Keywords: Australia, heavy metals, marine management, marine pollution
Marine pollution in Australia, with special emphasis on central New South Wales estuaries and adjacent continental margin
This paper reviews the current knowledge and environmental status of Australian estuaries and continental margins in terms of sedimentary heavy metals. Although only 2.5% of Australian estuaries and 0.1% of the adjacent continental shelf have been surveyed for sedimentary heavy metals, some of the most contaminated maritime areas in the world have been located in this country. The most impacted regions are adjacent to single-purpose industrial complexes, e.g. smelters, refineries and chlor-alkali plants, whereas Port Jackson (Sydney) is by far the most contaminated mixed urbanised/industrialised estuary in Australia. The concentration of metals is substantially higher and more extensive in Australian estuaries than in sediments of the contintental margin. Even the continental margin adjacent to central New South Wales (NSW) where almost one third of the total Australian population live, shows only minor environmental impact. These data demonstrate the effectiveness of estuarine environments to act as traps for pollutants, and conversely, how efficiently contaminants are dispersed from the high-energy continental margins of Australia. In central NSW, the level of estuarine contamination is closely related to the extent of urbanisation/industrialisation. Extensive areas of Port Jackson are contaminated with heavy metals, especially Pb and Zn, and a large proportion of the estuary has sedimentary metals at concentrations where some adverse biological affects can be expected. Although much of the contamination is a legacy of past poor industrial practice, high metal concentrations in fluvial sediments entering the harbour indicate contaminants continue to be supplied to the waterway. There are many possible sources, but stormwater and leachates from extensive reclamation at the upper reaches of some tributaries and embayments may be important. The political significance of the coastal zone and the extent of impact on this environmental has recently (and belatedly) been realised, and new Commonwealth investigations and initiatives have been instigated. The first "State of the Environment of the Marine Environment Report" has been completed and the "Commonwealth Coastal Policy" has been initiated. However, the amount and quality of sedimentary contaminant data available in the coastal zone is totally inadequate to construct a national contaminant framework for this environment. This lack of good quality, regionally comparable data hinders the development of appropriate management strategies and construction of legislative structures for the coastal zone.