Although global plastic distribution is at the heart of 21st century environmental concerns, little information is available concerning how organic plastic additives contaminate freshwater sediments, ...which are often subject to strong anthropogenic pressure. Here, sediment core samples were collected in the Rhone and the Rhine watersheds (France), dated using 137Cs and 210Pbxs methods and analysed for nine phthalates (PAEs) and seven organophosphate esters (OPEs). The distribution of these organic contaminants was used to establish a chronological archive of plastic additive pollution from 1860 (Rhine) and 1930 (Rhone) until today. Sediment grain size and parameters related to organic matter (OM) were also measured as potential factors that may affect the temporal distribution of OPEs and PAEs in sediments. Our results show that OPE and PAE levels increased continuously in Rhone and Rhine sediments since the first records. In both rivers, ∑PAEs levels (from 9.1 ± 1.7 to 487.3 ± 27.0 ng g−1 dry weight (dw) ± standard deviation and from 4.6 ± 1.3 to 65.2 ± 11.2 ng g−1 dw, for the Rhine and the Rhone rivers, respectively) were higher than ∑OPEs levels (from 0.1 ± 0.1 to 79.1 ± 13.7 ng g−1 dw and from 0.6 ± 0.1 to 17.8 ± 2.3 ng g−1 dw, for Rhine and Rhone rivers, respectively). In both rivers, di(2-ethylhexyl) phthalate (DEHP) was the most abundant PAE, followed by diisobutyl phthalate (DiBP), while tris (2-chloroisopropyl) phosphate (TCPP) was the most abundant OPE. No relationship was found between granulometry and additives concentrations, while organic matter helps explain the vertical distribution of PAEs and OPEs in the sediment cores. This study thus establishes a temporal trajectory of PAEs and OPEs contents over the last decades, leading to a better understanding of historical pollution in these two Western European rivers.
Although global plastic distribution is at the heart of 21st century environmental concerns, little information is available concerning how organic plastic additives contaminate freshwater sediments, ...which are often subject to strong anthropogenic pressure. Here, sediment core samples were collected in the Rhone and the Rhine watersheds (France), dated using 137Cs and 210Pbxs methods and analysed for nine phthalates (PAEs) and seven organophosphate esters (OPEs). The distribution of these organic contaminants was used to establish a chronological archive of plastic additive pollution from 1860 (Rhine) and 1930 (Rhone) until today. Sediment grain size and parameters related to organic matter (OM) were also measured as potential factors that may affect the temporal distribution of OPEs and PAEs in sediments. Our results show that OPE and PAE levels increased continuously in Rhone and Rhine sediments since the first records. In both rivers, ∑PAEs levels (from 9.1 ± 1.7 to 487.3 ± 27.0 ng g−1 dry weight (dw) ± standard deviation and from 4.6 ± 1.3 to 65.2 ± 11.2 ng g−1 dw, for the Rhine and the Rhone rivers, respectively) were higher than ∑OPEs levels (from 0.1 ± 0.1 to 79.1 ± 13.7 ng g−1 dw and from 0.6 ± 0.1 to 17.8 ± 2.3 ng g−1 dw, for Rhine and Rhone rivers, respectively). In both rivers, di(2-ethylhexyl) phthalate (DEHP) was the most abundant PAE, followed by diisobutyl phthalate (DiBP), while tris (2-chloroisopropyl) phosphate (TCPP) was the most abundant OPE. No relationship was found between granulometry and additives concentrations, while organic matter helps explain the vertical distribution of PAEs and OPEs in the sediment cores. This study thus establishes a temporal trajectory of PAEs and OPEs contents over the last decades, leading to a better understanding of historical pollution in these two Western European rivers.
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•Phthalates (PAEs) appeared in riverine sediments before the 1900s.•Higher concentrations of PAEs than OPEs were observed in sediments of both rivers.•Tris(2-chloroisopropyl) phosphate (TCPP) was the dominant OPE in sediments.•Di(2-ethylhexyl) phthalate (DEHP) was the dominant PAE in sediments.•A positive correlation was found between plastic additive level and organic matter.
Fluvial suspended particulate matter (SPM) fluxes transport large amounts of contaminants that can affect water quality and river ecosystems. To better manage these inputs in river systems, it is ...essential to identify SPM and sediment sources. Many studies have applied a fingerprinting method based on using metals integrated into a numerical mixing model to estimate source contributions in a watershed. Most fingerprinting studies use contemporary SPM to trace historical inputs, whereas their metal concentrations were modified over time due to anthropogenic inputs. Moreover, total concentrations of these properties are subject to change due to diagenetic processes occurring in stored sediments. The aim of this study was to assess the relevance of using the non-reactive fraction of metals (i.e. metals and metalloids) in fingerprinting studies to estimate the historical contributions of SPM tributary inputs in a sediment core. To assess metal concentrations in the ‘conservative’ (i.e. non-reactive) fraction, SPM (samples of sources) and sediment core layers (targeted sediments) were subjected to total mineralization and soft extraction, and the non-reactive fraction was obtained by calculating the difference between the two extractions. This approach was applied on a sediment core from the Upper Rhône River (France), using geochemical signature in contemporary SPM of three major tributaries. We showed that the non-reactive fraction retains a higher number of metals in the range test for the deepest layers, which are characterized by significant anthropogenic inputs. Through apportionment modelling using Monte Carlo simulation, we demonstrated that the tributary contributions computed using the non-reactive fraction are more consistent with historical flood and water flow data and have lower uncertainties than with the total fraction. Working with the non-reactive fraction made it possible to decipher historical inputs of SPM using contemporary SPM samples. This approach enables robust identification of sub-catchment areas liable to provide large quantities of SPM. The non-reactive fraction can be used in a variety of environmental conditions and at various spatial and temporal scales to provide a robust quantification of sediment sources.
•Assessment of historical sediment sources with an original fingerprinting approach.•Apportionment modelling using total and residual concentrations of inorganic elements.•More tracers available with non-reactive fraction to discern historical SPM sources.•Total concentrations of tracers lead to inaccurate historical sources apportionment.•More reliable SPM contribution from Upper Rhône tributaries with residual fraction.
The Rhone River is one of the most nuclearized river in the world. Radionuclide concentrations in water and suspended sediments transferred to the marine environment were intensively monitored in ...this river over the last decades (2002–2018). Over this period of time, >12 and 25 time integrating samples were collected each year in filtered waters and suspended sediments, respectively, and analyzed for their radionuclide contents at ultra-trace levels by using top performance analytical tools. While >60% of plutonium, americium, cesium, cobalt, silver, beryllium and actinium radioisotopes are carried by sedimentary particles, sodium, tritium, antimony and strontium are mainly exported as dissolved species (>90%) due to their low affinity with particles. Most natural radionuclides contents show low seasonal variation. No significant trends are observed over the last two decades for these elements, even for 40K widely used in fertilizers after the middle of the last century, indicating that the basin has currently converged towards geochemical equilibrium for all of them. In contrast, the concentrations of numerous anthropogenic radionuclides originating from nuclear industries significantly declined since the beginning of the 2000s. Assuming no change of the current anthropic and climatic pressures over the next decades, apparent periods, i.e. the time required for a reduction by half the concentrations in the downstream part of the Rhône River, would be close to 6 years for most artificial radionuclides, except for tritium and other artificial radionuclides conveyed to the river by soil leaching and erosion (90Sr, 241Am, plutonium isotopes) which would be far longer. Referring to regional referential backgrounds, only few anthropogenic radionuclides specifically produced by nuclear industries are still detectable at the downstream part of the Rhone River and excess contents of tritium, 238Pu and 241Am are observed in filtered waters.
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•Contents of natural and anthropogenic radionuclides were monitored over the two last decades.•In filtered waters tritium contents are significantly higher than those of all other radionuclides.•Naturally occurring radionuclides contents show seasonal variation.•Most anthropogenic radionuclides contents declined over the two last decades, except for tritium, OBT, 90Sr and transuranium elements.•Resiliency of the river regarding this family of contaminant is going on for most of them.
Brominated flame retardants (BFRs) are anthropogenic compounds that are ubiquitous in most manufactured goods. Few legacy BFRs have been recognised as persistent organic pollutants (POPs) and have ...been prohibited since the 2000s. However, most BFRs continue to be used despite growing concerns regarding their toxicity; they are often referred to as novel BFRs (nBFRs). While environmental contamination due to chlorinated POPs has been extensively investigated, the levels and spatiotemporal trends of BFRs are comparatively understudied. This study aims to reconstruct the temporal trends of both legacy and novel BFRs at the scale of a river corridor. To this end, sediment cores were sampled from backwater areas in four reaches along the Rhône River. Age-depth models were established for each of them. Polychlorinated biphenyls (PCBs), legacy BFRs (polybrominated diphenyl ethers - PBDEs, polybrominated biphenyls - PBBs and hexabromocyclododecane - HBCDDs) and seven nBFRs were quantified. Starting from the 1970s, a decreasing contamination trend was observed for PCBs. Temporal trends for legacy BFRs revealed that they reached peak concentrations from the mid-1970s to the mid-2000s, and stable concentrations by the mid-2010s. Additionally, individual concentrations of nBFRs were two to four orders of magnitude lower than those of legacy BFRs. Their temporal trends revealed that they appeared in the environment in the 1970s and 1980s. The concentrations of most of these nBFRs have not decreased in recent years. Thus, there is a need to comprehend the sources, contamination load, repartition in the environment, and toxicity of nBFRs before their concentrations reach hazardous levels.
•Time trends of legacy BFRs in sediments along the Rhône River are similar.•Legacy BFRs reached their peak between the 1970s and the 2000s, and are now stable.•nBFRs concentrations are two to four times lower than that of legacy BFRs.•Some nBFRs appeared along the Rhône River as early as the 1970s–1980s.•No decreasing trend in nBFRs concentrations has been observed, so far.
As carriers of dissolved and particulate loads that connect continental surfaces to oceans, river systems play a major role in the global carbon cycle. Indeed, riverine particulate organic carbon ...(POC) is a melange of various origins characterized by their own 14C labeling. In addition, civil nuclear activities have brought new 14C source that remains poorly documented. We propose to unravel the Δ14C value of POC stored in a sedimentary archive collected downstream the most nuclearized European rivers (the Loire River). We postulate that riverine POC is a mixture of aquatic POC (which could be impacted by the liquid discharge from nuclear industry), terrestrial and petrogenic POC. With a combination of radiocarbon measurements, POC analyses and the palynofacies method, we assessed the respective Δ14C value of the POC origins. The gaps between the Δ14C values of the sedimentary POC and those of the atmosphere were the result of the dilution from dead-C, the freshwater reservoir effect imprinting the Δ14C of aquatic POC and the age and transit time of terrestrial POC within the catchment. Importantly, we consider that the unravelling of radiocarbon composition of riverine POC could be useful to determine either the transit time of material from source to sink, some past industrial or natural events, the resilience of the river system and milestones of the social and economic trajectory of a catchment. For the last three decades, riverine sediments could also act as a source of radiocarbon for the atmosphere.
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•Aquatic POC in sedimentary archives does not record 14C from the nuclear industry.•Δ14C values of terrestrial POC as a tool to determine the transit time of sediments within the watershed•Δ14C as a useful tool to document the trajectories of social and economic milestones
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
A broad range of contaminants has been recorded in sediments of the Loire River over the last century. Among a variety of anthropogenic activities of this nuclearized watershed, extraction of uranium ...and associated activities during more than 50 years as well as operation of several nuclear power plants led to industrial discharges, which could persist for decades in sedimentary archives of the Loire River. Highlighting and identifying the origin of radionuclides that transited during the last decades and were recorded in the sediments is challenging due to i) the low concentrations which are often close or below the detection limits of routine environmental surveys and ii) the mixing of different sources. The determination of the sources of anthropogenic radioactivity was performed using multi-isotopic fingerprints (236U/238U, 206Pb/207Pb and 208Pb/207Pb) and the newly developed 233U/236U tracer. For the first time 233U/236U data in a well-dated river sediment core in the French river Loire are reported here. Results highlight potential sources of contamination among which a clear signature of anthropogenic inputs related to two accidents of a former NUGG NPP that occurred in 1969 and 1980. The 233U and 236U isotopes were measured by recent high performance analytical methods due to their ultra-trace levels in the samples and show a negligible radiological impact on health and on the environment. The determination of mining activities by the use of stable Pb isotopes is still challenging probably owing to the limited dissemination of the Pb-bearing material marked by the U-ore signature downstream to the former U mines.
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•First results of 236U and 233U in a sediment core collected in the Loire River.•236U source contribution was deciphered using 233U/236U atomic ratio.•Stable lead isotopes were used to discriminate past uranium mining activities.•Lead isotopes showed only the influence of gasoline lead.
A broad range of contaminants has been recorded in sediments of the Loire River over the last century. Among a variety of anthropogenic activities of this nuclearized watershed, extraction of uranium ...and associated activities during more than 50 years as well as operation of several nuclear power plants led to industrial discharges, which could persist for decades in sedimentary archives of the Loire River. Highlighting and identifying the origin of radionuclides that transited during the last decades and were recorded in the sediments is challenging due to i) the low concentrations which are often close or below the detection limits of routine environmental surveys and ii) the mixing of different sources. The determination of the sources of anthropogenic radioactivity was performed using multi-isotopic fingerprints (236 U/ 238 U, 206 Pb/ 207 Pb and 208 Pb/ 207 Pb) and the newly developed 233 U/ 236 U tracer. For the first time 233 U/ 236 U data in a well-dated river sediment core in the French river Loire are reported here. Results highlight potential sources of contamination among which a clear signature of anthropogenic inputs related to two accidents of a former NUGG NPP that occurred in 1969 and 1980. It is important to mention that the 233 U and 236 U levels measured in this work by recent high performance analytical methods are at ultra-trace levels and present a negligible radiological impact on health and on the environment. The determination of the mining activities by the use of stable Pb isotopes is still challenging probably due to the limited dissemination of the Pbbearing material marked by the U-ore signature downstream to the former U mines.
Tritium of artificial origin was initially introduced to the environment from the global atmospheric fallout after nuclear weapons tests. Its level was increased in rainwaters by a factor 1000 during ...peak emissions in 1963 within the whole northern hemisphere. Here we demonstrate that tritium from global atmospheric fallout stored in sedimentary reservoir for decades as organically bound forms in recalcitrant organic matter while tritium released by nuclear industries in rivers escape from such storages. Additionally, we highlight that organically bound tritium concentrations in riverine sediments culminate several years after peaking emission in the atmosphere due to the transit time of organic matter from soils to river systems. These results were acquired by measuring both free and bound forms of tritium in a 70 year old sedimentary archive cored in the Loire river basin (France). Such tritium storages, assumed to be formed at the global scale, as well as the decadal time lag of tritium contamination levels between atmosphere and river systems have never been demonstrated until now. Our results bring new lights on tritium persistence and dynamics within the environment and demonstrate that sedimentary reservoir constitute both tritium sinks and potential delayed sources of mobile and bioavailable tritium for freshwaters and living organisms decades after atmospheric contamination.
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