Experimental constraints on redox-induced arsenic release and retention from aquifer sediments in the central Yangtze River Basin
Experimental constraints on redox-induced arsenic release and retention from aquifer sediments in the central Yangtze River Basin
复制标题
长江流域中部含水层沉积物氧化还原诱导砷释放和滞留的实验约束
DOI：
10.1016/j.scitotenv.2018.08.205
复制
发表时间：
2019-02-01
影响因子：
9.8
通讯作者：
Fendorf, Scott
中科院分区：
文献类型：
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作者：
Duan, Yanhua;Schaefer, Michael, V;Fendorf, Scott
我国近2000万人饮用受砷污染的地下水，影响着他们的健康。与南亚和东南亚三角洲内的观测优势不同，中国长江流域中部地下水As浓度季节性变化高达一个数量级。为了破译沉积物和地下水之间的季节性释放和保留的原因，我们进行了批量沉积物培养在不同的（强加的）氧化还原条件下。在N-2和O-2气体吹扫下进行孵育，以模拟田间观察到的条件。在所有情况下，缺氧条件下，导致作为释放到溶液中，而作为从好氧条件下的溶液中除去。这些实验证实，缺氧是一个先决条件，砷活化到地下水从长江流域沉积物。交替氧化还原条件导致铁矿物溶解、转化、结晶和沉淀，以及随后的As释放和保留在系统中。更重要的是，在深度>15米的含水层沉积物中释放的As通过多个氧化还原循环没有外源电子供体（碳源），沉积物中的有机质是足够的反应性，以支持微生物还原As（V）和F（III）。这些结果提供了直接的证据，以前所描述的机制解释所观察到的季节性变化的地下水As浓度在长江流域中部，在地表和地下水位的季节性变化驱动的氧化还原条件的变化，从而作为浓度。(C)2018爱思唯尔B. V.保留所有权利。
The consumption of arsenic (As) contaminated groundwater affects the health of almost 20 million people in China. Unlike the preponderance of observations within the deltas of South and Southeast Asia, groundwater As concentrations in the central Yangtze River Basin, China, vary by up to an order of magnitude seasonally. In order to decipher the cause of seasonal release and retention of As between sediments and groundwater, we conducted batch sediment incubations under varying (imposed) redox conditions. Incubations were conducted under both N-2 and O-2 gas purges to simulate conditions observed within the field. In all cases, anoxic conditions resulted in As release to solution while As was removed from solution under oxic conditions. These experiments confirm that anoxia is a prerequisite for As mobilization into groundwater from Yangtze River Basin sediments. Alternating redox conditions resulted in Fe minerals dissolution, transformation, crystallization, and precipitation, and subsequent As release and retention in the system. More importantly, aquifer sediments at depths >15 m release As through multiple redox cycles without an exogenous electron donor (carbon source), organic matter in the sediments is sufficiently reactive to support microbial reduction of As(V) and F(III). These results provide direct evidence for previously described mechanisms explaining the observed seasonal variation of groundwater As concentrations in the central Yangtze River Basin, where seasonal changes in surface and groundwater levels drive changes in redox conditions and thus As concentrations. (C) 2018 Elsevier B.V. All rights reserved.