KTH - International Groundwater Arsenic Research Group, Division of Land and Water Resources Engineering, Department of Sustainable Development, Environmental Sciences and Engineering, Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44 Stockholm, Sweden; Laboratorio de Hidroquímica, Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, 303, La Paz, Bolivia.
J Hazard Mater. 2013 Nov 15;262:924-40. doi: 10.1016/j.jhazmat.2013.06.078. Epub 2013 Jul 24.
Environmental settings in the southern area of Lake Poopó in the Bolivian highlands, the Altiplano, have generated elevated amounts of arsenic (As) in the water. The area is characterised by a semiarid climate, slow hydrological flow and geologic formations of predominantly volcanic origin. The present study aimed at mapping the extent of the water contamination in the area and to investigate the geogenic sources and processes involved in the release of As to the groundwater. Ground- and surface-water samples were collected from 24 different sites, including drinking water wells and rivers, in the southern Poopó basin in two different field campaigns during the dry and rainy seasons. The results revealed variable levels of As in shallow drinking water wells and average concentration exceeding the WHO guidelines value. Arsenic concentrations range from below 5.2 μg/L (the detection level) to 207 μg/L and averages 72 μg/L. Additionally, high boron (B) concentrations (average 1902 μg/L), and high salinity are further serious concerns for deteriorating the groundwater quality and rendering it unsuitable for drinking. Groundwater is predominantly of the Na-Cl-HCO3 type or the Ca-Na-HCO3 type with neutral or slightly alkaline pH and oxidising character. While farmers are seriously concerned about the water scarcity, and on a few occasions about salinity, there are no concerns about As and B present at levels exceeding the WHO guidelines, and causing negative long term effects on human health. Sediment samples from two soil profiles and a river bed along with fourteen rock samples were also collected and analysed. Sequential extractions of the sediments together with the calculation of the mineral saturation indices indicate that iron oxides and hydroxides are the important secondary minerals phases which are important adsorbents for As. High pH values, and the competition of As with HCO3 and dissolved silica for the adsorption sites probably seems to be an important process for the mobilisation of As in the shallow groundwaters of the region. Continuous monitoring and expansion of monitoring systems are necessary prerequisites for better understanding of the pattern of As mobilisation in the Southern Poopó Basin.
玻利维亚高原普普湖南部地区的环境导致水中砷（As）含量升高。该地区气候半干旱，水文流量缓慢，地质构造主要为火山成因。本研究旨在绘制该地区水污染范围图，并研究参与地下水释放 As 的地球成因来源和过程。在两次不同的实地考察中，在旱季和雨季，从普普湖南部盆地的 24 个不同地点收集了地下水和地表水样本，包括饮用水井和河流。结果表明，浅层饮用水井中砷含量不同，平均浓度超过世界卫生组织（WHO）指导值。砷浓度范围从低于 5.2μg/L（检测限）到 207μg/L，平均为 72μg/L。此外，高硼（B）浓度（平均 1902μg/L）和高盐度也是地下水质量恶化和不适宜饮用的严重问题。地下水主要为 Na-Cl-HCO3 型或 Ca-Na-HCO3 型，pH 值为中性或略呈碱性，具有氧化性。尽管农民严重关注水资源短缺问题，并且偶尔关注盐度问题，但他们并不担心 As 和 B 的含量超过世卫组织指导值，这会对人类健康造成长期负面影响。还从两个土壤剖面和河床以及 14 个岩石样本中采集并分析了沉积物样本。对沉积物进行连续提取并计算矿物饱和度指数表明，铁氧化物和氢氧化物是重要的次生矿物相，是 As 的重要吸附剂。高 pH 值以及 As 与 HCO3 和溶解硅酸钠在吸附位点的竞争，可能是该地区浅层地下水中 As 迁移的重要过程。连续监测和监测系统的扩展是更好地了解普普湖南部盆地 As 迁移模式的必要前提。
