Assessment of Heavy Metal Contamination in the Sediments of a River Draining into a Ramsar Site in the Indian Sub Continent

Concentrations of six heavy metals (Cd, Cr, Ni, Zn, Pb and Cu) in surface sediments of Achankovil river basin which is draining into a Ramsar site in India viz. The Vembanad wetland system was determined. To assess metal concentrations in sediment, numeric Sediment Quality Guidelines (SQGs) were employed. The concentrations of Zn, Cr and Pb in all sediment samples are lower than the proposed threshold effect concentrations which indicate that there are no harmful effects from these metals. On the other hand, the concentrations of Cd in one station, Cu in three stations and Ni in all stations exceeded the threshold effect concentrations indicated that these stations were in potential risk. The metal contamination in sediments was evaluated by applying Index Geoaccumulation, Metal Pollution Index, Enrichment factor and Multivariate statistical techniques. The low values of EF show that the enrichment of sediment by heavy metal was by natural processes.