Groundwater chemistry and occurrence of arsenic in the Meghna floodplain aquifer, southeastern Bangladesh
Groundwater chemistry and occurrence of arsenic in the Meghna floodplain aquifer, southeastern Bangladesh
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DOI：
10.1007/s00254-007-0907-3
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发表时间：
2008-05
期刊：
影响因子：
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通讯作者：
A. Zahid;M. Hassan;K. Balke;Matthias Flegr;D. Clark
中科院分区：
文献类型：
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作者：
A. Zahid;M. Hassan;K. Balke;Matthias Flegr;D. Clark
溶解的主要离子和重要的重金属，包括总砷和铁的地下水从浅（25-33米）和深（191-318米）管井在孟加拉国东南部进行了测量。这些分析的目的是帮助描述地球化学过程中活跃的含水层和沉积物中的砷的来源和释放机制的Meghna洪泛区含水层。地下水中Cl−的升高和Na+相对于Ca 2+、Mg 2+和K+的较高比例表明受Na+和Cl−来源的影响。使用化肥可能导致浅井样品中NH 4+和PO 43 −浓度较高。一般来说，大多数离子与Cl-正相关，其中Na+与Cl-表现出特别强的相关性，表明这些离子来自同一来源的盐水沃茨。Cl−/HCO 3 −比值和Cl−之间的关系也表明了淡水和海水的混合。溶解HCO 3 −的浓度反映了地下水系统中水-岩相互作用的程度和有机物的综合微生物降解。锰和铁的氢氧化物是突出的粘土地下沉积物和众所周知的是强吸附剂的重金属，包括砷。所有五个浅井样本的砷浓度都很高，超过了世卫组织建议的饮用水限值。非常低浓度的SO 42-和NO3-以及高浓度的溶解Fe和PO 43-和NH 4+离子支持地下含水层的还原条件。砷浓度与SO 42-和NO3-浓度呈负相关，但与Mo、Fe浓度呈弱相关，与P、PO 43-和NH 4+离子呈正相关。
Dissolved major ions and important heavy metals including total arsenic and iron were measured in groundwater from shallow (25–33 m) and deep (191–318 m) tube-wells in southeastern Bangladesh. These analyses are intended to help describe geochemical processes active in the aquifers and the source and release mechanism of arsenic in sediments for the Meghna Floodplain aquifer. The elevated Cl−and higher proportions of Na+relative to Ca2+, Mg2+, and K+in groundwater suggest the influence by a source of Na+and Cl−. Use of chemical fertilizers may cause higher concentrations of NH4+and PO43−in shallow well samples. In general, most ions are positively correlated with Cl−, with Na+showing an especially strong correlation with Cl−, indicating that these ions are derived from the same source of saline waters. The relationship between Cl−/HCO3−ratios and Cl−also shows mixing of fresh groundwater and seawater. Concentrations of dissolved HCO3−reflect the degree of water–rock interaction in groundwater systems and integrated microbial degradation of organic matter. Mn and Fe-oxyhydroxides are prominent in the clayey subsurface sediment and well known to be strong adsorbents of heavy metals including arsenic. All five shallow well samples had high arsenic concentration that exceeded WHO recommended limit for drinking water. Very low concentrations of SO42−and NO3−and high concentrations of dissolved Fe and PO43−and NH4+ions support the reducing condition of subsurface aquifer. Arsenic concentrations demonstrate negative co-relation with the concentrations of SO42−and NO3−but correlate weakly with Mo, Fe concentrations and positively with those of P, PO43−and NH4+ions.