Abstract Arsenic (As) contamination of drinking water is a worldwide problem. The natural origin of As, its mobility, and transport are of boundless interest in Bolivian Altiplano due to its presence in mineral deposits, brines, hot springs, and volcanic rocks. In this study, a geochemical spatial-temporal approach was used to understand the sources and factors that regulate the mobilization and fate of As in water bodies as well as sediments of Lower Katari Basin (LKB). The results reveal that high levels of As (288 µg/L), boron (B) (2473 µg/L), manganese (Mn) (7259 µg/L), and high salinity (23850 µS/cm) are present in shallow drinking water wells, which exceed the guideline values of the Bolivian regulation (NB-512) and WHO. The seasonal variation (mean monthly rainfall in the dry and rainy period: 6 – 89 mm) and its impact on water quantity (0.9 - 5.1 m3/s), in addition to the load of solids and liquids of residual origin (Pallina River), represent a risk of negative health impact for the communities at the banks of the Katari River. The hydrogeological study indicates that the groundwater flow was observed from southeast to northwest (SE - NW), which are indicated the interaction between groundwater and surface water in this region. The spatial distribution of As varies considerably due to geological characteristics of the area as well as due to the heterogeneously distributed evaporites in the sediments (alluvial, fluvial-lacustrine); however, the highest concentrations of As are observed in the alluvial sediments of the northern region. Sequential extraction (BCR) of sediment along with geochemical modeling (mineral saturation indices) indicates that the iron (Fe) and aluminum (Al) oxides as well as their hydroxides are the most important adsorbent minerals of As in the central and southern region of LKB. The hydrochemistry of water bodies in LKB is strongly influenced by the interaction with the sediment constituents and by the spatial-temporal variations. Therefore, the determination of the distribution of As among the different geochemical fractions was useful to find the relative proportions of As transported by different chemical mechanisms (adsorption/dissolution) and their spatial-temporal variation.

中文翻译：

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玻利维亚高原下卡塔里盆地水文地质系统中天然砷迁移的地球化学机制

摘要 饮用水中的砷 (As) 污染是一个世界性问题。由于存在于矿藏、盐水、温泉和火山岩中，As 的天然来源、其流动性和运输在玻利维亚高原具有无限的兴趣。在这项研究中，使用地球化学时空方法来了解调节 As 在水体以及下卡塔里盆地 (LKB) 沉积物中迁移和归宿的来源和因素。结果表明，浅层中存在高水平的 As (288 µg/L)、硼 (B) (2473 µg/L)、锰 (Mn) (7259 µg/L) 和高盐度 (23850 µS/cm)。饮用水井，超过玻利维亚法规 (NB-512) 和 WHO 的准则值。季节变化（旱雨期月平均降雨量：6 – 89 mm）及其对水量的影响（0. 9 - 5.1 m3/s)，加上残余来源的固体和液体（帕利纳河）的负载，对 Katari 河岸边的社区构成负面健康影响的风险。水文地质研究表明，从东南向西北（SE-NW）观察到地下水流，这表明该地区地下水与地表水之间存在相互作用。由于该地区的地质特征以及沉积物中不均匀分布的蒸发岩（冲积、河流-湖泊），As 的空间分布变化很大；然而，在北部地区的冲积沉积物中观察到最高浓度的砷。沉积物的序贯提取 (BCR) 以及地球化学模型（矿物饱和指数）表明，铁 (Fe) 和铝 (Al) 氧化物及其氢氧化物是 LKB 中部和南部地区最重要的 As 吸附矿物. LKB 水体的水化学受与沉积物成分的相互作用和时空变化的强烈影响。因此，确定不同地球化学组分中 As 的分布有助于确定不同化学机制（吸附/溶解）传输的 As 的相对比例及其时空变化。LKB 水体的水化学受与沉积物成分的相互作用和时空变化的强烈影响。因此，确定不同地球化学组分中 As 的分布有助于确定不同化学机制（吸附/溶解）传输的 As 的相对比例及其时空变化。LKB 水体的水化学受与沉积物成分的相互作用和时空变化的强烈影响。因此，确定不同地球化学组分中 As 的分布有助于确定不同化学机制（吸附/溶解）传输的 As 的相对比例及其时空变化。