Artisanal gold mining is gaining momentum in western Côte d'Ivoire. However, little information is available on the mineralized horizons and primary source of gold. The objective of our study is thus to investigate the artisanal mining sites of Doumbiadougou near Duékoué in order to characterize the gold horizons then the primary source of gold and to propose exploration guides. We carried out fieldwork in Doumbiadougou followed by lithostratigraphic correlations and interpretations at the University of Man. In Doumbiadougou, we observed saprolite derived from a felsic intrusive affected by sheared quartz veins of orientation ranging from N035 to N060°. On the lithostratigraphic level, two quarries served as a basis for study. Thus, in the quarry on eluvial, three horizons are observed from the bottom to the top: fine saprolite, ferruginous shell and ferruginous cuirass. The geological substratum is dominated by quartzites and micaschists. Then, the quarry on alluvium presents four horizons from the bottom to the top: clay, gravelly, clay-sandy, and sandy. Gold mineralization is primarily related to eluvial wells whose elements percolate and enrich alluvium in the surrounding shallows. This resulted in concentrating the gold in the gravelly horizon. The abundance of quartz in the gravelly mineralized horizon and in the veins as well as the substratum made of quartzite and micaschist gives an epigenic origin to the gold of Doumbiadougou. These veins and felsic intrusive that hosts them appear as guides to be sought for the mineral exploration project.

The study investigates the spatial and temporal variation in water quality parameters at nine different locations in Mé, Bété and Djibi Rivers as well as Aghien Lagoon near Abidjan city for twelve consecutive months. Physicochemical parameters concerned are pH, temperature, electrical conductivity, dissolved oxygen, chlorophyll-a, total phosphorus and total nitrogen. Dissolved heavy metals analyzed are Ni, Cu, Zn, Pb, Cd and As. The assessment of physicochemical parameters shown the deteriorate of water quality with significant changes particularly in the Djibi River with high mean concentrations of total phosphorus (0.51 mgP.L-1) and total nitrogen (7.60 mgN.L-1). Nevertheless, the overall mean concentrations of heavy metals in water Cu (1.43 µg.L-1), Cd (0.06 µg.L-1), Pb (0.2 µg.L-1), Zn (9.16 µg.L-1), As (0.3 µg.L-1), Ni (2.77 µg.L-1) were lower than WHO Standard for Drinking Water Quality. Dissolved heavy metal percentage indicates that the order of concentrations was Zn>Ni>Cu>Pb>As>Cd. Multivariate analysis of variance (ANOVA) was used to group the different sampling sites on the basis of spatial similarities and classification, based on contamination sources and origin of pollutants in rivers and lagoon. In conclusion, this study clearly infers the fact that the cause of pollution in this region is mainly due to domestic and industrial effluents, agriculture and finally natural source.