Acid sulfate soils underlie more than half of the Gnangara groundwater management area and pose a risk to the water quality of groundwater users where these are exposed by declining a watertable.
These soils contain sulfuric acid stored below the watertable in the mineral pyrite that is released and starts to leach when exposed to air. The acid release can trigger a cascade of other changes in soils that flow on to influence the quality of shallow groundwater including leaching of iron, aluminium and other metals in soils, salts and arsenic. While near surface acid sulfate soils are typically concentrated in wetlands and lakes, there are extensive areas of Bassendean sands where acid sulfate soils are associated with the shallow watertable on Gnangara mound.
This report assesses the likely extent and risks to groundwater users of poor water quality due to acidification from watertable decline under different abstraction scenarios (interventions) modelled in the Perth Regional Aquifer Modelling System.
Please download the document below.
