Geo hydro chemical and isotopic study of the effects of tannery effluents on the ground water quality in Kasur area

Isotopic technique was employed to study ground water recharge mechanism and the effect of tannery effluents on the quality of ground water in Kasur area. Water samples collected were shallow ground water, deep ground water, canal water, rain water and pond water. The physicochemical parameters (pH, dissolved oxygen and electrical conductivity) were measured in the field while stable isotopes of D-2 and O-18 were analyzed by using GD-150 gas source isotope ratio mass spectrometer. Depleted isotopic contents of delta D-2 and delta O-18 are characterized by canal recharge; enriched isotopic values are associated with rains recharge and intermediate values show the mixing of water from different sources. The shallow ground water had depleted isotopic values and is being recharged by the canal. However, isotopic signature of shallow groundwater in the surroundings of the pond has been modified by the seepage of the pond water. The deuterium excess values show the effect of evaporated pond water and these values increase as the distance from the pond increases. Electrical conductivity values and chloride contents decreased along the depth. The deep groundwater that is termed as the native groundwater is being recharged by rains at piedmont area/bedrock outcrops. Results indicate that the quality of shallow ground water has been deteriorated in the vicinity of stagnant pond water but quality of deep groundwater is good. Chromium is absent in deep ground water, its penetration is limited up to a maximum depth of 20 m.