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(486) Metal bioaccumulation in oysters: the importance of physico-chemical factors.
Ringwood, Amy*,1, Keppler, Charles1, 1 Marine Resources Research Institute, SCDNR, Charleston, SC, USA
ABSTRACT- Sediments function as primary sinks for metals in estuarine systems, but bioturbation and fluctuations in physico-chemical factors, etc. can make them bioavailable. Studies were conducted during summer and winter seasons in which oysters were deployed in cages in situ for one month and the bioaccumulation of metals (Cd, Cu, Zn, Pb, Ni) was determined. The potential relationships between sediment parameters (such as acid volatile sulfides (AVS) and total organic carbon (TOC)) and overlying water parameters (such as salinity, pH, dissolved oxygen) on metal bioaccumulation were evaluated. AVS was found to be a highly variable parameter, and although there was some indication that AVS levels could affect bioavailability, it was not found to be the primary determinant. According to the AVS model, bioaccumulation would not be predicted when the molar concentrations of the metals were less than the AVS levels. However, bioaccumulation was frequently observed even when AVS concentrations exceeded the molar concentrations of individual or combined metals. Oyster tissue metal levels were correlated more often to other factors such as sediment metal concentrations (total metal and SEM levels), TOC and salinity. There was some evidence that certain metals (e.g. Cu and Zn) tended to be preferentially bioaccumulated, even when other sediment metals were more elevated. These results indicate that bioaccumulation is a complex phenomenon that involves biological and physico-chemical components, so that tissue bioaccumulation cannot necessarily be readily predicted based on simple sediment parameters.
Key words: metals, bioavailability, oysters, AVS
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