期刊
ENVIRONMENTAL SCIENCE & TECHNOLOGY
卷 44, 期 1, 页码 102-108出版社
AMER CHEMICAL SOC
DOI: 10.1021/es901274s
关键词
-
资金
- German Research Foundation (DFG)
- German Ministry for Science and Education
- National Science Foundation (NSF) [EAR 0847683]
The redox state and speciation of the metalloid arsenic (As) determine its environmental fate and toxicity. Knowledge about biogeochemical processes influencing arsenic redox state is therefore necessary to understand and predict its environmental behavior. Here we quantified arsenic redox changes by pH-neutral goethite [alpha-(FeOOH)-O-III] mineral suspensions amended with Fe(II) using wet-chemical and synchrotron X-ray absorption (XANES) analysis. Goethite itself did not oxidize As(III) and, in contrast to thermodynamic predictions, Fe(II)-goethite systems did not reduce As(V). However, we observed rapid oxidation of As(III) to As(V) in Fe(II)-goethite systems. Mossbauer spectroscopy showed initial formation of Fe-57-goethite after Fe-57(II) addition plus a so far unidentified additional Fe(II) phase. No other Fe(III) phase could be detected by Mossbauer, EXAFS, SEM, XRD, or HR-TEM. This suggests that reactive Fe(III) species form as an intermediate Fe(III) phase upon Fe(II) addition and electron transfer into bulk goethite but before crystallization of the newly formed Fe(III) as goethite. In summary this study indicates that in the simultaneous presence of Fe(III) oxyhydroxides and Fe(II), as commonly observed in environments inhabited by iron-reducing microorganisms, As(III) oxidation can occur. This potentially explains the presence of As(V) in reduced groundwater aquifers.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据