The Extent of Heavy Metal Pollution by Chemical Partitioning and Risk Assessment Code of Sediments of Sewage-Fed Fishery Ponds at East Kolkata Wetland, a Ramsar Site, India

Sewage contaminated with toxic metals is being naturally treated in ponds at East Kolkata Wetlands (EKW) for fish cultivation traditionally. From the aquatic phase, these metals get settled on sediment and undergo partitioning. Some fractions are available and may accumulate in the cultivated products. The present study highlights the degree of partition of heavy metals Lead (Pb), Cadmium (Cd) and Chromium (Cr) in these pond sediments. The study reveals that Pb and Cr are significant (39% and 30%, respectively) in Fe-Mn bound fractions. Residual fraction is in the order of Pb > Cr > Cd. The easily available fraction of metals recorded higher in Cd (43.0%) and Cr (42.0%).The risk assessment code (RAC) analysis records that these metals could be considered as potential risk group of metals for higher mobility and availability in these pond ecosystems and is a significant concern for aquaculture products.