Birch G F, Lee J-H, Gunns T, Besley C H
Geocoastal Research Group, School of Geosciences, The University of Sydney, New South Wales, Australia.
Geocoastal Research Group, School of Geosciences, The University of Sydney, New South Wales, Australia; CoreLogic Asia Pacific, Sydney, New South Wales, Australia.
Sci Total Environ. 2024 Nov 10;950:175268. doi: 10.1016/j.scitotenv.2024.175268. Epub 2024 Aug 5.
The Greater Sydney (Australia) region is dissected by eleven major estuaries comprising a wide range of sizes, sediment and contaminant types, while the catchments also vary in size, land use type, populations size and geology/soils. The magnitude and breadth of the current study are rare and offered an unusual opportunity to provide new information on interactions between source, fate and effect relationships of a highly diverse estuarine-catchment environment using sedimentary metals (Co, Cr, Cu, Ni, Pb and Zn). Advanced methodologies used in this study revealed that although metal concentrations were generally high, ecological risk was surprisingly reduced due to the presence of metal-poor coarse sediment. Stormwater was identified as the dominant source of metals to estuaries of Greater Sydney and relates to development of high-density road networks. Industrial sources, frequently identified as a major contributor to estuarine contamination, was significantly reduced due to the decline of industry through decentralisation and gentrification and because waste is discharged to the sewer system, which is released offshore, or tertiary-treated to the Hawkesbury. Groundwater leachate associated with shoreline reclamation and wetland infilling and metals related to boating activities were important sources of metals impacting local bays and coastal lagoons. Temporal monitoring and unique modelling approaches indicated that the concentration of sedimentary metals is generally declining in these estuaries, (especially for Pb), except for areas with rapidly increasing urban populations. Multivariate statistical modelling was able to differentiate the 11 estuaries on a chemical basis by aligning Cu, Pb, Zn vectors with metal-rich estuaries and also identified catchment attributes (percent area, total yield, anthropogenic yield and population density) normalised to catchment areas as having a major influence on estuarine condition. The new knowledge derived from this study should be used to assess the environmental status of estuaries and to prioritise management actions in future investigations.
澳大利亚大悉尼地区被11个主要河口分割，这些河口大小各异，沉积物和污染物类型多样，而集水区在面积、土地利用类型、人口规模以及地质/土壤方面也各不相同。本研究的规模和广度实属罕见，提供了一个难得的机会，利用沉积金属（钴、铬、铜、镍、铅和锌），就高度多样化的河口-集水区环境中源、归宿和效应关系之间的相互作用提供新信息。本研究采用的先进方法表明，尽管金属浓度普遍较高，但由于存在贫金属的粗沉积物，生态风险出人意料地降低了。雨水被确定为大悉尼地区河口金属的主要来源，这与高密度道路网络的发展有关。工业源通常被认为是河口污染的主要贡献者，由于工业通过分散化和绅士化而衰落，并且由于废物被排放到下水道系统，该系统被排放到近海，或经过三级处理后排放到霍克斯伯里河，工业源已大幅减少。与海岸线开垦和湿地填埋相关的地下水渗滤液以及与划船活动相关的金属是影响当地海湾和沿海泻湖的重要金属来源。时间监测和独特的建模方法表明，除了城市人口迅速增加的地区外，这些河口的沉积金属浓度总体上呈下降趋势（尤其是铅）。多变量统计建模能够根据化学性质区分这11个河口，将铜、铅、锌向量与富含金属的河口对齐，还确定了按集水区面积归一化的集水区属性（面积百分比、总产量、人为产量和人口密度）对河口状况有重大影响。本研究获得的新知识应用于评估河口的环境状况，并在未来的调查中确定管理行动的优先次序。
