Concentration of heavy metals in the food chain components of the nearshore coastal waters of Kalpakkam, southeast coast of India

Abstract

Kalpakkam, located on the southeast coast of India, has witnessed intense nuclear power plant activities resulting in a substantial increase in social and industrial development. This has prompted the study of the concentrations of heavy metals in water, sediment, zooplankton and fish in the coastal waters of Kalpakkam to understand their pattern of distribution and bioaccumulation. The concentrations of metals were in the order Fe > Zn > Pb > Cr > Mn > Ni > Cu > Cd > Co in water, Fe > Zn > Mn > Pb > Cr > Cu > Ni > Cd > Co in zooplankton, Fe > Zn > Cu > Mn > Cr > Pb in fish and Fe > Cu > Zn > Pb > Cr > Ni > Cd in sediment. Metal concentrations in plankton were much higher than those in water, sediment and fish. The results showed wide variations in heavy metal concentrations in four food web components. The major sources of metals on the Kalpakkam coast are land-based anthropogenic ones. The coastal sediment is moderately polluted with Cu & Cd. Relatively low dissolved metal concentrations were observed when compared to other coastal waters. However, the results indicated that dermal absorption (CDIdermal) of Fe might be a matter of concern due to its carcinogenicity. The summer season had higher Metal Pollution Index (MPI) values, than the rest of the year. Metal pollution indices indicated that southwest monsoon (SWM) and northeast monsoon (NEM) periods had lower contamination (MPI: 1.0–2.0; Class-III) than the summer season (MPI: 2.0–4.0; Class-IV). The bioaccumulation of metal is faster and the content is much higher in zooplankton than in fish. Bioconcentration factors (BCF) were significantly different for different metals. Amongst the toxic metals the BCF was highest for Cr for both zooplankton and fish tissue. The metal concentrations in the fish species studied were sufficiently low that the fish tissue was safe for human consumption.