Geochemical characterization of potentially toxic elements in topsoil under different land-use patterns in the village of Guido (Midwestern Burkina Faso) using multivariate geostatistical techniques

Burkina Faso faces a major challenge of environmental degradation due to a booming of gold mining. To date, there is no available information regarding soil geochemical status of this rapidly transitioning land use from merely subsistence agriculture to market gardening and artisanal gold mining. Therefore, this case study investigates distribution of 13 potentially toxic elements in soil exposed to different land-uses. For that purpose, 226 topsoil samples were collected in a grid of 200 m × 200 m, and their pseudototal concentrations were determined by inductively coupled plasma mass spectrometer. Univariate statistics, multivariate and geostatistical techniques showed that chemical weathering of parent bedrocks contributed to La, Tl, Th, U and Ti distribution in the soil, whereas that of Au, Hg and Te were controlled by artisanal gold mining. Laterization of basaltic rocks appeared to be the main source of V, Ga and Sc. In contrast, spatial distribution of Sr and Ba might be attributed to application of inorganic fertilizers and agrochemicals and, to lesser degree, parent materials. The results of multivariate analyses were corroborated by the interpolated factor score maps. The high concentrations of V, Sc, Bi, Hg and Sb above the mean upper continental crust composition and world-average soil concentrations are likely to pose serious threats to human. The study showed that the soil geochemistry is affected by both geogenic and anthropogenic sources. Thus, understanding geochemical status of the soil is vital for developing sustainable agricultural practices and environmental protection schemes in the area.