Bioaccumulation of Heavy Metals in Certain Marine Animals Along the East Coast Chennai, Tamilnadu, India

摘要

Heavy metals are the most persistent pollutants and are disposed by and large from anthropogenic and ' natural activities. Heavy metals in the oceans and seas are mainly derrived from river or through direct fall out from industrial outlets that are situated near the coastal zones. Suspended heavy metals settle down to the ocean floor and are resuspended back into the water column along with the sediments and thus they are made bioavailable to the marine biota.rnIn the present study marine animals like fish, prawn, crab and mussel were collected alongthe East Coast north of Chennai. India (off Pulicat Lake to Chennai Harbour) and heavy metals such as Zn, Pb, Cu, Co, Cr, Ni and Cd were analysed in various tissues of fish, prawn and crab. Soft tissue of mussel was also analysed. The data revealed that the animals had accumulated heavy metals such as Zn, Pb, Cu, Co, Cr, Ni and Cd in varying degrees. The essential heavy metals like Zn and Ni were mainly derived from the food than from the marine environment as they were found below the detectable limit (i.e. < 0.01 ppm) in the water. Zn was found to be high and Ni less in concentration in all the tissues analysed. The other essential heavy metals such as Co, Cr, and Cu were found in abundance in the water and increased from the lower tropic level to the upper tropic level and hence were derived from the environment than from the food. The non-essential heavy metals such as Cd and Pb were found to be derived from the marine environment. The bioconcentration factors reveal that the animals have accumulated heavy metals from the water. The results in this study indicate that the heavy metal concentration in the marine animals analysed are below the thresholds associated with the toxicological effects and the regulatory limits as prescribed by OECD.