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

世界上许多地区的地下水，包括英国的部分地区，含有高浓度的砷（As）。砷在低浓度下也是有毒的，不幸的是，地下水是通过饮用或灌溉摄入砷的主要途径，随后被摄入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资源压力增加，从而增加世界各地的灌溉。在过去的几十年中，受As污染的饮用水及其处理受到了广泛的关注，通过处理或自然衰减过程从大量的灌溉水中去除As的研究较少，目前是一个未解决的挑战。本研究的目的是调查组成的被动处理系统中的As去除的基本过程，作为自然衰减过程的案例研究。该处理系统的选择是基于其潜在的低成本和零能量操作，在金属（oid）去除方面仍然非常有效，这减轻了对受体（水或土壤）的暴露。要解决的具体问题包括：哪些生物或非生物过程（或两者）正在消除作为在处理系统？被移除的As是如何绑定的，以及其未来释放的后果是什么（例如，由于地球化学参数的变化，废物管理做法）？我们能在自然环境中，特别是土壤中管理这些过程，以减轻As污染和生物利用度吗？研究结果将有助于应对管理砷污染灌溉水的挑战，以保障粮食安全和公共卫生。

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.