs to the laboratory foranalysis.
Sample analysis
The physico-chemical parameters of water quality testedinclude water temperature (T), pH, turbidity (Turb),electrical conductivity (EC), total phosphate (PO4
2−),nitrate (NO3
2−), ammonia (NH3), total sulphate(SO4
2−), biological oxygen demand (BOD5), chemicaloxygen demand (COD) and five heavy metal concen-trations, including cadmium (Cd2+); copper (Cu2+); al-uminium (Al3+); lead (Pb2+) and mercury (Hg2+). Watertemperature, pH and turbidity were measured using amercury thermometer, pH meter (Beckman, Model Φ50) and portable turbidity meter (HACH Company,Model 2100P), respectively. BOD5 and COD were de-termined using the OxiDirect BOD system (HACH) andSpectroQuant Nova 60 COD cell test (Merck) respec-tively, whereas heavy metal concentrations were mea-sured using inductively coupled plasma–optical emis-sion spectrometer (ICP–OES) 5300 DV and 2100 DV(Perkin-Elmer). Briefly, 20ml of each water sample wasfiltered through 0.45 μM filter to remove particulatematter prior to ICP–OES. Heavy metal solutions (rang-ing from 0.01 to 0.25 ppm) were prepared with steriledistilled water and preserved with a few drops of nitricacid. These solutions were used for generation of astandard curve to determine heavy metal concentrations.EC, PO4
2−, NO32−, NH3, and SO4
2− were analysed bythe Umgeni Water Analytical Services according toInternational Organization for Standardizations (ISO)methods 21, 156, 5, 157 and 5, respectively.
Statistical analysis
Data was subjected to descriptive statistical analysis (95%confidence limit) and analysis of variance (ANOVA),means, standard error and range (incorporating the general
linear model) using SAS (SAS version 8, SAS Institute,Cary, NC). Pearson product–moment correlation coeffi-cient was used to test differences among all possible pairsof physico-chemical parameters (SPSS Version 21.0,Armonk, NY, IBM Corp).
Results
Physico-chemical characteristics of water samples
Spatial and seasonal fluctuations of the selected envi-ronmental variables of the water samples are presentedin Table 1. Temperature profiles varied significantly(P<0.05) and ranged from 13 °C (A4—winter) to26.5 °C (A2/A5—summer) for the Umgeni River and12 °C (C3—winter) to 26 °C (C1/C3/C4—summer) forthe Umdloti River. The pH varied significantly(P<0.05) across the four seasons and ranged from6.30 to 8.45 (Umgeni River) and 5.96 to 7.94(Umdloti River) while turbidities ranged from 0.53 to15.6 NTU (Umgeni River) and 2.23 to 18.8 NTU(Umdloti River). The Umdloti River exhibited highturbidity levels during summer with sampling point C4(Hazelmere Dam) exhibiting increased turbidity duringthe summer and winter seasons. Seasonal variations inturbidity, COD and conductivity levels amongst thesampling points along the Umgeni River were observed,with weak fluctuations in BOD5 values. BOD5, CODand conductivity values for the Umgeni River rangedfrom 0.52mg L−1 (A2—summer) to 3.22mg L−1 (A4—autumn), 10.5 mg L−1 (A5—spring) to 63.4 mg L−1
(A4—spring) and 18.6 mS m−1 (A4—autumn) to5,180 mS m−1 (A1—summer), respectively. BOD5
values for the Umdloti River ranged from 0.58 mg L−1
(C4—spring) to 7.32 mg L−1 (C1—spring) while CODranged from 13.9 mg L−1 (C2—spring) to 72.9 mg L−1
(C1—spring). Drastic changes in COD values occurredat points C1 and C2 over the seasonal cycle with little orno variations in conductivity values at points C3 and C4.During spring and summer, all river water samples had<500 μg L−1 phosphate concentrations. However, bothUmgeni and Umdloti Rivers showed significantlyhigher (P<0.05) phosphate concentrations during au-tumn and winter with 2,470 μg L−1 (A3—winter) and2,590 μg L−1 (C4—autumn) observed. According to thephosphate levels recorded, all water samples compliedwith the recommended World Health Organization(WHO) phosphate limit of 0.5 mg L−1 during spring
2632 Environ Monit Assess (2014) 186:2629–2639
Tab
le1
Physico-chem
icalquality
ofwater
samples
collected
from
October
2008
(spring)
toJuly
2009
(winter)
Samplea
Physicalcharacteristics
Chemicalcharacteristics
Heavy
metalconcentrations
(mgL
−1)b
T°C
pHTurb.
NTU
BOD5
mgL−1
COD
mgL−1
EC
mSm
−1PO
4
μgL−1
NO3
mgL−1
NH3
mgL−1
SO4
mgL−1
Pb2+
Hg2
+Cd2
+Al3+
Cu2
+
Spring
A1
217.43
0.53
2.09
26.7
5100
<500
<0.05
<0.5
2210
0.082±0.002
0.023±0.002
0.172±0.0002
0.069±0.002
0.011±0.0001
A2
238.23
3.51
1.20
16.3
188
<500
4.21
<0.5
25.3
0.063±0.0002
0.027±0.001
0.191±0.0001
0.091±0.001
0.014±0.0002
A3
19.5
8.01
4.67
0.83
12.8
53.1
<500
2.34
1.22
33.7
0.055±0.0002
0.058±0.004
0.132±0.0009
0.086±0.0009
0.024±0.0004
A4
186.30
1.64
3.15
63.4
4210
<500
<0.05
<0.5
2159
0.047±0.0003
0.023±0.003
0.252±0.002
0.108±0.0003
0.010±0.0004
A5
226.49
3.65
0.60
10.5
1579
<500
<0.05
<0.5
707
0.064±0.0004
0.041±0.002
0.074±0.0001
0.140±0.002
0.013±0.0002
C1
21.5
5.96
5.28
7.32
72.9
132
<500
<0.05
<0.5
19.3
0.077±0.001
0.036±0.001
0.085±0.003
0.133±0.001
0.105±0.0002
C2
207.19
4.70
1.02
13.9
23.4
<500
<0.05
<0.5
8.35
0.135±0.0003
0.015±0.0004
0.071±0.001
0.039±0.001
0.087±0.0002
C3
19.5
7.01
5.67
1.78
24.2
19.2
<500
<0.05
<0.5
8.25
0.050±0.0004
0.018±0.001
0.198±0.0001
0.054±0.001
0.069±0.0004
C4
237.10
4.51
0.58
19.7
16.4
<500
<0.05
<0.5
5.30
0.087±0.0008
0.031±0.0004
0.283±0.0002
0.157±0.0006
0.069±0.0002
Summer
A1
25.5
7.44
0.64
2.36
40.4
5180
<500
<0.05
<0.5
2762
0.065±0.0002
0.020±0.003
0.416±0.0001
0.057±0.02
0.033±0.001
A2
26.5
8.45
3.93
0.52
23.4
49.9
<500
1.47
<0.5
20.4
0.081±0.0001
0.021±0.0003
0.272±0.0001
0.132±0.0004
0.025±0.0002
A3
258.20
6.99
0.81
39.7
51.8
<500
2.87
<0.5
27.6
0.059±0.0002
0.025±0.001
0.315±0.0003
0.077±0.005
0.027±0.0001
A4
208.33
15.6
1.30
24.1
132
<500
2.97
<0.5
12.3
0.051±0.0002
0.023±0.002
0.104±0.0001
0.118±0.01
0.011±0.0003
A5
26.5
7.77
9.31
0.67
16.1
58.2
<500
1.00
<0.5
17.0
0.062±0.0003
0.030±0.0052
0.242±0.0006
0.049±0.0003
0.009±0.0002
C1
267.84
2.23
5.11
61.3
55.0
<500
<0.05
<0.5
10.4
0.131±0.0004
0.01
±0.001
0.127±0.0002
0.170±0.009
0.114±0.0002
C2
257.94
6.98
1.64
43.0
23.3
<500
<0.05
<0.5
9.15
0.075±0.0005
0.019±0.002
0.068±0.0003
0.128±0.02
0.059±0.0002
C3
267.54
7.87
2.25
39.9
19.2
<500
<0.05
<0.5
7.65
0.104±0.0005
0.021±0.0002
0.183±0.0003
0.046±0.004
0.081±0.0001
C4
267.23
14.1
0.89
15.0
16.2
<500
<0.05
<0.5
5.14
0.042±0.01
0.018±0.007
0.145±0.0003
0.037±0.003
0.076±0.0001
Autum
n
A1
20.5
8.03
1.20
1.47
32.5
3880
580
<2.5
0.82
2259
0.038±0.0003
0.021±0.01
0.073±0.001
0.197±0.001
0.036±0.0002
A2
19.5
7.29
2.43
1.66
29143
1760
0.90
<0.5
14.2
0.042±0.0004
0.012±0.003
0.078±0.002
0.912±0.001
0.006±0.0002
A3
177.77
5.61
1.15
23.7
57.3
2460
3.25
<0.5
34.4
0.050±0.0005
0.029±0.001
0.108±0.01
0.259±0.0001
0.023±0.0001
A4
19.5
7.14
3.87
3.22
2718.6
940
2.03
<0.5
3.90
0.051±0.0005
0.018±0.0003
0.120±0.0003
0.087±0.0020
0.037±0.0003
A5
207.49
2.80
1.83
40.6
20.8
1020
0.71
<0.5
11.7
0.047±0.0004
0.123±0.0001
0.113±0.0002
0.058±0.001
0.008±0.001
C1
20.5
7.56
2.84
0.71
32.3
572
1530
<0.05
<0.5
168
0.069±0.0007
0.012±0.0008
0.169±0.0022
0.385±0.001
0.046±0.0005
C2
18.5
7.13
2.72
2.60
30.4
40.6
2100
0.46
<0.5
8.18
0.060±0.0001
0.020±0.0002
0.176±0.0002
0.600±0.0002
0.012±0.0002
C3
20.5
7.40
3.05
0.76
3120.6
2170
<0.05
<0.5
7.68
0.039±0.0002
0.020±0.0002
0.114±0.0003
0.930±0.0001
0.006±0.0001
C4
207.50
6.51
3.00
20.9
15.8
2590
0.20
<0.5
4.60
0.042±0.0002
0.013±0.0002
0.122±0.0002
1.875±0.0001
0.007±0.0006
Environ Monit Assess (2014) 186:2629–2639 2633
and summer with this limit being exceeded during theautumn and winter seasons.
Most samples exhibited low ammonia and nitrateconcentrations. However, nitrate concentrations weresignificantly different (P<0.05) during spring, summerand winter for the Umdloti River. Sulphate concentra-tions varied considerably at points A1, A3, A4, A5 andC1, particularly over spring and winter. Theseconcentrations ranged from 3.90 mg L−1 (A4—autumn)to 2762 mg L−1 (A1—summer) and 4.47 mg L−1
(C4—winter) to 161 mg L−1 (C1—winter) forthe Umgeni River and Umdloti River samples,respectively.
Heavy metals concentration of water samples
Heavy metal concentrations for the Umgeni River var-ied over the four seasons as follows: 0.023 to0.082 mg L−1 for Pb2+; 0.0126 to 0.1231 mg L−1 forHg2+; 0.073 to 0.416 mg L−1 for Cd2+; 0.049 to0.912 mg L−1 for Al3+ and 0.006 to 0.108 mg L−1 forCu2+ (Table 1). Heavy metal concentrations for theUmdlot i River var ied as fol lows: 0.039 to0.135 mg L−1 for Pb2+; 0.0122 to 0.1046 mg L−1 forHg2+; 0.068 to 0.283 mg L−1 for Cd2+; 0.037 to1.875 mg L−1 for Al3+ and 0.006 to 0.144 mg L−1 forCu2+ (Table 1). The South African Target Quality RangeGuidelines for the heavy metals (in surface waters)tested in this study are 0–0.01 mg L−1 for lead; 0–5 μg L−1 for cadmium; 0–0.001 mg L−1 for mercury;0–1 mg L−1 for copper and 0–0.15 mg L−1 for alumin-ium (DWAF 1996). According to these guidelines, allriver water samples exceeded the set limits for Al3+,Pb2+, Hg2+ and Cd2+ across all seasons while all sam-ples complied with the copper guideline throughout theseasons.
Correlation matrix of water quality parametersand heavy metal concentrations
The correlation matrices of the physico-chemical prop-erties and heavy metals of the water samples are pre-sented in Tables 2 and 3. The sampling stations belong-ing to a particular resource (Umgeni River or UmdlotiRiver) were pooled together to calculate the correlationmatrix. The correlation coefficients should therefore beinterpreted with caution as they are affected simulta-neously by spatial and temporal variations.Nevertheless, clear relationships can be readily inferred.T
able1
(contin
ued)
Samplea
Physicalcharacteristics
Chemicalcharacteristics
Heavy
metalconcentrations
(mgL
−1)b
T°C
pHTurb.
NTU
BOD5
mgL−1
COD
mgL−1
EC
mSm
−1PO
4
μgL−1
NO3
mgL−1
NH3
mgL−1
SO4
mgL−1
Pb2+
Hg2
+Cd2
+Al3+
Cu2
+
Winter
A1
177.77
2.63
1.62
53.1
3880
740
<2.5
1.08
2482
0.027±0.001
0.016±0.0001
0.263±0.001
0.162±0.003
0.061±0.002
A2
178.37
7.42
1.48
38164
1710
0.99
<0.5
14.9
0.032±0.0003
0.013±0.0001
0.132±0.001
0.278±0.001
0.093±0.001
A3
168.00
4.82
0.77
32.6
539
2470
1.48
<0.5
236
0.023±0.0005
0.019±0.003
0.097±0.0006
0.140±0.001
nd
A4
138.20
4.58
0.93
2832.3
1170
2.18
0.5
4.87
0.061±0.002
0.102±0.0008
0.105±0.001
0.112±0.001
0.108±0.002
A5
157.81
1.64
1.35
11.4
21.3
1000
0.65
<0.5
11.3
0.038±0.002
0.020±0.0005
0.207±0.002
0.149±0.001
0.075±0.0002
C1
14.5
7.49
5.39
1.79
16.7
440
2000
0.41
<0.5
161
0.061±0.0001
0.024±0.002
0.213±0.0008
0.183±0.001
0.084±0.001
C2
12.5
7.79
4.63
2.14
15.3
52.2
2050
0.65
<0.5
10.6
0.048±0.0008
0.012±0.0001
0.173±0.0009
0.109±0.0006
0.049±0.001
C3
127.67
3.44
2.53
21.2
19.3
1990
0.14
<0.5
7.73
0.080±0.0002
0.104±0.0003
0.126±0.0002
0.222±0.0002
0.103±0.001
C4
137.66
18.8
2.08
18.4
15.6
2560
0.21
<0.5
4.47
0.059±0.001
0.018±0.0040
0.184±0.0002
0.072±0.0001
0.144±0.0003
aA1–A5Umgeni
River;C
1–C4UmdlotiR
iver
[Spring(Septemberto
October);Sum
mer
(Novem
berto
March);Autum
n(A
prilto
May);Winter(Juneto
August)]
bValuesrepresentaverage
ofresults
takenfrom
tenreplicateanalyses±Standarddeviation;
nd=notd
etected
2634 Environ Monit Assess (2014) 186:2629–2639
BOD5 was positively correlated with EC (r=0.490) andSO4
2− (r=0.473) for the Umgeni River (Table 2).Temperature and COD also showed a positive correlation(r=0.457) for the Umdloti River (Table 3). BOD5 and pHwere negatively correlated for both the Umgeni (Table 2)and Umdloti Rivers (Table 3) with r values of -5.62 and -0.501, respectively. Similarly, for both rivers, BOD5 waspositively correlated with COD showing r values of 0.566and 0.731 for the Umgeni (Table 2) and Umdloti Rivers,respectively (Table 3). Electrical conductivity also exhibit-ed a positive correlation with SO4
2− in the Umgeni (r=0.988) and Umdloti Rivers (r=0.966).
Discussion
Studies involving comprehensive river water qualityassessment are imperative towards maintaining publichealth and the sustainability of freshwater resources(Kannel et al. 2007). In addition, water quality monitor-ing can improve understanding of the hydrochemicalsystem and aid water resource management practices(Alexakis 2011). In this study, the physico-chemicalquality, heavy metal concentrations and the effects ofseasonal variability on water quality indices of theUmgeni and Umdloti Rivers were investigated.
Table 2 Correlation matrix of physical parameters for Umgeni River
River A T pH TURB BOD COD EC SO4 Pb Hg Cd Al
T 1
pH 0.021 1
TURB 0.085 0.435 1
BOD −0.143 −0.562b −0.375 1
COD −0.144 −0.242 −0.215 0.556a 1
EC 0.107 −0.422 −0.531a 0.490a 0.508a 1
SO4 0.086 −0.385 −0.526a 0.473a 0.550a 0.988b 1
Pb 0.623b −0.038 −0.042 −0.108 −0.351 0.091 0.004 1
Hg −0.205 0.014 −0.034 −0.144 −0.045 −0.260 −0.259 0.146 1
Cd 0.521a 0.018 −0.170 0.154 0.350 0.382 0.402 0.308 −0.262 1
Al −0.192 −0.090 −0.096 0.006 0.008 −0.162 −0.156 −0.305 −0.261 −0.349 1
a Correlation is significant at the 0.05 level (two-tailed)b Correlation is significant at the 0.01 level (two-tailed)
Table 3 Correlation matrix of physical parameters for Umdloti River
River C T pH TURB BOD COD EC SO4 Pb Hg Cd Al
T 1
pH −0.324 1
TURB 0.034 0.005 1
BOD 0.182 −0.501a −0.079 1
COD 0.457a −0.252 −0.182 0.731b 1
EC −0.162 0.129 −0.185 −0.156 0.092 1
SO4 −0.183 0.153 −0.168 −0.226 −0.001 0.966b 1
Pb 0.418 −0.222 −0.158 0.319 0.298 −0.229 −0.252 1
Hg −0.417 0.121 −0.163 0.033 −0.017 −0.179 −0.160 0.090 1
Cd −0.090 −0.086 0.044 −0.249 −0.418 0.003 0.003 −0.103 −0.161 1
Al 0.039 −0.021 −0.155 0.062 −0.063 −0.069 −0.077 −0.286 −0.143 −0.125 1
a Correlation is significant at the 0.05 level (two-tailed)b Correlation is significant at the 0.01 level (two-tailed)
Environ Monit Assess (2014) 186:2629–2639 2635
Spatial and seasonal fluctuations of the physical andchemical environmental variables differed significantly(P<0.05) amongst the water samples (Table 1). Thisdynamism of surface water resources may present chal-lenges in monitoring and managing these water bodies.Water temperature, pH, turbidity, biological oxygen de-mand (BOD5), chemical oxygen demand (COD) andconductivity were higher during spring and summerwith the inorganic water quality parameters reachingpeak values during the autumn and winter seasons.The observed trend could be attributed to the evapora-tion and decreased flow of water from rivers during thedry seasons and subsequent dilution due to heavy pre-cipitation and run-off from the catchment areas duringthe wet season (Radhika and Gangaderr 2004). Seasonalvariation in water temperature at the sampling sitesshowed a typical trend, with peak values recorded insummer and low values in winter, as previously reported(Igbinosa and Okoh 2009). All water samples from bothrivers were below 25 °C during spring, autumn andwinter, which is the recommended limit for no riskaccording to the South African water quality guidelinesfor domestic use (DWAF 1995). Temperature has amarked influence on the chemical and biochemical re-actions that occur in water bodies. High temperature forinstance, increases the toxicity of many substances suchas heavy metals and pesticides. It also increases thesensitivity of living organisms to toxic substances(Momba et al. 2006). The fact that sampling point A4is located within the KrantzKloof Nature Reserve andsurrounded by extensive natural vegetation could haveprobably contributed to the low water temperature re-corded at this point during summer as compared to theother points along the Umgeni River within the sameseason. Similar findings were also documented by DaSilva and Sacomani (2001).
Generally, the pH regimes fell within the SouthAfrican water quality pH protection limit of 5–9(DWAF 1996). The Blue Drop report (2009) suggestedthat pH values lower than 7 were probably due toleachates and rain runoff waters from abandoned mines.Higher pH of waters could be ascribed to increasedphotosynthetic assimilation of dissolved inorganic car-bon by planktons (Iqbal et al. 2004). A similar effectcould also be produced by water evaporation throughthe loss of half bound CO2 and precipitation of mono-carbonate (Wang et al. 2007). Turbidity is caused by thepresence of suspended matter, which usually consists ofa mixture of inorganic matter, such as clay and soil
particles, and organic matter (Momba et al. 2006). Thevariety of sources, character and size of suspendedsolids means that the measurement of turbidity givesonly an indication of the extent of pollution. High tur-bidity therefore indicates the presence of organicsuspended material which promotes the growth of mi-croorganisms (Momba et al. 2006). High turbidityvalues during the summer period could be attributed toincreased surface runoff and erosion, through summerrains. Excessive turbidity in surface waters, destined forhuman consumption can cause potential problems forwater purification processes such as flocculation andfiltration, which may increase treatment costs (Igbinosaand Okoh 2009). There may also be a tendency for anincrease in trihalomethane (THM) precursors, when high-ly turbid waters are chlorinated. The observed pH andturbidity range in this study is similar to that reported byIgbinosa andOkoh (2009) for TyumeRiver in the EasternCape Province of South Africa.
BOD5 is used to indicate the extent of organic pollu-tion in aquatic systems, which adversely affects waterquality. All Umgeni River samples fell within the uni-versal water quality index of 3 mg L−1 BOD5
(Boyacioglu 2007) over the different seasons, exceptfor point A4 which exceeded this standard during springand summer. Decreased BOD5 values during autumnand winter correlated well with the findings of Ouyanget al. (2006), who found a good correlation betweentemperature and BOD5 during winter. It is likely thatwater temperature during autumn and winter affectedthe solubility of oxygen in water, since temperature isknown to affect the solubility and availability of oxygen(Akan et al. 2008). Dissolved oxygen partially oxidizesorganic matter, therefore, the increase in oxygen con-centration in the water results in a decrease in organicmatter concentration and hence oxygen demand.Although no COD limits for aquatic systems are stipu-lated in the South African water quality guidelines, highCOD values obtained in this study are alarming andsuggest that both organic and inorganic substances, aswell as organic contaminants from municipal sewagetreatment plants and other industries, are entering thesewater systems. Several factors including temperature,ionic mobility and ionic valences influence water con-ductivity (Iqbal et al. 2004). In turn, conductivity qual-itatively reflects the status of inorganic pollution and is ameasure of total dissolved solids and ionised species inthe water. The electrical conductivities of the watersamples varied greatly for Umgeni River during the
2636 Environ Monit Assess (2014) 186:2629–2639
study period. The conductivity of the water samplecollected at the mouth of the Umdloti River (C1) de-creased during summerwhile conductivities of the watersamples from points C2, C3 and C4 remained relativelyunchanged. In addition, the high concentrations of elec-trical conductance values recorded in the water samplescollected from the river mouths (A1 and C1) depend onthe high or low tide of the ocean i.e. the impact ofseawater.
Elevated phosphate levels in the river water samplesduring autumn and winter could be attributed to thedecreased flux in the river systems during these dryseasons whereas the low concentrations detected inspring and summer could be a consequence of thedilution effect. This trend of fluctuating phosphate levelsduring the wet and dry seasons was also observed infour major rivers investigated in other part of Africa(Ololade and Ajayi 2009). Other investigators havepointed out that eutrophication-related problems in tem-perate zones of aquatic systems begin to increase whenthe ambient total phosphate concentration exceeds0.035 mg L−1.
For river water, nitrate and sulphate are often used asindicators of pollution status and anthropogenic load(Suthar et al. 2010). All the samples tested in this studyfell below the recommended WHO nitrate limit of50 mg L−1 (WHO 1996) for all seasons. Jaji et al.(2007) stated that unpolluted natural waters usuallycontain only minute amounts of nitrate, implying thatthese rivers are not necessarily adversely affected byanthropogenic activities. In this study, sulphate concen-trations were strongly correlated with EC for both riversin agreement with previous report that indicated thatsulphate concentrations are strongly impacted with EC(Olıas et al. 2004). Acid-sulphate soils are known todischarge high amounts of SO4
2− complexes and heavymetal species (Nystrand and Österholm 2004), thus it isalso possible that the soils surrounding the rivers couldhave contributed to the results obtained.
The phosphate levels obtained in this study wereexceedingly high for aquatic life, irrigation purposes,and livestock watering and recreational activities with aguideline value <0.05 mg L−1 (FEPA - FederalEnvironmental Protection Agency (FEPA) 1991). TheUmgeni River water samples exceeded the nitrates guide-line value of <0.5 mg L−1 making this river unsuitable foraquatic life and irrigation purposes. However, both riversare utilisable for livestock watering and recreational ac-tivities as they complied with the <10 mg L−1 guideline
for nitrates across all seasons (FEPA 1991; USEPAUnited State Environmental Protection Agency 2004).The concentrations of phosphate, nitrate and sulphate inthe river samples over the sampling periods fell with therange previously reported for some other river watersamples (Abbas et al. 2008; Osode and Okoh 2009).Ammonia is important in water quality assessments be-cause it can indicate sewage and animal feces pollution.Furthermore, it can reveal bacterial pollution (WHO2003). Ammonia levels were low and did not exceedthe guidelines as stipulated in DWAF 1996. Thus it canbe inferred that the rural human settlements surroundingthe Umgeni River do not contribute significantly towardspoor quality of this river.
Gross heavy metal contamination of the water re-sources was evidenced by the repeated non-complianceof the water samples with the South African WaterQuality guidelines (DWAF 1996) across the seasonalcycle. Heavy metals are among the most common envi-ronmental pollutants, and their occurrence in waters in-dicates pollution from natural or anthropogenic sources.Themain natural sources of metals in waters are chemicalweathering of minerals and soil leaching while the an-thropogenic sources are mainly associated with industrialand domestic effluents, urban storm water runoff, landfillleachate, mining of coal and ore and atmospheric sources(Papafilippaki et al. 2008). All heavy metals in surfacewaters exist in colloidal, particulate and dissolved phases.Rivers are a dominant pathway for metal transport withmany reports on temporal changes, especially seasonalvariations, in heavy metal concentrations in these watersystems (Iwashita and Shimamura 2003). The solubilityof trace metals in surface water is predominantly con-trolled by water pH, water temperature, the river flow andthe redox environment of the river system. Lower pHincreases the competition between metal and hydrogenions for binding sites whereas a decrease in pH may alsodissolve metal-carbonate complexes, releasing free metalions into the water column (Papafilippaki et al. 2008).This effect was noticeable at sampling points A2–A5 andC1–C3 where a decrease in water pH from summer toautumn resulted in increased concentrations of the differ-ent heavy metals. Higher metal concentrations during thedry seasons compared to the wet seasons could also bedue to water evaporation during the dry season anddilution due to precipitation and runoff during the rainyseason. These observations have been reported in otherstudies (Singh et al. 2008). The observed lead concentra-tion in this study is lower than the average concentration
Environ Monit Assess (2014) 186:2629–2639 2637
of 0.31 and 0.25 mg/l detected in Juru River and JajawiRiver in Malaysia, respectively (Abbas et al. 2008).However, mercury and cadmium concentrations fellwithin the reported range for most of the samples. Theconcentration of copper in the river water samples mon-itored in this study is less than that previously reported,except in winter when higher concentrations were detect-ed. Cadmium is harmful towards most organisms even insmall quantities and its potential to bioaccumulate in foodchains is concerning (Goyer et al. 2004; Bandara et al.2010; Stout et al. 2010). At elevated concentrations,cadmium is acutely toxic and can cause severe renaldamage with renal failure (Paasivirta 2007). The majoradverse effects of aluminium in water used for domesticpurposes are aesthetic, although chronic human healtheffects at high concentrations can occur. Aluminium isalso used in water treatment processes, which may resultin increased concentrations of aluminium in the finalwater (DWAF 1996). At neutral and alkaline pH, theconcentration of copper in surface waters is usually low,typically, 0.003 mg L−1, whereas in acidic waters, copperreadily dissolves, and substantially higher concentrationsmay occur (DWAF 1996).
In conclusion, the concentrations of most of theinvestigated parameters exceeded the recommendedlimit of the South African Guidelines and WorldHealth Organization tolerance limits for freshwaterquality. We therefore conclude that waters from thesewater bodies are potentially hazardous to public healthand this further highlights the need for implementationof improved management strategies of these river catch-ments for continued sustainability. Results from thisstudy further reiterate the need for a continuous pollu-tion monitoring programme of South African surfacewater resources, both short- and long term to ensureadequate protection of these precious resources.
References
Abbas, F. M., Ahmad, A. A., Ismail, N., & Easa, A. M. (2008).Multivariate analysis of heavy metals concentrations in riverestuary. Environmental Monitoring and Assessment, 143,179–186.
Akan, J. C., Abdulrahaman, F. I., Dimari, G. A., & Ogugbuaja, V.O. (2008). Physiochemical determination of pollutants inwastewater and vegetable samples along the Jakara wastewa-ter channel in Kano Metropolis, Kano State, Nigeria.European Journal of Scientific Research, 23(1), 122–133.
Alexakis, D. (2011). Assessment of water quality in theMessolonghi-Etoliko and Neochorio region (West Greece)
using hydrochemical and statistical analysis methods.Environmental Monitoring and Assessment, 182, 397–413.
Anderson, J., Arblaster, K., Bartley, J., Cooper, T., Kettunen, M.,Kaphengst, T., Kaphengst, A., Laaser, C., Umpfenbach, K.,Kuusisto, E., Lepistö A., & Holmberg, M. (2008) Climatechange—Induced water stress and its impact on natural andmanaged ecosystems. Policy Department Economic andScientific Policy.
Bandara, J. M. R. S., Wijewardena, H. V. P., & Seneviratne, H. M.M. S. (2010). Remediation of cadmium contaminated irriga-tion and drinking water: a large scale approach. ToxicologyLetters, 198, 89–92.
Boyacioglu, H. (2007). Development of a water quality indexbased on a European classification scheme. Water SouthAfrica, 33, 101–106.
Da Silva, A. M. M., & Sacomani, L. B. (2001). Using chemicaland physical parameters to define the quality of Pardo Riverwater (Brazil). Water Research, 35, 1609–1616.
DEAT, Department of Environmental Affairs and Tourism. (2006).South Africa Environment Outlook, (pp. 371). A report onthe state of the environment. Department of EnvironmentalAffairs and Tourism, Pretoria, SA.
DWAF, Department of Water Affairs and Forestry (1995). SouthAfrican water quality management series. Procedures toAssess Effluent Discharge Impacts. WRC Report No. TT64/94. Department of Water Affairs and Forestry and WaterResearch Commission, Pretoria, SA.
DWAF, Department of Water Affairs and Forestry. (1996). SouthAfrican Water Quality Guidelines—Domestic Uses (2nd ed.).Pretoria: Department of Water Affairs and Forestry.
DWAF, Department of Water Affairs and Forestry. (2003).Strategic framework for water services. Pretoria:Government Printer.
Fatoki, O. S., Lujiza, N., &Ogunfowokan, A. O. (2002). Trace metalpollution in Umtata River.Water South Africa, 28, 183–190.
Federal Environmental Protection Agency (FEPA) (1991).National guidelines and standards for industrial effluents,gaseous emissions and hazardous waste management inNigeria, (pp. 49), Government notice.
Goyer, R. A., Liu, J., & Waalkes, M. P. (2004). Cadmium andcancer of prostate and testis. Biometals, 17, 555–558.
Hacioglu, N., & Dulger, B. (2009). Monthly variation of somephysicochemical and microbiological parameters in Bigastream (Biga, Canakkale, Turkey). African Journal ofBiotechnology, 8, 1927–1937.
Igbinosa, E. O., & Okoh, A. I. (2009). Impact of discharge waste-water effluents on the physic-chemical qualities of a receiv-ing watershed in a typical rural community. InternationalJournal of Science and Technology, 6, 175–182.
Inanda Dam Precinct and Resource Management Plan (IDPRMP)(2007). Background Information Document, (pp. 1–29).Department of Water Affairs and Forestry (DWAF).
Iqbal, F., Ali, M., Salam, A., Khan, B. A., Ahmad, S., Qamar, M.,et al. (2004). Seasonal variations of physico-chemical char-acteristics of River Soan water at Dhoak Pathan Bridge(Chakwal), Pakistan. International Journal of Agricultureand Biology, 6, 89–92.
Iwashita, M., & Shimamura, T. (2003). Long-term variations indissolved trace elements in the Sagami River and its tribu-taries (upstream area). Science of The Total Environment,312, 167–179.
2638 Environ Monit Assess (2014) 186:2629–2639
Jaji, M. O., Bamgbose, O., Odukoya, O. O., &Arowlo, T. A. (2007).Water quality assessment of Ogun River, south west Nigeria.Environmental Monitoring and Assessment, 133, 447–482.
Kannel, P. R., Lee, S., Lee, Y., Kanel, S. R., & Khan, S. P. (2007).Application of water quality indeces and dissolved oxygen asindicators for river classification and urban impact assessment.Environmental Monitoring and Assessment, 132, 93–110.
McMichael, A. J., Kjellstrom, T., & Smith, K. (2001).Environmental health. In M. H. Merson, R. E. Black, & A.J. Mills (Eds.), International public health (pp. 379–438).Gaithersburg: Aspen.
Momba, M. N. B., Tyafa, Z., Makala, N., Brouckaert, B. M., &Obi, C. L. (2006). Safe drinking water still a dream in ruralareas of South Africa. Case study: The Eastern CapeProvince. Water South Africa, 32, 715–720.
Nystrand, M. I., & Österholm, P. (2004). Metal species in a Borealriver system affected by acid sulfate soils. AppliedGeochemistry, 21, 133–141.
Olıas,M., Nieto, J.M., Sarmiento, A.M., Ceron, J. C., &Cánovas, C.R. (2004). Seasonal water quality variations in a river affected byacid mine. Science of the Total Environment, 333, 267–281.
Ololade, I. A., &Ajayi, A. O. (2009). Contamination profile of majorrivers along the highways in Ondo State, Nigeria. Journal ofToxicology and Environmental Health Sciences, 1, 38–53.
Osode, A. N., & Okoh, A. I. (2009). Impact of discharged waste-water final effluent on the physicochemical qualities of areceiving watershed in a suburban community of theEastern Cape Province. Clean, 37, 938–944.
Ouyang, Y., Nkedi-Kizza, P., Wu, Q. T., Shinde, D., & Huang, C.H. (2006). Assessment of seasonal variations in surface waterquality. Water Research, 40, 3800–3810.
Paasivirta, J. (2007). Long term effects of bioaccumulation inecosystems. In B. Beek (Ed.), The Handbook ofEnvironmental Chemistry Bioaccumulation—New Aspectsand Developments, Earth and Environmental Science (pp.201–233). Berlin, Heidelberg: Springer.
Papafilippaki, A. K., Kotti, M. E., & Stavroulakis, G. G. (2008).Seasonal variations in dissolved heavy metals in the KeritisRiver, Chania, Greece. Global NEST Journal, 10, 320–325.
Pradhan, U. K., Shirodkar, P. V., & Sahu, B. K. (2009). Physico-chemical characteristics of the coastal water off Devi estuary,Orissa and evaluation of its seasonal changes using chemo-metric techniques. Current Science, 96, 1203–1209.
Prüss-Üstün, A., Bos, R., Gore, F., & Bartram, J. (2008). Saferwater, better health: costs, benefits and sustainability of
interventions to protect and promote health. World HealthOrganization, Geneva. (Available from http://www.who.int/quantifying_ehimpActs/publications/safewater/en/index.html) Accessed 15 August 2009.
Radhika, C. G., & Gangaderr, T. (2004). Studies on abiotic pa-rameters of a tropical fresh water lake—Vellayani Lake,Thiruvanthapuram District, Kerala. Pollution Research, 23,49–63.
HDPRMP Hazelmere Dam Precinct and Resource ManagementPlan (2007). Background Information Document, (pp. 1–30).Department of Water Affairs and Forestry (DWAF).
Singh, A. P., Srivastava, P. C., & Srivastava, P. (2008).Relationships of heavy metals in natural lake waters withphysico-chemical characteristics of waters and differentchemical fractions of metals in sediments. Water, Air, andSoil Pollution, 188, 181–193.
Stout, L. M., Dodova, E. N., Tyson, J. F., & Nusslein, K. (2010).Phytoprotective influence of bacteria on growth and cadmi-um accumulation in the aquatic plant Lemna. WaterResearch, 44, 4970–4979.
Suthar, S., Sharma, J., Chabukdhara, M., & Nema, A. K. (2010).Water quality assessment of river Hindon at Ghaziabad,India: impact of industrial and urban wastewater.Environmental Monitoring and Assessment, 165, 103–112.
USEPA (United State Environmental Protection Agency). (2004).EPA groundwater and drinking water current standards.Washington: EPA office of water.
Wang, X. L., Lu, Y. L., Han, J. Y., He, G. Z., &Wang, T. Y. (2007).Identification of anthropogenic influences on water quality ofrivers in Taihu watershed. Journal of EnvironmentalSciences, 19, 475–481.
WHO (2003). Ammonia in drinking-water. Background documentfor preparation of WHO guidelines for drinking-water qual-ity. Geneva, World Health Organization (WHO/SDE/WSH/03.04/1)
WHO,World Health Organization (WHO). (1996).Guidelines fordrinking water quality (2nd ed.). Geneva: Health criteria andother supporting information, World Health Organization.
WRC Water Research Commission (2002). State of rivers report:Mngeni River and neighbouring rivers and streams. WRCReport no. TT 200/02, Water Research Commission,Pretoria, SA.
Yassi, A. L., Kjellstrom, T., deKok, T., & Guidotti, T. (2001).Basic Environmental Health. New York: Oxford UniversityPress.
Environ Monit Assess (2014) 186:2629–2639 2639
