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Objective

Recommendation

Key issues

What has been achieved 1998-2003

Tasmania Together

Related Issue Reports

Objective

To better identify, assess, and reduce the risks of environmental contamination arising from disturbance of acid sulphate soils.

Recommendation

It is recommended that:

• systematic mapping of acid sulphate soils at finer scales is undertaken within the areas identified as potentially hosting acid sulphate soils in order to prioritise and target responses;
   
• monitoring and assessment of land use changes that may exacerbate disturbance of acid sulphate soils is undertaken as part of the overall approach to monitoring land cover change;
   
• monitoring of appropriate water quality parameters is undertaken in at-risk locations in coastal waters in the north of the State in order to detect impacts arising from acid sulphate soils and to prioritise management efforts;
   
• implementation of remediation strategies is initiated in locations already identified where disturbance of acid sulphate soils is impacting on the water quality; and
   
• management awareness programs are developed for land use once priority risk areas are identified.
   

Key issues

The disturbance and exposure of acid sulphate soils by earth moving practices and fluctuations in groundwater levels can facilitate the oxidation of pyrite, resulting in the generation of sulphuric acid. Implications relate to the direct impact of acid on the receiving environment and the indirect impact of acid in mobilising toxic metals. A Natural Heritage Trust funded report has confirmed the presence of acid sulphate soils in Tasmania and has identified that acid is being released from some sites, which host acid sulphate soils (Gurung 2001). Further detail is provided in the Disturbance of Acid Sulphate Soils Issue Report, and the NHT report in detail is available from Mineral Resources Tasmania. Some of the key points from the Issue Report include the following.

• There is the opportunity to adapt land management practices to mitigate the risk to the environment and to downstream users arising from disturbance of acid sulphate soils. This will help to avoid costly and potentially irreversible environmental damage.
   
• The risk of disturbance of acid sulphate soils is high. Some of the areas that are at risk are productive and fertile land under intensive use with agricultural drainage schemes. Increasing land and water development pressure, as well as the current land-use practices in the northern Tasmanian coastal areas, are likely to increase the likelihood of exposing potential acid sulphate soils.
   
• Parts of north-west Tasmania contain particular 'hot-spots'. Sediments with the potential to host acid sulphate soils occur mostly in the Smithton and Woolnorth areas.
   
• Elevated levels of mobilised trace heavy metals in soil and water can be toxic to aquatic life if released into the drainage system. This can occur during high flow events or as a result of a rise in the groundwater table. Elsewhere in Australia, several massive fish kills in coastal rivers have been caused by acid flush during major flood events. Land areas impacted by exposed acid sulphate soils have poor fertility, high vegetation dieback and are prone to surface scalding and erosion.
   

What has been achieved 1998-2003

The State Policy on Water Quality Management (1997) highlited the need to identify and assess the potential risk arising from the presence of acid sulphate soils. The Natural Heritage Trust funded reconnaissance survey and report on acid sulphate soils responded to this need. The report highlights the presence of acid sulphate soils, however, the information was limited. Currently, there are no awareness programs for management of acid sulphate soils and there is no site-specific remediation occurring.

Tasmania Together

Relevant Tasmania Together goals and standards for 'Land' are listed in the linked file. The Tasmania Together Progress Board reported on progress toward targets for benchmarks set (Tasmania Together Progress Board 2003). Indicators, targets and baseline data are available in the latest Progress Report June 2003. Further information, including progress report updates, is available from Tasmania Together.

Related Issue Reports