Speciation of Cu and Zn in Two Colored Oyster Species Determined by X-ray Absorption Spectroscopy.
In oysters, Cu and Zn concentration can reach extraordinarily high (1-2% of tissue dry weights), leading to intense green or blue colors in oyster tissues. It is thus puzzling how oysters detoxify the excessively accumulated metals. Here, we used X-ray absorption spectroscopy to examine the Cu and Zn speciation in two "colored" oysters (Crassostrea hongkongensis and Crassostrea sikamea) collected from a severely metal-contaminated estuary. In contaminated oysters, we found a much higher proportion of tissue Cu and Zn as oxygen- or nitrogen-bonded species, contrasting to the sulfur-bonded (thiolate) species in normal oysters. Speciation of Cu and Zn in mantle was similar to that in gills, both of which were different from that in the digestive gland. In C. sikamea, the difference of metal speciation between normal and contaminated individuals was of similar pattern but less pronounced than that in C. hongkongensis. In normal oysters, Cu existed mainly as Cu(I) bound to sulfur, whereas in contaminated oysters mainly as Cu(II) bound to oxygen or nitrogen. Our study provided direct and semiquantitative information on the changes of metal speciation in contaminated oysters, indicating that oysters could efficiently detoxify the excessively accumulated Cu and Zn by storing them in oxygen- and nitrogen-bonded complexes in metal-rich environments.
†Key Laboratory of the Coastal and Wetland Ecosystems, Ministry of Education, College of Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China.
Qiao-Guo
QG
Tan
‡Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China.
Yu
Y
Wang
†Key Laboratory of the Coastal and Wetland Ecosystems, Ministry of Education, College of Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China.|§Division of Life Science, Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong.
Wen-Xiong
WX
Wang
D000818:Animals; D003300:Copper / Q000032:analysis*; D049896:Crassostrea / Q000378:metabolism*; D004784:Environmental Monitoring; D006801:Humans; D008658:Inactivation, Metabolic; D013455:Sulfur / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis; D056928:X-Ray Absorption Spectroscopy; D015032:Zinc / Q000032:analysis*
D014874:Water Pollutants, Chemical; D013455:Sulfur; D003300:Copper; D015032:Zinc