Trace metal concentrations in sediments and oysters of Botany Bay, NSW, Australia

Surfical sediment (< 63 microm) trace metal concentrations (Zn, Cu, Pd, Cd, As) were analyzed from seven sites in Botany Bay, NSW, Australia, to assess the extent of contamination from the surrounding urban areas. The northwest shoreline of Botany Bay contained high surfical sediment trace metal concentrations relative to the southern shoreline. Surfical sediment Pb concentrations (10-120 microg/g) were above the current ANZECC/ARMCANZ interim sediment guideline value (50 microg/g) for the protection of benthic ecosystems at the northwest sites. Cooks River was identified as a major source of trace metals. Oysters grown in Botany Bay have greater Zn, Cu, and Cd concentrations than two relatively pristine reference locations, Jervis Bay and Batemans Bay, indicating that the Botany Bay region has elevated biologically available metal concentrations. Oyster tissue trace metal concentrations were below the Australian and New Zealand Food Authority standards. Translocation of oysters to sites around the bay identified Pb and Cd as the only trace metals to be accumulated over 3 months. Copper concentrations in transplanted oysters declined at most sites, indicating that the sites investigated in this study have less bioavailable copper than Woolooware Bay, the source of the oysters. The shallow waters along the southern shoreline are protected from the tidal flow that carry contaminated sediments and the biologically available trace metals appear to be low.