Speciation of arsenic in sulfidic waters

被引：0
作者：
Richard T Wilkin
Dirk Wallschläger
Robert G Ford
机构：
[1] National Risk Management Research Laboratory,U.S. Environmental Protection Agency, Office of Research and Development
[2] Trent University,Environmental and Resource Studies Program
来源：
Geochemical Transactions | / 4卷
关键词：
Arsenic; Arsenite; NaHS; Arsenic Speciation; Sulfide Concentration;
D O I：
暂无
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摘要：
Formation constants for thioarsenite species have been determined in dilute solutions at 25°C, ΣH2S from 10-7.5 to 10-3.0 M, ΣAs from 10-5.6 to 10-4.8 M, and pH 7 and 10. The principal inorganic arsenic species in anoxic aquatic systems are arsenite, As(OH)30, and a mononuclear thioarsenite with an S/As ratio of 3:1. Thioarsenic species with S/As ratios of 1 : 1,2 : 1, and 4 : 1 are lesser components in sulfidic solutions that might be encountered in natural aquatic environments. Thioarsenites dominate arsenic speciation at sulfide concentrations > 10-4.3 M at neutral pH. Conversion from neutral As(OH)30 to anionic thioarsenite species may regulate the transport and fate of arsenic in sulfate-reducing environments by governing sorption and mineral precipitation reactions.
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