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The Mahanadi River, surrounding estuaries along the coastal water are important to understand the relationship between heavy metals, ecosystem and human health, as the region being used largely by fisher communities for the potential fishing ground and agriculture. The study evaluates the ecological risk index of heavy metals in the surface sediments along the coastal environment of the Bay of Bengal between 2011 and 2012. The metals concentrations were varied from a maximum in Manganese (4,137 mg/kg) to a minimum in Cadmium (17 mg/kg). The factor analysis result shows that higher concentration of cadmium (Cd), chromium (Cr), Nickel (Ni), lead (Pb), and Zinc (Zn) were significant environmental risk in the study region. The cluster analysis indicated that the creek sediment is heavily polluted than the estuary ecosystem of the coastal environment. Enrichment factor and Geo-accumulation Index of the surface sediment resulted that, the Cd was high enrichment and was moderate to severe in the study region. Pollution load index denoted that the sampling sites in the creek sediment were more polluted than coastal due to the influence of agricultural runoff, industrial and anthropogenic. The Cr, Cu, Ni, Pb, and Cd concentrations result in the potential toxicity to the aquatic organisms based on the comparison with the SQGs. Indicates the average magnitude of the metals in the study period in the decreasing order of Mn, Cr, Cu, Ni, Pb, and Cd which were alarming except iron (Fe) in the estuary and coastal ecosystem of the Bay of Bengal. The present investigation would be a first-hand informant to understand the impact of heavy metals in the ecosystem in the region. The result inputs need to be monitored further in the long term basis for isotopic sediment dating to reconstruct the contamination history for the ecosystem modeling, sustainable ecosystem, and coastal zone management.
Keywords: estuary, heavy metal, pollution index, ecological risk, sediment quality