Effect of microbial mediated iron plaque reduction on arsenic mobilityin paddy soil
WANG Xinjun , CHEN Xueping , YANG Jing , WANG Zhaosu , SUN Guoxin
DOI:
Received December 31, 2008,Revised May 09, 2009, Accepted , Available online
Volume 21,2009,Pages 1562-1568
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The potential of microbial mediated iron plaque reduction, and associated arsenic (As) mobility were examined by iron reducing
bacteria enriched from As contaminated paddy soil. To our knowledge, this is the first time to report the impact of microbial iron plaque
reduction on As mobility. Iron reduction occurred during the inoculation of iron reducing enrichment culture in the treatments with
iron plaque and ferrihydrite as the electron acceptors, respectively. The Fe(II) concentration with the treatment of anthraquinone-2,
6-disulfonic acid (AQDS) and iron reducing bacteria increased much faster than the control. Arsenic released from iron plaque with
the iron reduction, and a significant correlation between Fe(II) and total As in culture was observed. However, compared with control,
the increasing rate of As was inhibited by iron reducing bacteria especially in the presence of AQDS. In addition, the concentrations
of As(III) and As(V) in abiotic treatments were higher than those in the biotic treatments at day 30. These results indicated that
both microbial and chemical reductions of iron plaque caused As release from iron plaque to aqueous phase, however, microbial iron
reduction induced the formation of more crystalline iron minerals, leading to As sequestration. In addition, the presence of AQDS
in solution can accelerate the iron reduction, the As release from iron plaque and subsequently the As retention in the crystalline iron
mineral. Thus, our results suggested that it is possible to remediate As contaminated soils by utilizing iron reducing bacteria and AQDS.
