Environmental Engineering Reference
In-Depth Information
regulation related to private and individual extraction of groundwater aggravates this
situation in general in the capital city. The availability of the groundwater resources
from the bore wells situated in the campus is inadequate in the summer season in addi-
tion to the water quality problems. Hence, major water supply for the campus domes-
tic and gardening needs depends on Delhi Jal Board water supply and meagre amount
of groundwater from the existing bore wells. The maximum and minimum tempera-
tureofstudyareais46°Cand4°C,respectively.TheaverageannualrainfallinDelhi
is 765 mm, three fourths of which falls in July, August and September.
Materials and Methods
In order to understand the water quality of the available water source within the
campus, nine groundwater samples were collected in pre- (May 2011) and post-
monsoon (November 2011) seasons to assess the groundwater quality from avail-
able bore wells. The locations of the sampling sites, recorded using global
positioningsystem(GPS,Garmin),areshowninFig.
1
. At each site, water samples
were collected in clean polypropylene bottles, rinsed two times with groundwater to
be sampled. The physico-chemical parameters were determined by the following
standard protocol (APHA
2005
).pHandECweremeasuredusingrespectiveelec-
trodes. Alkalinity, bicarbonate and chloride were determined by titration method.
Total hardness and calcium were estimated by EDTA titration method, and magne-
sium estimated by the difference of the hardness and calcium. Sodium and potas-
sium were estimated by flame photometer (Elico Model CL-378). Sulphate and
nitrateestimationsweredonebytheUV-spectrophotometer(LabIndiaModelUV
3000).Fluoridewasmeasuredusinganionanalyzer(OrionModel4star)withan
ion selective electrode. The analytical precision for the measurement was deter-
mined by calculating the ionic balance error, which is generally found to be within
ﾱ5 %. The changes in saturation state has been used to distinguish different stages
of hydrochemical evolution and to identify which geochemical reactions are impor-
tant in controlling water chemistry (Koetsiers and Walraevens
2006
). Aqueous spe-
ciation computed with WATEQ4F program (Ball and Nordstrom
1992
) was used to
better define the possible chemical reactions in the aquifer system to assess the state
of equilibrium between groundwater and minerals present in terms of saturation
index (SI) using the following equation:
(
)
SI =
log
IAPK
t
/
where SI is saturation index of a mineral, IAP is ion activity product of the dissoci-
ated mineral, and
K
t
is equilibrium solubility at mineral temperature. SI < 0 indicates
that the groundwater is under-saturated with respect to a particular mineral (mineral
dissolution condition). SI > 0 reflects whether the groundwater is oversaturated with
respect to a particular mineral (mineral precipitation condition). SI = 0 is equilib-
rium state.
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