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CHARACTERISTICS OF LAKE WATER, SEDIMENT
AND ITS IMPACT ON GROUNDWATER Praveen Kumar S* and Santhaveerana Goud B*** Environmental Engineering, Department of Civil Engineering, Bangalore University, Bangalore – 56.** Department of Civil Engineering, Bangalore University, Bangalore – 56.
Allasandra and Bellandur lakes were considered for the present study. These
lakes are located in the outskirts of Bangalore City and cover an area of
21.06 and 365 hectares respectively. The lake water, sediment and a
groundwater sample near the lakes were collected and analysed for Cu, Pb,
Cd, Ni, Mn, Zn and Cr using Atomic Absorption Spectrophotometer (AAS).
Elevated concentrations of physico-chemical parameters were recorded in
the lake and groundwater. The heavy metal concentration in Allasandra lake
is well with in the limits and can be used for agricultural soils. The study
revealed that the lakes were polluted because of untreated municipal waste
water entering the lakes, there by polluting the surface water. Spatial
distribution of BOD was analysed using GIS software.
INTRODUCTION:
Lakes in urban areas are available natural resources which provide several
beneficial uses for urban population such as harvesting rainwater, recharging
the ground water table, mitigation of floods, pisciculture, capacity to supply
water in emergencies such as fire fighting and plenty of recreational
opportunities such as boating, swimming, walking and jogging in the lake
bund. .
Lakes are often seen as main targets for development in urban areas due to
pressure of human activities like urbanisation, industrialisation etc. As a
result of these activities most of the urban lakes are getting degraded beyond
the point of recovery. Encroachments, siltation, weed infestation, discharge
of domestic sewage, industrial effluents, surface run off carrying pesticides
and other chemicals used in agriculture are the main cause for degradation of
these lakes. The overall impact of these activities has resulted in
1. Deterioration of lake water quality
2. Sedimentation and shrinkage
3. Increase in mosquito breeding causing health hazards
4. Increase in productivity to support flora and fauna
5. Loss of aesthetic values and decrease in tourism potential
Description:
Two lakes namely Allalasandra and Bellandur lakes were selected for
the study. They are located between 77 35’ and 13 05’ and 77 40’ and 13
55’ respectively. The water spread area of the Allalasandra lake is 16.84
hectares and Bellandur lake is 365 hectares. The maximum depth at the
deepest point is 1.5 m in Allalasandra and Bellandur lake is 5 m . The
capacity of Allalasandra lake is 0.43 MCM (Million cubic meter) and
Bellandur lake is 17.67 MCM.
The total quantity of wastewater from the catchment area due to
different activities such as domestic and commercial was about 10 MLD
entering into the Allalasandra lake.
The quantity of wastewater from the catchment area entering
Bellandur lake is about 62 MLD i.e., from C valley 22 MLD, K valley 21
MLD, Agaram and Madivala 16 MLD and from earthen drain is 3 MLD
and 162 MLD treated water from K and C valley secondary treatment plant
is entering the lake. The total quantity of treated and untreated water
entering the Bellandur lake is about 224 MLD.
Objectives:
1. To study the characteristics of Allasandra and Bellandur lake
water
2. To study the groundwater quality in the vicinity of the selected
lakes.
3. To study the characteristics of sediment with respect to heavy
metals of the selected lakes.
4. To study the spatial distribution of BOD by using MapInfo and
Surfer software.
Methodology
Five sampling points were selected at appropriate places for sample
collection of lake water in Allalasandra and Bellandur lakes. The location
of the points is as shown in Figure 1 and 2 respectively for Allalasandra
and Bellandure lakes . Several water quality parameters such as pH,
electrical conductivity, temperature, turbidity, dissolved oxygen, total
hardness, calcium hardness, magnesium hardness, potassium, BOD, iron,
copper, lead, cadmium, nickel, manganese, total chromium and zinc were
analysed for lake and ground water. Similarly lead, cadmium, nickel, total
chromium and zinc parameters were selected for sediment analysis. Three
sampling points for sediment analysis and two points for groundwater were
taken for analysis.
The samples were analysed as per the standards (standard methods for
the examination of water and wastewater 1998). The lake water data
collected was analysed by using Map Info and Surfer Software to know the
spatial distribution of pollutants in the lake water.
RESULTS AND ANALYSIS
The quality of the surface water of Allalasandra lake is shown in Table 1 and
that of Bellandur lake in Table 3. The concentration of heavy metals in the
sediments of Allalasandra and Bellandur are shown in the Table 2 and 4.
The groundwater quality in the vicinity of the selected lakes is shown in
Tables 2 and 4 respectively.
DISCUSSIONS.
Allalasandra lake
Concentration of some of the parameters like pH, electrical conductivity,
turbidity, chlorides, total hardness, calcium, magnesium, total dissolved
solids, sulphates, nitrates, and iron ranged between 7.4-7.6, 0.8-1.2, 0.6-30,
88-288, 257-244, 135-230, 60-198, 686-804,16-34, 0.4-0.8 and 0.24-1.3mg/l
respectively. When compared to drinking water standards, the concentration
exceeds the limits for most of the parameters.
With respect to few parameters namely pH, sulphates, nitrates, Cu,
Pb, Mn, Cr and Zn are with in the limits specified for drinking water. The
sodium absorption ratio and percentage of sodium estimated for the
Allalasandra lake water was found to be good (BIS 1991) for irrigation.
The lake water can be used for irrigation as per FAO (1979) standards for
heavy metals.
The concentration of lead, cadmium, nickel, total chromium and zinc
in the sediment of Allalasandra lake was found to be 6.8, 0.1, 2.0, 7.2 and
20.2 mg/Kg respectively. Comparing it with the permissible limits as per
Csillag et. al., 1998 shows that the concentration are well within the limits.
The groundwater quality adjacent to Allalasandra lake is as shown in
Table 2. The concentration of some of the parameters such as pH, chlorides,
total hardness, calcium, magnesium, total dissolved solids, sulphates, iron
and manganese are exceeding the permissible limits of drinking water
standards (IS: 10500 – 1991). The concentration of heavy metals such as
copper, lead, cadmium, total chromium and zinc are within the permissible
limit.
The reason for the deterioration of groundwater quality may be due to the
continuous percolation of polluted surface water.
The spatial distribution of BOD in Allalasandra lake as shown in
Figure 1, depicts that at the inlet points the BOD is high (164mg/l) and it
goes on to decrease with increase in the distance towards the outlet point.
Compared to outlet point i.e. 3 and middle point 2 and 5 (i.e. at the left bank)
the BOD is less at 3. At point 5 (left bank) which is also located in the
middle portion of the lake, the concentration of BOD is comparatively high,
so the reason may be due to the inflow of wastewater just on the upstream
side of point 5 on the left bank. The decrease in the BOD of the lake water
during its retention in the lake may be due to the process of self purification
and the results shows that the decrease in the BOD is very significant.
BELLANDUR LAKE
Concentration of some of the parameters like pH, turbidity, chlorides,
total hardness, calcium, magnesium, total dissolved solids, sulphates,
nitrates, and iron ranged between 7.0-8.0, 12-35, 48-140,170-290,148-240,
22-116, 542-812, 12-35,0.25-7 and 0.2–0.4mg/L. The concentration of pH,
turbidity, calcium, magnesium, total dissolved solids, sulphates and iron are
exceeding the drinking water limits (IS: 10500 – 1991). With respect to a
few parameters namely chlorides, total hardness, nitrates are within the
limits specified for drinking water. Concentrations of heavy metals like
copper, lead, cadmium, manganese, total chromium and zinc are 0.013,
BDL, BDL, 0.178, 0.0015 and 0.5 mg/l respectively. When compared with
drinking water standards the concentration of manganese is exceeding the
limits. The sodium absorption ratio value and percentage sodium estimated
for the Bellandur lake water was found to be good (BIS 1991) for irrigation.
The lake water can be used for irrigation as per FAO (1979) standards for
heavy metal concentration.
The concentration of lead, cadmium, nickel, total chromium and zinc
in the sediment of Bellandur lake was found to be 23.03, 0.767, 65.5, 81.0
and 110 mg/kg. Comparing it with the permissible limits as per Csillag et.
al., 1998 it shows that the concentrations are not within the limits.
The ground water quality adjacent to Bellandur lake is as shown in
Table 4. The concentration of some of the parameters such as chlorides, total
hardness, calcium, magnesium, total dissolved solids, sulphates, nitrates,
manganese are exceeding the permissible limits of drinking water standards
(IS: 10500 – 1991).
The spatial distribution of BOD in Bellandur lake as shown in Figure 2,
depicts that at the inlet points the BOD is high (215 mg/l) and it goes on to
decrease towards the outlet . The decrease in the BOD of the lake water
during its stay in the lake may be due to the process of self-purification and
the results shows that the decrease in the BOD is very significant.
Conclusion
Allalasandra lake
The lake water quality is poor with respect to turbidity, chlorides, total
hardness, calcium, magnesium, total dissolved solids, iron and manganese,
which restricts its use for domestic purpose.
The sediment quality with respect to heavy metals is with in the permissible
limit to use it for agricultural applications.
The groundwater quality is poor with respect to pH, chlorides, total
hardness, calcium, magnesium, total dissolved solids, sulphates, iron and
manganese to use it for drinking purpose.
The phosphate concentration is greater than 100 µg, therefore the lake water
can be categorised as eutrophic lakes.
The dissolved oxygen is below 4 ppm, therefore no aquatic life was found.
The decrease in BOD level from 164 to 6 mg/l with in the lake during its
movement from inlet to outlet showed, 96.34% reduction, therefore the lake
system has very good self purification potential.
The lake water is good for agricultural use as per SAR (Sodium Absorption
Ratio) for irrigation water quality classification.
The lake water can be used for irrigation as it satisfies FAO (1979) standards
for heavy metals namely Cd, Cr, Cu, Fe, Pb, Ni and Mn.
Bellandur lake
The lake water quality is poor with respect to pH, turbidity, calcium,
magnesium, total dissolved solids, sulphates, iron and manganese, restricts
its use for domestic purpose.
The sediment quality with respect to heavy metals is not with in the limits
and it cannot be used for agricultural applications.
The ground water quality is poor with respect to chlorides, total hardness,
calcium, magnesium, total dissolved solids, sulphates, nitrates, lead and
manganese to use it for drinking purpose.
The phosphate concentration is greater than 100 µg, therefore the lakes can
be categorized as hypereutrophic lakes.
The dissolved oxygen is below 4 ppm, therefore no aquatic life was found.
The decrease in BOD level with in the lake during its movement from inlet
to outlet is 91.16% (from 215 to 19 mg/l) , therefore the system is very
significant in decreasing the BOD.
The lake water is good for agricultural use as per SAR (Sodium Absorption
Ratio) for irrigation water quality classification.
The lake water can be used for irrigation as it satisfies FAO (1979) standards
for heavy metals namely Cd, Cr, Cu, Fe, Pb, Ni and Mn.
References
(1)Proceedings of National Seminar on Resurrection of Lakes, 8th Jun-2002.
(2)Ramachandra T. V. and Ahalya N, Limgis2001, Monograph on
“Essentials in limnology and Geographic Information System (GIS)”
(3) International workshop on Integrated Water Management, Bangalore
University (June 2001).
(4)Arnold E. Greenberg, APHA, Chairman (1998), 20th Edition, “Standard
methods for the examination of water and waste water”.
(5) IS 3025: Methods of Sampling and Test (Physical and Chemical) for
Water and Wastewater.
(6)UNEP/WHO/UNESCO/WMO Programme on Global Water quality
monitoring and assessment gems/water operational guide, National Water
Research Institute, Canada.
(7)Erin Carison et. al., (2002) University of Northern Iowa, Department of
Mathematics, A Statistical Examination of Water Quality in Two Iowa
lakes; American Journal of Underground Water Research, Volume 1.
Table1: Allasandra Lake water quality
Parameters Sample
1
Sample
2
Sample
3
Sample
4
Sample
5
Rang
e
P.L.
(IS:10
500)
PHYSICAL
PARAMETERS
PH 7.4 7.5 7.4 7.6 7.5 7.4- 6.5-
7.6 8.5
Electrical
conductivity
0.9 1.2 1 0.8 0.95 0.8-
1.2
Temperature 25 C 25 25.4 23.7 24.2 23.7-
25.4
Turbidity 30 21.4 10.8 0.6 7.5 0.6-
30
10
CHEMICAL
PARAMETERS
Dissolved
oxygen
1.0 1.0 2.6 1.7 1.02 11-
2.6
Total alkalinity 280 266 251 238 258 230-
280
Chlorides 150 288 88 176 144 88-
288
250
Total hardness 257 315 333 311 344 257-
344
300
Calcium 197 230 135 210 204 135-
230
75
Magnesium 60 102 198 101 140 60-
198
30
Sodium 110 101 100 120 98 98-
120
Total dissolved
solids
740 804 710 686 738 686-
804
500
Sulphates 34 31 31 16 33 16-34 150
Nitrates 0.8 0.8 0.4 0.63 0.42 0.4-
0.8
45
Phosphates 0.6 0.5 0.3 0.4 0.62 0.3-
0.62
Potassium 42 45 34 42 34 34-45
BOD 164 38 06 06 44 6-164
Table2:Allalasandra Ground Water Quality
Physical
parameters
Sample 1 Sample 2 P.L.
(IS:10500)
PH 6.6 6.2 6.5-8.5
Electrical
conductivity
1.3 1.5
CHEMICAL
PARAMETERS
Total alkalinity 266 242
Chlorides 419 323 250
Total hardness 379 214 300
Calcium 347 168 75
Magnesium 32 46 30
Sodium 130 164
Total dissolved
solids
1080 1140 500
Sulphates 82 168 150
Nitrates 2.2 7.36 45
Phosphates 0.01 0.02
Potassium 10 16
Table3:Heavy metal concentration in lake water, sediment and groundwater.
Heavy
metals
Lake
water
Ground
water
P.L.
(IS:10500)
Sedimen
t of lake
bed
Standards
for
agricultural
soils
Copper 0.013 0.018 0.05 37.4
Lead 0.001 0.03 0.1 6.8 8.33
Cadmium 0.005 0.001 0.05 0.1 0.125
Nickel 0.08 0.075 - 20 1.67
Manganese 0.178 0.82 0.1 54
Total 0.0015 0.024 0.05 7.2 8.33
chromium
Zinc 0.001 0.04 5.0 20.2 25
Table4:Bellandur lake water quality
Parameters S1 S2 S3 S4 S5 Range P.L.
(IS:105
00)
PHYSICAL
PARAMETERS
PH 7.5 7.0 8.0 7.6 7.0 7.0-8.0 6.5-8.5
Electrical
conductivity
1.2 1.1 0.946 1.1 1.0 1-0.946
Temperature 24.2 30 29.2 31 290 24.2-31
Turbidity 35 31 12 30 31 12-35 10.0
CHEMICAL
ARAMETERS
Dissolved oxygen 0.3 1.4 3.0 6 0.5 0.3-6
Total alkalinity 584 284 330 530 560 284-
560
Chlorides 140 124 115 48 130 48-140 250
Total hardness 286 254 170 290 280 290-
170
300
Calcium 170 209 148 240 230 148-
240
75
Magnesium 116 45 22 50 50 22-116 30
Sodium 90 100 70 98 110 70-110
Totaldissolved
solids
812 750 542 780 640 542-
812
500
Sulphates 16 18 20 12 35 12-35 150
Nitrates 0.36 0.4 0.25 0.8 7 0.25-7 45
Phosphates 0.85 0.3 0.4 0.6 0.95 0.3-
0.95
Potassium 42 34 38 35 30 30-42
BOD 215 19 10 20 50 19-215
Table5:Bellandur Ground water quality
Physical parameters Sample 1 Sample
2
P.L.
(IS:10500)
PH 6.3 6.2 6.5-8.5
Electrical
conductivity
2.6 2.2
CHEMICAL
PARAMETERS
Total alkalinity 144 192
Chlorides 907 640 250Total hardness 339 610 300
Calcium 286 590 75
Magnesium 53 20 30
Sodium 86 220
Total dissolved
solids
3254 2080 500
Sulphates 176 110 150
Nitrates 27.2 65.4 45
Phosphates 0.06 0.04
Potassium 18 22
Table6:Heavy metal concentration in lake water, sediment and groundwater.
Heavy
metals
Lake
water
Ground
water
P.L.
(IS:10500)
Sediment
of lake
bed
Standard
Copper 0.013 0.018 0.05 64.96
Lead BDL 3.7 0.1 23.03 8.33
Cadmium BDL 0 0.05 0.767 0.125
Nickel 0.08 0.075 65.5 1.67
Manganese 0.178 0.82 0.1 211.3
Total
chromium
0.0015 0.024 0.05 81.0 8.33
Zinc 0.5 0.52 5.0 110 25
Recommended