ROLE OF LAKE SEDIMENTS IN GROUND WATER QUALITY (18.06.2013) (Final)
ROLE OF LAKE SEDIMENTS IN
All India Council for Technical Education (AICTE)
◦ Role of Lake sediments in Ground water quality – TAPTEC
◦ Pilot plant studies on the treatability of combined industrial effluent – MODROB
Andhra Pradesh State Council of Science and Technology (APCOST)
Water Quality of Inlet, Outlet Nallahs and the Lake
Environmental Survey of Kattedan Industrial Area
RESEARCH CONDUCTED SO FAR &
IDENTIFICATION OF PROBLEM
Studies limited to assessment of quality
Theoretical calculations on nutrient load
Reduction in size of the lake
Budha poornima accident & Impact of sediments
Lack of detailed information on Lake sediments
Deterioration of Ground water quality
Relation between sediments and ground water quality not established
Lack of Information & commitment on measures to be taken for
Noor Mohammad Kunta, Pink Colour due to discharge of untreated effluents from dyeing industries
• To study the land use practices in the catchment area
• To determine the water quality of incoming nallahs, Lake, outlet,
surrounding ground water, Sediments and Pore water and to study
progressive deterioration of lake
• To study variation in water quality during its journey
• Conducting soil column studies
• Application of mathematical model
• Conduct performance studies on CETPs
• Pilot plant studies on the treatability of combined industrial effluent
• Suggest remedial measures
PROBLEMS FACED BY URBAN LAKES
• Urbanization, Industrialization and
• Tampering of Inflow and Outflow
Channels & Improper design
• Indiscriminate dumping of Waste • Continuous Flow of Untreated Waste
• Invasive Weed • Pollution due to Idol Immersion
IMPACTS ON LAKE
Loss of water storage capacity
Lake water contamination
Ground water Pollution?
Loss of aquatic species
Loss of traditional Livelihood like fishing
Loss of recreational opportunities
Loss of aesthetics
Release of volatile gases and foul smell – air pollution.
Land Use Practices
Catchment Area of Hussain Sagar Lake
Salient Features of the Lake:
S.No Parameter Specification
1 Year of Construction 1562 AD
2 Catchment Area Classification
Area of built up land (class – 1) 90 Sq Km
Area of built up land (class – 2) 68 Sq Km
Area of scrub forests 18 Sq Km
Area of crop lands 12.5 Sq Km
Area of lands with scrub 35 Sq Km
Area of lands without scrub 8.5 Sq Km
Area of water bodies 8 Sq Km
Total 240 Sq Km
3 Maximum water spread area 5.7 Sq km
4 Volume of lake 28.6 X 106 m3
5 Average depth at full capacity 5.02 m
6 Shoreline length 14 Km
Hydrological Data of Hussain Sagar Lake Water
Bathymetric contour map and Inlet and outlet nallas of Hussain sagar Lake (HUDA 2005)
Ground, Surface Water and sediment Sampling Locations in and around Hussain
Analysis of Samples Collected from the four Nallahs and the Lake
Inlet Nullahs Outlet Nullahs (Lake)
Min Max Min Max
pH 6.9 8.5 7.8 8.1
Conductivity (mhos/cm) 2170 3600 2550 2700
Chlorides (ppm) 112 530 387 496
Sulphates (ppm) 26 299 235 340
Phosphates (ppm) 0.03 1.6 1.2 2.6
Hardness (ppm) 270 380 - -
Alkalinity (mg/lit) 432 560 - -
COD (mg/lit) 496 1120 107 186
BOD (mg/lit) 225 373.3 4 70
DO (mg/lit) 0 2.7 - -
TSS (mg/lit) 150 540 30 54
TDS (mg/lit) 980 2110 974 1242
Turbidity (NTU) 19 90
Nitrates (mg/lit) 58 85 7.24 13.7
Fluorides (mg/lit) 0.5 1 - -
WATER QUALITY IN INLET & OUTLET NALLAHS
Dissolved solids, TSS and Hardness pH, DO & Other Dissolved solids
CONCENTRATIONS OF POLLUTANTS IN INLET AND OUTLET NALLAHS
GPS used for navigation
GPS Hand rover
Collection of water samples using Water Sampler
NAVIGATION AND SAMPLING IN THE ALKE
Table 5: Lake Water Quality Parameters
Pramaeter Min Max Mean
pH 8.2 8.4 8.3
Conductivity (mhos/ cm) 1000 1120 1063.33
Chlorides (mg/l) 116 325 145.73
Sulphates (mg/l) 12 40 21.28
Phosphates (mg/l) 0 1 0.65
Hardness (mg/l) 232 360 281
Calcium Hardness (mg/l) 110 290 186.87
Magnesium Hardness (mg/l) 14 186 87.87
Sodium (ppm) 71 76 73.56
Calcium (ppm) 44 122 75.37
Magnesium (ppm) 3.3 46 21.25
Lead (mg/l) 0.3 0.5 0.38
Chromium (mg/l) 0.3 0.5 0.368
QUALITY OF LAKE WATER
Phosphates Lead Chromium
PHOSPHATE AND HEAVY METALS CONCENTRATION IN LAKE
Hardness, Chlorides and Conductivity pH and Dissolved Solids
CONCENTRATIONS OF POLLUTANTS IN LAKE WATER
Variation in Physico-Chemical Parameters of Hussain Sagar Lake water
during different years, a, b- Pollutants with increasing Trend. c- Pollutants
with Random Trend
Hardness Nitrates Phospates COD BOD pH EC TDS Cl
COLLECTION AND STORAGE OF SEDIMENT SAMPLES
Collection of surface sediment samples using Ekman Grab Sampler
Collection of deep sediments using Kajak – Brinkhurst Core Sampler
Collection and Storage of Core sediment Samples
Extraction of Pore water from sediments
Pore water samples were extracted from the sediments using filter presses and
centrifuge and then filtered through wattman filter paper using vacuum filtration
techniques before analysis.
Graph showing the concentration of Pollutants in Ground Water
Conductivity and Hardness Dissolved Solids
Conductivity Calcium Hardness
Lead Potassium Phosphates pH
Graph showing the concentration of Various Pollutants in Ground Water
FIELD STUDIES AND RESULTS
Ground water sampling locations, contours of chlorides concentration around Hussain Sagar
Lake and stream lines considered for comparative analysis
factor obtained from the
conducted on Soil
Column Experiment is
almost equal to the
points in a certain
stream path which flows
in downstream direction.
Sample Points Field Values C/C0
Streamline A-A 0.84
48 154 0.86
39 128 0.83
40 108 0.84
Streamline B - B 0.76
57 88 0.68
42 72.5 0.82
41 57 0.78
Streamline C - C 0.8
30 296 0.76
31 240 0.81
33 195 0.81
52 160 0.82
Streamline D - D 0.82
25 224 0.78
26 192 0.86
27 160 0.83
Field observations of Chlorides concentration in ground water samples of respective streams
and C/Co values
The analytical equation
representing solute flow in the
aquifer used for the study is
48 154 147
39 128 137
40 108 132
Streamline B - B
46 130 168
57 88 160
42 72.5 135
41 57 132
Streamline C - C
30 296 169
31 240 166
33 195 147
52 160 127
Streamline D - D
25 224 141
26 192 136
27 160 128
Comparison of mathematical model results with
Comparison of Solute Concentrations obtained from Field data and Mathematical model values
Comparison of Solute Concentrations obtained from Field data and Mathematical model values
POLLUTION CONTROLAND REMEDIAL MEASURES
The reasons for contamination of lakes are attributed to
Discharge of untreated / partially treated complex industrial effluents in to
lakes through inlet nallahs.
Inadequate sewage treatment facilities for the treatment of domestic sewage
entering the lake.
Indiscriminate disposal of solid waste in the catchments of nallahs carrying
water to the lake
Improper maintenance of drains / nallahs, which accumulate silts and solid
waste throughout the year and flows in to the lake in huge volumes during
Immersion of Idols and dumping of material used for worship and
Washing of cloths, cattle etc.
Domestic sewage from the nearby colony (about 3600Cum/day) is added to
the industrial wastewater (1200Cum/day) in the ratio of 3:1 directly in contact
chamber to increase the bacterial content. Variation in quality parameters of
untreated and treated effluents are listed in Tables below.
Characteristics Raw water Treated water
Total Hardness (mg/l)
Calcium Hardness (mg/l)
Total Suspended Solids (mg/l)
Total dissolved Solids (mg/l)
7 to 10
7 to 8
Characteristics of Raw and Treated water of the CETP
BOD removal Efficiency
of Aeration Tank (%)
COD removal Efficiency of
Aeration Tank (%)
Total Suspended Solid removal efficiency of clarifloculator and BOD & COD
removal efficiencies of aeration tank during study period
Jeedimetla Effluent Treatment Ltd
a) Raw effluent is collected in two equalization and neutralization tanks after
removing the floating material using screens.
b) Raw water is then pumped into the flash mixer unit after neutralizing with
c) Rapid mixing of coagulants (polyelectrolyte) with effluents was done, for
the formation of flocks and then the effluent flows into the Clarifloculator
d) Settled sludge from the clarifier is sent into sludge thickener and then to
centrifuge where the liquid and the sludge separation takes place.
e) The liquid effluent from Overflow sump reaches to Diffused air flotation
(DAF), where the fine suspended particles are removed by air floatation
using compressed air.
f) The sewage in the Distribution Chamber is mixed thoroughly with effluent
in 2: 11/2 ratio and then pumped to the ASP unit.
g) With the help of Mechanical Aerators provided in the aeration tank the
microorganisms present in the combined effluent consumes oxygen and
stabilize the organic matter.
h) The effluent from the ASP then reaches the Final Clarifier. The average
discharge of treated effluent is 3300 cum/day.
Variation in concentration of various parameters in the inlet and outlet of the
treatment plant during year 1999.
Table shows the range of concentration of various inlet and outlets of the plant.
Parameter Inlet Outlet
pH 7.4 - 8.2 7.1 - 7.9
Total Dissolved Solids 49990 - 55000 21000 - 25370
Suspended Solids 210 - 320 33 - 90
COD 10880 - 12160 2172 - 2614
BOD 3400 - 3952 40.4 - 73.6
PILOT PLANT STUDIES ON KATTEDAN INDUSTRIAL EFFLUENT
Experimental setup of Pilot Plant consisting of Influent tank the Reactor and Effluent
Design parameters of continuous flow stirred tank aerobic reactor
S.No Parameter Value
1 Volume of the reactor, l 4.5
2 Flow rate, l / day 3
3 Hydraulic Retention Time, q in hrs 36
4 Sludge Retention Time, qc in days 8.2 – 9.6
5 Food to Microorganism ratio, F/M (BOD/VSS) 0.04 – 0.15
6 Rate of Air supply, l / min 1.6
7 Sludge Volume Index, SVI 85
8 COD removal Efficiency ( After 20 days), % 90
9 Mixed Liquor Suspended Solids (MLSS), X in mg/l 6800 -7900
Difference in clarity of untreated and treated effluents of the Pilot plant
The variation in the BOD & COD concentrations
The BOD and COD removal efficiencies of the reactor during the study period
Steady growth of pollutant levels over a period of time indicating increased human
activity in the catchment area.
The measures undertook to abate pollution of the lake are inadequate.
Lake acts as a sink for the pollutants entering through incoming Nallahs.
Relatively higher concentrations of Dissolved solids present in the pore water than in
the dry sediments.
It was observed Very high concentrations of Electric conductivity in Pore water,
High values in Inlet Nallahs, Medium concentrations in near by Ground water and
low concentrations in lake water.
The concentration of Chlorides also followed same pattern as conductivity.
High concentrations of Calcium, Magnesium and Hardness were found in pore
water, Medium and low concentrations were observed in ground water and lake
water respectively indicates accumulation of non-metal concentration in the
sediment bed and transportation of the same in to the ground water through
High concentrations of Lead, Chromium, Cadmium and Zinc were found in
Sediments, Medium concentrations in Lake water and nil concentrations in
surrounding ground water, Which indicate accumulation and adsorption of metals in
the sediment bed.
Sediment bed acts as filter media for heavy metals and source of pollution for non-
metals in ground water. Hence it is evident that sediment bed has a significant role in
controlling/contributing to ground water pollution.
The Performance Studies conducted on Sanghi Polymers indicates that Suspended
Solid removal efficiency varied from 69.8% to 75%. The BOD removal efficiency of
the plant ranged between 52.4% and 87.2% and the COD removal efficiency varied
between 50% and 82.9%.
The Performance Studies conducted on Jeedimetla Effluent Treatment Plant indicate
that when compared to the performance of the treatment plant in 1989, 1990 with
1999 the organic removal efficiency of the plant was high in 1999 due to addition of
domestic sewage with combined effluent
Mixing of easily biodegradable effluent with complex organic effluents in a common
effluent treatment plant would increase the efficiency of the treatment plant resulting
reduction in the pollution load on receiving water body.
COMMENTS BY THE REVIEWERS ON THE THESIS AND REPLIES BY THE SCHOLAR
S.No Comments by the Examiner Response by the Scholar
Chapter - 1
Scientific articulation is needed. In a scientific report, usage like
"somebody" should be avoided. Complete check for language is
Modified the thesis with respect to scientific articulation. Also
checked and modified for Spellings and Grammar.
Reference at critical places is necessary. For eg., classification of
Hussain Sagar Lake as Dystrophic lake needs references for both
attributes and classification schema.
References included and style of representing reference is modified
throughout the thesis.
Significance of the present investigation needs to be brought out
very clearly here. For eg., how different is this work different from
the work of Srikanth et al.,(1993), Anitha et al.,(1995), Reddy et al
2001, and Rao, C.S.(2005) carried out on Hussain Sagar??
Elaborated the work carried out by the contemporary researchers,
gaps were identified and related with present study.
Srikanth et al (1995) compared mercury levels in lake water with
the levels in surrounding ground water. There was no mention
about sediment quality and its role in transmitting lake pollution to
Anitha et al (1995) studied the impact of industrial effluent on
aquatic life in Hussainsagar lake. It is purely the study related to the
Reddy et al (2001) probably the study conducted by the scholar of
Rao C.S (2005) conducted studies on the sediment quality of the
lake and also carried out Heavy metal speciation study on Hussain
sagar lake sediments. Categorization of sediments and role of
sediments in transmitting pollutants to ground water is lacking in
Chapter - 2
The Literature Review chapter is more like a listing of so-and-so has
published so-and-so paper. Nowhere, the scientific content of the earlier
works are presented in logical and coherent way. This chapter needs a
complete overhaul incorporating various components necessary for this
investigation like sediment transport, sampling strategy, geo-chemical
analyses, and standards adopted in a lucid way. Plethora of literature is
available on above aspects and the candidate is expected to group these
works under different categories, identify the gaps and highlight the need
for the investigated approach.
Modified this Chapter as per suggestions of the reviewer.
Standard and uniform reference style must be followed throughout the
Modified reference style as per suggestion of the reviewer.
Chapter - 3
In this Chapter, details on the hydrology, hydrogeology and land use
practices of the catchment and downstream of Hussainsagar is expected.
The downstream groundwater details beyond 1 km zone will provide
more insight on the effect of continent transport from the reservoir.
Hydrology and Land use practices in the catchment area of the lake was
obtained through the studies conducted by the self and reports of various
organizations (APPCB, HUDA, SAFEGE and AIC etc.) working on the
remediation of the lake. Since the research is basically on lake sediments, the
scholar concentrated more on the catchment area of the lake, which is the
source of pollutants in the lake.
What is the basis of arriving at the runoff coefficients? SCS-CN and
MUSCLE techniques are more appropriate for estimating the runoff and
soil loss potentials. Most of the data presented in this chapter seems to be
from some outdated report (dating back to 1990) rather than generated
from the candidate. Each table made using data from that report needs to
be credited by mentioning it in the caption.
Run off coefficients were obtained from APPCB report (1990). Majority of the
experimental work was carried out during the years from 1997 to 2000 and
few technical literature published during that period was referred.
Suggestion of reviewer with regard to source of information is reviewed and
What are the sampling strategy and analytical procedures adopted to
arrive at Table 3.9?
The source of information provided in this table is from "M. Narayana Rao &
Amal K. Datta, 'Waste Water Treatment', Second Edition, IBH Publishing Co.
Pvt. Ltd (1987)
Any map should contain coordinates, scale, legend etc. Both figures 3.1
and 3.2 are not containing any of these details.
Modified as per suggestion of the reviewer.
Chapter - 4
1 The Chapter heading is not adequately reflecting the contents. Modified per suggestion of the reviewer.
Instead of mentioning "standard procedures were adopted", better cite
the reference and detail the salient aspects.
Modified per suggestion of the reviewer.
For how much time samples were sorted before analyses? Whether any
precautions were taken to prevent the biological activities and
Standard methods for examination of water and water analysis, 16th edition
(1985), APHA, AWWA, APCF was refered for Collection, storage,
transportation and analysis of water samples and USEPA Guidelines for
Analysis of Polluted Soils (1994) were followed for Sampling, collection,
Transportation, Storage and analysis of water and sediment samples.
In page - 50, it is mentioned that along with the other parameter pH was
also measured in laboratory. For studies of this kind, Insitu pH are
pH of the samples were measured in the laboratory on the same day of
Why there is a clustering of water sampling adjoining the bund only?
Regular sampling downstream would have been more useful.
Groundwater samples collected from the existing bore/open wells available
between 0 and 1.5 km from shore line. Since the hydraulic gradient of the
groundwater flow was from NWW to SEE, more samples were collected in
the downstream of the lake in SEE direction.
Figure 4.11: grain size distribution curves are usually plotted on semi-log
This figure shows percentage of finer particles passing through the specific
size of sieve of dry sieve analysis. The sediments obtained by core samplers
were used for this analysis. Particles ranging from 4.75 to <0.075 mm were
present in these samples and includes sand, silt, clay and organic content.
Chapter - 5
This is a very small chapter and it could fit into the chapter-4 (sample
collection and analyses). The rational for breaking it as a separate chapter
is not clear.
As suggested, this chapter is now included in Chapter - 4
Figure-5.1: Is this methodology developed by the candidate or already
established? If developed by some other worker, reference is needed.
Lokesh. “Transmission of Pollutants through Soils into Subsurface water in
certain industrial pockets of Karnataka- problems and Litigation”. A thesis
submitted to University of Mysore August (2000), was referred before
finalizing the methodology
Why only one sample collected for this test? Compaction alone may not be
the correct criteria. Why important properties like Eh, CEC, sorption, and
specification were not considered?
One soil sample from Indira park used for the soil analysis and soil column
studies. More emphasis was given to Sediment and groundwater quality.
From the field data it is evident that there is transportation of elements viz.
chlorides, sulphates, sodium and potassium from pore water of sediments to
the groundwater and the concentration of these elements decreases from
nearest well to the farthest well. The scholar made an attempt to apply
suitable model to resemble the change in concentration using a mathematical
model and could succeeded in assessing only one pollutant i.e. chlorides.
Page-88: Please quantify the "sufficient time" allowed for the saturation of
the column with solution. I suppose it is a function of soil type.
Soil column was filled with the effluent and soaked the soil column until it
gets saturated. Sample collection from the sampling ports was started after
achieving constant discharge at the sampling port. This was achieved 38
hours after the soil column was filled with the effluent.
Chapter - 6
This Chapter is more like presenting the statistics of the data given in
earlier chapters rather than scientific processing, analyses and
interpretation. The data analyses and rationalizing the scientific aspects
are lacking. As observed in the previous chapters, the same data is
represented both as a table (Table 6.2, Figure 6.2 a,b,c; Table 6.3, Figures
6.3-6.6) and figure. This may help only in making the thesis bulky.
Analytical results of water samples from four Inlet nallahs, two Outlet
channels, Lake water, sediment and pore water samples from sixteen
locations of Hussain Sagar Lake and groundwater samples from fifty seven
locations around the lake were assessed and the results of all the samples
were represented in Chapter - 4. Summary of the results with minimum,
maximum and mean values of that particular group was analyzed and
discussed in this chapter.
Many fold increases in dissolved salts between the inlet and outlet nallahs
are not reflected by corresponding changes in TDS and conductivity, Why?
Table no. 6.1 shows the analytical results of Inlets and outlets. Out of many
chemical parameters of water quality, this table only shows parameters like
chlorides, sulphates, nitrates etc. Other significant parameters like hardness,
alkalinity etc are not accounted for in outlet quality. Since conductivity is the
representative parameter for total solids, absence of major parameters like
carbonates and bicarbonate may not give true representation.
In page no. 102, section 6.4.1: concentration measured from core, grab
and pore water samples are compared but no inferences were drawn on
the contaminant retention/mobility.
Table 6.3 shows Maximum, minimum and mean values of heavy metals in
Core, Grab and pore water of sediments. the constituents core sample is
nothing but contents of grab sample after removal of pore water from it. The
mean values of Heavy metal concentrations in core and grab samples are
almost same and there are negligible concentrations in pore water. On the
other hand negligible concentrations of heavy metals were observed in
groundwater. It indicates that Heavy metals are retained and became part of
hardened sediments and there is negligible mobility towards groundwater.
I have serious reservations on the way the solute transport model is
made. Before adopting any model, the candidate needs to understand its
suitability for the chosen area.
(i) What is the representative K value chosen for arriving at V? In the
investigated area, aquifers are hard rocks, the transport is mostly channel
flow, and not porous media flow. How many layers were considered and
what are their hydraulic conductivities?
(ii) What are the secular changes in water table gradient and its role in
(iii) What are the boundary conditions and their influence?
(iv) Why the model was not calibrated and tested?
(v) Like K, a is also a function of direction. A single value cannot represent
the issue addressed here.
In brief, the modeling carried out in this research is over simplified and
has no practical significance. This could be the reason for significant
deviation between measured and modeled values (Figures 4.6, a-d).
The Hydraulic conductivity value 'K' value Chosen was 1.0X105 m/s
One of the objectives of the present study is to differentiate sediments in to
hard sediments, surface sediments and pore water and find out what type of
pollutant accumulate in particular category of sediment. With the field values
it was evident that concentrations of non metals viz. Chlorides and sulphates
decreased from nearest to farthest ground water well indicating dispersion
of these elements present in higher concentrations in pore water of
sediments. The scholar did not concentrate much on the dispersion model.
Hence the model developed by Fetter 1994, was successfully used to
demonstrate dispersion of element chlorides in to groundwater aquifer.
Speciation of different pollutants and accordingly their mobility is
expected in this chapter.
Studies on the speciation of pollutants have already been carried out by
Gurunadha Rao et al (2008). The literature on this is included in Chapter – 2
Chapter - 7
Conclusion no 1: It should be better to have low COD and BOD. If the
outlet values are lower than the inlet values, doesn't it mean dilution in
Yes. Lake is receiving higher concentrations of BOD and COD and getting
diluted in the lake and considerably lower values of these elements were
present in outlets. Since lake act as a sedimentation tank, these elements
undergo decomposition and settle at the bottom of the lake and accumulate
in sediments either in pore water or in sediments. This was the reason why
higher concentrations of end products of decomposition occur in sediments.
A solid conclusion on the specification of pollutants and a practically
validated, meaningful numerical dispersion pattern is expected here.
Studies on the speciation of pollutants have already been carried out by
Gurunadha Rao et al (2008). The literature on this is included in Chapter - 2
Chapter - 8
This Chapter seems like an appendage rather than part of the thesis. For
any CFSTR, parameters like (i) distribution of residence times in the
system, (ii) the quality of mixing, (iii) And the model used to describe the
system are very important. No mention is made about these anywhere.
This chapter was included as per the advice of the professors present in
Research Review meetings conducted by the Civil Engineering Department
prior to submission of the thesis.
Specific questions for Viva-Voce Examination
Why the results of “choosen” mathematical model
on pollutant mobility are very poor and have
significant deviation from the measured value?
Fetter’s (1994) equation was used to assess analytical values and compared with the field observations and
represented in tables 5.8 and 5.9 and in figure 5.16. The trend of observations are almost similar with minor
deviation. This deviation is attributed to interferences in the groundwater flow path.
Why no attempt was made to investigate the
speciation of different pollutants?
Studies on the speciation of pollutants have already been carried out by Gurunadha Rao et al (2008). The
literature on this is included in Chapter – 2
Why the data on chemistry of sediments, Ground
water and pore water were not analysed in terms
of mass balance?
Collection and analysis of samples from Inlet, lake water, outlet, sediments (including surface, core and pore
water) and surrounding ground water were carried out over a span of 3 years at different intervals of time
and different seasons. The results of mass balance studies may not be representative due to variation in time
Why important points like Eh, CEC and sorption
were not considered?
One soil sample from Indira park used for the soil analysis and soil column studies. More emphasis was given
to Sediment and groundwater quality. From the field data it is evident that there is transportation of
elements viz. chlorides, sulphates, sodium and potassium from pore water of sediments to the groundwater
and the concentration of these elements decreases from nearest well to the farthest well. The scholar made
an attempt to apply suitable model to resemble the change in concentration using a mathematical model and
could succeed in assessing only one pollutant i.e. chlorides.
What are the bases of selecting the single hydraulic
conductivity (K) and dispersivity (α)
One of the objectives of the present study is to differentiate sediments in to hard sediments, surface
sediments and pore water and find out what type of pollutant accumulate in particular category of sediment.
With the field values it was evident that concentrations of non metals viz. Chlorides and sulphates decreased
from nearest to farthest ground water well indicating dispersion of these elements present in higher
concentrations in pore water of sediments. The scholar did not concentrate much on the dispersion model.
Hence the model developed by Fetter 1994, was successfully used to demonstrate dispersion of element
chlorides in to groundwater aquifer.
What is the effect of lake contamination in the
groundwater quality of downstream areas?
With reference to field observations represented in Table nos.5.7, and 5.9 and Figure nos. 5.10 through 5.14,
the pollutant concentration in ground water decreases from nearest well to the farthest well indicating
pollutant contribution from contaminated lake.
Can any general approaches be suggested for the
restoration of so many other lakes in other part of
Measures for restoration of polluted lakes are described in recommendations in Page no. 156 of the thesis.
The relationship of sediment physical properties
on its adsorption capacity may be explained?
Particle size, porosity and initial pollutant concentration in sediment are the main factors affecting pollutant
release through the sediment water interface. If a chemical is adsorbed to sediment particles, it will
accumulate in the bed and suspended load of aquatic systems and will not reach groundwater. If a chemical
is not adsorbed, it will accumulate in the water column of aquatic system, leach through the sediment
profile and may reach groundwater.
9 Bring out the conclusion from column studies?
The objective of conducting soil column studies is to find out reduction in concentration of pollutant after
passing specific distance through the soil column and compare concentration factors (C/Co) with the field
observed values. The concentration factors are presented in Table nos. 5.8 and 5.9. These factors are
matching with minor difference.
Whether the data from column studies can be
used to forecast the groundwater contamination
in nearby area?