Coastal acid sulfate soils
Coastal acid sulfate soils (CASS) are soils and sediments containing iron sulfides, the most common being pyrite. When exposed to air due to drainage or disturbance, these soils produce sulfuric acid, often releasing toxic quantities of iron, aluminium and heavy metals into the environment. It can be extremely toxic to plants and animals.
Prolonged exposure of coastal acid sulfate soils to air also causes 'soil ripening' - an irreversible loss of water resulting in physical, chemical and biological changes to the soil.
CASS may be present in most low-lying coastal regions in South Australia.
A strategy for dealing with CASS was developed in 2002 by the Coast Protection Board, in collaboration with the CSIRO's Coastal Acid Sulfate Soils Program (CASSP).