Distribution of heavy metals in Elcho Island, Northern Territory, Australia

The concentration of four metals in waters and seven metals in oysters, clams and sediments from Elcho Island, Northern Territory, were determined during the dry season of 1987. The measured concentration of cadmium, zinc, copper and lead in unfiltered water were: cadmium, 0.02–0.27; zinc, 0.09–3.70; copper, 0.60–4.78; lead, 0.12–2.39 μg 1−1, and iron, cadmium, zinc, manganese, copper, nickel and lead in oysters, 13.07–273.55, 0.29–10.63, 2.39–8.51, 0.25–4.84, 0.45–8.76, 0.16–0.59, 2.59–9.38 μg g−1 wet weight, and in clam, 94.84–419, 6.0–20.3, 1.09–6.28, 2515–6256, 0.47–3.18, 1.71–5.64, 0.45–2.17 μg g−1 wet weight, and in sediments, 3219.1–10871.1, 1.36–2.68, 2.7–6.55, 19.4–105.7, 0.65–1.91, 4.16–21.8 and 5.66–23.9 μg g−1 dry weight. Accumulation of manganese in razor clam was highest in spite of low concentration in the surrounding sediment, therefore it could be used as a bioindicator of manganese in a tropical environment. The level of cadmium and lead exceeded the National Health and Medical Research Council (NHMRC) recommended limit. In general, level of other metals were lower as compared to the concentration of these metals in Darwin Harbour