Microbes Enhance Mobility of Arsenic in Pleistocene Aquifer Sand from Bangladesh

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• 作者：Ratan K. Dhar ; Yan Zheng ; Chad W. Saltikov ; Kathleen A. Radloff ; Brian J. Mailloux ; Kazi. M. Ahmed ; Alexander van Geen
• 刊名：Environmental Science & Technology
• 出版年：2011
• 出版时间：April 1, 2011
• 年：2011
• 卷：45
• 期：7
• 页码：2648-2654
• 全文大小：791K
• 年卷期：v.45,no.7(April 1, 2011)
• ISSN：1520-5851

文摘

Dissimilatory metal-reducing bacteria can mobilize As, but few studies have studied such processes in deeper orange-colored Pleistocene sands containing 1鈭? mg kg^鈭? As that are associated with low-As groundwater in Bangladesh. To address this gap, anaerobic incubations were conducted in replicate over 90 days using natural orange sands initially containing 0.14 mg kg^鈭? of 1 M phosphate-extractable As (24 h), >99% as As(V), and 0.8 g kg^鈭? of 1.2 M HCl-leachable Fe (1 h at 80 掳C), 95% as Fe(III). The sediment was resuspended in artificial groundwater, with or without lactate as a labile carbon source, and inoculated with metal-reducing Shewanella sp. ANA-3. Within 23 days, dissolved As concentrations increased to 17 渭g L^鈭? with lactate, 97% as As(III), and 2 渭g L^鈭? without lactate. Phosphate-extractable As concentrations increased 4-fold to 0.6 mg kg^鈭? in the same incubations, even without the addition of lactate. Dissolved As levels in controls without Shewanella, both with and without lactate, instead remained <1 渭g L^鈭?. These observations indicate that metal-reducers such as Shewanella can trigger As release to groundwater by converting sedimentary As to a more mobilizable form without the addition of high levels of labile carbon. Such interactions need to be better understood to determine the vulnerability of low-As aquifers from which drinking water is increasingly drawn in Bangladesh.