Characterization of groundwater contaminant sources in the coastal sand dune aquifer, Prakasam district, A.P. India

Abstract

The fresh groundwater regime in the study area covered with sand dunes is in critical condition, both on quantity and quality aspects. To address the issue of groundwater contaminant sources and its seasonal variations, 10 sets of groundwater samples were collected during 3-year study period (2009–2012). The ionic abundance on an average is constant and in the order of Cl− > Na+ = HCO3 > SO4 2− > NO3 − > Ca2+ = Mg2+ > K+ > CO3 −. Major ion chemistry and Br− content of groundwater indicated marginal salinization during the drought period and it was limited to only peripheries of study area. However, large-scale NO3 −contamination was seen in ~70 % of collected samples. Though the study area is covered with high agriculture activity consuming large-scale inorganic and organic fertilizers, the groundwater contamination in agriculture areas is not as large as in the village environs. Nitrate concentration in the groundwater of village environs is almost double than that of agriculture areas irrespective of season. This could be due to unlined drainage network together with lack of proper domestic and sewerage disposal mechanism. However, no major threat of salinization to the fresh water aquifer is foreseen, even though it is surrounded by saline water bodies.