Baseline Concentrations of 11 Elements as a Function of Land uses in Surface Soils of the Katangese Copperbelt Area (D.R. Congo)

Abstract

The Katangese Copperbelt Area (KCA) located south-eastern of D.R. Congo presents high concentration of Metal Trace Elements (MTE) due to a rich natural geochemical background and intense mining activities. However, the lack of data on specific baseline concentrations makes it difficult to assess and monitor the environmental quality of soils in the region. In this study, 11 MTE were measured across three land uses (croplands, forest and mining areas) to assess their baseline concentrations in topsoils of the KCA. Results showed the following (geometric) mean concentrations (mg.kg-1) in cropland soils: Al (54.6), Co (0.5), Cr (0.1), Cu (3.7), Fe (33.0), Mn (44.8), Ni (0.2), Pb (0.6), Zn (1.0), Ti (2.4), pH (5.3); in forests: Al (148.0), Cd (0.1), Co (1.9), Cr (2.2), Cu (12.3), Fe (156.4), Mn (86.9), Ni (1.1), Pb (1.9), Zn (3.7), Ti (0.4), pH (4.3); and in mining areas: Al (42.8), Cd (1.3), Co (7.0), Cr (0.1), Cu (115.5), Fe (53.3), Mn (26.1), Ni (0.5), Pb (8.2), Zn (93.1), Ti (0.3), pH (5.8). Cu and Zn were higher in mining areas compared to other land uses, demonstrating a prevalent influence of mining activities in altering the natural background of metals concentrations in the region. By contrast, croplands and forest shared a similar trend of Al and Mn contents, suggesting a mild influence of agricultural activity. This study is the first attempt to establish reference values of MTE contents in the KCA soils and thus provides valuable information for legislative purposes and for soil quality assessment.