Understanding Arsenic removal processes: passive treatment systems as proxies for natural environments

世界许多地区的地下水，包括英国的部分地区，都含有高浓度的砷。砷在低浓度时也是有毒的，不幸的是，地下水是通过饮用或灌溉吸收砷的主要途径，然后吸收到以植物为基础的食物，如大米(土壤-植物-人类途径)。这种情况在未来几年可能会恶化，因为气候变化可能会导致水压力增加，从而增加世界各地的灌溉。与受砷污染的饮用水及其处理在过去几十年中受到的关注不同，通过处理或自然衰减过程从大量灌溉水中去除砷的研究较少，目前是一个尚未解决的挑战。这项研究的目的是研究复合被动处理系统中砷去除的基本过程，作为自然衰减过程的案例研究。选择这种处理系统是基于它潜在的低成本和运行在零能量下，在减少接触受体(水或土壤)的金属(类)去除方面仍然非常有效。要解决的具体问题包括：在处理系统中，哪些生物或非生物过程(或两者)正在去除？这些物质是如何被清除的，其未来释放的后果是什么(例如，由于生物地球化学参数的变化、废物管理做法)？我们能否在自然环境中管理这些过程，特别是土壤，以减少污染和生物利用度？这项研究的结果将有助于应对为粮食安全和公共卫生管理受砷污染的灌溉用水的挑战。

Groundwater in many regions of the world, including parts of the UK, contains high Arsenic (As) concentrations. Arsenic is toxic also at low concentrations and, unfortunately, groundwater is a major route for intake of As either via drinking or via irrigation and subsequent uptake into plant-based foodstuff such as rice (soil-plant-human pathway). This situation may worsen in coming years as climate change may lead to increasing water stress and thus increasing irrigation around the world. In contrast to the attention that As-contaminated drinking water and its treatment have received over the past decades, removing As from large quantities of irrigation water via treatment or natural attenuation processes has been less extensively studied and is a currently unsolved challenge. The aim of this study is to investigate the fundamental processes of As removal in composed passive treatment systems, as case studies for natural attenuation processes. The choice of this treatment system is based that it is potentially low-cost and operating on zero-energy, still very efficient in metal(oid) removal which mitigates exposure to receptor (water or soil). Specific questions to be addressed include: Which biotic or abiotic processes (or both) are removing As in the treatment systems? How is the removed As bound and what are the consequences for its future release (e.g., due to changes in biogeochemical parameters, waste management practices)? Can we manage these processes in natural environments, particularly soils, to attenuate As contamination and bioavailability? The outcome of the study will help in addressing the challenge of managing arsenic-contaminated irrigation water for food security and public health.