THESIS
2015
xi, 52 pages : illustrations ; 30 cm
Abstract
Elevated levels of trace metals in the water column and sediment in the estuarine areas in the coastal area of South China have been observed. Oysters have been selected as a potential biomonitor to reflect the trace metal bioavailability and pollution level in a biomonitoring program due to the abundance and hyper-accumulation characteristics of oysters in South China. We provided an initial step to examine the feasibility of oysters as bioindicators of Cd and Zn bioaccumulation with respect to metal biokinetics. The results showed that assimilation efficiencies (AE) and efflux rate constants (k
e) of Cd and Zn in the oysters Crassostrea hongkongensis and Crassostrea sikamea collected from fields and oysters Crassostrea hongkongensis exposed in the laboratory could not be modified by me...[
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Elevated levels of trace metals in the water column and sediment in the estuarine areas in the coastal area of South China have been observed. Oysters have been selected as a potential biomonitor to reflect the trace metal bioavailability and pollution level in a biomonitoring program due to the abundance and hyper-accumulation characteristics of oysters in South China. We provided an initial step to examine the feasibility of oysters as bioindicators of Cd and Zn bioaccumulation with respect to metal biokinetics. The results showed that assimilation efficiencies (AE) and efflux rate constants (k
e) of Cd and Zn in the oysters Crassostrea hongkongensis and Crassostrea sikamea collected from fields and oysters Crassostrea hongkongensis exposed in the laboratory could not be modified by metal exposure. However, the dissolved uptake rate constants of Cd and Zn varied. A transplant experiment using oysters Crassostrea hongkongensis in an estuary was also conducted to quantify the changes of metal biokinetics (cadmium and zinc) and the responses of metallothionein-like proteins (MTLPs). We further demonstrated that oysters displayed rather weak ability to modify their biokinetics and metallothionein turnover under metal exposure. The incoming Cu and Zn were not stored in MTLPs pool. Generally, Cd and Zn bioaccumulation in the oysters mainly derive from the food rather than from the dissolved phase. Variations of k
u contributed little to the variation of Cd and Zn concentration in oysters. Thus, Cd and Zn concentrations in oysters might reflect Cd and Zn pollution in the environments due to the conservative characteristics of k
e and AE of metals in the oysters.
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