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Ecotoxicity data constitute the basic information to support the derivation of ecological benchmark values, whatever the stressor concerned. However, the set of appropriate data may be limited, especially with regard to chronic exposure conditions. The available data are often biased in favor of acute data from laboratory-controlled conditions, much easier to acquire. To make the best use of the available knowledge and better inform the effects of ionizing radiation chronic exposure on nonhuman species, we investigated the transposition to ionizing radiation ecotoxicity of one method proposed for chemicals to extrapolate chronic information from acute toxicity data. Such a method would contribute to enriching chronic data sets required for the derivation of benchmark values, making them more robust when used as reference values for ecological risk assessment. We developed accordingly the Acute to Chronic Transformation for Radiotoxicity data (ACTR) approach, which we validated. We introduced then the new concept of Endpoint Sensitivity Distribution (ESD). This finally allowed us to compare purely chronic and ACTR-built ESDs for different taxa. For some of them, the predicted and observed distributions looked very similar. This promising ACTR method appeared applicable with a reasonable level of confidence, but its generalization asks for improvements, some being already identified.

International audience; Studies conducted on the Rhône River (France) highlights that, in the current context of climate change, the frequency of lowflow situations are likely to increase throughout its basin. For these extreme periods, it is expected that the proportion of organic matter (OM) contained in suspended particles will increase. However, the fixation of several contaminants is strongly linked to OM, where its form favors their complexation/adsorption. This is confirmed by the results of the CANADER project conducted on the Rhône River and its main tributaries (Saône, Ardèche and Durance Rivers) where the concentrations in suspended solids of several contaminants (anthropogenic metals, mercury and radionuclides) tend to increase during low water periods. For several anthropogenic metals (Cr, Ni, Zn), concentrations sometimes exceed the probable effect concentration (PEC). The decrease on natural metals (from the earth's crust) coupled with the increase in methyl-mercury (suggesting bioaccumulation of concentrations in phytoplankton) shows that a significant proportion of the OM that transits at low flow is autochthonous. The first results of sterol analysis suggest that OM origins differ depending the Rhône River and its tributaries, and further work must be done to characterize the sources of these particles.; Les études menées sur le Rhône soulignent que dans le contexte actuel de changement climatique les situations de faible débit et d’étiage seront probablement de plus en plus fréquentes. Pour ces périodes extrêmes, il est attendu que la proportion de matière organique (MO) contenue dans les particules en suspension augmente. Or, la fixation de certains contaminants est fortement liée à la MO car sa forme favorise la complexation/adsorption de ceux-ci. C’est ce que confirment les résultats du projet CANADER conduit sur le Rhône et ses principaux affluents (Saône, Ardèche et Durance) où les concentrations dans les matières en suspension de certains contaminants (métaux anthropiques, mercure et radionucléides) ont tendance à augmenter en période d’étiage. Pour certains métaux anthropiques (Cr, Ni, Zn), les concentrations dépassent parfois le seuil d’effet probable (PEC). Par ailleurs, la diminution des métaux naturels (issus de la croûte terrestre – Co Cs Rb et V) couplée à l’augmentation du méthylmercure (suggérant une bioaccumulation des concentrations dans le phytoplancton) montre qu’une proportion non négligeable de la MO qui transite à l’étiage est autochtone. Les premiers résultats de mesure des stérols suggèrent que l’origine de cette MO diffère selon le Rhône et ses affluents, et des travaux additionnels doivent être réalisés pour caractériser les sources de ces particules.

International audience; The increasing need on energy and fluvial transport due to industrialization during the last century resulted in the construction of dams along rivers. To improve the production of electricity and avoid problems due to sedimentation, dam flushing operations are periodically organized. The Rhône Sediment Observatory investigated the impacts of such operations on suspended particulate matter (SPM) dynamics (resuspension and fluxes) and quality (physicochemical characteristics and contamination) during a flushing operation performed in June 2012 on 3 major dams on the Rhône River downstream the Lake Geneva (Verbois, Chancy-Pougny and Génissiat dams). The concentrations of several contaminants (hydrophobic organic contaminants, trace metal elements, radionuclides) as well as particulate organic carbon (POC) and particle size distribution were measured on SPM samples collected during this event at a permanent monitoring station (150 km downstream of the last flushed dam). Data obtained at this station from 2011 to 2016 were also used to compare the SPM and contaminant concentrations and fluxes during the 2012 dam flushing operations with those during flood events and baseflow regime. For the same water discharge, mean SPM concentrations during flushing were on average 6–8 times higher than during flood events recorded from 2011 to 2016. While of short duration (19 days), the flushing operations led to the massive resuspension of SPM and contributed to a third of the mean annual SPM flux. The SPM contamination was generally lower during flushing than during baseflow or flood, probably due to the fact that SPM during flushing operations is only issued from resuspended sediment, with no autochtonous particles nor recently eroded soil. The only exception are polycyclic aromatic hydrocarbons and bis(2-ethylhexyl)phthalate with higher concentrations during flushing, which must be issued from the resuspension of legacy-contaminated sediments stored behind the dams before the implementation of emission regulations. The observed increase of organically bound tritium is related to the resuspension of fine tritiated particles from watchmaking activities of the past century. During flushing, the variations of POC and contaminant concentrations are mostly driven by particle size.

Artificial radionuclides including radiocesium (134Cs and 137Cs) and radiosilver (110mAg) were released into the environment following the Fukushima Dai-ichi nuclear power plant accident in March 2011. These particle-bound substances deposited on soils of north-eastern Japan, located predominantly within a ∼3000 km2 radioactive fallout plume and drained by several coastal rivers to the Pacific Ocean. The current dataset (Evrard et al., 2021), which can be accessed at https://doi.org/10.1594/PANGAEA.928594, compiles gamma-emitting artificial radionuclide activities measured in 782 sediment samples collected from 27 to 71 locations across catchments draining ∼6450 km2 during 16 fieldwork campaigns. These campaigns were conducted in Japan between November 2011 and November 2020 in river catchments draining the main radioactive plume. This database may be useful to evaluate and anticipate the post-accidental redistribution of radionuclides in the environment and for the spatial validation of models simulating the transfer of radiocesium across continental landscapes.

The determination of copper (Cu) speciation and its bioavailability in natural waters is an important issue due to its specific role as an essential micronutrient but also a toxic element at elevated concentrations. Here, we report an improved anodic stripping voltammetry (ASV) method for organic Cu speciation, intended to eliminate the important problem of surface-active substances (SAS) interference on the voltammetric signal, hindering measurements in samples with high organic matter concentration. The method relies on the addition of nonionic surfactant Triton-X-100 (T-X-100) at a concentration of 1 mg L−1. T-X-100 competitively inhibits the adsorption of SAS on the Hg electrode, consequently 1) diminishing SAS influence during the deposition step and 2) strongly improving the shape of the stripping Cu peak by eliminating the high background current due to the adsorbed SAS, making the extraction of Cu peak intensities much more convenient. Performed tests revealed that the addition of T-X-100, in the concentration used here, does not have any influence on the determination of Cu complexation parameters and thus is considered "interference-free." The method was tested using fulvic acid as a model of natural organic matter and applied for the determination of Cu speciation in samples collected in the Arno River estuary (Italy) (in spring and summer), characterized by a high dissolved organic carbon (DOC) concentration (up to 5.2 mgC L−1) and anthropogenic Cu input during the tourist season (up to 48 nM of total dissolved Cu). In all the samples, two classes of ligands (denoted as L1 and L2) were determined in concentrations ranging from 3.5 ± 2.9 to 63 ± 4 nM eq Cu for L1 and 17 ± 4 to 104 ± 7 nM eq Cu for L2, with stability constants logKCu,1 = 9.6 ± 0.2–10.8 ± 0.6 and logKCu,2 = 8.2 ± 0.3–9.0 ± 0.3. Different linear relationships between DOC and total ligand concentrations between the two seasons suggest a higher abundance of organic ligands in the DOM pool in spring, which is linked to a higher input of terrestrial humic substances into the estuary. This implies that terrestrial humic substances represent a significant pool of Cu-binding ligands in the Arno River estuary.

International audience; Les études menées sur le Rhône soulignent que dans le contexte actuel de changement climatique les situations de faible débit et d’étiage seront probablement de plus en plus fréquentes. Pour ces périodes extrêmes, il est attendu que la proportion de matière organique (MO) contenue dans les particules en suspension augmente. Or, la fixation de certains contaminants est fortement liée à la MO car sa forme favorise la complexation/adsorption de ceux-ci. C’est ce que confirment les résultats du projet CANADER conduit sur le Rhône et ses principaux affluents (Saône, Ardèche et Durance) où les concentrations dans les matières en suspension de certains contaminants (métaux anthropiques, mercure et radionucléides) ont tendance à augmenter en période d’étiage. Pour certains métaux anthropiques (Cr, Ni, Zn), les concentrations dépassent parfois le seuil d’effet probable (PEC). Par ailleurs, la diminution des métaux naturels (issus de la croûte terrestre – Co Cs Rb et V) couplée à l’augmentation du méthylmercure (suggérant une bioaccumulation des concentrations dans le phytoplancton) montre qu’une proportion non négligeable de la MO qui transite à l’étiage est autochtone. Les premiers résultats de mesure des stérols suggèrent que l’origine de cette MO diffère selon le Rhône et ses affluents, et des travaux additionnels doivent être réalisés pour caractériser les sources de ces particules.

International audience; Location of river-groundwater exchange zones and biodiversity hotspot is essential for a river management plan,especially for Mediterranean karstic rivers. This location is often difficult and time-consuming when long riversectors are considered. We studied a 13 km-long sector of the Cèze River (Southern France) located in a karsticcanyon.We compared five indicators of river-groundwater exchanges: longitudinal profiles of temperature, electricalconductivity and 222Rn concentrations in the surface water of the river, chemical characteristics of thehyporheic water and hyporheic biodiversity. Upwelling zones occurred downstream of geomorphological heterogeneities(here at the tail of gravel bars). Surface water chemistry, especially electrical conductivity and222Rn concentrations, clearly traces large scale gaining sections, which were not associated to valley narrowingbut with lateral springs, suggesting a crucial role of the geological structuration of the karstic plateau ofMéjanne-le-Clap. Hyporheic water chemistry fits with the large-scale hydrological pattern, but with a high variabilitycorresponding to local heterogeneities. The stygobite fauna (obligate groundwater organisms) and benthicEPTC (Ephemeroptera, Plecoptera, Trichoptera and Coleoptera) occurred preferentially in the gainingsections fed by groundwater, likely because of oligotrophicwater and cooler temperature. The spatial distributionof river-groundwater exchange zone and hyporheic biodiversity may be thus predicted using changes in surfacewater chemistry, especially for electrical conductivity and 222Rn concentrations.; zabr

International audience; Land-based micropollutants are the largest pollution source of the marine environment acting as themajor large-scale chemical sink. Despite this, there are few comprehensive datasets for estimatingmicropollutant fluxes released to the sea from river mouths. Hence, their dynamics and drivers remainpoorly understood. Here, we address this issue by continuous measurements throughout the Rhone River ^basin (~100,000 km2) of 1) particulate micropollutant concentrations (persistant organic micropollutants: polychlorobiphenyls [PCBi] and polycyclic aromatic hydrocarbons [PAHs]; emerging compounds: glyphosate and aminomethylphosphonic acid [AMPA]; and trace metal elements [TME]), 2)suspended particulate matter [SPM], and 3) water discharge. From these data, we computed daily fluxesfor a wide range of micropollutants (n ¼ 29) over a long-term period (2008-2018). We argue that almosttwo-thirds of annual micropollutant fluxes are released to the Mediterranean Sea during three shortterm periods over the year. The watershed hydro-climatic heterogeneity determines this dynamic bytriggering seasonal floods. Unexpectedly, the large deficit of the inter-annual monthly micropollutantfluxes inputs (tributaries and the Upper Rhone River) compared to the output (Beaucaire station) claims ^for the presence of highly contaminated missing sources of micropollutants in the Rhone River water- ^shed. Based on a SPM-flux-averaged micropollutant concentrations mass balance of the system and theestimates of the relative uncertainty of the missing sources concentration, we assessed their locationwithin the Rhone River catchment. We assume that the potential missing sources of PAHs, PCBi and TME ^would be, respectively, the metropolitan areas, the alluvial margins of the Rhone River valley, and the ^unmonitored Cevenol tributaries.

International audience; We re-analyzed field data concerning potential effects of ionizing radiation on the abundance of mammals collected in the Chernobyl Exclusion Zone (CEZ) to interpret these findings from current knowledge of radiological dose-response relationships, here mammal response in terms of abundance. in line with recent work at fukushima, and exploiting a census conducted in february 2009 in the CEZ, we reconstructed the radiological dose for 12 species of mammals observed at 161 sites. We used this new information rather than the measured ambient dose rate (from 0.0146 to 225 µGy h −1) to statistically analyze the variation in abundance for all observed species as established from tracks in the snow in previous field studies. All available knowledge related to relevant confounding factors was considered in this re-analysis. this more realistic approach led us to establish a correlation between changes in mammal abundance with both the time elapsed since the last snowfall and the dose rate to which they were exposed. this relationship was also observed when distinguishing prey from predators. the dose rates resulting from our re-analysis are in agreement with exposure levels reported in the literature as likely to induce physiological disorders in mammals that could explain the decrease in their abundance in the ceZ. our results contribute to informing the Weight of Evidence approach to demonstrate effects on wildlife resulting from its field exposure to ionizing radiation.

International audience; Understanding the processes governing the behavior of radiocesium in the sea is still essential to make accurate assessments of its potential impacts on marine ecosystems. One of the most important of this process is the desorption that may occur at the river-sea interface due to changes in physico-chemical conditions, including ionic strength and solution composition. It has been the object of many studies using various kinds of field measurements or laboratory experiments, but there was no global interpretation of these works and their results. The present review summarizes relevant laboratory experiments studying desorption of Cs (stable or radioactive) from particles in sea or brackish waters.To date, 32 experimental studies have been carried out on 68 Cs-bearing samples since 1964. A wide range of desorbed fraction (0-86%) is observed, partly depending on the experimental design. For particles containing radiocesium issued from a contamination in the environment, the desorption ranges from 0 to 64% of the particulate activity, with a median at only 3%. Particles contaminated in laboratory show a range between 6 and 86% with a multimodal distribution. The desorption initiates at low salinity (3-4) and rapidly reaches a threshold around 10-15. Laboratory experiments show that two first-order reactions govern the kinetics of the process, with half-life reaction times of one hour and a few days. These two reactions are probably linked to the adsorption of Cs onto different particles sites. Also, the dynamic of Cs desorption depends on its initial distribution on these different sites, in relation with the history of its contamination and an aging effect.

International audience; Submarine groundwater discharge (SGD) is considered as a good indicator of the natural behavior of coastal aquifers especially in the case of intense groundwater withdrawal or when the aquifer recharge conditions are limited. Indeed, a decrease in SGD flows would result in saline intrusion compromising the groundwater reservoir use. The need for SGD studies in Mediterranean and semi-arid environments have long been recognized and little is known on low and diffuse flows. For this reason, the detection and quantification of low and diffuse SGD flows have been attempted in a Mediterranean porous aquifer with low potential of recharge and high touristic pressure from using a multi-tracing approach combining aerial thermal infrared images (TIR), temperature (T), electric conductivity (E.C.), major ions, selected trace elements, H-2, O-18, Rn-222, Ra-223 and Ra-224. The TIR images allowed the detection of slight temperature variations at the seawater surface. Contrasted lithology and strong water-rock interactions due to groundwater residence time of many decades favor the Rn-222, Ra-223 and Ra-224 contents in groundwater that reach the seashores. Low temperature and E.C, as well as high radon and radium activities, evidenced SGD flows in agreement with the known flow conditions within the aquifer. The quantification of SGD flows revealed in very good agreement with the known recharge rates of the aquifer that validates its conceptual hydrogeological model. For the first time in the Mediterranean or in semi-arid context, a natural tracing experiment based on geochemistry and isotope hydrology tools allowed the quantification of SGD flows to validate the hydrogeological conceptual model and to solve the water balance at the whole aquifer scale. Such a methodology could be applied worldwide to other similar coastal aquifers with low and diffuse SGD flow conditions.

International audience; Tritium is a radionuclide commonly observed worldwide in riverine systems. In the Rhône River downstream the Lake Geneva (Switzerland and France), its occurrence is also related to its use for its luminescent properties in watchmaking paints. In fact, tritium is regularly observed at anomalous levels in this river and extreme events such as flushing operations might conduct to its transport downstream. In the Rhône River, characterized by 21 dams downstream the Geneva Lake, such operations are regularly organized to remove the sediments and limit problematic consequences such as siltation and increased flooding hazards. The consequences of dam flushing operations on tritium concentrations were thus investigated. Samples of Suspended Particulate Matter (SPM) and water were collected in the Rhone River downstream of Geneva in June 2012, during a planned flushing operation of three upstream reservoirs (Verbois, Chancy-Pougny and Génissiat). The concentrations of tritiated water (HTO) and organically bound Tritium (OBT) were measured and compared to reference concentrations. The flushing operations had no impact on the HTO concentration while the increases observed were related to the authorized releases of HTO from a nuclear power plant located downstream the dams. High increases of OBT concentrations were observed at two stations (Creys-Malville and Jons) without clear spatial or temporal trends. Since similarly high OBT concentrations had already been observed in suspended and deposited sediments during normal flow condition, these anomalous peaks could be explained by the heterogeneous spatial distribution of OBT in sediment sources that were resuspended during the flushing operations. The results highlight the need to investigate the amount of OBT currently stored in the upstream Rhone River as it might be significant.

International audience; Microplastics have become widely dispersed throughout the marine environment in and around Japan since the 1960s, which correspond to the onset of mass plastic production and use in this country. Our study documents a possible abrupt microplastics depositional event in continental shelf and deep-sea environments triggered by a tsunami. The sediment layers contaminated by microplastics correspond with sedimentary horizons where 137Cs signals were measured, indicating deposition after 1960s nuclear tests. The microplastics were observed in the 2011 Tohoku-Oki tsunami deposits. Tsunamis can thus contribute to the wide dispersal of microplastics from coastal to deep-sea areas, and these anthropogenic particles can be used to date very recent turbidite deposits.

Determination of submarine groundwater discharge (SGD) from karstic coastal aquifers is important to constrain hydrological and biogeochemical cycles. However, SGD quantification using commonly employed geochemical methods can be difficult to constrain under the presence of large riverine inputs, and is further complicated by the determination of the karstic groundwater endmember. Here, we investigated a coastal region where groundwater discharges from a karstic aquifer system using airborne thermal infrared mapping and geochemical sampling conducted along offshore transects. We report radium data (223Ra, 224Ra, 228Ra) that we used to derive fluxes (water, nutrients) associated with terrestrial groundwater discharge and/or seawater circulation through the nearshore permeable sediments and coastal aquifer. Field work was conducted at different periods of the year to study the temporal variability of the chemical fluxes. Offshore transects of 223Ra and 224Ra were used to derive horizontal eddy diffusivity coefficients that were subsequently combined with surface water nutrient gradients (NO2− + NO3−, DSi) to determine the net nutrient fluxes from SGD. The estimated DSi and (NO2− + NO3−) fluxes are 6.2 ± 5.0 *103 and 4.0 ± 2.0 *103 mol d−1 per km of coastline, respectively. We attempted to further constrain these SGD fluxes by combining horizontal eddy diffusivity and 228Ra gradients. However, SGD endmember selection in this area (terrestrial groundwater discharge vs. porewater) adds further uncertainty to the flux calculation and thus prevented us from calculating a reliable flux using this latter method. Additionally, the relatively long half-life of 228Ra (5.75 y) makes it sensitive to specific circulation patterns in this coastal region, including sporadic intrusions of Rhône river waters that impact both the 228Ra and nutrient surface water distributions. We show that SGD nutrient fluxes locally reach up to 20 times the nutrient fluxes from a small river (Huveaune River). On a regional scale, DSi fluxes driven by SGD vary between 0.1 and 1.4% of the DSi inputs of the Rhône River, while the (NO2− + NO3−) fluxes driven by SGD on this 22 km long coastline are between 0.1 and 0.3% of the Rhône River inputs, the largest river that discharges into the Mediterranean Sea. Interestingly, the nutrient fluxes reported here are similar in magnitude compared with the fluxes quantified along the sandy beach of La Franqui, in the western Gulf of Lions (Tamborski et al., 2018), despite the different lithology of the two areas (karst systems vs. unconsolidated sediment).

(IF 2.67; Q2); International audience; Tritium is a radioisotope of hydrogen with a half-life of 12.32 years and was used for its luminescent properties by the watchmaking industry from 1962 to the 2008. Tritiated luminescent salts were integrated in the paints applied on the index and dial of watches and clocks. French and Swiss watchmaking workshops used more than 28 000 TBq of tritium over this period of time and produced almost 350 million watches. Despite the end of tritiated salts use in watchmaking workshops in 1992 in France and 2008 in Switzerland, high level of organically bound tritium (OBT) are still observed in sediments of the Rhône River downstream the Lake Geneva. Contamination of the Rhône River by tritiated hot particles since 1962 up to nowadays remains poorly documented. In order to assess the long term behavior and fate of technogenic tritium in this river and its trajectories in the river system, two sediment cores were collected at the upstream (UC) and downstream (DC) part of the Rhône River in France and OBT contents were determined. For both sedimentary cores, maximum OBT contents were registered over the 1980s when tritium was intensively used by watchmaking industries. These residual OBT contents are 1 000 to 10 000 fold higher than current natural background levels in riverine sediments. The OBT contents progressively decreased since 1989 with close effective half-life in upstream and downstream area (5 ± 2 years). The OBT contents were lower in DC than in UC due to the dilution by uncontaminated sediments delivered by tributaries not affected by the watchmaking industries. Trajectories analysis indicates that the resiliency of the Rhône River system in regards to this contamination would be reached in 14 to 70 years and in 14 to 28 years respectively for the upstream and downstream part of the river.

International audience; Radioisotopes have been used in earth and environmental sciences for over 150 years and provide unique tools to study environmental processes in great detail from a cellular level through to an oceanic basin scale. These nuclear techniques have been employed to understand coastal and marine ecosystems via laboratory and field studies to understand how aquatic organisms respond to environmental stressors including temperature, pH, nutrients, metals, organic anthropogenic compounds and biological toxins. Global marine issues, such as ocean warming, deoxygenation, plastic pollution, ocean acidification, increased duration and intensity of toxic harmful algal blooms (HABs), and coastal contamination are all impacting marine environments, thereby imposing various environmental and economic risks. Being able to reliably assess the health of coastal and marine ecosystems, and how they may respond to future disturbances, can provide vital information for society in the sustainable management of their marine environments. This paper summarises the historical use of radiotracers in these systems, describes how existing techniques of radioecological tracing can be developed for specific current environmental issues and provides information on emerging issues that would benefit from current and new radiotracer methods. Current challenges with using radioecological tracers and opportunities are highlighted as well as opportunities to maximise the uptake of these methods to greatly increase the ability of environmental managers to conduct evidence-based management of coastal and marine ecosystems

7Be and 234Thex activities were determined in sediment cores off the Rhone River mouth (Gulf of Lions), in order to trace the initial transport and deposition of riverine suspended particulate matter (SPM) and evaluate the impact of flood events through 7 cruises carried out between 2007 and 2008. Consistently high 7Be and 234Thex inventories of 2000–3000 mBq cm−2 and 3000–5000 mBq cm−2, respectively, were observed within a ~5 km radius off the Rhone River mouth. Their spatial distributions showed a gradual decrease with increasing distance from the Rhone River mouth, and the decrease in 7Be was more pronounced than that of 234Thex, indicating that recent riverine SPM is rapidly deposited in the area located near the river mouth. This area is also characterized by high accumulation rates determined using 137Cs or 210Pbex. Both 7Be and 234Thex inventories increased in 2008 compared to 2007, and are correlated to the cumulated SPM flux for normal and flood discharge. Moreover, the 7Be/234Thex inventory ratio appears to be a potential tracer to identify the dominant influence of recently deposited particles between terrestrial and marine waters. This ratio provides an effective tool to assess river and marine influence: Zone I at a distance inferior to 3.0 km, with 7Be/234Thex inventory ratio over 0.50 (surface area near river mouth ~ 7 km2) is dominated by riverine influence; in contrast, Zone III at a distance superior to 8.5 km, with 7Be/234Thex inventory ratio less than 0.10 (surface area off river mouth beyond 150 km2) is predominantly under a marine influence. In between, an intermediate area (Zone II at a distance between 3.0 and 8.5 km, with 7Be/234Thex inventory ratios between 0.10 and 0.50) displays a mixed influence. This zoning could help in further understanding the spreading of particle-reactive contaminants and its initial sedimentary deposition in the Gulf of Lions.

International audience; PurposeDam reservoirs sometimes need to be fully drawn down, an operation that induces sediment resuspension. In the case of contaminated sediments, such resuspension may promote the remobilization of trace metals from the solid to the dissolved phase, threatening the water quality. The objective of this study is to evaluate the kinetic release and removal processes of trace metals during the resuspension of polluted sediments from a dam reservoir.Materials and methodsTotal contents of trace elements were analyzed in the surface sediments collected in the dam. Ascorbate and sequential extractions were used to assess the trace metal fractionation. Aliquots of wet sediments were resuspended during a week using a 3-L glass reactor. Three solid/solution ratios (2.7, 5.0, and 9.4 g L−1) were tested. The pH, Eh, dissolved oxygen, and temperature were continuously measured, and water samples were collected through a small pipe inserted into the reactor. Evolution of dissolved organic carbon, alkalinity, major ions, and trace element concentrations were measured in the water over the resuspension experiments. Another resuspension experiment was carried out to determine the quantity of elements that could be adsorbed onto the glass wall of the reactor.Results and discussionHigh levels of As, Cd, Pb, and Zn were measured in the reservoir sediments, compared to the quality guidelines. The temporal evolutions of the dissolved elements were similar during the resuspension experiments, regardless of the mass of sediment used. Depending on the elements, different trends can be highlighted: (1) Cd, Cr, Cu, Ni, V, and Zn were not remobilized; (2) Al, Mo, As, Ba, and Sr continuously increased during the experiments; and (3) Mn, Co, Fe, and Pb increased at the beginning of the experiments and then were removed from the dissolved phase. Co was likely adsorbed onto Mn oxyhydroxides, whereas Pb appeared to be regulated by the Fe oxyhydroxides. The results from sequential extractions did not allow to relate these groups to specific distributions in the solid phase.ConclusionsThe greater risk of water quality degradation for this reservoir would be posed by the remobilization of As, which showed the greatest and the most prolonged release during resuspension, because it could not be removed onto particles due to its speciation. Dissolved As reached a maximum of 30 μg L−1 at the conclusion of the experiments, a concentration above the drinking water standard but well below the acute toxicity levels reported in the literature for fishes.

International audience

The objective of this paper is to present a model simulating and predicting the exchange kinetics of lead (Pb) between contaminated sediments and water during resuspension events potentially occurring in reservoirs. We developed an innovative model that combines thermodynamic speciation of particulate surfaces (oxides and Particulate Organic Carbon (POC)), thermodynamic Pb speciation in water, and kinetic modelling of exchanges between free Pb and particulate sites (i.e., dissolution of a carbonate carrier phase, adsorption/coprecipitation and desorption/dissolution to/from oxides, and adsorption and desorption/degradation to/from particulate organic particles). We used results from laboratory resuspension experiments performed on sediments from three contaminated dam reservoirs to calibrate a new chemical speciation model. Uptake and release processes to/from sediments were found to be controlled by at least two successive reactions that are associated with two particulate pools (here oxides and POC). Kinetic adsorption and desorption rates were calibrated for seven experimental conditions. Variability in kinetic rates allowed evaluation of the effect of the solid-to-liquid ratio and sediment origin on exchange kinetics at the water-particle interface. The kinetic release of dissolved Pb by desorption or dissolution from the oxides was reproduced almost identically between the experiments, regardless of the solid-to-liquid ratio or sediment origin. Long-term readsorption on POC sites is more variable, even if ranges of variation in the adsorption and desorption kinetic rates related to POC remain limited, considering that tested sediments vary significantly. CAPSULE: A kinetic model simulating the dynamics of lead (Pb) during sediment resuspension was developed and calibrated to laboratory experiments performed on three contaminated sediments.

The Rhone River (France) has been used for energy production for decades and 21 dams have been built. To avoid problems due to sediment storage, dam flushing operations are periodically organized. The impacts of such operations on suspended particulate matter (SPM) dynamics (resuspension and fluxes) and quality (physico-chemical characteristics and contamination), were investigated during a flushing operation performed in June 2012 on 3 major dams from the Upper Rhone River. The concentrations of major hydrophobic organic contaminants (polychlorinated biphenyls, polycyclic aromatic hydrocarbons - PAHs, bis(2-ethylhexyl)phthalate [DEHP] and 4-n-nonylphenol), trace metal elements, particulate organic carbon (POC) and particle size distribution were measured on SPM samples collected during this event as well as on those obtained from 2011 to 2016 at a permanent monitoring station (150 km downstream). This allows to compare the SPM and contaminant concentrations and fluxes during the 2012 dam flushing operations with those during flood events and baseflow regime. At equal water discharge, mean SPM concentrations during flushing were on average 6–8 times higher than during flood events recorded from 2011 to 2016. While of short duration (19 days), the flushing operations led to the resuspension of SPM and contributed to a third of the mean annual SPM flux. The SPM contamination was generally lower during flushing than during baseflow or flood, probably due to the fact that flushing transports SPM only issued from resuspended sediment, with no autochtonous particles nor eroded soil. The only exception are PAHs and DEHP with higher concentrations during flushing, which must be issued from the resuspension of legacy-contaminated sediments stored behind the dams before the implementation of emission regulations. During flushing, the variations of POC and contaminant concentrations are also mostly driven by particle size. Finally, we propose a list of recommendations for the design of an adequate monitoring network to evaluate the impact of dam flushing operations on large river systems.

International audience; This presentation concerns the modelling of the transport mode and the suspension and deposition velocities of solids particles in rivers. The comparison between the transport modes typically defined according to the Rouse number and the movement’s thresholds of the Shields parameter revealed inconsistencies. They are assumed to be a consequence of the differences between the application domain of the Shields parameter, based on the friction of the water flow on the bed and the Rouse number based on the conditions in the turbulent area. It is proposed to reduce these inconsistencies by proposing a new regard on the erosion process which allows assessing the transport mode of particles according to their transfers from the river bed to the turbulent layers of the water flow. The presented model is inspired from the resistance approaches applied in the domain of aerosols with the assumption that the vertical flux of particles is constant whatever the depth and that the erosion process can be considered through two successive steps which are the abrasion of bottom sediments and the suspension of abraded particles. With these assumptions, the suspension and deposition velocities are expressed as a function of the velocities (of settling and Brownian and turbulent diffusion and the transport modes are determined according to the ratio between the suspension and deposition velocities of the unstructured particles. Because the thickness of the diffusive exchange layer is determined as a function of the particles sizes, the water flow conditions and the bed roughness, the model allows finally assessing the transport mode of particles as a function of their size, the water flow and the bed roughness. The comparisons between these transport modes and the movement’s thresholds of the Shields parameter shows a significant reduction of the inconsistencies previously observed with the Rouse number that highlights the important role, while often neglected, of the diffusive exchange layer located between the bed and the turbulent flow.

International audience; After the nuclear accidents at Chernobyl and Fukushima and due to a growing use of radionuclides, radiation protection of the environment is a major concern. Studies show an increased sensitivity to ionizing radiation (IR) during development. However, there are few data on the molecular mechanisms leading to the effects of IR on embryogenesis and moreover for chronic exposures. In this context, the objective of this thesis is to better understand the effects of exposure to IR on the development of zebrafish (Danio rerio), a model organism in ecotoxicology and in biomedicine. Fertilized eggs were exposed to gamma rays emitted by a 137Cs source at low to moderate dose rates (from 0.005 mGy/h to 50 mGy/h), then analysed from the gastrula stage (6 hours) to the larval stage (5 days) by an integrative approach from molecular effects to behavioural effects. Part of this work has focused on studying the effects of IR at an early stage of zebrafish development after exposure to IR. For this, a multi-omics approach with the study of the transcriptome and the methylome has been implemented. A transcriptomic study at the shield stage with dose rates ranging from 0.005 mGy/h to 50 mGy/h was carried out and demonstrated a moderate but significant effect on the regulation of oxidative stress and mitochondrial activity. At 5 and 50 mGy/h, the genes involved in the development of the central nervous system (CNS) and muscles are affected. The methylome study has revealed hypomethylation of the promoter sequences of genes involved in the development of the CNS and muscles, associated with a modification of gene expression. These results on early embryonic stages, highlight potential effects on the development of the CNS and muscles. The other part of this work focused on assessing the effects of IR exposure at later developmental stages using a system biology approach. For this, analyses were carried out from the molecular scale to the phenotypic scale. At the molecular level, a multi-omics analysis of the transcriptome and the proteome has highlighted the modulation of genes involved in the retinoic acid pathway, the development of the CNS and muscles in embryos and larvae exposed to 0.5; 5 and 50 mGy/h. Labelling by in-situ hybridization confirmed the misregulation of the transcription factors her4.4 in the CNS and myog in the muscles of embryos exposed to IR. At the tissue level, disruption of muscle myofibrils and alteration of neuromuscular junctions are detected in embryos exposed to 5 and 50 mGy/h. In order to assess an individual effect at phenotypic scale, the locomotor behaviour of the larvae was assessed under stress conditions. A significant decrease in larval motility was detected between 0.5 mGy/h and 50 mGy/h. This work has shown effects of IR on the development of the CNS and muscles from early development at the molecular level. These effects are confirmed at later stages of development. This study suggests that the molecular disturbances observed during early development are predictive of the effects observed at later developmental stages. In addition, this thesis work allows us to propose a model of "Adverse Outcome Pathway" where the deregulation of the retinoic acid pathway by exposure to IR will lead to effects on the development of the CNS and muscles.

International audience; As result of the great east Japan earthquake on March 2011 and the damages of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), huge amount of radionuclides, especially 137Cs, were released to the Japanese Pacific coast. By consequence, several marine species have been contaminated by direct uptake of radionuclides from seawater or through feeding on contaminated preys. In the present study we propose a novel radioecological modelling approach aiming to simulate the radionuclides transfer to pelagic marine species by giving to the organism body-size a key role in the model. We applied the model to estimate the 137Cs content in 14 commercially important species of the North-Western Pacific Ocean after the FDNPP accident. Firstly, we validated the model and evaluated its performance using various observed field data, and we demonstrated the importance of using such modelling approach in radioecological studies. Afterwards, we estimated some radioecological metrics, such as the maximum activity concentration, its corresponding time and the ecological half-life, which are important in assessment of the previous, current and future contamination levels of the studied species. Finally, we estimated the time duration required for each species to reach the pre-accident 137Cs activity concentrations. The results showed that the contamination levels in the planktivorous species have generally reached the preaccident levels since about 5 years after the accident (since 2016). While in the case of the higher trophic level species, although the activity concentrations are much lower than the regulatory limit for radiocesium in seafood in Japan (100 Bq kg-1), these species still require another 6–14 years (2018–2026) to reach the pre-accident levels.

International audience; The bioavailability of trace elements (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Zn) in lowly to moderately contaminated coastal sediments from the Berre lagoon, France, was assessed by comparing their potentially bioavailable concentrations and bioaccumulated concentrations in the polychaete Alitta succinea. No linear correlations were observed contrarily to what is generally observed in similar works in areas with highly contaminated sediment. Correlations between trace and major elements (Fe, Ca, S, Mg, P, Al) in Alitta succinea tissues and their distribution in organism tissues show that, in such lowly to moderately contaminated sediments, biological variabilities should be considered. Normalization procedures allow to take into account these variabilities and to identify that sediment contamination is partly involved in the benthic ecosystem degradation of the Berre lagoon. Alitta succinea cannot be used as relevant bioindicator for Zn and Co bioavailability in sediment, since these elements are regulated by this organism.

International audience; Trace metal contamination in the European sardine and anchovy food web was investigated in the Gulf of Lions, NW Mediterranean Sea, including seawater and size fractions of plankton. The results highlighted: i) higher and more variable concentrations in the smaller plankton size classes for all metals except cadmium; ii) higher concentrations in anchovy versus sardine for all elements except lead; iii) different patterns of metal bioaccumulation through the food web: cobalt, nickel, copper, silver, lead and zinc displayed continuously decreasing concentrations (with the exception of increased zinc in fish only), while mercury concentrations dropped considerably in larger plankton size classes and rose significantly in fish. Lastly, cadmium concentrations were found to be highest in intermediate plankton size classes, with very low levels in fish. The need to efficiently characterize the biological composition of plankton in order to fully identify its role in the mobilization and transfer of metals was highlighted.

International audience; The Fukushima Daiichi nuclear disaster that occurred on March 11, 2011, was caused by the T¯ohoku tsunami, whichwasitselftriggeredbythedevastating9.0Mwmomentmagnitude earthquake. This study investigates spatial and temporal changes of the suspended particulate matter (SPM) content in the North-Eastern part of Japan (Pacific Ocean) using a geostationary ocean color sensor. The Geostationary Ocean Color Imager (GOCI), which is centered on the Korean peninsula but could also observe the Japanese area, is able to acquire eight images per day, thus allowing the analysis of rapid daily changes in water mass. TheanalysisofGOCIdatashowsthatSPMconcentrationnotably increasedbothalongthecoastandwithintheBayofSenda¨ıshortly after the tsunami. Motionless patterns of SPM were observed at 2, 14, 25, and 37 km from the coast. It is shown that SPM concentrationrapidlydecreasedonemonthlater.TheSPMconcentrationdid not remain high thefollowing year, contrary to what was observed for the Sumatra Tsunami in 2004. The origin of SPM is also investigated in this study. Our analysis suggests that some of the SPM originates from the resuspension of bottom sediments due to the reflectionofthetsunamionthecoastlinethatleadstothemigration of marine particles toward the sea surface. The fate of the SPM concentration is then discussed based on the analysis of meteorological conditions, river discharge, and tsunami wave properties

International audience; We have studied the recent history of organically bound tritium (OBT) and carbon-14 in suspended organic matter carried by the Rhône from the analysis of two cores collected in the sedimentary cone off the river mouth. Measured OBT and carbon-14 concentrations highlight characteristic anthropogenic traces in the suspended matter of the Rhône, with a peak of tritium and carbon-14 commencing at the start of the 1970s and extending over some 30 years. In spite of the influence of the atmospheric nuclear tests of the 1950s and 1960s, and of the discharges of carbon-14 by the nuclear industries located along the Rhône, carbon-14 levels are low due to the diluting effect of a refractory carbon component very low in carbon-14 present in the coastal sediments. OBT levels are well above the modern background created by the global imprint of bomb-tritium. Detailed study of the impact of the various contribution to the tritium peak indicates that these traces are mostly the result of the sediments in the Rhône being contaminated by past tritium releases by the watchmaking industry in the upper Rhône

International audience; The contamination of freshwater systems by metals is a worldwide problem due to their toxicity, abundance and persistence in the environment. One of the main processes affecting their residence time in freshwater systems is their solid-liquid fractionation, often modeled by the Kd approach defined as the concentration ratio between the particulate and dissolved phases under the assumptions of reversibility, equilibrium and trace conditions. Because Kd is an empirical parameter that depends on several environmental factors, its variability can cover orders of magnitude for a single element. Such variability is unknown for most case studies, but the modelers need it to evaluate the uncertainty of their calculations. In order to fill this gap, this paper presents statistical Kd distributions for in situ suspended matters as a function of suspended load, dissolved organic carbon and pH. They were obtained using a database containing 8564 Kd values from 50 elements, classified as a function of three exchange conditions (adsorption, desorption and in situ) and two environmental components (suspended and deposited sediments). These distributions and relations can be used to reduce of several order of magnitudes the global variability of Kd values in the case where in situ data are not available. © 2019

International audience; Platinum (Pt) is considered a Technology Critical Element (TCE) and an emerging metallic contaminant with increasing release into the environment. Gaps in knowledge and understanding of environmental levels, fate and effects of Pt still exist, especially in the marine environment. This work presents Pt concentrations in the northwestern Mediterranean coast including: (i) temporal variability from sediment cores and farmed mussels in the Toulon Bay (historically affected by intense human activities) and (ii) spatial distribution from recent wild mussels collected along ∼ 700 km coastline with contrasting ecosystems (including natural reserves), quantified using voltammetry and inductively coupled plasma-mass spectrometry. The historical (>100 years) record of Pt in sediments from the Toulon Bay suggests the existence of non-negligible Pt sources older than those related to vehicle emission devices, such as petrol industry and coal-fired activities. A strong Pt increase in more recent sediments (from ∼12 to 16 ng g−1) and mussels (8-fold increase from ∼0.12 to 0.80 ng g−1) covering the past 25 years reflect the overall evolution of Pt demand in Europe (∼20-fold increase for vehicle catalysts in 20 years). Spatial biomonitoring of Pt in mussels along the northwestern Mediterranean coast is assumed to reflect inter-site differences of Pt exposure (0.09–0.66 ng g−1) despite seasonal effect on tissue development. This study highlights the need for thorough and regular monitoring of Pt levels in sediments and biota from urbanized coastal areas in order to better assess the environmental impact of this TCE, including potential risks for marine organisms. © 2018

International audience; Many of the freshwater Kd values required for quantifying radionuclide transfer in the environment (e.g. ERICA Tool, Symbiose modelling platform) are either poorly reported in the literature or not available. To partially address this deficiency, Working Group 4 of the IAEA program MODARIA (2012–2015) has completed an update of the freshwater Kd databases and Kd distributions given in TRS 472 (IAEA, 2010). Over 2300 new values for 27 new elements were added to the dataset and 270 new Kd values were added for the 25 elements already included in TRS 472 (IAEA, 2010). For 49 chemical elements, the Kd values have been classified according to three solid-liquid exchange conditions (adsorption, desorption and field) as was previously carried out in TRS 472. Additionally, the Kd values were classified into two environmental components (suspended and deposited sediments). Each combination (radionuclide x component x condition) was associated with log-normal distributions when there was at least ten Kd values in the dataset and to a geometric mean when there was less than ten values. The enhanced Kd dataset shows that Kd values for suspended sediments are significantly higher than for deposited sediments and that the variability of Kd distributions are higher for deposited than for suspended sediments. For suspended sediments in field conditions, the variability of Kd distributions can be significantly reduced as a function of the suspended load that explains more than 50% of the variability of the Kd datasets of U, Si, Mo, Pb, S, Se, Cd, Ca, B, K, Ra and Po. The distinction between adsorption and desorption conditions is justified for deterministic calculations because the geometric means are systematically greater in desorption conditions. Conversely, this distinction is less relevant for probabilistic calculations due to systematic overlapping between the Kd distributions of these two conditions. © 2018

International audience; This paper presents an approach aimed at assessing multiple criteria spatial risk, where several methods are used for decision aiding purposes, with an application on marine nuclear releases. The case study simulates a post-accident analysis evaluating the impact upon the bay of Toulon of an accidental nuclear release. The problem is characterized by the presence of spatial features, multiple criteria describing the involved assets and uncertainties represented through multiple release scenarios and their corresponding probabilities.

International audience; The database for hydrological observatories (BDOH) is an efficient tool for storage which allows the combination of water discharge data, suspended particulate matter (SPM) and particulate contaminants concentrations, produced thought a same observatory network, to calculate time series fluxes. This application is used in the Rhone Sediment Observatory (OSR) program to estimate SPM and their associated contaminants fluxes along the Rhone River and its main tributaries. However, incomplete time series need to be filled prior to computation in BDOH. Hence, a sensitivity test was run to evaluate the effect of different estimation methods of SPM concentration and particulate mercury time series on final instantaneous and accumulated fluxes on the Rhone River at the two main stations of the OSR network (Jons and Arles). The results demonstrate that the differences between SPM and particulate mercury annual fluxes assessed with different estimation methods are less than 5%. However, at monthly scale, estimation methods can create higher differences (26-51%). In the future, these preliminary results will be completed with the estimation of the uncertainties associated with particle flux measurements.; La Base de Données pour les Observatoires en Hydrologie (BDOH) est un outil de bancarisation qui permet de combiner les mesures de débit, de matières en suspension (MES) et de contaminants particulaires issues d'un même réseau de stations pour calculer des chroniques de flux instantanés et cumulés. Cette application est utilisée dans le cadre de l'Observatoire des Sédiments du Rhône (OSR) pour estimer les flux de MES et de contaminants associés (Hg, PCB,...) en transit dans le Rhône et ses principaux affluents. Cependant, avant le calcul de ces chroniques, les données mères lacunaires doivent être reconstituées. Un test de sensibilité a été mené afin d'évaluer l'impact de différentes méthodes d'estimation des chroniques de concentrations en MES et en Hg particulaire sur les calculs de flux instantanés et cumulés dans le Rhône aux deux stations principales de l'OSR (Jons et Arles). Les résultats montrent que, quelle que soit la méthode d'estimation utilisée, les flux annuels de MES et de Hg particulaire ne diffèrent pas plus de 5 %. A l'échelle mensuelle, en revanche, les différentes méthodes génèrent des variabilités plus élevées (26-51 %). En perspective, ces premiers résultats seront complétés par l'évaluation des incertitudes quantitatives sur les calculs de flux particulaires.

International audience; Tritium (3H) is a radioactive isotope of hydrogen. In the environment, the most common form of tritium is tritiated water (HTO). However, tritium can also be incorporated into organic molecules, forming organically bound tritium (OBT). The present study characterized the effects of tritium on the health of the fathead minnow, Pimephales promelas. Fish were exposed to a gradient of HTO (activity concentrations of 12,000, 25,000 and 180,000 Bq/L) and OBT using food spiked with tritiated amino acids (OBT only, with an activity concentration of 27,000 Bq/L). A combined exposure condition where fish were placed in 25,000 Bq/L water and received OBT through feed was also studied. Fish were exposed for 60 days, followed by a 60 day depuration period. A battery of health biomarkers were measured in fish tissues at seven time points throughout the 120 days required to complete the exposure and depuration phases. HTO and OBT were also measured in fish tissues at the same time points. Results showed effects of increasing tritium activity concentrations in water after 60 days of exposure. The internal dose rates of tritium, estimated from the tissue free-water tritium (TFWT) and OBT activity concentrations, reached a maximum of 0.65 µGy/h, which is relatively low considering background levels. No effects were observed on survival, fish condition, and metabolic indices (gonado-, hepato- and spleno- somatic indexes (GSI, HSI, SSI), RNA/DNA and proteins/DNA ratios). Multivariate analyses showed that several biomarkers (DNA damages, micronucleus (MN) frequency, brain acetylcholinesterase (AChE), lysosomal membrane integrity (LMI), phagocytosis activity and reactive oxygen species (ROS) production) were exclusively correlated with fish tritium internal dose rate, showing that tritium induced genotoxicity, as well as neural and immune responses. The results were compared with another study on the same fish species where fish were exposed to tritium and other contaminants in natural environments. Together with the field study, the present work provides useful data to identify biomarkers for tritium exposure and better understand modes of action of tritium on the fathead minnow.

[Departement_IRSTEA]Eaux [ADD1_IRSTEA]Hydrosystèmes et risques naturels [ADD2_IRSTEA]Systèmes aquatiques soumis à des pressions multipleshttps://archives-publications.inrae.fr/pub00058048.pdf; International audience; The increasing need on energy and fluvial transport due to industrialization during the last century resulted in the construction of infrastructures along rivers, as dams or sluices. Thus, nineteen hydro-electrical dams were built along the Rhône River (France) since 1950. To improve the production of electricity and avoid problems due to sediment storage within these infrastructures, dam flushing operations are organized periodically. It has been demonstrated by numerous studies that several contaminants are strongly fixed to suspended particulate matters (SPM), especially the finest, and may be dispersed during flushing operations. Investigations were conducted in the upper Rhône River to evaluate the impact of dam flushing operations on suspended sediment and associated contaminants (metals, organic contaminants and radionuclides) concentrations and fluxes. The releases took about three weeks in June 2012, and almost fifty suspended sediment samples were collected at six stations along the upper Rhône River. Results demonstrated that suspended sediment concentration and flux were very high in the vicinity of the dam, but most of the sediments were stored in the upper part of the river. Thus, fluxes registered at other stations (approx. 100km downstream) were similar to those observed during flood events. For most of the contaminants (Polychlorobiphenyls-101 (PCB101), Cu, Hg . . . ), concentrations were lower during dam flushing periods than during flood events or normal flow condition. This difference could be explained by particulate organiccarbon (POC) concentrations that were also lower. Only Benzo[a]Pyrene had concentrations significantly higher (+ 50%). Spatial trend demonstrate an increase for all contaminants at the exception of PCB101 that remained constant with distance from upstream dams. Those variations may be related to POC, particle sizes, or additional source of contaminants such as industries or other tributaries. Finally, dam flushing fluxes of contaminants were similar to flood-related fluxes and represent a non-negligible part of the annual fluxes. In 2012, 36% of the annual flux of sediments were transported during this flushing event.

International audience; Artificial radionuclides are commonly observed in the environment due to their authorized releases by the nuclearindustry, atmospheric fallouts from past events (nuclear weapon testing, Chernobyl and Fukushima accidents) andother accidental releases. Wildlife is chronically exposed to the associated ionizing radiation, leading to the needof demonstration of the level of radiological risk for fauna and flora. Investigations was conducted according to therecommendations and guidance provided by the International Commission on Radiological Protection (ICRP) tocharacterize ecological impact of the presence of such artificial radionuclides in the Rhône River (France). First,radionuclides doses were estimated using the ERICA Assessment Tool at a monitoring station near the outlet of theRhône River at Arles. Second, an integrated ecological risk assessment was conducted on current liquid releases ofthe 4 Nuclear Power Plants (NPP) located along the river. This second approach deals specifically with the problemof mixtures of radioactive substances and chemicals.Monitoring results related to particulate and dissolved concentrations were available at Arles from 2006 to 2013with at least representative monthly concentration for anthropogenic radionuclides. Dose rate estimation was conductedfor the Reference Organisms defined in the ERICA Tool. Results demonstrated that doses resulting fromartificial radionuclides (137Cs, 54Mn, 110mAg, 60Co. . . ) were significantly lower than the expected backgrounddose rate and the PNEDR (Predicted No-Effect Dose Rate - 10μGh.h-1). The higher dose rates were estimated forinsect larvae (0.01μGy.h-1) and the lower for phytoplankton (0.0001μGy.h-1).A multiple stressors approach was conducted using Species Sensitivity Distributions (SSD) in combination withmixture models (concentration addition (CA) and independent action (IA)). This approach allowed the derivationof an integrated proxy of the ecological impact of radioactive and stable stressors, the so-called msPAF (multisubstancesPotentially Affected Fraction of species). The msPAF results indicated a negligible potential ecologicalrisk in the context of routine effluents from nuclear plants, with a higher contribution of ionizing radiation to theoverall impact compared to the 8 stable chemicals considered.

International audience; Evaluating the sources of nutrient inputs to coastal lagoons is required to understand the functioning of these ecosystems and their vulnerability to eutrophication. Whereas terrestrial groundwater processes are increasingly recognized as relevant sources of nutrients to coastal lagoons, there are still limited studies evaluating separately nutrient fluxes driven by terrestrial groundwater discharge and lagoon water recirculation through sediments. In this study, we assess the relative significance of these sources in conveying dissolved inorganic nutrients (NO3−, NH4+ and PO43−) to a coastal lagoon (La Palme lagoon; France, Mediterranean Sea) using concurrent water and radon mass balances. The recirculation of lagoon water through sediments represents a source of NH4+ (1900–5500 mol d−1) and PO43− (22–71 mol d−1), but acts as a sink of NO3−. Estimated karstic groundwater-driven inputs of NO3−, NH4+ and PO43− to the lagoon are on the order of 200–1200, 1–12 and 1.5–8.7 mol d−1, respectively. A comparison between the main nutrient sources to the lagoon (karstic groundwater, recirculation, diffusion from sediments, inputs from a sewage treatment plant and atmospheric deposition) reveals that the recirculation of lagoon water through sediments is the main source of both dissolved inorganic nitrogen (DIN) and phosphorous (DIP) to La Palme lagoon. These results are in contrast with several studies conducted in systems influenced by terrestrial groundwater inputs, where groundwater is often assumed to be the main pathway for dissolved inorganic nutrient loads. This work highlights the important role of lagoon water recirculation through permeable sediments as a major conveyor of dissolved nutrients to coastal lagoons and, thus, the need for a sound understanding of the recirculation-driven nutrient fluxes and their ecological implications to sustainably manage lagoonal ecosystems.

International audience; Ecological risk assessment has globally become the basis for environmental decision-making within government and industry for chemical substances. Regarding radioactive substances, recently revised International and European Basic Safety Standards are pushing the development of memberstate policy on environmental regulation in the field of radiological protection. Within this framework, existing derived effect benchmarks for ionising radiation and non-human species need to be more robust to reinforce their credibility when used as levels of exposure considered to be safe for the environment. Actually, the derivation of such benchmarks has mainly relied on laboratory studies from a limited number of species. Moreover lab species would be apparently less radiosensitive than for example terrestrial wildlife chronically exposed to ionising radiation in the Chernobyl Exclusion Zone. Additionally to the results of such comparison that still need to be confirmed, another way to challenge benchmarks is to improve the quality/quantity of radiotoxicity data constituting the basis for a statistically-based comparison. This is the major focus of this paper where we demonstrate through various examples how to make the comparison more robust (i) by analysing the discrepancy between lab and field at the taxonomic level rather than at the ecosystem level,(ii) by extending the knowledge base making use of acute radiotoxicity data,(iii) by identifying environmenta lfactors modifying radiological dose-effect relationship in the field.

This study presents a specifically designed Mercury module in a coupled benthic-pelagic reactive-transport model - Bottom RedOx Model (BROM) that allows to study mercury (Hg) biogeochemistry under different conditions. This module considers the transformation of elemental mercury (Hg(O)), divalent mercury (Hg(II)) and methylmercury (MeHg). The behavior of mercury species in the model is interconnected with changes of oxygen, hydrogen sulfide, iron oxides, organic matter, and biota. We simulated the transformation and transport of Hg species in the water column and upper sediment layer under five different scenarios, combining various levels of oxygenation and trophic state in the Berre lagoon, a shallow eutrophic lagoon of the French Mediterranean coast subjected to seasonal anoxia. The first scenario represents the conditions in the lagoon that are compared with experimental data. The four other scenarios were produced by varying the biological productivity, using low and high nutrient (N and P) concentrations, and by varying the redox conditions using different intensity of vertical mixing in the water column. The results of the simulation show that both oxidized and reduced sediments can accumulate Hg, but any shifts in redox conditions in bottom water and upper sediment layer lead to the release of Hg species into the water column. Eutrophication and/or restricted vertical mixing lead to reducing conditions and intensify MeHg formation in the sediment with periodic release to the water column. Oxygenation of an anoxic water body can lead to the appearance of Hg species in the water column and uptake by organisms, whereby Hg may enter into the food web. The comparison of studied scenarios shows that a well-oxygenated eutrophic system favors the conditions for Hg species bioaccumulation with a potential adverse effect on the ecosystem. The research is relevant to the UN Minimata convention, EU policies on water, environmental quality standards and Mercury in particular. VISTA - a basic research program Norwegian Academy of Science and Letters 6164 Statoil 6164 project PREDHYPO A*MIDEX project - Investissements d'Avenir French Government program ANR-11-IDEX-0001-02 Norwegian Research Council SKATTEfunn project Aquatic Modeling Tools 272749 NILU CIMA IMBER Future Earth Coasts Future Earth Ocean KAN info:eu-repo/semantics/publishedVersion

[Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAU; International audience; The database for hydrological observatories (BDOH) is an efficient tool for storage which allows the combination of water discharge data, suspended particulate matter (SPM) and particulate contaminants concentrations, produced thought a same observatory network, to calculate time series fluxes. This application is used in the Rhône Sediment Observatory (OSR) program to estimate SPM and their associated contaminants fluxes along the Rhône River and its main tributaries. However, incomplete time series need to be filled prior to computation in BDOH. Hence, a sensitivity test was run to evaluate the effect of different estimation methods of SPM concentration and particulate mercury time series on final instantaneous and accumulated fluxes on the Rhône River at the two main stations of the OSR network (Jons and Arles). The results demonstrate that the differences between SPM and particulate mercury annual fluxes assessed with different estimation methods are less than 5%. However, at monthly scale, estimation methods can create higher differences (26-51%). In the future, these preliminary results will be completed with the estimation of the uncertainties associated with particle flux measurements.; La Base de Données pour les Observatoires en Hydrologie (BDOH) est un outil de bancarisation qui permet de combiner les mesures de débit, de matières en suspension (MES) et de contaminants particulaires issues d’un même réseau de stations pour calculer des chroniques de flux instantanés et cumulés. Cette application est utilisée dans le cadre de l’Observatoire des Sédiments du Rhône (OSR) pour estimer les flux de MES et de contaminants associés (Hg, PCB, …) en transit dans le Rhône et ses principaux affluents. Cependant, avant le calcul de ces chroniques, les données mères lacunaires doivent être reconstituées. Un test de sensibilité a été mené afin d’évaluer l’impact de différentes méthodes d’estimation des chroniques de concentration en MES et en Hg particulaire sur les calculs de flux instantanés et cumulés dans le Rhône aux deux stations principales de l’OSR (Jons et Arles). Les résultats montrent que, quelle que soit la méthode d’estimation utilisée, les flux annuels de MES et de Hg particulaire ne diffèrent pas plus de 5%. A l’échelle mensuelle, en revanche, les différentes méthodes génèrent des variabilités plus élevées (26-51%). En perspective, ces premiers résultats seront complétés par l’évaluation des incertitudes quantitatives sur les calculs de flux particulaires.

L’action B1 de l’Observatoire des Sédiments du Rhône (OSR5) vise à pérenniser le réseau de suivi des flux de matières en suspension (MES) et de contaminants associés. Ce rapport dresse le bilan des avancées réalisées sur l’ensemble du réseau en 2019 en termes de stations actives, de prélèvements de MES et d’analyses physico-chimiques, ainsi que sur les calculs de flux de contaminants dans la Base de Données des Observatoires en Hydrologie (BDOH). L’année 2019 a été marquée par la première année d’exploitation de la station de mesure sur le Rhône à Saint-Vallier, avec l’acquisition de données de débit et de turbidité par la CNR. Par ailleurs, un piège à particules a été installé en amont, au niveau du village d’Andancette, depuis fin 2018. Aussi, en 2019, une nouvelle méthode de bancarisation et de stockage des échantillons a été mise en place, avec l’acquisition d’une enceinte -80°C et l’utilisation de la plateforme Banquise.