Concentrations of copper, zinc and lead in the Sydney rock oyster, Saccostrea commercialis (Iredale and Roughley) from the Georges River, New South Wales.

Copper, zinc and lead were analysed from samples of non-commercially grown Sydney rock oysters collected from the Georges River estuary in spring 1987. The results, when compared with previous data from 1975, indicated a marked increase in the concentration of copper (up to 40%) and zinc (up to 300%). For several sites, the recommended (National Health and Medical Research Council) levels for copper and zinc (70 micrograms g-1 and 1000 micrograms g-1 respectively) were exceeded. There appears to be a decrease in the concentration of lead since 1975. The gradient of increasing copper and zinc concentrations with increasing distance upstream from the mouth of the estuary reported in 1975 could not be statistically validated. A significant correlation was found between copper and zinc loadings in the oysters. It was noted that data collected in 1975 were based on commercially grown oysters. The use of commercially grown oysters, rather than indigenous oysters, to examine interaction of contaminant load and distance upstream, is complicated as commercial oysters are moved within the estuary and between estuaries to maximise growth potential.

Duke Scholars

Author Kenneth R Brown Electrical and Computer Engineering