Introduction to Acid Sulfate Soils in the Port Macquarie-Hastings Region
Acid Sulfate Soils (ASS) contain iron sulfides (mainly pyrite) which can generate large amounts of sulfuric acid when exposed to air. These soils formed naturally over the last 10,000 years, and are safe unless dug up or drained.
ASS are widespread in our estuarine floodplains and wetlands (including mangrove tidal flats, salt marshes and tea-tree swamps). Before drainage and oxidation, they are termed Potential ASS. Actual ASS are formed when the naturally occurring iron sulfides (pyrite) in the soil become exposed to air (through drainage or excavation) and subsequently oxidise, forming sulfuric acid.