Geochemical assessment of arsenic contamination in well water and sediments from several communities in the Nawalparasi District of Nepal
Geochemical assessment of arsenic contamination in well water and sediments from several communities in the Nawalparasi District of Nepal
复制标题
对尼泊尔纳瓦尔帕拉西地区几个社区井水和沉积物中砷污染的地球化学评估
DOI：
10.1007/s12665-014-3231-8
复制
发表时间：
2014
影响因子：
2.8
通讯作者：
Masakazu Tani
中科院分区：
文献类型：
--
作者：
Akiko Nakano;Kiyoshi Kurosawa;Uddin Md. Shamim;Masakazu Tani
井水砷污染是尼泊尔特莱地区Nawalparasi县的一个严重问题。2011年12月，对该地区24个社区的137口威尔斯进行了当地调查。调查结果表明，威尔斯管井中砷的平均浓度为350 μg/L，近98%的威尔斯管井超过了世界卫生组织规定的10 μg/L的砷限量标准。在18-22 m和50-80 m深度范围内发现了砷含量超过400 μg/L的高污染井水。在位于北纬27.517°和27.543°之间、东经83.648°和83.748°之间的Patkhauli、Mahuawa、Thulokunwar和Goini较浅的威尔斯井中检测到超过500微克/升的高砷水平。在Kashiya、Goini、Sanokunwar、Thulokunwar和Mahuawa五个社区进行的钻孔取样显示，每个社区有两个含水层，分别位于14-22米和41-50米左右的两个深度。在各群落高砷含水层附近18-21 m深度分布着深灰色或黑色的富含有机质的泥炭质粘土层。五个群落沉积物中铁和砷之间均呈正相关。可以推断，这些结果是由于溶解铁羟基氧化物分子与砷从固相。微生物代谢具有很大的潜力，诱导溶解和释放砷附着在固相进入水相取决于氧化还原电位和pH值的水平。
Arsenic contamination of well water is a serious issue in the Nawalparasi District of the Terai region in Nepal. A local investigation was carried out on 137 tube wells in 24 communities of the district in December 2011. The investigation revealed that the average arsenic concentration in the tube wells was 350 μg/L, and that nearly 98 % of the wells exceeded the WHO guideline arsenic level limit of 10 μg/L. Highly contaminated well water, with more than 400 μg/L of arsenic, was found within the limited depth ranges of 18–22 and 50–80 m. High arsenic levels exceeding 500 μg/L were detected in shallower wells at Patkhauli, Mahuawa, Thulokunwar, and Goini located between 27.517° and 27.543°N and between 83.648° and 83.748°E. Boring sampling at five communities of Kashiya, Goini, Sanokunwar, Thulokunwar, and Mahuawa revealed two aquifers located at the two depths around 14–22 and 41–50 m in each community. Dark gray or black-colored peaty clay layers rich in organic matter were distributed at depths of 18–21 m beside the upper aquifers with high arsenic concentration in each community. Positive correlations were shown between iron and arsenic in the sediments from the five communities. It can be inferred that these results were caused by dissolution of iron-oxyhydroxide molecules with arsenic from solid phases. Microbial metabolisms have a great potential to induce the dissolution and release arsenic attached on the solid phases into aqueous phases depending on the level of redox potential and pH.