A comparative study on the arsenic levels in groundwaters of gangetic alluvium and coastal aquifers in india

Abstract

Arsenic contaminated groundwater causes danger to the health of millions of people in India. In this context, a comparative study has been made to evaluate the Arsenic (As) concentration in groundwater of Gangetic alluvium, West Bengal and south eastern coastal aquifer at Kalpakkam, India. The variations of Ar concentration with lithologies, depth of aquifers, sources and distribution of Ar and hydrochemical facies of groundwater has been clearly identified from the two localities. In Gangetic alluvium, As concentrations appear to be mostly low in groundwater from deep aquifers and it is interesting to note that in almost all the formations of coastal aquifer, the concentration increases with increase of depth. The shallow ground water of the southern coastal aquifer reveals the presence of oxidizing conditions and frequently flushing during the monsoonal period, which may also dilute or reduce the concentrations. The poor relationship between As and Fe indicates the As release into the groundwater depends on several processes such as mineral weathering, O2 consumption, and NO3 reduction and is de-coupled from Fe cycling.