Arsenic repartitioning during biogenic sulfidization and transformation of ferrihydrite
Arsenic repartitioning during biogenic sulfidization and transformation of ferrihydrite
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DOI：
10.1016/j.gca.2009.10.023
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发表时间：
2010-02-01
影响因子：
5
通讯作者：
Fendorf, Scott
中科院分区：
文献类型：
--
作者：
Kocar, Benjamin D.;Borch, Thomas;Fendorf, Scott
铁(氢)氧化物是砷(As)的强吸着剂，与溶解的硫化物反应时，会发生还原溶解和转化。在这里，我们研究了在生物硫酸盐还原过程中，含As亚铁水合物的转化和溶解，以及随后As在次生相之间的重新分配。用含有硫酸盐和乳酸盐的人工地下水洗脱最初含有As(V)-铁水石包覆砂的柱，接种硫酸盐还原细菌Desulfovibrio uggaris(Hildenborough)。在较低的As(V)负载量(最大吸附容量的10%)下，硫酸盐还原和乳酸氧化反应迅速而稳定。在低As负荷下，Fe固相转变的主要产物为硫酸盐还原带(柱入口附近)内的无定形FeE和下游Fe(II)((AQ))浓度增加的磁铁矿，As从硫化物生成和Fe(III)(S)贫化带置换出来。在较高的As(V)负载量(吸附最大值的50%)下，硫酸盐还原和乳酸氧化最初是缓慢的，但随着时间的推移逐渐增加，到实验结束时，所有的As(V)都被还原为As(III)。在较高的砷负荷下，与磁铁矿相反，绿锈(S)是主要的铁固相产物。与负载无关，As与磁铁矿和残余亚铁水合物密切相关，而不受绿锈和硫化铁的影响。我们的观察表明，在Fe(Hydr)氧化物附近发生的硫化作用导致了Fe的固相转变和As分配的变化，特别是活性Fe(III)或Fe(II)通过硫化物氧化或络合作用抑制了As硫化物矿物的形成。(C)2009爱思唯尔有限公司。保留所有权利。
Iron (hydr)oxides are strong sorbents of arsenic (As) that undergo reductive dissolution and transformation upon reaction with dissolved sulfide. Here we examine the transformation and dissolution of As-bearing ferrihydrite and subsequent As repartitioning amongst secondary phases during biotic sulfate reduction. Columns initially containing As(V)-ferrihydrite coated sand, inoculated with the sulfate reducing bacteria Desulfovibrio vulgaris (Hildenborough), were eluted with artificial ground-water containing sulfate and lactate. Rapid and consistent sulfate reduction coupled with lactate oxidation is observed at low As(V) loading (10% of the adsorption maximum). The dominant Fe solid phase transformation products at low As loading include amorphous Fes within the zone of sulfate reduction (near the inlet of the column) and magnetite downstream where Fe(II)((aq)) concentrations increase; As is displaced from the zone of sulfidogenesis and Fe(III)((s)) depletion. At high As(V) loading (50% of the adsorption maximum), sulfate reduction and lactate oxidation are initially slow but gradually increase over time, and all As(V) is reduced to As(III) by the end of experimentation. With the higher As loading, green rust(s), as opposed to magnetite, is a dominant Fe solid phase product. Independent of loading, As is strongly associated with magnetite and residual ferrihydrite, while being excluded from green rust and iron sulfide. Our observations illustrate that sulfidogenesis occurring in proximity with Fe (hydr)oxides induce Fe solid phase transformation and changes in As partitioning; formation of As Sulfide minerals, in particular, is inhibited by reactive Fe(III) or Fe(II) either through sulfide oxidation or complexation. (C) 2009 Elsevier Ltd. All rights reserved.