Assessment of potentially toxic elements in sediment cores from reservoirs in the Upper Tiete River Basin, Brazil

Abstract

This study evaluated concentrations of potentially toxic elements (PTEs)—As, Sb, Co, Cr, Zn, U, and Th—in sediment cores from the Jundiai and Taiaçupeba reservoirs in the Upper Tiete Water Basin, Sao Paulo, Brazil. These reservoirs are vital for supplying water to the São Paulo metropolitan area but face risks from agricultural and industrial activities. The research aimed to determine whether PTE enrichment in sediments is due to natural or anthropogenic factors, assess the influence of sediment geochemistry and grain size, and evaluate risks to public health and biota. Granulometric analysis and enrichment factors were used to interpret the results, with As, Cr, and Zn compared to sediment quality guidelines. Significant Zn contamination was found in the Taiaçupeba reservoir, exceeding the Probable Effects Level (PEL), suggesting mining-related contamination. This highlights the need for further research on Zn’s spatial distribution, ecological risks, and bioavailability in the Taiaçupeba reservoir. Conversely, Sb, Co, Cr, U, and Th were linked to natural processes. Arsenic showed a local geologic anomaly in both reservoirs. This research emphasizes the importance of geochemistry as a critical tool for interpreting PTEs in trace element environmental monitoring. Geochemical parameters, including Hf, Ta, Sc, and K, and rare earth elements, were essential for understanding sedimentary dynamics and anthropogenic impacts. This approach enhances the effectiveness of PTE impact assessments and can be applied to other dam reservoirs worldwide.