Chongqing Key Laboratory of Soil Multi-Scale Interfacial Process, Department of Soil Science, College of Resources and Environment, Southwest University, Chongqing 400715, PR China; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China.
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China.
Water Res. 2021 Oct 15;205:117657. doi: 10.1016/j.watres.2021.117657. Epub 2021 Sep 11.
The arsenic (As)-bearing eutrophic waters may suffer from the dual conditions of harmful algal blooms and release of As, driven by algal-induced hypoxia/anoxia. Here, we investigate the use of interfacial oxygen (O) nanobubble technology to combat the hypoxia and control As exposure in simulated mesocosm experiments. It was observed that remediation of algal-induced hypoxia at the sediment-water interfaces (SWI) by application of O nanobubbles reduced the level of dissolved As from 23.2 μg L to <10 μg L and stimulated the conversion of As(III) to the less toxic As(V) (65-75%) and methylated As (10-15%) species. More than half of the oxidation and all the methylation of As(III) resulted from the manipulation by O nanobubbles of microbes responsible for As(III) oxidation and methylation. Hydroxyl radicals were generated during the oxidation of reductive substances at the SWI in darkness, and should be dominant contributors to As(III) abiotic oxidation. X-ray absorption near-edge structure (XANES) spectroscopic analysis demonstrated that surface sediments changed from being sources to acting as sinks of As, due to the formation of Fe-(hydr)oxide. Overall, this study suggests that interfacial O nanobubble technology could be a potential method for remediation of sediment As pollution through the manipulation of O-related microbial and geochemical reactions.
含砷（As）的富营养化水可能会受到藻类诱导的缺氧/缺氧的驱动，同时遭受有害藻类大量繁殖和砷释放的双重影响。在这里，我们研究了利用界面氧（O）纳米气泡技术来对抗缺氧并控制模拟中观实验中砷的暴露。结果表明，通过应用 O 纳米气泡修复沉积物-水界面（SWI）中的藻类诱导缺氧，将溶解态砷的水平从 23.2μg/L 降低到 <10μg/L，并刺激了 As(III)向毒性较低的 As(V)（65-75%）和甲基化 As（10-15%）的转化。O 纳米气泡对负责 As(III)氧化和甲基化的微生物的操纵，导致超过一半的 As(III)氧化和所有的 As(III)甲基化。在黑暗中，SWI 处还原性物质的氧化过程中会产生羟基自由基，应该是 As(III)非生物氧化的主要贡献者。X 射线吸收近边结构（XANES）光谱分析表明，由于 Fe-（水合）氧化物的形成，表层沉积物的作用从砷源转变为砷汇。总的来说，这项研究表明，通过操纵与 O 相关的微生物和地球化学反应，界面 O 纳米气泡技术可能是一种修复沉积物砷污染的潜在方法。
