Assessment of potentially toxic elements level in surface sediments of rivers in a territory of strong industrial legacy

Potentially Toxic Elements (PTEs) accumulation in river sediments poses a serious risk to ecosystems and human health. This study assessed the industrial impact on PTEs pollution levels in surface sediments of the Furan and Ondaine rivers (France), focusing on As, Cd, Co, Cr, Cu, Ni, Mo, Pb, and Zn. The statistical results showed variability between the geochemical background and the values measured in the study (Cd, Co, Cr, Cu, Mo, Zn), indicating anthropogenic input. Compared to the Threshold Effect Concentration (TEC) and Probable Effect Concentration (PEC) thresholds, the samples with concentrations higher than PEC were grouped around the valley bottom of major rivers (Cr, Ni, Pb), except for As, which was found everywhere due to its local natural anomaly. The Enrichment Factor (EF) highlighted anthropogenic sources of PTEs in the two major rivers, which exhibited a combined reactivity with industrial density for some elements. Ni and Mo EF increased in the Ondaine river with the accumulation of encountered industries, while a decrease was observed for Cr, Cu, Mo, Ni, and Pb EF in the Furan river with the increasing distance to industries. Beyond the sources of PTEs contamination, the main concern was their toxicity to aquatic organisms and humans. To evaluate the ecological risk, an integrated excess hazard index was developed to identify the most dangerous samples, which were not always linked to urban or industrial activities. This was the case for some samples gathered far from high-density industry but close to agricultural or natural areas (driven by Cd high content and toxicity). This study provided an identification and characterization of human-linked PTEs pollution in surface sediments of urban rivers within a district with strong industrial legacy.