首页|Abiotic aerobic oxidation pathways of stibnite revealed by oxygen and sulfur isotope systematics of sulfate
Abiotic aerobic oxidation pathways of stibnite revealed by oxygen and sulfur isotope systematics of sulfate
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Abiotic aerobic oxidation pathways of stibnite revealed by oxygen and sulfur isotope systematics of sulfate
The environmental threat posed by stibnite is an important geoenvironmental issue of cur-rent concern.To better understand stibnite oxidation pathways,aerobic abiotic batch exper-iments were conducted in aqueous solution with varying δ18OH2O value at initial neutral pH for different lengths of time(15-300 days).The sulfate oxygen and sulfur isotope composi-tions as well as concentrations of sulfur and antimony species were determined.The sulfur isotope fractionation factor(Δ34SSO4-stibnite)values decreased from 0.8‰ to-2.1‰ during the first 90 days,and increased to 2.6‰ at the 180 days,indicating the dominated intermediate sulfur species such as S2O32-,S0,and H2S(g)involved in Sb2S3 oxidation processes.The in-corporation of O into sulfate derived from O2(～100％)indicated that the dissociated O2 was only directly adsorbed on the stibnite-S sites in the initial stage(0-90 days).The proportion of O incorporation into sulfate from water(27％-52％)increased in the late stage(90-300 days),which suggested the oxidation mechanism changed to hydroxyl attack on stibnite-S sites promoted by nearby adsorbed O2 on stibnite-Sb sites.The exchange of oxygen between sul-fite and water may also contributed to the increase of water derived O into SO42-.The new insight of stibnite oxidation pathway contributes to the understanding of sulfide oxidation mechanism and helps to interpret field data.
Sulfide oxidationδ34SSO4δ18OSO4Oxygen source of sulfate
School of Environment Studies,China University of Geosciences,Wuhan 430074,China
Key Laboratory of Mine Ecological Effects and Systematic Restoration,Ministry of Natural Resources,Beijing 100081,China
State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution,Ministry of Ecology and Environment,Wuhan 430074,China
Institute of Geological Survey,China University of Geosciences,Wuhan 430074,China
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Sulfide oxidation δ34SSO4 δ18OSO4 Oxygen source of sulfate
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