An initial Phase 1 acid sulfate soil investigation of the Riverglades wetland during February 2008 showed acid sulfate soils to be a priority concern within this wetland complex. Based on Phase 1 recommendations, a Phase 2 investigation was undertaken for the Riverglades wetland to determine the nature, severity and the specific risks associated with acid sulfate soil materials. The wetland had dried during previous drought conditions, but had partially rewet at the time of sampling.The 24 hour reactive metals tests were undertaken to determine those metals and metalloids extractable with a moderately strong acid i.e. potentially available from binding sites on soil minerals such as iron (Fe), manganese (Mn) and aluminium (Al) oxides. Although comparisons can be made with soil and sediment quality guidelines, these are defined for total concentrations and not partial extractions. The results showed that concentrations were below the sediment quality guideline (SQG) and soil ecological investigation level (EIL) for those elements where guidelines are available. Although concentrations of other elements did not breach sediment quality guideline and soil ecological investigation level trigger values, the concentrations of some elements were high enough that they may impact water quality if mobilised, particularly for aluminium (Al) and iron (Fe). The contaminant and metalloid dynamics tests were undertaken to assess the release of metals during a water extraction, and to assess dynamics in response to saturation over time by incubating soil materials for periods of 1, 7, 14 and 35 days. The degree to which metal and metalloid concentrations exceed ANZECC/ARMCANZ guideline values was used to characterise the degree of hazard. For Riverglades, aluminium (Al), iron (Fe) and vanadium (V) were assigned a moderate hazard with concentrations exceeding ANZECC/ARMCANZ guidelines by more than 10 times. The dominant control on metal solubility is the pH of the extractions. Three of the soils had slightly acidic pH, increasing to pH7 by day 35, and one had moderately acidic pH. High aluminium (Al) was found only in the slightly more acidic surface layer, and it remained high as pH increased, significantly above equilibrium concentrations. It is concluded that much of the aluminium (Al) exists as colloidal particles, thus less toxic than Al3+ the dominant form at lower pH.Iron (Fe) and manganese (Mn) increased with time, the dominant control being a large decrease in Eh. The concentrations of most metals were otherwise low, but Cobalt (Co) increased to slightly above ANZECC/ARMCANZ guidelines probably due to release from iron (Fe) or manganese (Mn) oxides. The metalloid arsenic (As) increased in concentration in 3 of the 4 samples studied, probably released from iron (Fe) oxides, but appeared to stabilise by day 35. Vanadium (V) also increased in one sample to a concentration of more than 6 x the ANZECC/ARMCANZ guideline.The Riverglades wetland has been classified as medium conservation status by the SA Murray Darling Basin Natural Resources Management Board (Miles et al. 2010). The main hazards considered in this study that may impact on wetland values are acidification, contaminant mobilisation, and deoxygenation. The wetland has been allocated a high risk rating due to acidification and a high contaminant risk for soils. For surface waters, the risk is largely dependent on surface and sub-surface hydrology and is thus scenario dependent. Taking into account the range of likely scenarios, from very low flows (highest risk) to very high flows (lowest risk), the risk to surface waters in the wetland has been allocated medium risk rating for acidification and high risk for contaminant mobilisation respectively.As such, a risk assessment for deoxygenation was not undertaken as it was determined that there was no hazard from monosulfidic materials in this wetland.In designing a management strategy for dealing with acid sul
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