Retention of immobile Se(0) in flow-through aquifer column systems during bioreduction and oxic-remobilization.
Retention of immobile Se(0) in flow-through aquifer column systems during bioreduction and oxic-remobilization.
复制标题
在生物还原和氧化再活化过程中，流通式含水层柱系统中固定 Se(0) 的保留。
DOI：
10.1016/j.scitotenv.2022.155332
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Ho MS
中科院分区：
文献类型：
--
作者：
Ho MS
硒(Se)是一种具有多种人为来源的有毒污染物，包括核裂变产生的79Se。Se在地球圈中的迁移性通常受其氧化状态的控制，因此，了解不同氧化还原条件下Se的形态对于Se污染场地的安全管理具有重要意义。在这里，我们研究了Se在沉积物地下水柱系统中的行为。实验采用与环境有关的硒浓度，使用一系列地下水成分，并在170日的 期间考察了电子供体(即生物刺激)和地下水硫酸盐添加的影响。使用X射线吸收光谱和标准地球化学技术来跟踪沉积物中与Se有关的浓度和形态的变化。添加和不添加硫酸盐的给电子体修饰体系保留了高达90%的添加Se(VI)(AQ)，沉积物中伴生的Se形态以三角Se(0)为主，可能还有微量Se(-II)；没有观察到Se胶体的形成。然后在二次氧化和海水入侵扰动实验中测试了沉积物中伴生的Se物种的再动员潜力。在所有处理中，沉积物伴生的Se(即三角Se(0))在实验的时间尺度(170 天)内很大程度上抵抗再动员。然而，在扰动实验中，较少的Se从硫酸盐沉积物中被再活化，这表明先前的硫酸盐还原条件可能会缓冲Se的再活化和迁移。
Selenium (Se) is a toxic contaminant with multiple anthropogenic sources, including79Se from nuclear fission. Se mobility in the geosphere is generally governed by its oxidation state, therefore understanding Se speciation under variable redox conditions is important for the safe management of Se contaminated sites. Here, we investigate Se behavior in sediment groundwater column systems. Experiments were conducted with environmentally relevant Se concentrations, using a range of groundwater compositions, and the impact of electron-donor (i.e., biostimulation) and groundwater sulfate addition was examined over a period of 170 days. X-Ray Absorption Spectroscopy and standard geochemical techniques were used to track changes in sediment associated Se concentration and speciation. Electron-donor amended systems with and without added sulfate retained up to 90% of added Se(VI)(aq), with sediment associated Se speciation dominated by trigonal Se(0) and possibly trace Se(-II); no Se colloid formation was observed. The remobilization potential of the sediment associated Se species was then tested in reoxidation and seawater intrusion perturbation experiments. In all treatments, sediment associated Se (i.e., trigonal Se(0)) was largely resistant to remobilization over the timescales of the experiments (170 days). However, in the perturbation experiments, less Se was remobilized from sulfidic sediments, suggesting that previous sulfate-reducing conditions may buffer Se against remobilization and migration.