Simultaneous Microbial Reduction of Iron(III) and Arsenic(V) in Suspensions of Hydrous Ferric Oxide
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- 作者：Kate M. Campbell ; Davin Malasarn ; Chad W. Saltikov ; Dianne K. Newman ; Janet G. Hering
- 刊名：Environmental Science & Technology
- 出版年：2006
- 出版时间：October 1, 2006
- 年：2006
- 卷：40
- 期：19
- 页码：5950 - 5955
- 全文大小：276K
- 年卷期：v.40,no.19(October 1, 2006)
- ISSN：1520-5851
文摘
Bacterial reduction of arsenic(V) and iron(III) oxidesinfluences the redox cycling and partitioning of arsenic(As) between solid and aqueous phases in sediment-porewater systems. Two types of anaerobic bacterialincubations were designed to probe the relative order of As(V) and Fe(III) oxide reduction and to measure the effectof adsorbed As species on the rate of iron reduction, usinghydrous ferric oxide (HFO) as the iron substrate. In oneset of experiments, HFO was pre-equilibrated with As(V) andinoculated with fresh sediment from Haiwee Reservoir(Olancha, CA), an As-impacted field site. The second setof incubations consisted of HFO (without As) and As(III)- andAs(V)- equilibrated HFO incubated with Shewanella sp.ANA-3 wild-type (WT) and ANA-3
arrA, a mutant unableto produce the respiratory As(V) reductase. Of the twopathways for microbial As(V) reduction (respiration anddetoxification), the respiratory pathway was dominant underthese experimental conditions. In addition, As(III) adsorbedonto the surface of HFO enhanced the rate of microbial Fe(III) reduction. In the sediment and ANA-3 incubations, As(V) was reduced simultaneously or prior to Fe(III),consistent with thermodynamic calculations based on thechemical conditions of the ANA-3 WT incubations.
arrA, a mutant unableto produce the respiratory As(V) reductase. Of the twopathways for microbial As(V) reduction (respiration anddetoxification), the respiratory pathway was dominant underthese experimental conditions. In addition, As(III) adsorbedonto the surface of HFO enhanced the rate of microbial Fe(III) reduction. In the sediment and ANA-3 incubations, As(V) was reduced simultaneously or prior to Fe(III),consistent with thermodynamic calculations based on thechemical conditions of the ANA-3 WT incubations.