IOSR Journal of Environmental Science, Toxicology and Food Technology (IOSR-JESTFT) e-ISSN: 2319-2402,p- ISSN: 2319-2399.Volume 10, Issue 6 Ver. III (Jun. 2016), PP 63-71 www.iosrjournals.org DOI: 10.9790/2402-1006036371 www.iosrjournals.org 63 | Page Distribution and Fractionation of Heavy Metals in Surface Sediments of Chilika Lagoon, East Coast of India Sadaf Nazneen and Priyanka Patel School of Environmental Sciences, Jawaharlal Nehru University, New Delhi -110067, India Abstract: 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 I geo and 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. I. Introduction The estuaries and lagoon are major repositories of land based pollutants. Sediments in these systems act both as source and sink of heavy metals.Once metals reach the water column, they associate with particulate phases, binding to the fine-grained sediment components, such as hydrous iron and/or manganese oxides, sulphides, organic compounds and clay minerals [1].Heavy metals can be adsorbed on the particle surfaces of clays, iron, and manganese oxyhydroxides or organic matter present in the lattice of secondary minerals, such as, carbonates or sulphides; occluded in amorphous iron and manganese oxyhydroxides, sulfides or remains of biological organisms; and present in the lattice of primary minerals [2].The different chemical species of metal rather than its total concentration is crucial to understand its effects on biota, as well as its biogeochemical transformation and fate under varying environmental conditions. The exchangeable, acid soluble and oxidisable are known as extractable species. In unpolluted sediments, the metals exist in residual fraction mostly. With the increase in heavy metal pollution, the species of metals in the extractable fraction increases [3]. Anthropogenic impacts alter the predominant environmental conditions (e.g. pH, redox potential, organic matter) which in turn remobilize the sediment-bound metal ions and make them bioavailable to the environment. Therefore metal fractionation was performed on sediments to infer the different associations of metals present in the sediments. The metals were extracted by BCR sequential extraction method into acid soluble, reducible and oxidisable fractions.Chilika is the largest lagoon in Asia, designated Wetland of International importance under Ramsar convention in 1981. Chilika is a dynamic ecosystem partly due to its connection with the Bay of Bengal on the eastern side and freshwater inflow from 52 rivers and rivulets joining it in the north and west. Historically the lagoon has undergone a considerable reduction in surface area, in part, due to input from natural processes but mostly due to human activities. The anthropogenic activities in its catchment basin have increased substantially in the past decade. Intensification in agriculture has lead to the increase in soils and sediments reaching the lagoon. The western catchment contributes nearly 536 m 3 S -1 , and the distributaries of the Mahanadi River (Daya, Bhargavi, and Nuna rivers) contribute an average of 850 m 3 S -1 [4].Lack of catchment basin management has led to the influx of a huge amount of suspended sediment into the lagoon, which has altered the ecology of the lagoon significantly. The purpose of this investigation is to document the heavy metal concentration and metals' affinity for specific geochemical phases in the recently deposited sediments in the lagoon.