Palaeo-hydrogeological control on groundwater As levels in Red River delta, Vietnam
Palaeo-hydrogeological control on groundwater As levels in Red River delta, Vietnam
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DOI：
10.1016/j.apgeochem.2008.06.015
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发表时间：
2008-11-01
影响因子：
3.4
通讯作者：
Jakobsen, Rasmus
中科院分区：
文献类型：
--
作者：
Jessen, Soren;Larsen, Flemming;Jakobsen, Rasmus
研究红河三角洲地下水砷含量的地质控制作用。沿沿着横跨三角洲南部和中部的45 km样带，在11口监测威尔斯井中进行了特定深度的地下水取样和地球物理测井，并对有关红河三角洲第四纪地质发展的文献进行了审查。对30个水样进行了As、主要离子、Fe ~（2+）、H_2S、NH_4、CH_4、δ O ~（-18）和δ D的分析，地球物理测井系列包括自然伽马、地层和流体电导率。样带的西南部与灰色河口粘土和三角洲砂的沉积物相交，形成一个宽15-20 km、深50-60 m的全新世下切河谷。样带的东北部分由60-120米的更新世黄色冲积层组成，位于10-30米的河口粘土下面，上面覆盖着10-20米的全新世沉积物单板。样威尔斯井的δ O-18值（-12.2 ‰ ~-6.3 ‰）和水头分布表明，河口粘土单元将水流系统分为上部全新世含水层和下部更新世含水层。地下水样品均为缺氧的，含有Fe 2+（0.03-2.0 mM）、Mn（0.7-320 μ M）、SO 4（
To study the geological control on groundwater As concentrations in Red River delta. depth-specific groundwater sampling and geophysical logging in 11 monitoring wells was conducted along a 45 km transect across the southern and central part of the delta, and the literature on the Red River delta's Quaternary geological development was reviewed. The water samples (n = 30) were analyzed for As, major ions, Fe2+, H2S, NH4, CH4, delta O-18 and delta D, and the geophysical log suite included natural gamma-ray, formation and fluid electrical conductivity. The SW part of the transect intersects deposits of grey estuarine clays and deltaic sands in a 15-20 km wide and 50-60 m deep Holocene incised valley. The NE part of the transect consists of 60-120 m of Pleistocene yellowish alluvial deposits underneath 10-30 m of estuarine clay overlain by a 10-20 m veneer of Holocene sediments. The distribution of delta O-18-values (range - 12.2 parts per thousand to -6.3 parts per thousand) and hydraulic head in the sample wells indicate that the estuarine clay units divide the flow system into an upper Holocene aquifer and a lower Pleistocene aquifer. The groundwater samples were all anoxic, and contained Fe2+ (0.03-2.0 mM), Mn (0.7-320 mu M), SO4 (