Depthwise Variation of Selenium in Groundwater in Parts of Punjab, India

Abstract

Selenium is an essential trace element in human diet with carcinogenic effect when consumed in excess. This paper examines the depthwise variartion of selenium in the aquifers of northeastern Punjab (India) in the Indo-Gangetic Plains in a piedmont zone. Out of 210 km2 hydrogeologically studied area in parts of Hoshiarpur and Nawanshahr districts of Punjab State, about 50% of area was found affected by high selenium concentration problem in groundwater. Three aquifer groups were identified, i.e., aquifer group I, II and III with depth ranges of about 75-95 m (thickness ~90 m), 120-230 m (thickness ~110 m) and beyond 255 m, respectively. A clay horizon of about 15-35 m thickness separates aquifer group of I and II and that of about 15-30 m thickness aquifer group of II and III. Aquifer group I is unconfined, aquifer group II is semi-confined and aquifer group III is confined in nature. High concentrations of selenium is observed in aquifer groups I and II with concentrations decreasing with depth. Aquifer group III is devoid of selenium. The symptoms of high contents of selenium started emerging when people deepened their wells in the 1970s to a depth of 20-45 m in a sandy clay horizon. This, however, is yet to be verified and warrants further investigation.