Evaluation of Pollution Due to Gold Mining at Ity-Floleu Area in Sub-Prefecture of Zouan-Hounien, Western Côte d’Ivoire

Résumé fourni par la source

This study aims to evaluate the mineral pollution of a gold mining environment in the sub-Prefecture of Zouan-Hounien (C? ;te d’Ivoire). Samples were taken from surface water and flesh and skin samples of the Cavally River fish species over a period of two successive years. Concentrations in major elements, trace elements (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn), nutrients () and physico-chemical parameters in situ were measured. The results obtained show that the surface waters have very low pH with an average of 5.70. For nutrient salts, the deterioration of water quality in the study area is mainly related to alterations by nitrates, phosphates and sulphates. The concentrations of Fe, Cu, Hg and Pb are above the existing standards (international, FAO/WHO) for the majority of the stations, thus causing the deterioration of the surface water quality. Therefore, their use for agricultural irrigation could have negative impact on the health of the population and on biodiversity. Regarding the bioindicating species, the results obtained after analysis of samples showed that the fish (carp and machoiron) have Fe, Cu, Hg and Pb concentrations higher than the existing standards (international, FAO/WHO) exposing consumers to high health risks. This study showed good correlation between the high values of surface water turbidity and the proximity of gold washing sites. The use of the principal component analysis (PCA) of the physicochemical dataset revealed comparable behaviors for certain minerals within the groups (Fe, K, Mg, Mn and Na) and (As, Cd, Cu, Ni, Pb, Zn and Ca) in water. The Ascending Hierarchical Classification (AHC) analysis has defined three different classes of surface water in the study area. The presence of mineral trace elements in these receiving environments is of natural origin but would be strongly accentuated by human activities.

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