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Speciation and mobility of antimony and arsenic in a highly contaminated freshwater system and the influence of extreme drought conditions
Journal article   Peer reviewed

Speciation and mobility of antimony and arsenic in a highly contaminated freshwater system and the influence of extreme drought conditions

Steven Doherty, Matthew K Tighe, Luke A Milan, Leanne Lisle, Calvin Leech, Bernt Johannessen, Valerie Mitchell, Jessica Hamilton, Scott G Johnston and Susan C Wilson
Environmental Chemistry, Vol.18(7), pp.321-333
22/12/2021
DOI: https://doi.org/10.1071/EN21103
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Speciation and mobility of antimony and arsenicView
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UN Sustainable Development Goals (SDGs)

This output has contributed to the advancement of the following goals:

#3 Good Health and Well-Being
#6 Clean Water and Sanitation

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Abstract

Aqueous and solid-state antimony (Sb) and arsenic (As) speciation is assessed in an Australian freshwater system contaminated by mining of primary sulfide minerals. The study aims to understand metalloid transformation and mobilisation in the system, and coincides with a severe drought providing the opportunity to examine the influence of extreme low-flow conditions. X-ray absorption spectra identified only SbV in <2 mm sediments, despite boulder size stibnite evident in the creek. Roméite-group minerals were detected by X-ray diffraction in oxidation rims of creek-bed stibnite, which potentially limit the contribution of dissolved SbIII to the waterway. Arsenic in <2 mm sediments was dominated by AsV (17–91 %) and orpiment (16–93 %), while the co-occurrence of AsIII (11–36 %) with orpiment suggests that primary As minerals are an important ongoing source of AsIII to the system. Dissolved metalloids (<45 µm filtered) dominated total water column concentrations and comprised mainly pentavalent species. Arsenic(III) was however identified in most water samples (up to 6.6 µg L−1), while dissolved SbIII was only detected in one sample (3.4 µg L−1) collected during the drought period. Dissolved AsV increased significantly in samples collected in low-flow conditions, considered a result of reductive dissolution of sediment Fe-oxyhydroxide host phases, but a similar increase in dissolved Sb was not observed. This study highlights a greater risk from As in this system, and the likelihood of increased As mobility under the warmer and drier environmental conditions predicted with climate change, especially during first-flush events.

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