The mining industry constitutes a major economic sector, supporting development while generating significant environmental challenges. Indeed, it produces large quantities of residues from ore processing that are stored in dedicated basins called tailings storage facilities (TSF). These residues also contain various types of trace metal elements and cyanides that can be released into the environment. In this context, the aim of this work is to analyze and characterize the water quality in the TSF of the Sabodala mine and, on the other hand, to identify the hydrogeochemical phenomena that condition the behavior of pollutants. Samples were collected monthly (between 2022 and 2025) at two points (tailings discharge and decant water), and various physico-chemical parameters (pH, sulfates, cyanides and trace metal elements (As, Sb, Cd and Ni)) were analyzed. From this work, it emerges that: The waters of the tailings storage facility overall have a neutral to alkaline pH, with an average of 9.88 in raw tailings and a lower average of 7.98 in decant water. The higher sulfate concentrations in the decant water reflect a gradual oxidation of sulfides, which locally contributes to a decrease in pH. A strong decrease in cyanide contents is observed between the raw tailings and the decant water, suggesting significant degradation or dilution in the TSF enclosure. Trace metal elements show contrasting behaviors. Arsenic has high and highly variable concentrations in the raw tailings, but is significantly lower in the settling water, indicating a partial migration to the liquid phase. Cadmium, weakly present in both matrices, appears very little mobile. Nickel, although more concentrated in the tailings, migrates only weakly towards water. Conversely, antimony shows a more marked mobility, with contents in water sometimes higher than those measured in the raw tailings. Various physico-chemical processes such as oxidation, precipitation, volatilization and photodegradation are responsible for the behavior of the parameters studied, making the risk to surrounding surface and groundwater low.
KeywordsTailings Storage FacilityWater QualityCyanidesTrace Metal Elements
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