Acid sulfate soils: a national demonstration site for innovative management

Outcomes and Key Findings

Funding / collaborators

  • CRC for Contamination Assessment and Remediation of the Environment
  • Queensland Department of Environment and Resource Management
  • Southern Cross GeoScience

Project description

The aim of the National Demonstration Site for Innovative Acid Sulfate Soil Management is to trial and assess the efficacy of innovative hydrogeochemical control methods and risk assessment methods on acid sulfate contaminant remediation on a field scale in a nationally-significant location. The broad research objectives are:

  1. To examine the efficacy of innovative hydrogeochemical control methods - such as lime-assisted tidal exchange (LATE), inundation with and without liming material additions, drain shallowing, and permeable reactive barriers - on acid sulfate contaminant remediation in the field.
  2. To provide a field site suitable for the verification of the risk assessment technologies to be developed in this and other CRC CARE projects.

This National Demonstration Site for Innovative Acid Sulfate Soil Management is located at the East Trinity site adjacent to Cairns, north-eastern Australia. This site was formerly a mixture of tidal mangrove swamp and salt marsh. In the early 1970s, the 724 ha site was bunded with floodgates installed to exclude tidewater but to allow drainage from the site. This development failed because the drainage allowed oxidation of the sulfidic soil materials - generating a reservoir of sulfuric acid and soluble aluminium, iron, heavy metals and arsenic (Hicks et al. 1999; Dent 2004).

Aerial photo of East Trinity and bund wall

Lime Assisted Tidal Exchange (LATE) is the remediation strategy and is the focus of this CRC CARE funded project. The strategy is based on reintroducing tidal exchange and raising watertables as a means to reduce acidic solute discharge, induce acid consuming geochemical transformations and neutralisation of wetland soils and drainage water.

East Trinity Floodgates

The major focus of our research is to assess the effectiveness of LATE and its potential application to other sites by:

  • conducting field based studies exploring interactions between hydrology and redox dependent geochemical transformations
  • undertaking experiments to unravel the key reaction pathways and kinetics of Fe and S that control acidification and metal contaminants (e.g. As) in acid sulfate soils.
East Trinity Iron Accumulation

Team members

  • Prof Richard Bush, Southern Cross University
  • Prof Leigh Sullivan, Southern Cross University
  • Dr Scott Johnston, Southern Cross University
  • Dr Annabelle Keene, Southern Cross University
  • Dr Ed Burton, Southern Cross University
  • Bernie Powell, DERM
  • Col Ahern, DERM
  • Dr Angus McElnea, DERM
  • Doug Smith, DERM
  • Salirian Claff, Southern Cross University
  • Crystal Maher, Southern Cross University