HEAVY METALS IN THREE MOLLUSCS AND SEDIMENTS FROM VELLAR ESTUARY, SOUTHEAST COAST OF INDIA

The intensity of heavy metals (Mg, Fe, Mn, Zn, Cd, Co, Cu, Pb) were estimated in sediment, shell and tissue of the molluscs Cerithidea cingulata, Crassostrea madrasensis and Meretrix meretrix from two stations of Vellar Estuary, Southeast coast of India. The concentrations of the heavy metals analyzed exhibited variations in sediments, tissue and shell of the study animal from the 2 stations. Zn and Cu concentration were below the alarming level, whereas Mg (274.0 +/- 12) content was higher in shell and tissue. The Fe (416.6 +/- 1.7) content was higher in sediment in Station 1, but it was the second highest metal to be recorded in sediment, shell and tissue. To understand the background concentration the level of these metals were studied in the sediment. Cd and Co were minimum accumulated in all the metals estimated in sediment and animal whereas Mg was maximum in sediment. Similarly all the metals analysed were within the safety level. The combined correlation of both the stations between the sediment verses, sediment, tissue verses, tissue, shell verses. Shells were positively correlated and significant at P<0.001 and P <0.05 level. The result revealed that continuous input of pollutant due to human activities, industries might have a significant contribution of these metals in all the stations.