A sulfur-stable-isotope-based screening tool for assessing impact of acid sulfate soils on waterways

Kieryn Kilminster, Ian Cartwright

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7 Citations (Scopus)


Early warning indicators for waterways affected by acid sulfate soils (ASS) are valuable tools for water management organisations. Oxidised ASS may discharge high concentrations of metals, acid and sulfur to surrounding water. The origin of sulfate may be determined by 34S values. 34S values of dissolved sulfate in ∼300 samples of fresh, brackish and estuarine surface water from south-west Western Australia ranged from 6.6 to 31.4‰ (Caon Diablo Troilite). An indicator was developed based on [SO42], [Cl-] and 34S that categorised samples into groups with similar isotopic influences (iso-groups). Signals of disturbed ASS were identified in ∼4.5% of sites. Multivariate statistical analysis showed that water quality had deteriorated at ASS-influenced sites. Although highly variable, average aluminium concentrations were higher (up to 0.12mgL-1, compared with 0.05mgL-1 elsewhere) in samples that are influenced by ASS disturbance. The categorisation of samples into iso-groups provides a simple tool to prioritise sites for further investigation. This study shows that 34S values provide an early warning indicator for water affected by disturbed ASS, particularly in localities where rainfall is marine dominated with a similar 34S to seawater.

Original languageEnglish
Pages (from-to)152-161
Number of pages10
JournalMarine and Freshwater Research
Issue number2
Publication statusPublished - 24 Feb 2011


  • acid sulfate soils
  • acidification
  • early warning indicator
  • estuarine water
  • freshwater
  • metal pollution
  • sulfate reduction
  • sulfur isotope

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