Copper addition by organic matter degradation in the freshwater reaches of a turbid estuary
This study reports on the relationship between copper (Cu) behavior and organic matter (OM) transformation along the turbidity gradient in the freshwater reaches of the Gironde Estuary. During a one-year survey, surface water and suspended particulate matter (SPM) were sampled at least monthly at three sites along the Garonne Branch, representing the main fluvial branch of the Gironde Estuary. Additionally, a longitudinal high resolution profile was sampled along the Garonne Branch, covering the turbidity gradient from the river water endmember to the maximum turbidity zone (MTZ). Seasonal variability and spatial distribution of Cu in both the dissolved phases (<0.2μm, Cu0.2 and <0.02μm, Cu0.02) and particulate Cu (CuP) clearly suggested Cu0.2 addition during summer, that increased the Cu0.2 concentrations by a factor ~2, mainly manifested by an increase in the Cu0.02 fraction. At the annual timescale (2004), this internal Cu reactivity increased Cu0.02 fluxes in the Garonne Branch by ~20% (3.6tyear-1), with the equivalent of ~2.9tyear-1 derived from the CuP fraction and ~0.7tyear-1 from the colloidal (0.02-0.2μm) fraction, without involving and/or affecting the CuC18 (hydrophobic metal-organic complexes) fraction.Combining data on Cu speciation with the results obtained by several independent techniques (DOC and POC measurements, 3D-fluorescence, and TEM) suggested close relationships between Cu behavior and OM transformation/restructuration along the turbidity gradient in the Garonne Branch. The observed Cu0.02 addition was related to increasing humification (humification index HIX increased from 9 to 12, network formation) and labile OM degradation (Iγ/Iα ratio decreased from 0.70 to 0.44), going along with decreasing DOC and POC concentrations. Mass-balances suggest that in the studied system, degradation of OM may account for the release of ~25μmol potentially bioaccessible Cu0.02 per mole of particulate organic carbon mineralized. \textcopyright 2011 Elsevier B.V.
(Science of the Total Environment. vol. 409, n° 0048-9697, pp. 1539--1549, 12/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UB
Contamination des mollusques bivalves par des phycotoxines : interactions entre niveaux de toxicité et réponses physiologiques
Résumé non disponible
(pp. 1-8, 12/04/2026)
PHYC, DYNECO, IFREMER, LEMAR, IRD, IFREMER, UBO EPE, CNRS, UEB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRM, IFREMER
Non-steady state modeling of early diagenetic processes following a major flood event in the Rhône prodelta (NW Mediterranean Sea, France)
(12/04/2026)
EDF R&D STEP, EDF R&D, EDF [E.D.F.], EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LPG-ANGERS, LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, IPGP, INSU - CNRS, UPD7, UR, IPG Paris, CNRS
Otolith microchemistry interrogation of comparative contamination by Cd, Cu and PCBs of eel and flounder, in a large SW France catchment
Individual European flounder and European eel levels of contamination by cadmium, copper and 7PCBs were related to their retrospective pattern of habitat use, using a combined toxicology and otolith microchemistry approach. The results showed that both species used the freshwater, the upper and lower estuarine habitats. There was a strong difference in the level of contamination of eel compared to flounder, with higher levels of PCBs, copper (Cu) and cadmium (Cd) in eel. The differences of contamination between muscle and liver were also specific to the considered species. The choice of the river habitat at an early age seemed to increase the risk of exposure to PCBs. The results suggested that the use of the upper estuary was related to a higher level of copper for both species and of PCBs for the flounder. The higher level of liver cadmium was measured for fish spending the longer time in the lower estuary.
(Estuarine, Coastal and Shelf Science. vol. 92, n° 0272-7714, pp. 332-338, 12/04/2026)
UR EPBX, CEMAGREF, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS
Anaerobic ammonium oxidation mediated by Mn-oxides: from sediment to strain level
Nitrite and N-29(2) productions in slurry incubations of anaerobically sediment after (NO3)-N-15 or (NH4)-N-15 labelling in the presence of Mn-oxides suggested that anaerobic Mn-oxides mediated nitrification coupled with denitrification in muddy intertidal sediments of Arcachon Bay (SW Atlantic French coast). From this sediment, bacterial strains were isolated and physiologically characterized in terms of Mn-oxides and nitrate reduction as well as potential anaerobic nitrification. One of the isolated strain, identified as Marinobacter daepoensis strain M4AY 14, was a denitrifier. Nitrous oxide production by this strain was demonstrated in the absence of nitrate and with Mn-oxides and NH4 amendment, giving indirect proof of anaerobic nitrate or nitrite production. Anaerobic Mn-oxide-mediated nitrification was confirmed by N-29(2) production in the presence of (NO3)-N-15 and (NH4)-N-14 under denitrifying conditions. Anaerobic nitrification by M4AY14 seemed to occur only in the absence of nitrate, or at nitrate levels lower than that of Mn-oxides. Most of the other isolates were affiliated with the Shewanella genus and were able to use both nitrate and Mn-oxides as electron acceptors. When both electron acceptors were present, whatever their concentrations, nitrate and Mn-oxide reduction co-occurred. These data indicate that bacterial Mn-oxide reduction could be an important process in marine sediments with low oxygen concentrations, and demonstrate for the first time the role of bacteria in anaerobic Mn-mediated nitrification. (C) 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.
(Research in Microbiology. vol. 162, n° 0923-2508, pp. 848-857, 12/04/2026)
MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, LMGEM, CNRS, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, LMGEM, CNRS, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, LMGEM, CNRS
Fate of arsenic-bearing phases during the suspended transport in a gold mining district (Isle river Basin, France)
Arsenic-rich (~ 140-1520 mg.kg− 1) suspended particulate matter (SPM) was collected daily with an automatic sampler in the Upper Isle River (France) draining a former gold mining district in order to better understand the fate of arsenic during the suspended transport (particles smaller than 50 μm). Various techniques at a micrometric scale (EPMA, quantitative SEM-EDS with an automated particle counting including classification system and μXRD) were used to directly characterize As-bearing phases. The most frequent ones were aggregates of fine clay particles. Their mineralogy varied with particle sources involved. These aggregates were formed by chlorite-phlogopite-kaolinite assemblages during the high flow and chlorite-illite-montmorillonite during the low flow. Among all the observed As-carriers in SPM, these clay assemblages were the least As-rich (0.10 up to 1.58 wt.% As) and their median As concentrations suggested that they were less concentrated during the high flow than during the low flow. Iron oxyhydroxides were evidenced by μXRD in these clay aggregates, either as micro- to nano-sized particles and/or as coating. (Mn, Fe)oxyhydroxides were also present as discrete particles. Manganese oxides (0.14-1.26 wt.% As) transport significantly more arsenic during the low flow than during the high flow (0.16-0.79 wt.% As). The occurrence of Fe oxyhydroxide particles appeared more complex. During the low flow, observations on banks and in wetlands of freshly precipitated Fe hydroxides (ferrihydrite-type) presented the highest As concentrations (up to 6.5 wt.% As) but they were barely detected in SPM at a microscale. During the high flow, As-rich Fe-oxyhydroxides (0.10-2.80 wt.% As) were more frequent, reflecting mechanical erosion and transport when the surface water level increased. Arsenic transfers from SPM to corresponding aqueous fraction mostly depend on As-carrier stability. This study shows the temporal occurrence of each type of As-bearing phases in SPM, their As concentrations at a particle scale and abundance according to hydrological periods.
(Science of the Total Environment. vol. 409, n° 0048-9697, pp. 4986-4999, 12/04/2026)
ISTO, INSU - CNRS, UO, UT, CNRS, GRESE, UNILIM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, ALS, LBNL, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Biogeochemical modelling of anaerobic vs. aerobic methane oxidation in a meromictic crater lake (Lake Pavin, France)
Methane is a powerful greenhouse gas and its concentration in the atmosphere has increased over the past decades. Methane produced by methanogenic Archae can be consumed through aerobic and anaerobic oxidation pathways. In anoxic conditions found in freshwater environments such as meromictic lakes, CH4 oxidation pathways involving different terminal electron acceptors such as NO 3 , SO2 4 , and oxides of Fe and Mn are thermodynamically possible. In this study, a reactive transport model was developed to assess the relative significance of the different pathways of CH4 consumption in the water column of Lake Pavin. In most cases, the model reproduced experimental data collected from the field from June 2006 to June 2007. Although the model and the field measurements suggest that anaerobic CH4 oxidation may contribute to CH4 consumption in the water column of Lake Pavin, aerobic oxidation remains the major sink of CH4 in this lake.
(Applied Geochemistry. vol. 26, n° 0883-2927, pp. 1919-1932, 12/04/2026)
LGE, UPD7, IPG Paris, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LMGE, UBP, UdA, CNRS, ISTO, INSU - CNRS, UO, UT, CNRS
Variability of fresh- and salt-water marshes characteristics on the west coast of France: A spatio-temporal assessment
The degradation of water quality and the multiple conflicts of interest between users make marsh restoration very important. A Water Quality Evaluation System (WQES) was developed for river systems by the European Water Framework Directive (WFD). Some form of biologically-based, habitat-specific reference standard seems absolutely essential for wise management and stewardship of marsh ecosystems. The goal of this study was to develop a statistical method to define and to characterize a water body typology for drained marshes of the Charente-Maritime wetlands on the French Atlantic coast, placing particular emphasis on environmental factors as hydraulic functioning, human activities and pedological substratum. The Charente-Maritime marshes represent a good field study because of his high diversity of types of marshes and of anthropogenic activities in a restrictive area thus erasing spatial climatic effect (latitude effect). The statistical method developed here had permitted to define and characterize 12 different water bodies, 7 in freshwater (F1 to F7) and 5 in salt water marshes for the Charente-Maritime area. This typology demonstrated an important link between the size catchment area, nitrate concentrations, and leaching of precipitation from cultured soils. Even though the Charente-Maritime marshes are strongly impacted by humans, they may still retain the ability to remove nitrate. The increasing gradient of water renewal in the freshwater marshes from F1 to F7 explained the decreasing gradient of eutrophication. A better management of the hydrodynamic of the marshes can avoid eutrophication risk on the coastal sea area. Reliance on the WFD parameter set necessarily placed limits on the kinds of interpretations that could be made and on the study's potential contribution to the basic science of marshes. Ecologically-based insights regarding both external flows (links between ecosystems, meta-ecosystem theory) and internal flows (structure of the planktonic food web) seem an essential prerequisite for further advances in the study of marsh ecosystems.
(Water Research. vol. 45, n° 0043-1354, pp. 4152 - 4168, 12/04/2026)
LIENSs, INSU - CNRS, ULR, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LCEE [Poitiers], UP, CNRS, UNIMA
Modeling biogeochemical processes in sediments from the Rhône River prodelta area (NW Mediterranean Sea)
In situ oxygen microprofiles, sediment organic carbon content, and pore-water concentrations of nitrate, ammonium, iron, manganese, and sulfides obtained in sediments from the Rhône River prodelta and its adjacent continental shelf were used to constrain a numerical diagenetic model. Results showed that (1) the organic matter from the Rhône River is composed of a fraction of fresh material associated to high first-order degradation rate constants (11-33 yr−1); (2) the burial efficiency (burial/input ratio) in the Rhône prodelta (within 3 km of the river outlet) can be up to 80 %, and decreases to ~20 % on the adjacent continental shelf 10-15 km further offshore; (3) there is a large contribution of anoxic processes to total mineralization in sediments near the river mouth, certainly due to large inputs of fresh organic material combined with high sedimentation rates; (4) diagenetic by-products originally produced during anoxic organic matter mineralization are almost entirely precipitated (>97 %) and buried in the sediment, which leads to (5) a low contribution of the re-oxidation of reduced products to total oxygen consumption. Consequently, total carbon mineralization rates as based on oxygen consumption rates and using Redfield stoichiometry can be largely underestimated in such River-dominated Ocean Margins (RiOMar) environments.
(Biogeosciences. vol. 8, n° 1726-4170, pp. 1351-1366, 12/04/2026)
IPGP, INSU - CNRS, UPD7, UR, IPG Paris, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, NIOO-KNAW, LAERO, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNRS, BIAF, UA, OCEANIS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
On the coupling of wave and three-dimensional circulation models: Choice of theoretical framework, practical implementation and adiabatic tests
Many theoretical approaches and implementations have been proposed for the coupling of the three-dimensional ocean circulation with waves. The theoretical models are reviewed and it is shown that the formulation in terms of the quasi-Eulerian velocity circumvents the essential difficulty of alternative formulations for the Lagrangian mean velocity. Namely, models based on this Lagrangian velocity require an estimation of wave-induced motions to first order in the horizontal gradients of the wave field in order to estimate the vertical flux of wave pseudo-momentum. So far, only three-dimensional wave models have been able to provide these estimates, and all published theories based on the simpler Airy theory are not consistent at the leading order, because they ignore or incorrectly estimate the vertical momentum flux. With an adiabatic example on a sloping bottom it is shown that this inconsistency produces very large spurious velocities. These errors are independent of the slope for the inviscid case, and are still significant when a realistic vertical mixing is applied. A quick diagnostic of the potential accuracy of a theoretical model is the vertical profile of the wave-induced forcing terms: if it is not uniform over depth in adiabatic conditions then it will produce spurious artificial flow patterns in conditions with shoaling waves. Although conceptually more challenging, the quasi-Eulerian velocity theories only introduce minor modifications of the solution procedure for the standard primitive equations: a modification of the surface boundary condition for the mass conservation, the addition of the Stokes drift in the tracer advection equations, and sources of momentum and turbulent kinetic energy with associated surface and bottom fluxes. All the necessary modifications of primitive equation models are given in detail. This implementation is illustrated with the MARS3D model, which passes the test of the adiabatic shoaling waves.
(Ocean Modelling. vol. 40, n° 1463-5003, pp. 260 - 272, 12/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOS, IFREMER, DYNECO, IFREMER