Potentially toxic elements and geochemical signatures in sediments and soils from Biritiba-Mirim reservoir, Brazil

• Soil and sediment geochemistry traced natural or anthropogenic trace element inputs. • High chemical similarity between catchment soils and reservoir sediments. • Pb enrichment in soil and sediments resulting from the atmospheric deposition . • Anthropogenic As inputs in sediment associated with reservoir impoundment . • Cu upward increase in sediment resulting from agricultural activities. This study evaluated potentially toxic elements (PTEs) – V, Cr, Ni, Cu, Zn, Pb, As, Sb, and Co – in sediment cores and surface soils from the Biritiba-Mirim reservoir in Brazil. The study investigated the influence of nearby soil on the sediments in the reservoir, the accumulation of PTEs in the sediment core layers, and enrichment factors from anthropogenic or natural sources. The methodology focused on the geochemical and physico-chemical characteristics of soils and sediment. The results compose a database with regional interest in the environmental quality of a relevant water supply system for Brazil’s most populous city, as well as to international researchers studying the geochemistry of trace elements in dam reservoir environments. The mean PTEs concentrations, in mg/kg, found in soils and sediments, respectively, were V (116 | 214), Cr (32.7 | 52.8), Ni (7.9 | 13.9), Cu (58 | 65), Zn (61 | 57), Pb (69 | 74), As (5.6 | 25.7), Sb (0.39 | 0.90), and Co (1.97 | 3.40). The study hypothesized arsenic enrichment near sediment core transition zones, with positive correlations between As with Sediment Erosion Flux (SEF), indicating the impact of reservoir flooding on the sediment quality. Signatures of chemical correlation were found between reservoir sediments and catchment soils, which presented signs of copper and lead enhanced by anthropogenic release.