Geochemical and chemometric analysis of soils from a data scarce river catchment in West Africa

Abstract

Metal levels beyond stipulated thresholds are a considerable concern for environmental pollution regulators and public health administrators around the globe. Data is, however, lacking in most regions especially developing countries for practical policy decision making and management. In this study, we obtain 49 high-resolution soil cores from three vertical profiles in the Densu River Basin of Ghana and measured the concentrations of major and trace metals (Ca, K, Fe, Ti, Cr, Cu, V, Ni, and Zn). The aim was to examine and provide data on metal levels to serve as baseline information on mobilization studies for waste management. Geochemical methods for estimation of metal enrichment and accumulation were employed to determine enrichment and pollution, sources, and mobilization of the metals. Hierichical cluster and principal components analyses were used to examine metal associations and the effects soil physicochemical properties on the metals. The results show spatial variations in metal concentrations within and between individual soil profiles and are attributed to variability in soil formation processes and the locations where samples were collected, respectively. Moderate to high enrichment factors (EF) and geo-accumulation (Igeo) indices were observed for Vanadium (V) and Chromium (Cr) in all soil profiles indicating some level of anthropogenic interference leading to pollution possibly from vehicular and agricultural inputs. The Pourbaix diagrams, however, show that the Cr and V abundances may be natural. Our analysis also show that most of the metals investigated are of natural (i.e., geologic) origin but further investigations are recommended. The combination of field observations and established methods such as geochemical and statistical analyses have aided in extracting beneficial information from the small sample size.