Depositional environments and historical contamination as a framework to reconstruct fluvial sedimentary evolution

In this study, we explore the variability of sedimentation conditions (e.g., grain-size, accumulation rate, contamination) according to fluvial depositional environments. Indeed, sediment cores are commonly used as archives natural and anthropogenic activities in hydrosystems, but their interpretation is often complex, especially a context where many factors may affect quality, continuity, resolution record. It therefore critical thoroughly understand nature dynamics an environment which core sampled be able interpret it. To that end, four environments from bypassed reach Rhône River were comparatively investigated through geophysics order assess range conditions: floodplain, semi-active secondary channel, active dam reservoir. Sediment retrieved each characterised Total Organic Carbon, organic contaminants). Robust age-depth models elaborated for based on 137Cs, 210Pbex, Persistent Pollutants (POPs) trends. The results show recorded different time-period, contamination levels particular, shift polychlorinated biphenyls (PCBs) polybrominated diphenyl ethers (PBDEs) predominant POP sediments can observed, tipping point being set 1970s. Two types infrastructure-induced legacy related two periods river engineering also identified using grain-size analysis. combination geophysical methods (Ground Penetrating Radar) confirmed relevant methodology should promoted contexts reconstruct sedimentary evolution corridors. study highlights challenges dating recent proposes multi-proxy POPs