Abstract 137 Cs is a long-lived man-made radionuclide introduced in the environment worldwide at the early beginning of the nuclear Era during atmospheric nuclear testing’s followed by the civil use ...of nuclear energy. Atmospheric fallout deposition of this major artificial radionuclide was reconstructed at the scale of French large river basins since 1945, and trajectories in French nuclearized rivers were established using sediment coring. Our results show that 137 Cs contents in sediments of the studied rivers display a large spatial and temporal variability in response to the various anthropogenic pressures exerted on their catchment. The Loire, Rhone, and Rhine rivers were the most affected by atmospheric fallout from the global deposition from nuclear tests. Rhine and Rhone also received significant fallout from the Chernobyl accident in 1986 and recorded significant 137 Cs concentrations in their sediments over the 1970–1985 period due to the regulatory releases from the nuclear industries. The Meuse River was notably impacted in the early 1970s by industrial releases. In contrast, the Seine River display the lowest 137 Cs concentrations regardless of the period. All the rivers responded similarly over time to atmospheric fallout on their catchment, underlying a rather homogeneous resilience capacity of these river systems to this source of contamination.
Platinum (Pt) is a Technology Critical Element (TCE) which, since the 1990s, has been mainly used in the industry in catalytic converters for automobile emission control. Previous studies have shown ...Pt contamination of road-side sediments and surface sediments in urban rivers and lakes but few of them have addressed temporal variations. The present work presents historical Pt concentration trends in 137Cs-dated sediment cores from floodplains or secondary channels at the outlets of three major French watersheds (Loire, Rhone, and Seine Rivers) covering the past ∼110 years, i.e., from the 1910s to 2021. Platinum baseline levels in the sediment were estimated for the Loire River (0.76 ± 0.22 μg kg−1 for the period ∼1910-∼1955) and the Rhone River (1.64 ± 0.41 μg kg−1), and historical Pt variations seem to reflect variations in hydrodynamics and grain size composition. Since the early 2000s, Pt concentrations in the Loire and the Rhone River sediments tend to increase (>2.5 μg kg−1) and were attributed to the use of car catalytic converters, an emerging technology since the 1990s using >50 % of European Pt demand. High and variable historical Pt concentrations (up to 14.6 μg kg−1) in the Seine River sediments may reflect legacy Pt sources due to former anthropogenic activities in this watershed, such as the use of Pt-based catalysts for petroleum refinery since the end of the 1940s, coal handling and precious metals refining, probably concealing the likely presence of an emerging traffic-related Pt signal. This first comparison of historical Pt concentration trends in sediments from contrasting watersheds allows to distinguish signals originating from different natural and anthropogenic sources (background level, historical sources, road traffic).
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•Few studies on Pt level in sediment for reconstructing the past geochemical quality•Ad-CSV analysis on selected sediments collected in dated cores in 3 French rivers•Temporal evolution of Pt concentrations (trajectory) between 1910 and 2021•Signals originating from different natural (baseline) and anthropogenic sources•Highest Pt concentrations in the Seine R. to past/historical and emerging sources
137Cs is a long-lived man-made radionuclide introduced in the environment worldwide at the earlybeginning of the nuclear Era during atmospheric nuclear testing’s followed by the civil use of ...nuclearenergy. Atmospheric fallout deposition of this major artificial radionuclide was reconstructed atthe scale of French large river basins since 1945, and trajectories in French nuclearized rivers wereestablished using sediment coring. Our results show that 137Cs contents in sediments of the studiedrivers display a large spatial and temporal variability in response to the various anthropogenicpressures exerted on their catchment. The Loire, Rhone, and Rhine rivers were the most affected byatmospheric fallout from the global deposition from nuclear tests. Rhine and Rhone also receivedsignificant fallout from the Chernobyl accident in 1986 and recorded significant 137Cs concentrations intheir sediments over the 1970–1985 period due to the regulatory releases from the nuclear industries.The Meuse River was notably impacted in the early 1970s by industrial releases. In contrast, theSeine River display the lowest 137Cs concentrations regardless of the period. All the rivers respondedsimilarly over time to atmospheric fallout on their catchment, underlying a rather homogeneousresilience capacity of these river systems to this source of contamination.
