期刊
GEOCHIMICA ET COSMOCHIMICA ACTA
卷 144, 期 -, 页码 157-172出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.gca.2014.08.037
关键词
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资金
- National Science Foundation [NSF EAR-1014946]
- Division Of Earth Sciences
- Directorate For Geosciences [1014946] Funding Source: National Science Foundation
Using UV/VIS spectrophotometry the equilibrium constants for the formation of monothiotungstate, WO3S2- (WO42- + H2S <-> WO3S2- + H2O; log K-01 = 3.08 +/- 0.11), dithiotungstate, WO2S22- (WO3S2- + H2S <-> WO2S22- + H2O; log K-12 = 3.22 +/- 0.22), trithiotungstate, WO3S2- (WO2S22- + H2S <-> WO3S2- + H2O; log K-23 = 2.76 +/- 0.10), and tetrathiotungstate, WS42- (WO3S2- + H2S <-> WS42- + H2O; log K-34 similar to 2.36) were determined. The equilibrium constants describing the formation of thiotungstates are approximately two orders of magnitude less than the equilibrium constants for the formation of the analogous thiomolybdates. These equilibrium constants for thiotungstates were used to model tungstate speciation in sulfidic waters. The model predicts that thiotungstate species are negligible in most natural waters, but are likely to be important in circum-neutral, anoxic waters with >= 0.1 mM S(-II) concentrations. Natural waters that are conducive to thiotungstate formation include the Black Sea, Tyro and Bannock Basins, and porewaters with high rates of sulfate reduction such as those common in salt marshes. Preliminary field investigations indicate that thiotungstate formation may lead to increased W solubility. (C) 2014 Elsevier Ltd. All rights reserved.
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