Distribution and Fractionation of Heavy Metals in Surface Sediments of Chilika Lagoon , East Coast of India

Heavy metal contamination was assessed in the sediments of Asia’s largest lagoon, Chilika lake lying on the east coast of India. Sediments were collected from 11 locations, from four different sectors and were analysed for Pb, Cu, Zn, Co, Cd, Ni, Mn and Fe. Based on the Igeoand CF values the results obtained reveal that sediments are highly polluted with Cu, Zn and Ni at some location, whereas a moderate pollution for Pb is observed at most of the sites.Slight pollution of Cr was also observedat few sites.According to PLI, sites near the sea mouth and river confluence are highly polluted due to agricultural, municipal and domestic wastes. Large boat traffic is another major cause of metal pollution. Metal speciation analysis reveals residual fraction is the most dominant fraction for most of the metals, followed by reducible fraction. The carbonate bound fraction for Mn (11.96-34.46), Pb (3.43 – 27.46%), Zn (0.2 – 26.29%) fall in medium risk category according to the Risk Assessment Code (RAC). The results expose that heavy metal contamination is prominent in Chilika lake sediments due to increased agriculture in the basin, discharge of untreated waste and boat traffic.