What are acid sulfate soils?
Acid Sulfate Soils (ASS) are soils that contain iron sulfides and are found in low-lying coastal areas below AHD (Australian Height Datum) 5.0 metres.
The formation of iron sulfides occurred around 10,000 years ago, when coastal lands were inundated with sea water.
When soil containing iron sulfides is disturbed and exposed to air, the iron sulfides react with oxygen to produce sulphuric acid, making the soils very acid and toxic.
Effects of acid sulfate soils
It affects plants, can damage concrete, iron, steel and some aluminium alloys, affects the food chain of aquatic ecosystems leading to fish kills and can cause disease.
Fish kills are the most obvious effect of acid sulfate soils. Where fish are not immediately killed, the corrosive nature of sulfuric acid increases their susceptibility to fungal infections, which can lead to diseases such as epizootic ulcerative syndrome (also known as 'red spot').
Acid sulfate soils present a major challenge to the development, management and use of coastal areas. The construction of marinas, golf courses, coastal lake developments and drainage canals can expose acid sulfate soils to air and cause oxidisation if not managed appropriately.
The range of environmental impacts of acid sulfate soils includes:
- Human health impacts from disturbed ASS may include dermatitis from contact and eye irritation from dust
- Effects on the ecology of wetlands through fish kills and impacted shallow freshwater and brackish aquifer systems
- Economic loss through lowered crop productivity and impacts on commercial and recreational fisheries
- Infrastructure damage as leachate can corrode concrete and steel infrastructure
Thinking of disturbing acid sulfate soils?
Prior to excavating or filling on land, please refer to the relevant planning scheme acid sulfate soils overlays and planning scheme policies. You may need development approval for your proposed works.
For more information on how to identify or manage acid sulfate soils, see the Department of Environment and Heritage Protection
Local scale acid sulfate soils mapping
Council has recently mapped acid sulfate soils in collaboration with the Department of Environment and Resource Management. The coastal study areas were chosen due to the suspected presence of acid sulfate soils close to the surface of the land, and the conflicts this might present for future development plans.
The study areas include:
- Southern Bribie Island
- Donnybrook to Toorbul
- Pine Rivers area (land around Hays Inlet and North and South Pine Rivers estuaries)
The maps produced are anticipated to:
- Improve development proposals, as maps inform the development industry about the location and depth of acid sulfate soils within the study areas, to facilitate compliance with the State Planning Policy 2/02: Planning and Managing Development Involving Acid Sulfate Soils
- Inform residents, developers and Council planning and operational processes of the risks associated with disturbing, and the management and remediation of, acid sulfate soils
- Inform Council's education campaigns and research priorities associated with acid sulfate soils management