Dynamics and quantification of dissolved metals in a highly contaminated river-estuarine system

Abstract

Dynamics of heavy metals such as Fe, Mn, Co, Ni, Cu, Zn, Cr, Pb and Cd in surface water of Brahmani river-estuarine system were studied taking 25 samples from different sampling locations along the complete stretch. Irrespective of season, Fe was most abundant in both river (avg. 260.15 µg/l ) and estuarine (avg. 119.9 µg/l) samples, whereas Cd (avg. 1.59 µg/l) and Co (avg.1.55 µg/l) were the lowest in the river and estuarine samples respectively. The average concentrations of all the dissolved metals were much higher than the world river average. The average concentrations Cr and Cd for the river were above the criteria of maximum concentration (CMC) as prescribed by US Environmental Protection Agency. Results of factor analyses revealed that anthropogenic contributions were the source for the increase in dissolved metal concentrations. Canonical discriminate function indicated that it was moderately successful in discriminating the groups as predicted. River Brahmani with an annual discharge of 18.58 x 106m3 carries 6.907 x 103 tons of total heavy metals into Bay of Bengal and the calculated rate of erosion in the basin is 176.582 kg km-2 year-1.