Accumulation, depuration and risk assessment of cadmium (Cd) and lead (Pb) in clam Corbicula fluminea (O. F. Müller, 1774) under laboratory conditions

The present study investigated the accumulation and depuration of two heavy metals Cd and Pb in the freshwater clam Corbicula fluminea under laboratory conditions. Treated clam was exposed to single and combined treatments of Cd and Pb at the concentration of 5 mg/L and 10.5 mg/L for 10 days, respectively. The animal was then placed in metal free water in the following 5 days for depuration experiment. Heavy metal concentrations were determined by an inductively coupled plasma optical emission spectrometer (ICP OES). The limit of detection (LOD) and recovery for Cd and Pb were 0.01, 0.06 µg/g WW, and 80, 83% respectively. Results showed that the clam was able to accumulate Cd and Pb at the maximum rate of 0.26 and 0.37 (µg/g/day), respectively; and depurates at the rate of 0.32 and 0.08 (µg/g/day), respectively. At the end of uptake period, the concentrations of Cd and Pb in the soft tissues of single and combined exposures were 1.8 and 1.1 µg/g wet weight (WW) and 1.2 and 0.8 µg/g WW, respectively. The clam also showed rapid depuration of Cd and Pb. At the end of depuration, the concentrations of Cd and Pb in the soft tissues were only 0.2 and 0.8 µg/g WW in single and 0.17 and 0.4 µg/g WW in combined exposure, respectively. The results of the present study also shown that there was a competition between Cd and Pb in the tissues of the clam. The total target hazard quotients and the hazard index indicated that people might experience adverse health effects through consuming contaminated C. fluminea.