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Historic mining practices at Hillgrove Mine in the Upper Macleay River Catchment have created a 300km dispersion of soil and sediment downstream of the mine contaminated with arsenic (As) and antimony (Sb). This project aimed to understand the chemical and mineralogical transformations that occur as Sb and As enriched sediment moves down the river, to understand Sb and As bioavailability throughout the catchment and to understand fluctuations in Sb and As water concentrations for improved risk assessment and setting of environmental quality objectives. All the project objectives have been achieved. A catchment water monitoring data base has been established over varying river conditions. Bioavailability in plants has been extensively researched throughout the different catchment environments both in the field and in laboratory pot trials. This data has also supported rehabilitation decisions at Hillgrove Mine Site. Metalloid uptake in the upper trophic levels of the more highly contaminated upper catchment ecosystem has been established but concentrations in organisms in the lower catchment were low or non detect. Antimony and As sediment associations have also been established. Integration of data for risk assessment is still on-going but so far results have been presented or accepted for presentation at two international conferences, published as one journal paper and submitted for two others, and written up as part of three student honours theses. Project data also supports catchment decision making through the Premiers Office led Macleay Catchment Contamination Working Group. |
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