首页> 外文期刊>Applied Geochemistry: Journal of the International Association of Geochemistry and Cosmochemistry >Hydrogeochemistry of arsenic and other inorganic constituents in groundwaters from La Pampa, Argentina
【24h】

Hydrogeochemistry of arsenic and other inorganic constituents in groundwaters from La Pampa, Argentina

机译:阿根廷拉潘帕市地下水中砷和其他无机成分的水文地球化学

获取原文
获取原文并翻译 | 示例
获取外文期刊封面目录资料

摘要

Groundwaters from Quaternary loess aquifers in northern La Pampa Province of central Argentina have significant quality problems due to high concentrations of potentially harmful elements such as As, F, NO3-N, B, Me, Se and U and high salinity. The extent of the problems is not well-defined, but is believed to cover large parts of the Argentine Chaco-Pampean Plain,. over an area of perhaps 10(6) km'-. Groundwaters from La Pampa have a very large range of chemical compositions and spatial variability is considerable over distances of a few km. Dissolved As spans over 4 orders of magnitude (<4-5300 mug l(-1)) and concentrations of F have a range of 0.03-29 mg l(-1), B of 0.5-14 mg l(-1), V of 0.02-5.4 mg l(-1), NO3-N of <0.2-140 mg l(-1), Mo of 2.7-990 mug l(-1) and U of 6.2-250 mug l(-1). Of the groundwaters investigated, 95% exceed 10 mug As l(-1) (the WHO guideline value) and 73% exceed 50 mug As l(-1) (the Argentine national standard). In addition, 83% exceed the WHO guideline value for F (1.5 mg l(-1)), 99% for B (0.5 mg l(-1)), 47% for NO3-N (11.3 mg l(-1)), 39% for Mo (70 mug l(-1)), 32% for Se (10 mug l(-1)) and 100,% for U (2 mug l(-1)). Total dissolved solids range between 730 and 11400 mg l(-1), the high values resulting mainly from evaporation under ambient semi-arid climatic conditions. The groundwaters are universally oxidising with high dissolved-O-2 concentrations. Groundwater pHs are neutral to alkaline (7.0-8.7). Arsenic is present in solution predominantly as As(V). Groundwater As correlates positively with pH, alkalinity (HCO3), F and V. Weaker correlations are also observed with B, Mo, U and Be. Desorption of these elements from metal oxides, especially Fe and Mn oxides tinder the high-pH conditions is considered an important control on their mobilisation. Mutual competition between these elements for sorption sites on oxide minerals may also have enhanced their mobility. Weathering of primary silicate minerals and accessory minerals such as apatite in the loess and incorporated volcanic ash may also have contributed a proportion of the dissolved As and other trace elements. Concentrations of As and other anions and oxyanions appear to be particularly high in groundwaters close to low-lying depressions which act as localised groundwater-discharge zones. Concentrations up to 7500 mug l(-1) were found in saturated-zone porewaters extracted from a cored borehole adjacent to one such depression. Concentrations are also relatively high where groundwater is abstracted from close to the water table, presumably because this zone is a location of more active weathering reactions. The development of groundwaters with high pH and alkalinity results from silicate and carbonate reactions, facilitated by the arid climatic conditions. These factors, together with the young age of the loess sediments and slow groundwater flow have enabled the accumulation of the high concentrations of As and other elements in solution without significant opportunity for flushing of the aquifer to enable their removal. (C) 2002 NERC. Published by Elsevier Science Ltd. All rights reserved. [References: 58]
机译:阿根廷中部拉潘帕省北部的第四纪黄土含水层的地下水存在严重的质量问题,这是由于高浓度的潜在有害元素(例如,As,F,NO3-N,B,Me,Se和U)和高盐度。问题的程度尚不确定,但据信涵盖了阿根廷查科-潘潘平原的大部分地区。在大约10(6)km'-的区域上。拉潘帕(La Pampa)的地下水具有非常广泛的化学成分,并且在几公里的距离内空间变异性很大。溶解的As跨度超过4个数量级(<4-5300杯l(-1)),F的浓度范围为0.03-29 mg l(-1),B的范围为0.5-14 mg l(-1), V为0.02-5.4 mg l(-1),NO3-N <0.2-140 mg l(-1),Mo为2.7-990杯l(-1)和U为6.2-250杯l(-1) 。在所调查的地下水中,超过10杯As 1(-1)(世卫组织准则值)的95%和超过50杯As 1(-1)(阿根廷国家标准)的73%。此外,F(1.5 mg l(-1))超过WHO准则值的83%,B(0.5 mg l(-1))超过99%的NO3-N(11.3 mg l(-1)的47%) ),Mo(70杯l(-1))39%,Se(10杯l(-1))32%,U(2杯l(-1))100%。总溶解固体量介于730和11400 mg l(-1)之间,高值主要来自环境半干旱气候条件下的蒸发。地下水普遍以高溶解O-2浓度氧化。地下水的pH是中性到碱性(7.0-8.7)。砷主要以As(V)的形式存在于溶液中。地下水As与pH,碱度(HCO3),F和V正相关。B,Mo,U和Be也观察到较弱的相关性。这些元素从金属氧化物(尤其是铁和锰氧化物)中解吸,从而制约了高pH条件,被认为是对其迁移的重要控制。这些元素之间在氧化物矿物上的吸附位点之间的相互竞争也可能增强了它们的流动性。黄土中初级硅酸盐矿物和辅助矿物(如磷灰石)和掺入的火山灰的风化也可能贡献了一部分溶解的砷和其他微量元素。在靠近低洼洼地的地下水中,As和其他阴离子和氧阴离子的浓度似乎特别高,这些低洼洼地起着局部地下水排放区的作用。从邻近一个凹陷处的有芯钻孔中提取的饱和区孔隙水中的浓度高达7500马克l(-1)。从地下水位附近抽取地下水的浓度也相对较高,大概是因为该区域是风化反应较活跃的位置。干旱气候条件促进了硅酸盐和碳酸盐反应的产生,从而形成了具有高pH和碱度的地下水。这些因素以及黄土沉积物的年轻年龄和缓慢的地下水流使溶液中高浓度的砷和其他元素得以积累,而没有大量机会冲洗含水层以将其除去。 (C)2002 NERC。由Elsevier Science Ltd.出版。保留所有权利。 [参考:58]

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号