Strengths of ecosystem services concept for radiation protection.

The successful ecosystem services concept, defined as the benefits people obtain from ecosystems is still not really reflected in the current approaches for protecting public and environment against radiation promoted by the International Commission on Radiological Protection or other similar approaches. Yet some recent thoughts from international organizations lead us to believe that an eco-based approach could be more promoted in the coming years in environmental radiation protection field. The French Institute for Radiation Protection and Nuclear Safety has identified different fields of application of this concept into radiation protection, in line with its integrated approach of radiological risks management. As the ecosystem services approach makes it possible to highlight biophysical and socio-economic approaches of the impacts of ionizing radiation on ecosystems, it represents a subject of primary importance for future works conducted by IRSN. However, the operationality of the ecosystem services concept is the subject of many debates. In many situations, scientists have not yet fully understood how radioactive contamination could affect ecosystem services, and how to articulate with certainty cause and effect relationships between state of an ecosystem and provision of services. In addition, the concept is also accompanied by contradictory perceptions of the status of humans in ecosystems. To solve these knowledge gaps and uncertainties, it is necessary to acquire robust data on the impacts of radiation on ecosystems both under experimental and realistic conditions, and to integrate all potential consequences (direct and indirect, ecotoxicological but also economic and cultural).

Contamination of planktonic food webs in the Mediterranean Sea: Setting the frame for the MERITE-HIPPOCAMPE oceanographic cruise (spring 2019).

This paper looks at experiential feedback and the technical and scientific challenges tied to the MERITE-HIPPOCAMPE cruise that took place in the Mediterranean Sea in spring 2019. This cruise proposes an innovative approach to investigate the accumulation and transfer of inorganic and organic contaminants within the planktonic food webs. We present detailed information on how the cruise worked, including 1) the cruise track and sampling stations, 2) the overall strategy, based mainly on the collection of plankton, suspended particles and water at the deep chlorophyll maximum, and the separation of these particles and planktonic organisms into various size fractions, as well as the collection of atmospheric deposition, 3) the operations performed and material used at each station, and 4) the sequence of operations and main parameters analysed. The paper also provides the main environmental conditions that were prevailing during the campaign. Lastly, we present the types of articles produced based on work completed by the cruise that are part of this special issue.

Sediment pollution: An assessment of anthropogenic and geogenic trace element contributions along the central Algerian coast.

Sediment cores from the central Algerian coast were collected to investigate the distribution, sources and risk of trace metals. The local geochemical background of metals was defined from the core S collected in an uncontaminated area of the coast. The anthropogenic inputs in Algiers Bay elevated Ag, Cd, Pb and Zn concentrations as their maximum were 3.1, 3, 2.1 and 1.8 times the background values, respectively. Meanwhile, increased contents of Arsenic (up to 21.1 mg/kg) were detected in all sites. Correlations and PCA suggest that lithogenic sources controlled metal deposition, while most sediment arsenic was agriculture-derived. Organic matter acted as a sink or source for some trace metals. According to EFs, the study area showed slight to moderate enrichment with respect to Ag, As, Pb, Cd, Zn and Cu, whereas they remained uncontaminated with Cr, V, Co and Ni. This study provides a needed baseline for future environmental investigations.

Distribution and accumulation of metals and metalloids in planktonic food webs of the Mediterranean Sea (MERITE-HIPPOCAMPE campaign).

Particle-size classes (7 fractions from 0.8 to 2000 µm) were collected in the deep chlorophyll maximum along a Mediterranean transect including the northern coastal zone (bays of Toulon and Marseilles, France), the offshore zone (near the North Balearic Thermal Front), and the southern coastal zone (Gulf of Gabès, Tunisia). Concentrations of biotic metals and metalloids (As, Cd, Cr, Cu, Fe, Mn, Ni, Sb, V, Zn) bound to living or dead organisms and faecal pellets were assessed by phosphorus normalisation. Biotic metals and metalloids concentrations (except Cr, Mn, and V) were higher in the offshore zone than in the coastal zones. In addition, biotic Sb and V concentrations appeared to be affected by atmospheric deposition, and biotic Cr concentrations appeared to be affected by local anthropogenic inputs. Essential elements (Cd, Cu, Fe, Mn, Ni, V, Zn) were very likely controlled both by the metabolic activity of certain organisms (nanoeukaryotes, copepods) and trophic structure. In the northern coastal zone, biomagnification of essential elements was controlled by copepods activities. In the offshore zone, metals and metalloids were not biomagnified probably due to homeostasis regulatory processes in organisms. In the southern coastal zone, biomagnification of As, Cu, Cr, Sb could probably induce specific effects within the planktonic network.

Occurrence, contamination level and ecological risk assessment of dissolved and particulate trace elements in rivers entering the southwestern Mediterranean Sea.

Metal pollution in rivers should not be overlooked before their entry into the sea. However, there are few studies for estimating such contamination in rivers entering the Algerian coastal waters. Semimonthly quantification of dissolved and particulate metals, near the mouths of two industrial-tainted rivers, El Harrach and Mazafran rivers, was carried out during a period of one year. All the trace metals analyzed are originating from anthropogenic sources (EF > 1.5), with higher contamination of dissolved Pb, Cd, Zn and Ni and a slight degree of contamination of particulate Cu and Zn (0 < Igeo < 1). Particulate metals show a stable complex with the particulate phase (e.g. 2 < LogKd < 6). The risk assessment results indicate that particulate Pb and Zn have a 33% likelihood of toxicity for adverse biological effects. A significant toxicity effect (ΣTUi >4) of the combined particulate metals (Pb, Cd, Cu, Zn, Cr, Ni and As) was primarily due to the higher particulate Cd, Zn, and Cr availability.

Hydro-climatic drivers of land-based organic and inorganic particulate micropollutant fluxes: The regime of the largest river water inflow of the Mediterranean Sea.

Land-based micropollutants are the largest pollution source of the marine environment acting as the major large-scale chemical sink. Despite this, there are few comprehensive datasets for estimating micropollutant fluxes released to the sea from river mouths. Hence, their dynamics and drivers remain poorly understood. Here, we address this issue by continuous measurements throughout the Rhône 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 fluxes for a wide range of micropollutants (n = 29) over a long-term period (2008-2018). We argue that almost two-thirds of annual micropollutant fluxes are released to the Mediterranean Sea during three short-term periods over the year. The watershed hydro-climatic heterogeneity determines this dynamic by triggering seasonal floods. Unexpectedly, the large deficit of the inter-annual monthly micropollutant fluxes inputs (tributaries and the Upper Rhône River) compared to the output (Beaucaire station) claims for the presence of highly contaminated missing sources of micropollutants in the Rhône River watershed. Based on a SPM-flux-averaged micropollutant concentrations mass balance of the system and the estimates of the relative uncertainty of the missing sources concentration, we assessed their location within the Rhône 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 Rhône River valley, and the unmonitored Cevenol tributaries.

Impact of dam flushing operations on sediment dynamics and quality in the upper Rhône River, France.

The Rhône 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 Rhône 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.

Organic Copper Speciation by Anodic Stripping Voltammetry in Estuarine Waters With High Dissolved Organic Matter.

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 logK Cu,1 = 9.6 ± 0.2-10.8 ± 0.6 and logK Cu,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.

Assessing UV filter inputs into beach waters during recreational activity: A field study of three French Mediterranean beaches from consumer survey to water analysis.

In order to assess the release of UV filters from the sunscreen used by beachgoers into seawater within the bathing zone, a field campaign was carried out during the summer of 2017 at three beaches in Marseille, along the French Mediterranean coast. A social survey analyzed beachgoer attendance, the quantities and types of suncare products used and the bathing frequencies, while the bathing water was analyzed spatially and temporally so as to quantify both mineral and organic UV filters directly released and recovered. During the peak recreational time at the three beaches, both mineral and organic UV filters were detected in higher concentrations in the bathing area than offshore. In general, higher concentrations were recovered in the water top surface layer than in the water column, giving respectively 100-900 and 20-50 µg/L for TiO2, 10-15 and 1-3 µg/L for ZnO, 40-420 and 30-150 ng/L for octocrylene, and 10-15 and 10-350 ng/L for avobenzone. More than 75% of the 471 interviewees reported bathing every time they go to the beach, with 68% using a suncare product 2.6 times on average. From these data we estimated that an average mass of 52 kg/day or 1.4 t/month of suncare products are possibly released into bathing water for a beach attended by 3000 people daily. The mass ratio of UV filters in such products typically ranges from 0.03 to 0.1, allowing us to propose theoretical maximum concentrations in the beach water. Our recovery of measured UV filter concentrations in seawater compared to the theoretical concentrations revealed two distinct scenarios for the mineral and organic filters. While up to 49% of the mineral filters used by beachgoers may be released into the seawater, the organic filters were minimally recovered in the environment, most likely due to internalization through the skin barrier or partial photodegradation.

Patterns of trace metal bioaccumulation and trophic transfer in a phytoplankton-zooplankton-small pelagic fish marine food web.

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.

Modelling geochemical and kinetic processes involved in lead (Pb) remobilization during resuspension events of contaminated sediments.

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.

How to assess trace elements bioavailability for benthic organisms in lowly to moderately contaminated coastal sediments?

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.

Groundwater-driven nutrient inputs to coastal lagoons: The relevance of lagoon water recirculation as a conveyor of dissolved nutrients.

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.

210Po and 210Pb trophic transfer within the phytoplankton-zooplankton-anchovy/sardine food web: a case study from the Gulf of Lion (NW Mediterranean Sea).

The transfer of (210)Po and (210)Pb in the food web of small pelagic fishes (from phytoplankton and zooplankton to anchovy Engraulis encrasicolus and sardine Sardina pilchardus) is investigated in the Gulf of Lion (GoL). We present original data of (210)Po and (210)Pb activity concentrations, C and N stable isotope ratios, measured (i) from different size classes of phytoplankton and zooplankton during spring and winter in different environments of the GoL, and (ii) in two fish species. Significant spatial patterns based on (210)Po, (210)Pb activity concentrations and (210)Po/(210)Pb ratios in the different plankton size classes are evidenced by hierarchical clustering, both in spring and winter. This variability, also observed for C and N stable isotopes ratios, is connected to local specific pelagic habitats and hydrodynamics. The sampling strategy suggests that (210)Po bioaccumulation in the GoL remains at a constant level from the first (dominated by phytoplankton) to the second trophic level (zooplankton), while (210)Pb bioaccumulation shows an increase in winter. Based on stable N isotope ratios and (210)Po activity concentrations measured in anchovies and sardines, we evidence (210)Po bio-magnification along the trophic food web of these two planktivorous pelagic fishes.

Rare earth element distributions and fractionation in plankton from the northwestern Mediterranean Sea.

Rare earth element (REE) concentrations were measured for the first time in plankton from the northwestern Mediterranean Sea. The REE concentrations in phytoplankton (60-200 µm) were 5-15 times higher than those in four size fractions of zooplankton: 200-500 µm, 500-1000 µm, 1000-2000 µm and >2000 µm. The concentrations within these zooplankton fractions exhibited the same ranges with some variation attributed to differences in zooplankton taxonomy. The REE concentrations in plankton were poorly related to the reported REE concentrations of seawater, but they correlated well with the calculated REE(3+), concentrations especially with regard to middle REE (MREEs) and heavy REEs (HREEs). Plankton and seawater revealed different PAAS-normalised REE distributions, with the greatest differences observed in the light REEs. Interestingly, a comparison of PAAS-normalized sediment particles from the study of Fowler et al. (1992) showed concentrations of the same order of magnitude and a similar REE distribution without MREE enrichment. Based on this comparison, we propose a conceptual model that emphasizes the importance of biological scavenging of REEs (especially LREEs) in surface waters.

Tritium and 14C background levels in pristine aquatic systems and their potential sources of variability.

Tritium and (14)C are currently the two main radionuclides discharged by nuclear industry. Tritium integrates into and closely follows the water cycle and, as shown recently the carbon cycle, as does (14)C (Eyrolle-Boyer et al., 2014a, b). As a result, these two elements persist in both terrestrial and aquatic environments according to the recycling rates of organic matter. Although on average the organically bound tritium (OBT) activity of sediments in pristine rivers does not significantly differ today (2007-2012) from the mean tritiated water (HTO) content on record for rainwater (2.4 ± 0.6 Bq/L and 1.6 ± 0.4 Bq/L, respectively), regional differences are expected depending on the biomass inventories affected by atmospheric global fallout from nuclear testing and the recycling rate of organic matter within watersheds. The results obtained between 2007 and 2012 for (14)C show that the levels varied between 94.5 ± 1.5 and 234 ± 2.7 Bq/kg of C for the sediments in French rivers and across a slightly higher range of 199 ± 1.3 to 238 ± 3.1 Bq/kg of C for fish. This variation is most probably due to preferential uptake of some organic carbon compounds by fish restraining (14)C dilution with refractory organic carbon and/or with old carbonates both depleted in (14)C. Overall, most of these ranges of values are below the mean baseline value for the terrestrial environment (232.0 ± 1.8 Bq/kg of C in 2012, Roussel-Debet, 2014a) in relation to dilution by the carbonates and/or fossil organic carbon present in aquatic systems. This emphasises yet again the value of establishing regional baseline value ranges for these two radionuclides in order to account for palaeoclimatic and lithological variations. Besides, our results obtained from sedimentary archive investigation have confirmed the delayed contamination of aquatic sediments by tritium from the past nuclear tests atmospheric fallout, as recently demonstrated from data chronicles (Eyrolle-Boyer et al., 2014a,b). Thus Sedimentary archives can be successfully used to reconstruct past (14)C and OBT levels. Additionally, sediment repositories potentially represent significant storages of OBT that may account for in case of further remobilisation. We finally show that floods can significantly affect the OBT and (14)C levels within suspended particles or sediments depending on the origin of particles reinforcing the need to acquire baseline value range at a regional scale.

Unexpected biotic resilience on the Japanese seafloor caused by the 2011 Tohoku-Oki tsunami.

On March 11(th), 2011 the Mw 9.0 2011 Tohoku-Oki earthquake resulted in a tsunami which caused major devastation in coastal areas. Along the Japanese NE coast, tsunami waves reached maximum run-ups of 40 m, and travelled kilometers inland. Whereas devastation was clearly visible on land, underwater impact is much more difficult to assess. Here, we report unexpected results obtained during a research cruise targeting the seafloor off Shimokita (NE Japan), shortly (five months) after the disaster. The geography of the studied area is characterized by smooth coastline and a gradually descending shelf slope. Although high-energy tsunami waves caused major sediment reworking in shallow-water environments, investigated shelf ecosystems were characterized by surprisingly high benthic diversity and showed no evidence of mass mortality. Conversely, just beyond the shelf break, the benthic ecosystem was dominated by a low-diversity, opportunistic fauna indicating ongoing colonization of massive sand-bed deposits.

Genotoxicity of sediment extracts of the Berre lagoon (France).

To evaluate the genotoxic risk that contaminated sediment could constitute for benthic organisms, three contaminated (VA, VC and VN) and one uncontaminated (RN) sediment samples were collected in the Berre lagoon (France). Potentially bioavailable contaminants in sediments were obtained using sediment extraction with synthetic seawater adjusted to pH 4 or pH 6, simulating the range of pH prevailing in the digestive tract of benthic organisms. The genotoxic activities of these extracts were evaluated by three short-term bioassays: the Salmonella mutagenicity test using the Salmonella typhimurium strain TA102, the alkaline comet assay and the micronucleus assay on the Chinese Hamster Ovary cells CHO-K1. Results of the Salmonella mutagenicity assay detected a mutagenic response for RN extract at pH 6, and for VA extract at pH 4. Results of the comet and micronucleus assays detected low genotoxic/clastogenic activities for VA and VC extracts at pH 6 and higher activities for RN, VA and VC extracts at pH 4. To identify if metals (Al, Fe, Mn, As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn) were involved in these genotoxic activities, their concentrations were determined in the extracts, and their speciation was assessed by thermodynamic calculations. Results showed that extracts from sites VA, VC and VN generally presented the highest trace metal contents for both extractants, while the site RN presented lower trace metal contents but the highest Fe and Mn contents. Thermodynamic calculations indicated that Fe, Mn, As and in a lower extend Co, Ni and Zn were mainly present under free forms in extracts, and were consequently, more likely able to induce a genotoxic effect. Results globally showed no correspondence between free metal contents and genotoxic activities. They suggested that these positive results could be due to uncharacterized compounds, acting as direct genotoxic agents or enhancing the genotoxic properties of analyzed metals.

Pan-derived isotopic composition of atmospheric vapour in a Mediterranean wetland (Rhône River Delta, France).

A continuous record of atmospheric vapour isotopic composition (delta(A)) can be derived from the isotope mass balance of a water body submitted to natural evaporation. In this paper, we present preliminary results of the application of this method to a drying evaporation pan, located in a Mediterranean wetland, during a two-month summer period. Results seem consistent with few atmospheric vapour data based on the assumption of isotopic equilibrium with precipitation, but we observed a shift between pan-derived delta(A) and the composition of vapour samples collected by cold trapping. These results suggest that further investigations are necessary to evaluate the effect of diurnal variations of atmospheric conditions on the applicability of the pan-evaporation method, and on the representative of grab atmospheric samples. We also propose a sensitivity analysis for evaluating the impact of the different measured components on delta(A) calculation, and show an improvement in the method efficiency as the pan is drying.