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Hydrogeochemical characteristics of surface and groundwater in artisanal mining regions: a new integrated approach using hypothetical salt assemblages, stable isotope ratios and end-member mixing analysis.

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Title: Hydrogeochemical characteristics of surface and groundwater in artisanal mining regions: a new integrated approach using hypothetical salt assemblages, stable isotope ratios and end-member mixing analysis.
Authors: Refaee, Ahmed1,2,3 (AUTHOR) armmorsy2023@igsnrr.ac.cn, Song, Xianfang1,2,4,5,6 (AUTHOR) songxf@igsnrr.ac.cn, Yang, Lihu1,2,4,5,6 (AUTHOR) yanglihu@igsnrr.ac.cn, Rashad, Eslam2,7,8 (AUTHOR), Fan, Yang1,2,4 (AUTHOR), Ali, Khaled9 (AUTHOR)
Source: Environmental Geochemistry & Health. Jan2026, Vol. 48 Issue 1, p1-22. 22p.
Abstract: Sustainable water management in regions impacted by artisanal gold mining (ASGM) requires a clear understanding of hydrochemical evolution and salt transformation processes. This study examines hydrochemical changes in the Wadi Abbady through a combined approach of geochemical modeling and stable isotope analysis, with the aim of disentangling the roles of natural processes and human activities in alternating water quality. Physicochemical parameters, major ions, and isotopic signatures were analyzed to trace both natural and anthropogenic influences. Results reveal pronounced chemical evolution within the Nubian Sandstone Aquifer (NSA), primarily controlled by reverse ion exchange. Mining activities induce a hydrogeochemical transformation, converting meteoric surface water assemblages (Ca (HCO3)2-Mg (HCO3)2-NaHCO3-NaCl-Na2SO4) into slightly brackish water characterized by elevated sulfate salt concentrations (NaCl-Na2SO4-CaSO4-MgSO4-Ca (HCO3)2). Isotopic evidence indicate that the Quaternary Aquifer (QA) is not hydraulically connected to the deeper NSA, and is instead predominantly recharged by surface water through Wadi Abbady canals and irrigation return flows. End-Member Mixing Analysis (EMMA) using Cl− and δ18O indicates that irrigation canals contribute approximately 60–90% of the total recharge to the QA, while amalgamation ponds provide a smaller but consistent contribution of 10–40%. This mixing pattern highlights both the hydrogeological connection between surface and shallow groundwater systems and the increased vulnerability of the QA to contamination originating from ASGM activities. These findings advance current understanding of water quality evolution in mining-affected environments and highlight the vulnerability of local aquifer systems to unregulated mining practices. This study emphasizes the need for continuous monitoring and long-term hydrochemical assessment in comparable settings to support sustainable water management and mitigate the impacts of artisanal mining. [ABSTRACT FROM AUTHOR]
Database: Energy & Power Source
Description
Abstract:Sustainable water management in regions impacted by artisanal gold mining (ASGM) requires a clear understanding of hydrochemical evolution and salt transformation processes. This study examines hydrochemical changes in the Wadi Abbady through a combined approach of geochemical modeling and stable isotope analysis, with the aim of disentangling the roles of natural processes and human activities in alternating water quality. Physicochemical parameters, major ions, and isotopic signatures were analyzed to trace both natural and anthropogenic influences. Results reveal pronounced chemical evolution within the Nubian Sandstone Aquifer (NSA), primarily controlled by reverse ion exchange. Mining activities induce a hydrogeochemical transformation, converting meteoric surface water assemblages (Ca (HCO3)2-Mg (HCO3)2-NaHCO3-NaCl-Na2SO4) into slightly brackish water characterized by elevated sulfate salt concentrations (NaCl-Na2SO4-CaSO4-MgSO4-Ca (HCO3)2). Isotopic evidence indicate that the Quaternary Aquifer (QA) is not hydraulically connected to the deeper NSA, and is instead predominantly recharged by surface water through Wadi Abbady canals and irrigation return flows. End-Member Mixing Analysis (EMMA) using Cl− and δ18O indicates that irrigation canals contribute approximately 60–90% of the total recharge to the QA, while amalgamation ponds provide a smaller but consistent contribution of 10–40%. This mixing pattern highlights both the hydrogeological connection between surface and shallow groundwater systems and the increased vulnerability of the QA to contamination originating from ASGM activities. These findings advance current understanding of water quality evolution in mining-affected environments and highlight the vulnerability of local aquifer systems to unregulated mining practices. This study emphasizes the need for continuous monitoring and long-term hydrochemical assessment in comparable settings to support sustainable water management and mitigate the impacts of artisanal mining. [ABSTRACT FROM AUTHOR]
ISSN:02694042
DOI:10.1007/s10653-025-02878-y