Metal concentrations in waters, sediments and biota of the far south-east coast of New South Wales, Australia, with an emphasis on Sn, Cu and Zn used as marine antifoulant agents.

Abstract

Tin, Cu, Zn, Cd, Pb, Ag and Hg concentrations were measured in waters, sediments and three ubiquitous sedentary molluscs: the oyster, Saccostrea glomerata, a rocky intertidal gastropod, Austrocochlea porcata, and a sediment-dwelling gastropod, Batillaria australis, at 12 locations along the far south coast of NSW, Australia, from Batemans Bay to Twofold Bay during 2009. Metal concentrations in water for Sn, Cd, Ag and Hg were below detection limits (< 0.005 μg/L). Measurable water metal concentrations were Cu: 0.01-0.08 μg/L, Zn: 0.005-0.11 μg/L and Pb: 0.005-0.06 μg/L. Mean metal concentration in sediments were Sn < 0.01-2 μg/g, Cu < 0.01-605 μg/g, Zn 23-765 μg/g, Cd < 0.01-0.5 μg/g, Pb < 0.01-0.3 μg/g, Ag < 0.01-0.9 μg/g and Hg < 0.01-2.3 μg/g. Several locations exceeded the Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand (Australian and New Zealand guidelines for fresh and marine water quality 2000) low and high interim sediment quality guidelines' levels for Cu, Zn, Cd and Hg. Some sites had measurable Sn concentrations, but these were all well below the levels of tributyltin known to cause harm to marine animals. Elevated metal concentrations are likely to be from the use of antifoulants on boats, historical mining activities and agriculture in the catchments of estuaries. All molluscs had no measurable concentrations of Sn (< 0.01 μg/g) and low mean Ag (< 0.01-1.5 μg/g) and Hg (< 0.01-0.5 μg/g) concentrations. Mean Cu (24-1516 μg/g), Zn (45-4644 μg/g), Cd (0.05-5μg/g) and Pb (0.05-1.1 μg/g) in oysters were close to background concentrations. Oysters have Cd and Pb concentrations well below the Australian Food Standards Code (2002).] There were no significant correlations between metal concentrations in sediments and in organisms within locations, and no relationship with levels of boating activity and suspected antifouling contamination. Although not pristine, the low levels of metal contamination in sediments and molluscs in comparison with known metal-contaminated areas indicate that this region is not grossly contaminated with metals and suitable for the development of mariculture.].