title: Depuration of metals by the green-colored oyster Crassostrea sikamea.
abstract: The accumulation of metals (especially copper) in oysters has led to green-color now being found in Chinese estuaries. In the present study, the authors quantified the depuration of 8 metals (Ag, Cd, Co, Cr, Cu, Ni, Pb, and Zn) in green-colored oysters (Crassostrea sikamea) collected from an estuary that is heavily contaminated by metals as a result of industrial effluent releases. The oysters were depurated under laboratory conditions for 4 mo; the accumulated concentrations and the subcellular distribution of metals were measured at different time intervals. Results showed that the green color of oysters faded to light yellow (nearly normal) after 4 mo of depuration. Depuration of metals could be described by a first-order kinetic process. The calculated overall depuration rate constants of metals were in the range of 0.008 d(-1) to 0.024 d(-1) , with a biological retention half-life of 30 d to 70 d. The depuration rates of green-colored contaminated oysters were significantly higher for Cd, Cu, Cr, and Ni than the rates of oysters from a less contaminated site, whereas the depuration rates of Ag, Co, Pb, and Zn were comparable between the 2 populations. When corrected for the change of oyster tissue weight, the actual efflux rate constants of the metals (0.0708-0.1014 d(-1) ) were much higher than the overall depuration rate constants. Cellular debris and metallothionein-like proteins were the important fractions binding with the metals in the oysters. Significant changes in metal subcellular distribution were observed during the 4-mo depuration for Ag, Cd, Cu, and Zn. Metallothionein-like protein became more important in sequestering the metals during the depuration period, with a concomitant decrease in metals associated with the cellular debris fraction.
authors: Key Laboratory of Coastal and Wetland Ecosystems, Ministry of Education, College of Environment and Ecology, Xiamen University, Xiamen, China.
authors: Lei
authors: L
authors: Wang
authors: Wen-Xiong
authors: WX
authors: Wang
mesh_terms: D000818:Animals; D049896:Crassostrea / Q000378:metabolism*; D004784:Environmental Monitoring; D063366:Estuaries; D006207:Half-Life; D007700:Kinetics; D019216:Metals, Heavy / Q000032:analysis / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D019216:Metals, Heavy; D014874:Water Pollutants, Chemical
keywords: Contamination; Metal elimination; Oysters; Subcellular efflux