UFF, Department of Environmental Geochemistry, Fluminense Federal University, Outeiro São João Baptista, s/n. Centro, Niterói, Rio de Janeiro, Brazil.
UFRJ, Department of Geography, Federal University of Rio de Janeiro, Av. Athos da Silveira Ramos, 274 - Cidade Universitária, Rio de Janeiro, Rio de Janeiro, Brazil.
Environ Sci Pollut Res Int. 2018 Mar;25(9):9085-9100. doi: 10.1007/s11356-018-1215-z. Epub 2018 Jan 16.
Arsenic (As) is a dangerous and carcinogenic element and drinking water is its main pathway of human exposure. Gold mines are widely recognized as important sources of As pollution. This work proposes the assessment of As distribution along watersheds surrounding "Morro do Ouro" gold mine (Paracatu, southeastern Brazil). A balance approach between filtered As fluxes (As < 0.45 μm) and suspended particulate material (AsSPM) in different river segments was applied. Ultrafiltration procedure was used to categorize As into the following classes: particulate > 0.1 μm, colloidal < 0.1 μm to > 10 kDa, dissolved < 10 kDa to > 1 kDa, and truly dissolved < 1 kDa. By applying this approach, arsenic contributions from mining facilities were quantified in order to identify critical fluvial segments and support decision makers in actions of remediation. The mass balance indicated the occurrence of a decreasing gradient from upstream to downstream: (i) of the As concentrations higher than the limit established by Brazilian law (10 μg L); (ii) of the ratio between specific fluxes (g As km day) and those determined using an uncontaminated watershed (a proxy for estimating the anthropic contribution), from 103 to 101; (iii) of the specific fluxes As < 0.45 μm and AsSPM from 102 to 100; and (iv) of the negative balance output minus input for each river segment that suggests As accumulation in sediments along the rivers in both urban and rural areas, mainly due to SPM sedimentation and sorption by Fe oxyhydroxides. Ultrafiltration shattering showed concentrations of decreasing As with particle size; the SPM load (> 0.1 μm) was almost one order higher to dissolved load (< 1 kDa).
砷（As）是一种危险且致癌的元素，饮用水是其暴露于人体的主要途径。金矿被广泛认为是砷污染的重要来源。本研究旨在评估“莫罗多奥罗”金矿（巴西东南部帕拉卡图）周围流域中砷的分布情况。采用过滤砷通量（As<0.45μm）与不同河流段悬浮颗粒物（AsSPM）之间的平衡方法进行评估。采用超滤法将砷分为以下几类：颗粒>0.1μm、胶体<0.1μm至>10kDa、溶解<10kDa至>1kDa、真溶解<1kDa。通过应用该方法，可以量化采矿设施对砷的贡献，以确定关键的河流段，并为决策者提供修复行动的支持。质量平衡表明，从上游到下游存在浓度逐渐降低的趋势：（i）超过巴西法律规定的 10μg/L 浓度限制的砷含量；（ii）特定通量（g As·km·day）与使用未受污染流域确定的通量之比（作为估算人为贡献的替代物），从 103 降至 101；（iii）特定通量 As<0.45μm 和 AsSPM 从 102 降至 100；（iv）每个河流段的输出减去输入的负平衡，表明砷在城市和农村地区的河流沉积物中积累，主要是由于 SPM 沉降和 Fe 氢氧化物的吸附。超滤破碎显示，随着粒径的减小，砷浓度降低；SPM 负荷（>0.1μm）几乎比溶解负荷（<1kDa）高一个数量级。
