Role of Natural and Anthropogenic Influence on the Salinization of Groundwater from Basement Aquifers in the Middle Part of Mono River Basin, Togo

• 作者: Gbandi Djanéyé-Boundjou Kossitse Venyo Akpataku Limam Moctar Bawa Masamaéya D. T. Gnazou Serigne Faye
• 来源期刊: 环境保护(英文)
• 学科: 地球科学
• 关键词: Mono River Basin GROUNDWATER Silicates Weathering Anthropogenic Contamination SALINIZATION TOGO
• 年，卷（期）: hjbhyw_2020,（12）
• 页码范围: 1030-1051
• 页数: 22页
• 分类号: P64

摘要

This study aimed to identify the role of natural and anthropogenic influence on geochemical processes controlling groundwater salinization in the middle portion of the Mono River basin, Togo. Multivariate statistical analysis, geochemical masse balance modeling, and conventional graphical methods were applied to the chemical dataset obtained from 110 groundwater samples collected during two campaigns (March-May 2011 and April 2014). The results showed that groundwater is predominantly fresh, acidic to circumneutral and mixed cations-<span style="white-space:nowrap;">HCO^-<sub style="margin-left:-7px;">3</sub> </span>water types. The proportion of ions (Na⁺, K⁺, Cl^- and <span style="white-space:nowrap;">SO^2-<sub style="margin-left:-7px;">4</sub></span>) occurring ubiquitously in a saline environment increases substantially with TDS. Two factors, defined as natural and anthropogenic, account for 76.5% of the hydrochemical dataset variance. Based on the hierarchical cluster analysis, groundwater samples are classified into four clusters that corroborate the factor analysis results and illustrate different hydrochemical evolution stages along a topographically-driven groundwater flow path. The primary natural process contributing to cations and bicarbonate ions is the weathering of silicate minerals and possibly secondary carbonates by infiltrating water enriched with soil CO₂ gas. Groundwater salinization indicators including Cl^-, <span style="white-space:nowrap;">SO^2-<sub style="margin-left:-7px;">4</sub> and <span style="white-space:nowrap;">NO^-<sub style="margin-left:-7px;">3</sub></span></span>, originate from potential sources such as human and animal wastes, agrochemicals, and deforestation. Thermodynamic equilibrium conditions ranged from saturation to oversaturation with respect to quartz, chalcedony, amorphous silica, calcite, dolomite, sepiolite, and talc. In conjunction with the lowering of CO₂ par