UFR des Sciences de la Terre et des Ressources Minières, Laboratoire de Pédologie et de Géologie Appliquée, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
This study is a contribution to establishment a geochemical soil database around gold-bearing zones. The main objective is to evaluate the total current levels of heavy metals such as arsenic (As), cadmium (Cd), barium (Ba), vanadium (V), nickel (Ni), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), zinc (Zn), titanium (Ti), strontium (Sr) and lead (Pb) in soils around Gbétogo gold zone located at Seguela in Côte d'Ivoire. To achieve this, 5 soil pits were opened, described and sampled. A total of 19 samples from the 5 pits were collected and 10 other composites were taken from the surface horizons (0-20 cm) near the mine site. Heavy metals concentrations (As, Cd, Co, Cr, Cu, Ni, Pb and Zn) in soils were determined by X-ray fluorescence (XRF) and the hydrogen potential. The results indicate that the soils are acidic and essentially Cambisol-type. Some heavy metals such as Ni (21.8 to 128.05 mg.kg-1), Cu (27.17 to 96.31 mg.kg-1), Mn (226.57 to 3251.82 mg.kg-1), V (323.28 to 509.18 mg.kg-1), Ba (153.20 to 566.94 mg.kg-1) and Ti (4149.67 to 39823.88 mg. kg-1) have concentrations above the recommended standards representing a natural geochemical anomaly, while As, Cd, Zn, Sr and Pb have lower concentrations. Soils have mercury (Hg) contamination ranging from 1.94 to 15.95 mg.kg-1. The ranking, in descending order from highest to lowest concentrations, is as follows: Fe > Ti > Mn > V > Ba > Ni > Cu > Zn > Sr > Pb > Hg > As > Cd.