As release under the microbial sulfate reduction during redox oscillations in the upper Mekong delta aquifers, Vietnam: A mechanistic study

被引:19
|
作者
Phan, Van T. H. [1 ,2 ]
Bernier-Latmani, Rizlan [3 ]
Tisserand, Delphine [1 ]
Bardelli, Fabrizio [4 ]
Le Pape, Pierre [5 ]
Frutschi, Manon [3 ]
Gehin, Antoine [1 ]
Couture, Raoul-Marie [6 ]
Charlet, Laurent [1 ]
机构
[1] Univ Grenoble Alps, CNRS, IRD, IFSTTAR,Inst Sci Terre ISTerre, F-38000 Grenoble, France
[2] Vietnam Natl Univ Ho Chi Minh City VNU HCM, Ho Chi Minh City Univ Technol HCMUT, 268 Ly Thuong Kiet,Dist 10, Ho Chi Minh City, Vietnam
[3] Ecole Polytech Fed Lausanne, EML, EPFL ENAC IIE EML, Stn 6, CH-1015 Lausanne, Switzerland
[4] CNR Nanotec, Inst Nanotechnol, I-00186 Rome, Italy
[5] IMPMC, UMR CNRS UPMC IRD MNHN 7590, 4 Pl Jussieu, F-75252 Paris 05, France
[6] Univ Laval, Dept Chim, 1045 Ave Med, Quebec City, PQ G1V 0A6, Canada
关键词
Redox oscillations; Arsenic release; Microbial sulfate reduction; Elemental sulfur; ARSENIC MOBILITY; OXIDIZING BACTERIA; FRESH-WATER; ORGANIC-MATTER; RIVER DELTA; SP-NOV; GEOBACTER-SULFURREDUCENS; GROUNDWATER EXTRACTION; COMMUNITY STRUCTURE; REDUCING BACTERIA;
D O I
10.1016/j.scitotenv.2019.01.219
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
The impact of seasonal fluctuations linked to monsoon and irrigation generates redox oscillations in the subsurface, influencing the release of arsenic (As) in aquifers. Here, the biogeochemical control on As mobility was investigated in batch experiments using redox cycling bioreactors and As- and SO42--amended sediment. Redox potential (E-h) oscillations between anoxic (-300-0 mV) and oxic condition (0-500 mV) were implemented by automatically modulating an admixture of N-2/CO2 or compressed air. A carbon source (cellobiose, a monomer of cellulose) was added at the beginning of each reducing cycle to stimulate the metabolism of the native microbial community. Results show that successive redox cycles can decrease arsenic mobility by up to 92% during reducing conditions. Anoxic conditions drive mainly the conversion of soluble As(V) to As(III) in contrast to oxic conditions. Phylogenetic analyses of 16S rRNA amplified from the sediments revealed the presence of sulfate and iron - reducing bacteria, confirming that sulfate and iron reduction are key factors for As immobilization from the aqueous phase. As and S K-edge X-ray absorption spectroscopy suggested the association of Fe-(oxyhydr)oxides and the importance of pyrite (FeS2(s)), rather than poorly ordered mackinawite (FeS(s)), for As sequestration under oxidizing and reducing conditions, respectively. Finally, these findings suggest a role for elemental sulfur in mediating aqueous thioarsenates formation in As-contaminated groundwater of the Mekong delta. (C) 2019 Elsevier B.V. All rights reserved.
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页码:718 / 730
页数:13
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