Publications by authors named "Brice Mourier"

18 Publications

  • Page 1 of 1

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

Sci Total Environ 2021 Apr 14;764:142900. Epub 2020 Oct 14.

Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023, LEHNA, F-69518, Vaulx-en-Velin, France.

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 of natural and anthropogenic activities in hydrosystems, but their interpretation is often complex, especially in a fluvial context where many factors may affect the quality, continuity, and resolution of the record. It is therefore critical to thoroughly understand the nature and dynamics of an environment in which a sediment core is sampled to be able to interpret it. To that end, four depositional environments from a bypassed reach of the Rhône River were comparatively investigated through geophysics in order to assess the range of sedimentation conditions: a floodplain, a semi-active secondary channel, an active secondary channel, and a dam reservoir. Sediment cores were retrieved from each environment and thoroughly characterised (e.g., grain-size, Total Organic Carbon, organic contaminants). Robust age-depth models were elaborated for each core based on Cs, Pb, and Persistent Organic Pollutants (POPs) trends. The results show that each depositional environment recorded a different time-period, and therefore different contamination levels and trends. In particular, a shift from polychlorinated biphenyls (PCBs) to polybrominated diphenyl ethers (PBDEs) as the predominant POP in the sediments can be observed, the tipping point being set in the 1970s. Two types of infrastructure-induced legacy sediments related to two periods of river engineering in the reach were also identified using grain-size analysis. The combination of geophysical methods (Ground Penetrating Radar) and sediment cores is therefore confirmed as a relevant methodology that should be promoted in fluvial contexts in order to reconstruct the sedimentary evolution of fluvial corridors. The study also highlights the challenges of dating recent fluvial sediments and proposes a multi-proxy dating methodology using POPs contamination trends.
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http://dx.doi.org/10.1016/j.scitotenv.2020.142900DOI Listing
April 2021

Temporal trends of legacy and novel brominated flame retardants in sediments along the Rhône River corridor in France.

Chemosphere 2021 May 8;271:129889. Epub 2021 Feb 8.

Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023, LEHNA, F-69518, Vaulx-en-Velin, France.

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.
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http://dx.doi.org/10.1016/j.chemosphere.2021.129889DOI Listing
May 2021

Dataset of natural metal background levels inferred from pre-industrial palaeochannel sediment cores along the Rhône River (France).

Data Brief 2020 Oct 8;32:106256. Epub 2020 Sep 8.

CNRS, Univ Lyon, Université Lyon 2, UMR 5600 EVS, F-69676 Bron Cedex, France.

Natural metal background levels in sediments are critical to assess spatial and temporal trends of contamination in hydrosystems and to manage polluted sediments. This is even more sensitive that multi-factors such as geogenic basement, depositional context, and past or long-term pollution can affect the level of metals in sediments. This article provides natural metal background levels and ancillary data (location, chronology, grain-size, total organic carbon - TOC) in pre-industrial sediments along the Rhône River (France). Two distinct areas were selected to take into account the geological variability of the watershed: the Dauphiné Lowlands (Upper Rhône River) and the Tricastin Floodplain (Middle Rhône River). On each area, the sediment cores were retrieved from palaeochannel sequences and the sampled sections were dated by radiocarbon from the Roman to the Modern Times (AD 3-1878). Regulatory metals (Al, Fe, Cd, Cr, Cu, Ni, Pb, and Zn) and other trace elements (Ba, Co, Li, Mg, Mn, Na, P, Sr, Ti, V) were analysed following both (AR) and Total Extraction (TE) procedures. Classically, TE provides metal concentrations greater than AR because TE includes crystalline lattice, while AR is close to the potentially bio-accessible part of metals (used for ecotoxicological purposes). Due to the small number of samples and to the non-normal distribution of the results, a median-based approach was chosen to establish the geochemical background values and ranges (MGB) for each sample and area. These MGBs are valuable to identify pollution sources, to characterise a contamination (spread and timing), and to estimate the state of rivers regarding pollution legacy. Along the Rhône River, these two continental MGBs were used to reconstruct the metal geo-accumulation trajectories in river sediments from 1965 to 2018 [1].
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http://dx.doi.org/10.1016/j.dib.2020.106256DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7522338PMC
October 2020

Metal pollution trajectories and mixture risk assessed by combining dated cores and subsurface sediments along a major European river (Rhône River, France).

Environ Int 2020 11 26;144:106032. Epub 2020 Aug 26.

Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, F-69518 Vaulx-en-Velin Cedex, France.

In European rivers, research and monitoring programmes have targeted metal pollution from bed and floodplain sediments since the mid-20 century by using various sampling and analysis protocols. We propose to characterise metal contamination trajectories since the 1960s based on the joint use of a large amount of data from dated cores and subsurface sediments along the Rhône River (ca. 512 km, Switzerland-France). For the reconstruction of spatio-temporal trends, enrichment factors (EF) and geo-accumulation (Igeo) approaches were compared. The latter index was preferred due to the recurrent lack of grain-size and lithogenic elements in the dataset. Local geochemical backgrounds were established near (1) the Subalps and (2) the Massif Central to consider the geological variability of the watershed. A high contamination (Igeo = 3-5) was found for Cd, Cu and Zn from upstream to downstream over the period 1980-2000. This pattern is consistent with long-term emissions from major cities and the nearby industrial areas of the Upper Rhône (Geneva, Arve Valley), and Middle Rhône (Lyon, Chemical Corridor, Gier Valley). Hotspots due to Cu and Zn leaching from vineyards, mining, and highway runoff were also identified, while Pb was especially driven by industrial sources. The recovery time of pollution in sediment varied according to the metals and was shorter upstream of Lyon (15-20 years) than downstream (30-40 years). More widely, it was faster on the Rhône than along other European rivers (e.g. Seine and Rhine). Finally, the ecotoxicological mixture risk of metal with Persistent Organic Pollutants (POPs) for sediment-dwelling organisms showed a medium "cocktail risk" dominated by metals upstream of Lyon, although it is enhanced due to POPs downstream, and southward to the delta and the Mediterranean Sea. Overall, this study demonstrates the heterogeneity of the contamination trends along large fluvial corridors such as the Rhône River.
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http://dx.doi.org/10.1016/j.envint.2020.106032DOI Listing
November 2020

Sedimentological and geochemical data in bed sediments from a tropical river-estuary system impacted by a developing megacity, Ho Chi Minh City - Vietnam.

Data Brief 2020 Aug 27;31:105938. Epub 2020 Jun 27.

CARE, Ho Chi Minh City University of Technology, VNU-HCM, Viet Nam.

Sedimentological and geochemical data were obtained for bed sediments from a tropical estuary environment in Vietnam in October 2014, January 2016, and November 2016. The data include grain-size distribution, percentage of clay, silt and sand, percentage of organic matter, concentration of total particulate phosphorus (TPP), concentration of particulate inorganic phosphorus (PIP), concentration of particulate organic phosphorus (POP), percentage of total nitrogen (TN), percentage of total carbon (TC), trace metals concentrations (V, Cr, Co, Ni, Cu, Zn, As, Mo, Cd, Pb) and major elements (Al, Fe, Mn). Geochemical indexes (Enrichment factor EF and Geo-accumulation Index I-geo) and sediment quality guideline (mean Effect Range Median quotients) were calculated.
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http://dx.doi.org/10.1016/j.dib.2020.105938DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7339034PMC
August 2020

Correction to: Sedimentary phosphorus accumulation and distribution in the continuum of three cascade dams (Creuse River, France).

Environ Sci Pollut Res Int 2020 06;27(17):22138

PEIRENE EA 7500, Faculté des Sciences et Techniques, Université de Limoges, 123 Av. Albert Thomas, 87060, Limoges Cedex, France.

The missing Electronic Supplementary Material in the original paper is included in this paper.
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http://dx.doi.org/10.1007/s11356-020-08801-5DOI Listing
June 2020

Sedimentary phosphorus accumulation and distribution in the continuum of three cascade dams (Creuse River, France).

Environ Sci Pollut Res Int 2020 Feb 23;27(6):6526-6539. Epub 2019 Dec 23.

PEIRENE EA 7500, Faculté des Sciences et Techniques, Université de Limoges, 123 Av. Albert Thomas, 87060, Limoges Cedex, France.

Dam construction leads to both sediment discontinuities and the creation of internal phosphorus (P) loads in reservoirs capable of supporting eutrophication. Today, majority of large rivers are dammed and numerous of these infrastructures are constructed in cascade. However, few studies focus on the cumulative effect of the presence of dam on sediment P mobility and bioavailability in downstream reservoirs and rivers parts or throughout the continuum. The influence of three cascade dams has been studied herein on the sedimentary P distribution in surface bed sediments along a 17-km fluvial continuum of the Creuse River (Massif Central, France). The sediments (17 samples) were analyzed for their physical (grain size, specific surface area) and chemical (pH, contents of P, Fe, Al, Ca, Mn, organic matter (OM), and P fractionation) characteristics. Results indicated an amount of P 3 to 7 times higher in dam sediments (1.59 ± 0.51 mgP/g DW) than in free-flowing river sections (0.27 ± 0.11 mgP/g DW). Unexpectedly, sedimentary TP content did not decrease from the first to the third reservoir. The spatial variations of sediment characteristics between river and reservoirs were correlated with the retention of particles sized under 200 μm within the reservoirs. In reservoir sediment, P was mainly associated with the ascorbate fraction (P associated with the redox-sensitive Fe/Mn precipitates). Inside each dam reservoir, longitudinal variations of the sedimentary P distribution were mainly due to the increase of amorphous Fe precipitate content accumulated in fine sediments toward the dam, as characterized by a low Fe-Asc/P-Asc molar ratio. In the river sections, P distribution (mainly associated with HCl and ascorbate fractions) was not significantly influenced by cascade dams.
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http://dx.doi.org/10.1007/s11356-019-07184-6DOI Listing
February 2020

Phosphorus mobility in dam reservoir affected by redox oscillations: An experimental study.

J Environ Sci (China) 2019 Mar 10;77:250-263. Epub 2018 Aug 10.

Université de Limoges, PEIRENE EA 7500, Faculté des Sciences et Techniques, 123 Av. Albert Thomas, 87060 Limoges Cedex, France. Electronic address:

The internal sedimentary phosphorus (P) load of aquatic systems is able to support eutrophication, especially in dam-reservoir systems where sedimentary P stock is high and where temporary anaerobic conditions occur. The aim of this study therefore is to examine the response of sedimentary P exposed to redox oscillations. Surface sediments collected in the Champsanglard dam-reservoir (on the Creuse River, France) were subjected to two aerobic phases (10 and 12 days) alternated with two anaerobic periods (21 and 27 days) through batch incubations. The studied sediment contained 77 ± 3 μmol/g DW of P, mainly associated with the ascorbate fraction (amorphous Fe/Mn oxyhydroxides). The used sediment was rich in organic matter (OM) (21% ± 1%) with primarily allochthone signature. Our results showed that redox oscillations enhance dissolved inorganic phosphorus release at sediment/water interface. During the first anaerobic stage, the P release was mainly controlled by the dissolution/precipitation of iron minerals. The more pronounced increase of P release during the second anaerobic stage (44%) was due to various mechanisms related to the change in quality of dissolved organic matter (DOM), namely a higher SUVA and humification indices. The release of more refractory DOM (rDOM) served to lower the microbial metabolism activity, possibly favored iron oxyhydroxide aggregation and thus limiting iron reduction. In addition, rDOM is able to compete for mineral P sorption sites, leading to a greater P release. In reservoir with predominant allochthone OM input, the release of more aromatic DOM therefore plays an important role in P mobility.
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http://dx.doi.org/10.1016/j.jes.2018.07.016DOI Listing
March 2019

Where has the pollution gone? A survey of organic contaminants in Ho Chi Minh city / Saigon River (Vietnam) bed sediments.

Chemosphere 2019 Feb 2;217:261-269. Epub 2018 Nov 2.

Centre Asiatique de Recherche sur l'Eau, Ho Chi Minh University of Technology, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Viet Nam; University Grenoble-Alpes, UMR5001 CNRS, IRD, Grenoble INP, IGE, CS 40700, F-38000, Grenoble, France.

A wide range of persistent organic chemicals, including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), some insecticides, as well as polybrominated diphenyl ethers (PBDEs) and some perfluoroalkyl substances (PFASs) were analyzed in 17 bed sediments collected along the Saigon River and at adjacent canal mouths from upstream to downstream in Ho Chi Minh City (Vietnam). Concentrations were rather low for PAHs, as well as for legacy PCBs and dichloro-diphenyl-trichlorethane and metabolites (DDTs), or below detection limits for several PFASs and all PBDEs measured. Several insecticides (chlorpyrifos-ethyl, and the pyrethroids cypermethrin and λ-cyhalothrin) displayed rather high concentrations at a few sites within the city. There was no distinct upstream - downstream trend for PAHs, (DDTs) or PCBs. Although adjacent canal sediments tended to be more contaminated than Saigon River sediments, the differences were not significant. Emissions are almost certainly substantial for PAHs, and probably also for other contaminants such as PBDEs and some PFASs. During the dry season, contaminants are presumably stored in the city, either in canals or on urban surfaces. Heavy rainfall during the monsoon period carries away contaminated particle flows into the canals and then the Saigon River. The strong tidal influence in the river channel hinders the accumulation of contaminated particles. Contaminated deposits should accordingly be investigated further downstream in depositional environments, such as the mangrove.
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http://dx.doi.org/10.1016/j.chemosphere.2018.11.008DOI Listing
February 2019

Past and recent state of sediment contamination by persistent organic pollutants (POPs) in the Rhône River: Overview of ecotoxicological implications.

Sci Total Environ 2019 Jan 25;646:1037-1046. Epub 2018 Jul 25.

Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69518 Vaulx-en-Velin, France.

Twenty-one sediment samples were taken from five dated sediment cores collected along the Rhône River from 2008 to 2011. A total of 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), 7 polychlorinated biphenyls (PCBs), 8 polybrominated diphenyl ethers (PBDEs), 3 polybrominated biphenyls (PBBs), 3 hexabromocyclododecanes (HBCD) and 31 organochlorine pesticides (OCPs) were investigated to provide information on deposition dynamics in time and space, but also regarding the ecotoxicological risks associated with these contaminants. Median concentrations of total PBDEs are nine times lower than the levels of total PCBs along the entire studied stretch of the Rhône River. The results show that total PBDEs concentrations range from 0.06 to 239 μg·kg DW with a median value of 3.81 μg·kg DW and a maximum concentration measured in the years 2000s. These maximum concentrations are identical to those measured for total PCBs at the end of the 1990s, but show a different pattern of distribution. Abnormal dichlorodiphenyltrichloroethane (DDT) levels were also detected in the downstream section of the river, with a peak concentration of 147.5 μg·kg DW measured at the GEC site from 2005 onwards. Analyses of the enantiomeric fractions reveal a fresh input resulting from a technical formulation. Sediments from the core sampled at the most downstream site (GEC) are found to be highly toxic to organisms living nearby, particularly because of the total PCDD/Fs, DDE and DDT levels. In addition, based on available sediment quality guidelines, there may be a potential bioaccumulation risk for humans not only for these three compounds of concern but also for total PCBs and 7 out of the 8 analysed PBDEs.
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http://dx.doi.org/10.1016/j.scitotenv.2018.07.340DOI Listing
January 2019

Key parameters influencing metallic element mobility associated with sediments in a daily-managed reservoir.

Sci Total Environ 2017 Dec 1;605-606:666-676. Epub 2017 Jul 1.

Groupement de Recherche Eau Sol Environnement, Université de Limoges, 123 avenue Albert Thomas, 87060 Limoges Cedex, France.

In a hydroelectric reservoir, sediments are subject to remobilization events, water-level fluctuations and physicochemical changes. Depending on their associated metallic content, surficial oxic to suboxic sediments could constitute a major source of metals. To identify the key parameters that control metallic elements in terms of their mobility and sensitivity to reservoir management, sediments were subject to resuspension and drying/wetting cycle experiments over a wide range of pH values, solid/liquid ratios (S/L) and redox (Eh) conditions. During these tests, special attention was also paid to the influence of pretreatments on samples, i.e., drying, aeration and the leachate composition (ultrapure water vs. natural water); on the preservation of the sediment characteristics; and especially on metallic element release. The results of this study show that the pH, S/L ratio and Eh parameters are key variables in metal solubilization; the pH influences metal mobility primarily through sorption-desorption phenomena as well as the dissolution of metallic-bearing phases, the S/L ratio modifies the sorption-desorption equilibria, and the Eh primarily affects the reducible sensitive phases and associated metallic elements through dissolution-precipitation processes. Under environmental conditions, evolution of these parameters can lead to a >20% solubilization of the most mobile elements, i.e., As and Cd. These results are influenced by the sample pretreatment and experimental conditions. In fact, even if the solubilization patterns show no significant differences between dry and wet sediment depending on the physicochemical conditions, the magnitude of their release is significantly affected. Drying pretreatment induces changes in metal speciation, notably altering the distribution of the most weakly bound elements; there is almost half the amount of metallic elements associated with the exchangeable fraction in dry compared to wet sediments. The solubilization percentages were higher in the ultrapure phase than in reservoir water primarily due to the low pH, which influenced the sorption equilibria.
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http://dx.doi.org/10.1016/j.scitotenv.2017.06.236DOI Listing
December 2017

Impact of sediments resuspension on metal solubilization and water quality during recurrent reservoir sluicing management.

Sci Total Environ 2016 08 18;562:201-215. Epub 2016 Apr 18.

Groupement de Recherche Eau Sol Environnement, Université de Limoges, 123 avenue Albert Thomas, 87060 Limoges Cedex, France.

In dam contexts, sluicing operations can be performed to reestablish sediments continuity, as proposed by the EU Water Framework Directive, as well as to preserve the reservoirs' water storage capacity. Such management permits the rapid release of high quantities of reservoir sediments through the opening of dam bottom valves. This work aims to study the impact of such operation on the evolution of environmental physicochemical conditions notably changes in dissolved metallic elements concentrations (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) through field and laboratory investigations. Results were interpreted in terms of concentrations and fluxes, and compared with data collected on an annual basis regarding both suspended matter and metallic elements. The release of high quantities of sediments (4,500tons dry weight in 24h), with concentrations representing up to 300 times the inter-annual mean suspended sediments discharge, significantly modified water parameters, notably solid/liquid (S/L) ratio, pH and redox conditions. Despite the fact that they are mainly trapped in stable phases, a clear increase of the solubilized metals content was measured, representing up to 60 times the maximum values of current exploitation. This solubilization is related to desorption phenomena from sediments through changes in chemical equilibriums as highlighted by laboratory characterizations and experiments. These chemical modifications are mainly attributed to S/L ratio variations. Indeed, the low S/L ratios (≤1.3g·L(-1)) measured in situ are typically the ones for which metals solubilization is the highest, as shown by laboratory experiments. Additional thermodynamic modeling highlighted that the decrease in pH measured during the operation favors the release of the free forms of metallic elements (Al and Cu), and decreases the OM complexation influence. These changes, either in term of physical conditions or speciation, increasing metals long term bioavailability notably during redeposition phase, may have adverse effects on aquatic biota.
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http://dx.doi.org/10.1016/j.scitotenv.2016.03.178DOI Listing
August 2016

Influence of dams on sediment continuity: A study case of a natural metallic contamination.

Sci Total Environ 2016 Mar 12;547:282-294. Epub 2016 Jan 12.

Groupement de Recherche Eau Sol Environnement, Université de Limoges, 123 avenue Albert Thomas, 87060 Limoges Cedex, France. Electronic address:

Sediments play an important role on the quality of aquatic ecosystems, notably in the reservoir areas where they can either be a sink or a source of contaminants, depending on the management and hydrological conditions. The physicochemical properties of 25 surface sediments samples of a reservoir catchment (Vaussaire, Cantal, France) were studied. Results show a strong influence of dam presence, notably on the grain size and organic matter (OM) contents. The concentrations of trace metals and metalloids (As, Cd, Cr, Cu, Ni, Pb and Zn) were also measured and compared with worldwide reservoir concentrations and international sediment quality guideline levels in order to assess the intensity of the metallic contamination. Cr and Ni are the trace elements presenting the significantly highest values at the catchment scale. Enrichment Factors (EF), calculated using both local and national backgrounds, show that metals have mainly a natural origin, explaining especially the Cr and Ni values, linked with the composition of parental rocks. Unexpectedly, all the observed metal concentrations are lower in the reservoir than upstream and downstream, which might be related to the high fresh OM inputs in the reservoir, diluting the global metallic contamination. Multivariate statistical analyses, carried out in order to identify the relationship between the studied metals and sediment characteristics, tend to support this hypothesis, confirming the unusually low influence of such poorly-degraded OM on trace element accumulation in the reservoir.
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http://dx.doi.org/10.1016/j.scitotenv.2016.01.023DOI Listing
March 2016

Declining Dioxin Concentrations in the Rhone River Basin, France, Attest to the Effectiveness of Emissions Controls.

Environ Sci Technol 2015 Nov 19;49(21):12723-30. Epub 2015 Oct 19.

Université de Tours, GéHCO EA 6293, F-37000 Tours, France.

Emission-control policies have been implemented in Europe and North America since the 1990s for polychlorodibenzodioxins (PCDDs) and furans (PCDFs). To assess the effect of these policies on temporal trends and spatial patterns for these compounds in a large European river system, sediment cores were collected in seven depositional areas along the Rhone River in France, dated, and analyzed for PCDDs and PCDFs. Results show concentrations increase in the downstream direction and have decreased temporally at all sites during the last two decades, with an average decrease of 83% from 1992 to 2010. The time for a 50% decrease in concentrations (t1/2) averaged 6.9±2.6 and 9.1±2.9 years for the sum of measured PCDDs and PCDFs, respectively. Congener patterns are similar among cores and indicate dominance of regional atmospheric deposition and possibly weathered local sources. Local sources are clearly indicated at the most downstream site, where concentrations of the most toxic dioxin, TCDD, are about 2 orders of magnitude higher than at the other six sites. The relatively steep downward trends attest to the effects of the dioxin emissions reduction policy in Europe and suggest that risks posed to aquatic life in the Rhone River basin from dioxins and furans have been greatly reduced.
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http://dx.doi.org/10.1021/acs.est.5b03416DOI Listing
November 2015

Tracing the origin of suspended sediment in a large Mediterranean river by combining continuous river monitoring and measurement of artificial and natural radionuclides.

Sci Total Environ 2015 Jan 25;502:122-32. Epub 2014 Sep 25.

Laboratoire d'Etudes Radioécologiques en milieu Continental et Marin (LERCM), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Saint-Paul-lez-Durance, France.

Delivery of suspended sediment from large rivers to marine environments has important environmental impacts on coastal zones. In France, the Rhone River (catchment area of 98,000 km(2)) is by far the main supplier of sediment to the Mediterranean Sea and its annual solid discharge is largely controlled by flood events. This study investigates the relevance of alternative and original fingerprinting techniques based on the relative abundances of a series of radionuclides measured routinely at the Rhone River outlet to quantify the relative contribution of sediment supplied by the main tributaries during floods. Floods were classified according to the relative contribution of the main subcatchments (i.e., Oceanic, Cevenol, extensive Mediterranean and generalised). Between 2000 and 2012, 221 samples of suspended sediment were collected at the outlet and were shown to be representative of all flood types that occurred during the last decade. Three geogenic radionuclides (i.e., (238)U, (232)Th and (40)K) were used as fingerprints in a multivariate mixing model in order to estimate the relative contribution of the main subcatchment sources-characterised by different lithologies-in sediment samples collected at the outlet. Results showed that total sediment supply originating from Pre-Alpine, Upstream, and Cevenol sources amounted to 10, 7 and 2.10(6)tons, respectively. These results highlight the role of Pre-Alpine tributaries as the main sediment supplier (53%) to the Rhone River during floods. Other fingerprinting approaches based on artificial radionuclide activity ratios (i.e., (137)Cs/(239+240)Pu and (238)Pu/(239+240)Pu) were tested and provided a way to quantify sediment remobilisation or the relative contributions of the southern tributaries. In the future, fingerprinting methods based on natural radionuclides should be further applied to catchments with heterogeneous lithologies. Methods based on artificial radionuclides should be further applied to catchments characterised by heterogeneous post-Chernobyl (137)Cs deposition or by specific releases of radioactive effluents.
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http://dx.doi.org/10.1016/j.scitotenv.2014.08.082DOI Listing
January 2015

Historical records, sources, and spatial trends of PCBs along the Rhône River (France).

Sci Total Environ 2014 Apr 2;476-477:568-76. Epub 2014 Feb 2.

Irstea, UR MALY, rue de la Doua, CS70077, F-69626 Villeurbanne, France. Electronic address:

Despite bans on PCB use since 1975 (open systems) and 1987 (closed systems), concentrations of PCBs in riverine fish in France continue to exceed regulatory levels. We present historical records of PCB concentrations in sediment cores from eight sites on the Rhône River, from Lake Geneva to the Mediterranean Sea. Maximum PCB concentrations (sum of seven indicator PCBs) increase downstream, from 11.50 μg/kg at the most upstream site to 417.1 μg/kg at the most downstream site. At some sites peak concentrations occur in sediment deposited as recently as the 2000s. Hierarchical clustering (five clusters) identified differences in PCB congener profiles within and between sites. Exponential models fit to decadal time windows indicate that rapid reductions in concentrations during about 1990-2000 have slowed, and that it might be decades before target concentrations in sediment that correspond to regulatory thresholds in fish will be reached at some sites.
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http://dx.doi.org/10.1016/j.scitotenv.2014.01.026DOI Listing
April 2014

Spatial and temporal trends in PCBs in sediment along the lower Rhône River, France.

Sci Total Environ 2012 Sep 11;433:189-97. Epub 2012 Jul 11.

EA 6293 GéHCO Université François-Rabelais de Tours, Parc de Grandmont, 37200 Tours, France.

Despite increasingly strict control of polychlorinated biphenyl (PCB) releases in France since the mid-1970s, PCB contamination of fish recently has emerged as a major concern in the lower Rhône River basin. We measured PCB concentrations in Rhône sediment to evaluate the effects of PCB releases from major urban and industrial areas, sediment redistribution by large floods, and regulatory controls on PCB trends from 1970 to present. Profiles of PCBs (the sum of seven indicator PCB congeners) were reconstructed from sediment cores collected from an off-river rural reference site and from three depositional areas along the Rhône upstream and downstream from the city of Lyon, France. Core chronology was determined from radionuclide profiles and flood deposits. PCB concentrations increased progressively in the downstream direction, and reached a maximum concentration in 1991 of 281 μg/kg at the most downstream site. At the rural reference site and at the upstream Rhône site, PCB concentrations peaked in the 1970s (maximum concentration of 13 and 78 μg/kg, respectively) and have decreased exponentially since then. PCB concentrations in the middle and downstream cores were elevated into the early 1990s, decreased very rapidly until 2000, and since then have remained relatively stable. Congener profiles for three time windows (1965-80, 1986-93, and 2000-08) were similar in the three sediment cores from the Rhône and different from those at the rural reference site. The results indicate that permitted discharges from a hazardous-waste treatment facility upstream from Lyon might have contributed to high concentrations into the 1980-90s, but that industrial discharges from the greater Lyon area and tributaries to the Rhône near Lyon have had a greater contribution since the 1990s. There is little indication that PCB concentration in sediments downstream from Lyon will decrease over at least the short term.
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http://dx.doi.org/10.1016/j.scitotenv.2012.06.044DOI Listing
September 2012

Chemical extractions and predicted free ion activities fail to estimate metal transfer from soil to field land snails.

Chemosphere 2011 Oct 7;85(6):1057-65. Epub 2011 Sep 7.

Chrono-Environment, UMR 6249 University of Franche-Comté/CNRS UsC INRA, Place Leclerc, F-25030 Besançon Cedex, France.

This study investigates the relevance of several soil chemical extractions (calcium chloride, acetic acid, citric acid and a four-step sequential procedure) and predicted free metal ion activities in the soil solution to characterise the transfer of trace metals (Cd, Pb, and Zn) from soil to snail soft tissues over a large smelter-impacted area (Metaleurop Nord, Nord-Pas-de-Calais, France). The study was first performed on six snail species together and then specifically on Cepaea sp. and Oxychilus draparnaudi. When the six species were considered together, the accumulation of metals depended mostly on the species. When significant, total or extractable metal concentrations, or the predicted free ion activities, accounted for less than 7% of the variation of the metal concentrations in the snail tissues. Species-specific analyses showed that extractable concentrations explained approximately 25% of the variation of the metal concentrations in O. draparnaudi, and up to 8% in Cepaea snails. When using total soil concentrations and soil properties as explanatory variables, the models were generally slightly better, explaining up to 42% of the variance. The soil extraction procedures and predicted free ion activities used in this study did not accurately estimate the metal transfer from soil to snails and could not be used in risk assessment.
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http://dx.doi.org/10.1016/j.chemosphere.2011.07.035DOI Listing
October 2011