Abstract:
This study aims to investigate the geochemical background and baseline values of heavy metals in soils in the Xiangjiang River basin. Focusing on nine indicators, i.e., As, Cd, Cr, Cu, Hg, Pb, Zn, Ni, and pH, in both surface and subsurface soils and using methods such as iterative calculations, boxplot-based outlier removal, and content-area fractal analysis, this study investigated the background values in the soil environment within the basin' areas where multi-target geochemical survey had been conducted. Accordingly, the study discussed the factors influencing the geochemical background and baseline values of various stratigraphic units and soil types. The results indicate minimal differences in the results derived using these calculation methods. All methods consistently indicate that the background values of eight heavy metals exceed national averages, with those of Hg and Cd approaching twice the national background levels. This suggests that the Xiangjiang River basin has high geochemical background values of Hg and Cd. The background values of heavy metals in soils within the basin are closely related to parent rock types, with element enrichment levels and the number of elements enriched in soils generally increasing with a decrease in the age of strata, specifically for Cd. Across different soil types within the Xiangjiang River Basin, the geochemical background values of heavy metals are generally higher than their baseline values.The research results of this study provide an important basis for the ecological environment assessment and land planning of the Xiangjiang River Basin.