Bioaccumulation of heavy metals in marsh clams (Polymesoda Expansa) as bio indicator for pollution in Kelantan River, Malaysia.

Lead (Pb), Cadmium (Cd), Zinc (Zn) and Copper (Cu) are heavy metals that occur naturally in the environment. However, their levels are increasing due to anthropogenic activities. The aim of this study is to assess the concentration level of Pb, Cd, Zn, and Cu in bivalve of genus (Polymesoda Expansa) marsh clam from the Kelantan River tributaries namely Semarak and Geting River which are located near to sand mining area. More than 50 marsh clams were collected at these sites. Heavy metals in marsh clam were extracted using aqua regia methods and analysed using Atomic Absorption Spectrometer (AAS). The result shows the mean concentrations of Pb, Cd, Zn and Cu at Semarak River are 4.61 ppm, 2.16 ppm, 194 ppm and 6.20 ppm respectively. While the concentrations at Geting River are 4.43 ppm, 2.50 ppm, 196 ppm and 7.90 ppm respectively. The pattern of metal concentration within the whole tissue of marsh clams (Polymesoda Expansa) from Geting River and Semarak River can be presented as the following rank Zn > Pb > Cd >Cu. The mean concentration of selected metals (Zn, Cd, Pb) in the samples were exceeded the permissible limit provide by Malaysia Food Safety and Food Regulation 1985, FAO/WHO, Ministry of Health Thailand and Food and Drug administration of United States (USFDA). Therefore, continuous monitoring is essential to avoid increasing health risk for aquatic life as well as human.