Department of Geological Engineering, Faculty of Engineering, Niğde Ömer Halisdemir University, Main Campus, 51240 Niğde, Turkey; Department of Geological Engineering, Faculty of Mineral Resources Technology, University of Mines and Technology, P.O. Box 237, Tarkwa, Ghana.
Department of Earth Science, Faculty of Earth and Environmental Sciences, CK Tedam University of Technology and Applied Sciences, P.O. Box 24, Navrongo, Ghana.
J Contam Hydrol. 2021 Jan;236:103742. doi: 10.1016/j.jconhyd.2020.103742. Epub 2020 Nov 20.
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 > Ca > Mg > K and Cl > HCO > SO. 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.
由于地下水化学成分的溶解，半干旱盆地含水层易受长期盐化的影响，这是一个全球性的主要问题。尽管如此，由于含水层的复杂性，半干旱盆地含水层中地下水盐化来源示踪的弹性技术仍在不断发展。本研究通过不同离子比值、多元统计和地球化学模拟方法，证明了在加纳普鲁盆地使用这些方法理解地下水演化和追踪盐分的有效性。该盆地由沃尔特超群奥蒂/彭杰里组的泥质沉积物均质组成。本研究共采集了 81 个样本，来自盆地奥蒂/彭杰里组普鲁组的手挖井和钻孔。数据分析表明，主要离子的丰度顺序为：Na > Ca > Mg > K 和 Cl > HCO > SO。地下水的演化顺序为从 Na-HCO3、Na-HCO3-Cl、Na-Ca-HCO3 到 Na-Mg-HCO3 水型，其丰度依次降低。计算得出的大气成因指数（r2）表明，深地下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）、盐化和人为活动的控制。不同的离子比值图和空间分布图揭示了含水层系统中盐分的普遍存在，特别是在盆地的西南部。地下水盐化水平的 Revelle 指数评估表明，约有 19.8%的 RI 值>0.5 的地下水样本受到盐化的影响。地下水盐化是由相邻含水层的盐水入侵、混合作用、离子交换反应、水岩相互作用和人为活动引起的。涉及 PHREEQC 中矿物饱和度指数热力学计算的地球化学模拟表明，地下水对大多数碳酸盐和硅酸盐矿物相都处于饱和状态。
