Distribution and geochemical behaviour of antimony in the Gironde Estuary A first qualitative approach to regional nuclear accident scenarios

International audienceAntimony (Sb) is a highly toxic trace element for which environmental biogeochemical cycles are still relatively poorly known, especially in coastal aquatic systems. In addition, Sb is a fission product in nuclear power plants (NPPs), presenting non-negligible decay and consecutive exposition rates over short to mean terms (i.e., 125Sb isotope half-life of 2.76 years). Understanding the environmental behaviour and fate of natural stable isotopes and combining this with intrinsic properties of the respective radionuclides (e.g. half-life) is essential to predict the environmental fate and potential dispersion of radioisotopes before accidental NPP events. In the present work, the distribution and geochemical behaviour of stable Sb are determined for the first time in the highly turbid Gironde Estuary. Both dissolved and particulate concentrations along the estuarine salinity and turbidity gradients were quantified during low, intermediate and high freshwater discharges. Results clearly suggest that long residence times within the salinity and turbidity gradients favour the observed non-conservative, additive behaviour of Sb. Distribution coefficients (log10 Kd ≈ 3.5–4.4 l kg− 1) indicate that in the Maximum Turbidity Zone (MTZ; SPM ~ 1000 mg l− 1) ~ 90% of total Sb occurs in the particulate phase, compared to only ~ 10% in the less turbid portions of the estuary (SPM ≤ 100 mg l− 1). We propose a first/broad qualitative approximation (scenarios) to possible behaviour and dispersion of Sb radionuclides in case of accidental release from the Blayais NPP located on the Gironde Estuary. Our results suggest that the hydrological situation and the position of the MTZ during a potential accident can be primordial to residence time and distribution pathways in the estuary. We estimate that (i) high river discharge and a downstream position of the MTZ may favour Sb radionuclide adsorption onto particles, implying long (months to years) residence times in the estuary and a high risk of seasonal upstream transport into the city of Bordeaux, whereas (ii) under low discharge conditions, dissolved Sb species will predominate implying rapid transport and higher dispersion along the coast. © 2016 Elsevier B.V

Estuarine dissolved speciation and partitioning of trace metals: a novel approach to study biogeochemical processes

Estuaries are complex systems involving numerous biogeochemical gradients and processes that influence the behavior of trace metals. Lead (Pb), cadmium (Cd), and copper (Cu) speciation and partitioning were studied in the Gironde Estuary (SW France), using a multi-method approach in which data from innovative sensors and laboratory-based techniques were combined. For the first time in this system, the so-called dynamic fractions of the target metals (dissolved forms that are potentially bioavailable) were recorded on-board through voltammetry using unique antifouling gel-integrated microelectrode arrays (GIME) incorporated in a submersible sensing probe (TracMetal). Trace metals in the operationally defined dissolved <0.2 μm and <0.02 μm fractions, as well as complexed with suspended particles (collected after centrifugation) were quantified through sampling/laboratory-based techniques. High spatial resolution trace metal concentrations were monitored along the salinity gradient (S = 0.10 to S = 34.0) together with master bio-physicochemical parameters providing robust cruise-specific information on how well-known abiotic and biotic processes control the Gironde estuarine trace element partitioning, (i.e. conservative behavior, addition/removal). Combining conventional methods with GIME measurements showed: (i) the dominance of Cd dynamic species in the intra-estuarine total dissolved fraction (up to 90%), (ii) the importance of small colloids as trace metal carrier phases, desorbing and complexing dynamic fractions of Pb and Cu, and (iii) the potential influence of photo-redox processes remobilizing Pb under their dynamic forms (up to 80%). Data also suggest trace metal release/sorption by phytoplankton with an increase of dissolved Cu concentrations in the riverine branch, as well as Cu and Cd particulate concentrations showing higher levels towards productive coastal waters. This complete approach allowed to monitor key estuarine biogeochemical processes and highlighted the valuable use of the TracMetal to record subtle variations of potentially bioavailable dissolved metal fractions

Platinum in sediments and mussels from the northwestern Mediterranean coast: temporal and spatial aspects

International audiencePlatinum (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 plasmamass 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 intersite differences of Pt exposure (0.09e0.66 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

Platinum - an emerging contaminant in estuarine/coastal systems

2 pages.-- XV International Estuarine Biogeochemistry Symposium, Vigo, June 04-05 2019Continuously increasing mining, use and release of Technology Critical Elements (TCE) pose growing concerns regarding their environmental dispersion, fate, and ecotoxicology. Among them, platinum (Pt) still is an emerging contaminant applied in various relatively recent applications, including car catalytic converters (vehicle emission control) as well as anti-cancer drugs. Environmental Pt levels, its behaviour and reactivity in aquatic systems remain widely unknown, especially in estuarine/coastal environments that are under high anthropogenic pressure. Analytical challenges in terms of sensitivity and interference control required for Pt ultra-trace detection in marine matrices may explain such general lack of information. The inexistence of Certified Reference Materials is an additional problem. The present work presents Inter-comparison and validation of optimised Adsorptive Cathodic Stripping Voltammetry (Ad-CSV) and Inductively Coupled Plasma- Mass Spectrometry (ICP-MS) methods for Pt measurements in marine bivalves. Field monitoring studies on Pt biogeochemistry have been performed in key estuarine/coastal European systems, including Pt distribution between seawater, particles, and living organisms. Historical Pt contamination in a major fluvial-estuarine system and a highly urbanized harbour reflects past contamination and currently increasing Pt levels. Spatial biomonitoring in marine bivalves from contrasting areas along urbanized coastlines suggests a relation between the degree of “urban exposure” and Pt concentrations in soft tissues. While wild bivalves prove to be good biomonitors of Pt contamination, Pt in coastal water may have the potential to serve as a tracer of modern urban (medical, traffic) sources. Field observations suggest that biogeochemical processes leading to changes in Pt partitioning and carrier phases at short temporal scale may enhance its bioavailability, including in phytoplankton, and ultimately induce toxic effects on marine organismsThis work has greatly benefited from support by the FEDER Aquitaine-1999-Z0061, the COST Action TD1407, and the EU FP7 Ocean 2013.2 Project SCHeMA (Project-Grant Agreement 614002), which is gratefully acknowledgedPeer reviewe

Bioaccumulation of chromium in aquatic macrophyte Borreria scabiosoides Cham. & Schltdl.

International audienceThe capacity of Borreria scabiosoides Cham. & Schltdl. growing in hydroponics solutions to remove Cr (III) from water was evaluated. This macrophytes efficiently removed Cr from water at concentrations of 25 and 50 mg/l Cr−1. High resolution imaging secondary ion mass-spectrometry (HRI-SIMS) measurements were performed using scanning ion microprobe at the University of Chicago (UC-SIM). The inductively coupled plasma sector type mass spectrometer (HR-ICP-MS) was used to analyse all samples. In general, plant roots exhibited higher metal concentrations than the aerial plants parts. Borreria shows promise for the removal and store Cr from contaminated wastewater. The ion images demonstrated that Cr is preferentially accumulated in cell walls and in some vacuoles of cortical roots cells. The number of Cr deposits are higher in cortical parenchyma, particularly in vacuoles and cell walls, compared to stellar tissue

Impact écotoxicologiques et économiques des phénomènes de sous-oxygénation et de pollution des estuaires sur l'anguille européenne (Anguilla anguilla)?

International audienc