Abstract:
The present work is aimed at assessing the ground water quality of tehsil Mailsi
for the very first time. Twenty seven (27) ground water samples were collected for
physico chemical (pH, electrical conductivity, total dissolved solids and dissolved
oxygen), chemical (CO3, HCO3
-1
, Cl-1, NO3
-1, SO4
-2, Na+, Mg+, K+ and Ca+), heavy
metal (Zn, Cd, Pb, Cu, Ni, Cr and Co) and stable isotopic (Oand D)analysis.
Physico chemical analyses were performed in-situ by the help of portable meter.
CO3, HCO3
-1and Cl-1 were carried out by titration. Nitrates and sulphates were measured
by Ion Selective electrode and UV Spectrometer respectively. Heavy metal analysis was
carried out by polarograph 797 Computrace by VA-83 using Hanging Mercury Dropping
Electrode (HMDE). The stable isotope analyses were performed using a modified Varian
Mat GD-150 Mass Spectrometer. pH, EC,TDS and DO of groundwater samples were
found in the range of 7.30-8.12, 526 - 2410 μS/cm, 272 - 1667mg/L and 2.5 - 3.5 mg/L
respectively. Concentration of Cl-1, NO3
-1, SO4
-2, and HCO3
-1 were in the range of 19.3 -
287.12 mg/L, 1.0 - 114.57 mg/L, 0.2 - 37.13 mg/L and 304.39 - 778.36 mg/L
respectively. However, due to dominance of limestone in the area CO3 were absent in the
groundwater of Mailsi. Hydro chemical analysis by Piper diagram showed the ground
water of Mailsi is Na-HCO3 type and has less impact of sulfate and chloride. Whereas
18.5% zinc, 25.9% lead and 14.8% copper were found higher than permissible limit. The
overall results shows that the total dissolved solids and nitrates are very high in Mailsi
ground water samples and can have adverse effects on individuals. The water quality
index (WQi) calculation based on four parameters (pH, TDS, DO and NO3
-1) of the
groundwater of Mailsi was carried out. The results indicate a dominance of poor water
quality and harmful for drinking purposes.
The 18O values of groundwater ranges from -8.4 to -4.1 with the average of -7.3
and the D range from -57.5 to -2.1 with the average of -50.5. Isotopic data for Mailsi
groundwater lie on Local Metroic Waterline (LMWL) and Global Metroic Waterline
(GMWL) which reflects that aquifer system is recharged by precipitation and river. In
most part of study area the ‘d-excess’ values in groundwater samples are less than 10
indicating high evaporation rate. Relationship between 18O and the d-excess in t
