Sediment metal contaminations in sewage-fed aquaculture system of East Kolkata Wetland, West Bengal, India

Present work aimed to study the contamination of heavy metals (Copper, Lead, Manganese, and Zinc) in sediment from sewage fed aquaculture system of East Kolkata Wetlands, West Bengal, India from July 2016 to March 2017. Composite sediment samples were collected monthly from three sites (S1, S2, and S3) of the Nalban of the East Kolkata Wetlands. The samples were brought to the laboratory, processed, and analyzed. The concentrations of the metals were in the order Mn> Zn > Pb> Cu at S1; Mn> Zn > Cu >Pb at S2 and Zn > Mn > Pb > Cu at S3. The calculated average values of Contamination Factor (CF) were in the order Pb >Cu>Zn>> Mn at S1, Cu Zn > Pb >> Mn at S2, and Pb > Zn > Cu >> Mn at S3. In general, the wetland was rated as low to moderately contaminated. The estimated Pollution Load Index (PLI) values for the wetland also corroborated the inference. Suitable management practices like the proper waiting period for wastewater intake, continuing general cultural practices of maintaining water hyacinth in the marginal areas of the wetland, etc., should be religiously followed to prevent the wetland from further deterioration due to associated risk of pollution. Key words Heavy metal; Sediment pollution; Contamination factor; Pollution load index.