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首页> 外文期刊>Environmental Science & Technology >Mobilization of Arsenic During One-Year Incubations of Grey Aquifer Sands from Araihazar, Bangladesh
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Mobilization of Arsenic During One-Year Incubations of Grey Aquifer Sands from Araihazar, Bangladesh

机译：孟加拉国阿拉伊哈扎尔的灰色蓄水层沙土一年孵化过程中的砷动员

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Elevated As concentrations in shallow groundwater pose a major health threat in Bangladesh and similarly affected countries, yet there is little consensus on the mechanism of As release to groundwater or how it might be influenced by human activities. In this study, the rate of As release was measured directly with incubations lasting 11 months, using sediment and groundwater collected simultaneously in Bangladesh and maintained under anaerobic conditions throughout the study. Groundwater and gray sediment were collected as diluted slurries between 5 and 38 m in depth, a range over which ambient groundwater As concentrations increased from 20 to 100 μg L~(-1). Arsenic was released to groundwater in slurries from 5 and 12 m in depth at a relatively constant rate of 21 ± 4 (2 σ) and 23 ± 6 μg As kg~(-1) yr~(-1), respectively. Amendment with a modest level of acetate increased the rate of As release only at 12 m (82 ± 18 μg kg~(-1) yr~(-1)). Although the groundwater As concentration was initially highest at 38 m depth, no release of As was observed. These results indicate that the spatial distribution of dissolved As in Bangladesh and local rates of release to groundwater are not necessarily linked. Iron release during the incubations did not occur concurrently with As release, providing further confirmation that the two processes are not directly coupled. Small periodic additions of oxygen suppressed the release of As from sediments at all three depths, which supports the notion that anoxia is a prerequisite for accumulation of As in Bangladesh groundwater.
机译：在孟加拉国和受类似影响的国家中，浅层地下水中As的浓度升高对健康构成重大威胁，但是，关于As释放到地下水中的机理或人类活动如何影响As的共识很少。在这项研究中，通过持续11个月的温育直接测量了As的释放速率，使用了孟加拉国同时收集并在整个研究期间保持在厌氧条件下的沉积物和地下水。地下水和灰色沉积物被收集为深度在5至38 m之间的稀浆，在该范围内，周围地下水As的浓度从20μgL〜（-1）增加到100μgL〜（-1）。砷分别以21±4（2σ）和23±6μgAs kg〜（-1）yr〜（-1）的相对恒定速率释放到深度分别为5和12 m的泥浆中。适量醋酸盐的修正仅在12 m（82±18μgkg〜（-1）yr〜（-1））时提高了As的释放速率。尽管地下水As的浓度最初在38 m深度处最高，但未观察到As的释放。这些结果表明，孟加拉国溶解性砷的空间分布与当地向地下水的释放速率不一定相关。孵育过程中铁的释放与As的释放没有同时发生，这进一步证实了这两个过程没有直接耦合。定期少量添加氧气抑制了三个深度的沉积物中As的释放，这支持了缺氧是孟加拉国地下水中As积累的先决条件的观点。

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