Parrone Daniele, Ghergo Stefano, Preziosi Elisabetta, Casentini Barbara
Water Research Institute-National Research Council, IRSA-CNR, Via Salaria km 29.300, PB 10, 00015 Rome, Italy.
Toxics. 2022 May 27;10(6):288. doi: 10.3390/toxics10060288.
Arsenic is a potentially toxic element (PTE) that is widely present in groundwater, with concentrations often exceeding the WHO drinking water guideline value (10.0 μg/L), entailing a prominent risk to human health due to long-term exposure. We investigated its origin in groundwater in a study area located north of Rome (Italy) in a volcanic-sedimentary aquifer. Some possible mineralogical sources and main mechanisms governing As mobilization from a representative volcanic tuff have been investigated via laboratory experiments, such as selective sequential extraction and dissolution tests mimicking different release conditions. Arsenic in groundwater ranges from 0.2 to 50.6 μg/L. It does not exhibit a defined spatial distribution, and it shows positive correlations with other PTEs typical of a volcanic environment, such as F, U, and V. Various potential As-bearing phases, such as zeolites, iron oxyhydroxides, calcite, and pyrite are present in the tuff samples. Arsenic in the rocks shows concentrations in the range of 17-41 mg/kg and is mostly associated with a minor fraction of the rock constituted by FeOOH, in particular, low crystalline, containing up to 70% of total As. Secondary fractions include specifically adsorbed As, As-coprecipitated or bound to calcite and linked to sulfides. Results show that As in groundwater mainly originates from water-rock interaction processes. The release of As into groundwater most likely occurs through desorption phenomena in the presence of specific exchangers and, although locally, via the reductive dissolution of Fe oxy-hydroxides.
砷是一种潜在有毒元素（PTE），广泛存在于地下水中，其浓度常常超过世界卫生组织饮用水指导值（10.0μg/L），长期接触会对人体健康造成显著风险。我们在意大利罗马以北一个火山沉积含水层的研究区域调查了地下水中砷的来源。通过实验室实验，如选择性连续萃取和模拟不同释放条件的溶解试验，研究了一些可能的矿物学来源以及控制砷从代表性火山凝灰岩中迁移的主要机制。地下水中的砷含量在0.2至50.6μg/L之间。它没有呈现出明确的空间分布，并且与火山环境中典型的其他潜在有毒元素，如氟、铀和钒呈正相关。凝灰岩样品中存在各种潜在的含砷相，如沸石、铁的氢氧化物、方解石和黄铁矿。岩石中的砷含量在17 - 41mg/kg范围内，主要与由FeOOH构成的岩石的一小部分相关，特别是低结晶的FeOOH，其含有的砷占总砷的70%。次要部分包括特异性吸附的砷、共沉淀或与方解石结合以及与硫化物相关的砷。结果表明，地下水中的砷主要源自水 - 岩相互作用过程。砷释放到地下水中最有可能是通过在特定交换剂存在下的解吸现象发生的，并且尽管是局部的，但也通过铁的氢氧化物的还原溶解发生。
