Hydrogeochemical evaluation and mechanisms controlling groundwater in different geologic environments, Western Sokoto Ba

  • PDF / 6,423,881 Bytes
  • 28 Pages / 595.276 x 790.866 pts Page_size
  • 49 Downloads / 183 Views

DOWNLOAD

REPORT


Hydrogeochemical evaluation and mechanisms controlling groundwater in different geologic environments, Western Sokoto Basin, Northwestern Nigeria Saadu Umar Wali1 · Noraliani Alias1 · Sobri Bin Harun1 Received: 11 May 2020 / Accepted: 24 September 2020 © Springer Nature Switzerland AG 2020

Abstract The hydrogeochemistry of aquifers in the western Sokoto basin was assessed. The objective of this study is to identify the impact of geological variability on groundwater hydrochemistry and the mechanisms controlling the hydrochemistry of aquifers. Univariate statistics (several samples ANOVA), Pearson’s (r), and multivariate statistics-hierarchical cluster analysis (HCA) and Factor analysis (FA) were used to interpret the hydrochemistry of aquifers. Subsequently, geochemical modeling was applied to assess the saturation index (SI) of rock minerals. Forty groundwater samples were collected from Gwandu (n = 20) and Illo (n = 20) formations. ANOVA results indicated that geological variability exerted a considerable impact on groundwater in Gwandu and Illo aquifers. It is characterized by a substantial amount of C ­ a2+, ­Mg2+, 2− − + + ­SO4 , ­HCO3 , ­Na , and ­K . The hydrogeochemical facies indicated mixing conditions. FA and correlations analysis further revealed that groundwater received the noticeable influence of silicate weathering and dissolution of carbonates. There were significant differences in SI values for chrysotile, goethite, gypsum, H ­ 2(g), ­H2O(g), ­H2S(g), illite, and sepiolite minerals between the two geologic environments. Positive SI values for gibbsite were noticed in eleven sampling locations, indicative of potential recharge zones. Likewise, all the sampling locations have positive values for K-feldspar and are supersaturated with mica, suggesting both discharge and transition zones. The HCA classified aquifers into three clusters based on their hydrogeochemical characteristics. Geochemical modeling, univariate, and multivariate analyses are user-friendly tools for hydrochemical analysis. Keywords  Rock weathering · Ion exchange process · Saturation index · Schoeller index · Anthropogenic input · Sodium adsorption ratio

1 Introduction Increasing urbanization, industrialization, and irrigation farming in developing countries have imposed great pressure on groundwater resources, with its consequent depletion and/or permanent contamination of aquifers [9, 35, 60, 76, 95]. The hydrochemistry of aquifers is primarily influenced by geology, land use, quality of recharge water, soil–water interactions, recharge pathways, the

residence time of recharged water in aquifers, and aquifer rock–water reactions. Therefore, local or regional groundwater chemistry is affected by local anthropogenic activities and inherent hydrogeochemical configurations [29, 31, 80]. The hydrochemistry of some groundwater aquifers is naturally excellent, but over time, their composition can be modified by anthropogenic activities and to a less significant extent by natural factors.

*  Saadu Umar Wali, [email protected].