Delineation of sources of elevated trace elements in surface water and groundwater in Quaternary aquifers of southeastern Imphal valley, Northeast India

摘要

Concentrations of Fe, Mn, Pb, Al in both surface water and groundwater, and As, Sr, B, Li and Ba trace elements only in groundwater were observed to have exceeded the WHO and EPA limits in southeastern Imphal valley, Northeast India. Pearson correlation, factor analysis and cross-plots, along with oxygen isotope were used to identify the hydrochemical processes and to delineate the sources of the elevated trace elements. In groundwater samples, 15.6% of the total samples for Sr and 9.4% each for B, Li and Ba were revealed to have elevated values, from piedmont zone, which is related to the evaporite encrustation in Disang shales. 80% and 40% of surface water; and 9.4% and 25% of groundwater showed high concentrations of Al and Pb, respectively. Al and Pb concentrations were originated both from geogenic and anthropogenic sources. Fe and Mn exceed 70% and 20%, respectively, in surface water while 50% each in groundwater. High Fe and Mn might be resulted from reduction of Fe and Mn bearing minerals present in the study area. Excess of As in groundwater was observed from wells located at Kakching subdivision where leaching of As into groundwater from minerals such as kaolinite, montmorillonite, asenopyrite, chalcopyrite, geothite and magnetite and weathering of carbonaceous clay, silt and sand takes place. Other trace elements such as Zn, Bi, Co, Cr and Cd concentrations were all within the WHO limits.