Spatial Distribution, Ecological Risk and Analysis of Sources of Trace Metal Elements in Surface Sediments of Pond Thomas (Brenne), France.

This study aims to contribute to understanding the processes influencing the spatial distributions of trace metal elements in surface sediments of Brenne’s ponds (France) and assess potential pollution levels in the area. It was motivated by the lack of knowledge regarding the hydrogeochemical dynamics of limnic entities, which are ponds. To achieve this, 25 sediment samples were collected from Pond Thomas, considered as a ‘sentinel pond’, and underwent analysis for grain size, total organic carbon (TOC) concentrations, and trace metal elements (TMEs) (specifically Cu, Ni, Pb, As, Zn, Cr, and Cd). The results revealed that trace metal elements are primarily concentrated in two areas: the northwest section and the upstream region in the southern part of the pond. Applying various pollution indicators such as the enrichment factor (EF), geo-accumulation index (I_geo), and potential ecological risk index (RI), it was found that Pb and As are the most enriched elements, with respective EFs of 3.5 and 4.9. Their average concentrations exceed geochemical background values by 4 and 5.68 times in certain samples. The sediments in the southern part of the pond showed moderate contamination levels for As and Pb, with moderate to severe pollution (2 < I_geo < 3), reaching a maximum I_geo of 2.26 for As. Although the RI values across the pond are relatively low, Cd and As still pose moderate potential ecological risks. Additionally, principal component analysis and Pearson correlation analysis indicated two sources of TMEs in the area: Zn, As, Ni, Cd, Pb, and Cr are primarily from natural sources, while Cu appears to have a local anthropogenic origin. [ABSTRACT FROM AUTHOR]