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Geochemical evolution and tracing of groundwater salinization using different ionic ratios, multivariate statistical and geochemical modeling approaches in a typical semi-arid basin
Journal of Contaminant Hydrology ( IF 3.5 ) Pub Date : 2020-11-20 , DOI: 10.1016/j.jconhyd.2020.103742
Emmanuel Daanoba Sunkari , Mahamuda Abu , Musah Saeed Zango

The vulnerability of semi-arid basin aquifers to long-term salinization due to the dissolution of groundwater chemical constituents is a major global problem. Despite this, resilient techniques of tracing the sources of groundwater salinization in semi-arid basin aquifers are still evolving due to the aquifer complexities. This study proves the effectiveness of the use of different ionic ratios, multivariate statistical, and geochemical modeling approaches to understand groundwater evolution and trace salinization in the semi-arid Pru Basin of Ghana. The basin is homogeneously composed of argillaceous sediments of the Oti/Pendjari Group of the Voltaian Supergroup. A total of 81 samples from hand-dug wells and boreholes within the Pru Formation of the Oti/Pendjari Group in the basin were collected for this study. Quantitative analysis of the data shows that the abundance of major ions follows the order: Na+ > Ca2+ > Mg2+ > K+ and Cl > HCO3 > SO42−. The groundwater evolved from Na-HCO3, Na-HCO3-Cl, Na-Ca-HCO3 to Na-Mg-HCO3 water types in a decreasing order of abundance. Calculated meteoric genesis index (r2) indicates the dominance of deep meteoric water percolation effects on groundwater chemistry. Groundwater chemistry is principally controlled by water-rock interaction, ion exchange reactions, weathering (carbonate and silicate), salinization, and anthropogenic activities. Different ionic ratio plots and spatial distribution maps reveal the prevalence of salinization in the aquifer system, especially around the southwestern part of the basin. Revelle index assessment of the groundwater salinization level indicates that about 19.8% of the groundwater samples with RI values >0.5 is influenced by salinization. The groundwater salinization results from saline water intrusion from adjacent aquifers, mixing effects, ion exchange reactions, water-rock interaction, and anthropogenic activities. The geochemical modeling involving thermodynamic calculation of mineral saturation indices in PHREEQC indicates that groundwater is largely saturated with respect to majority of the carbonate and silicate mineral phases.



中文翻译:

在典型的半干旱盆地中,使用不同的离子比率,多元统计和地球化学建模方法,对地下水盐化的地球化学演化和追踪

由于地下水化学成分的溶解,半干旱盆地含水层对长期盐化的脆弱性是一个主要的全球性问题。尽管如此,由于含水层的复杂性,追踪半干旱盆地含水层中地下水盐碱化源的弹性技术仍在发展。这项研究证明了使用不同的离子比率,多元统计和地球化学建模方法来了解加纳半干旱Pru盆地的地下水演化和痕量盐渍化的有效性。该盆地是由Voltaian超群的Oti / Pendjari群的泥质沉积物均匀组成的。总共从该盆地奥蒂/彭加里群的Pru组的手挖井和钻孔中收集了81个样品用于这项研究。+  > Ca 2+  > Mg 2+  > K +和Cl > HCO 3 > SO 4 2−。地下水从Na-HCO3,Na-HCO3-Cl,Na-Ca-HCO3到丰富的Na-Mg-HCO3水类型逐渐减少。计算得出的大气成因指数(r2)表示深层大气水渗透对地下水化学的影响占主导地位。地下水化学主要受水-岩相互作用,离子交换反应,风化(碳酸盐和硅酸盐),盐碱化和人为活动控制。不同的离子比率图和空间分布图揭示了含水层系统中盐碱化的普遍性,特别是在盆地西南部附近。Revelle指数对地下水盐碱化程度的评估表明,RI值> 0.5的地下水样品中约有19.8%受盐碱化的影响。地下水盐碱化是由于相邻含水层的盐水入侵,混合效应,离子交换反应,水-岩相互作用和人为活动造成的。涉及PHREEQC中矿物饱和度指数热力学计算的地球化学模型表明,相对于大多数碳酸盐和硅酸盐矿物相而言,地下水大部分处于饱和状态。

更新日期:2020-11-25
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