Usages et qualité sur un territoire ostréicole
Ce rapport présente les résultats issus de recherches menées sur le Bassin d'Arcachon dans le cadre du projet de recherche OSQUAR, financé par la région Aquitaine. Il s'agit plus particulièrement du rapport du volet 2 du projet, qui mobilisait SHS et sciences du milieu sur la question des usages sur le territoire du Bassin d'Arcachon en lien avec la qualité du milieu.
(pp. 273, 30/08/2026)
UR ADBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Hydrological variability of major French rivers over recent decades, assessed from gauging station and GRACE observations
This study was carried out in the framework of the Surface Water and Ocean Topography (SWOT) programme of the French National Centre of Space Studies (CNES). Based on discharge measurements and Gravity Recovery and Climate Experiment (GRACE) determination of total water storage (TWS), we have investigated the hydrological variability of the main French drainage basins (Seine, Loire, Garonne and Rhône) using a wavelet approach (continuous wavelet analyses and wavelet coherence analyses). The results of this analysis have shown a coherence ranging between 82% and 90% for TWS and discharge, thus demonstrating the potential use of TWS for characterization of the hydrological variability of French rivers. Strong coherence between the four basin discharges (between 73% and 92%) and between their associated TWS data (from 82% to 98%) suggested a common external influence on hydrological variability. To determine this influence, we investigated the relationship between hydrological variability and the North Atlantic Oscillation (NAO), considered as an index of prevailing climate in Europe. Basin discharges show strong coherence with NAO, ranging between 64% and 72% over the period 1959–2010. The coherence between NAO and TWS was 62% to 67% for 2003–2009. This is similar to the coherence between NAO and basin discharges detected for the same period. According to these results, strong influence of the NAO was clearly observed on the TWS and discharges of the major French river basins.
(Hydrological Sciences Journal. vol. 59, n° 0262-6667, pp. 1844 - 1855, 30/08/2026)
M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, IRD, UPVD, AU, UR, UM, UG, UA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Influence of organic matter from urban effluents on trace metal speciation and bioavailability in river under strong urban pressure
In aquatic systems, dissolved organic matter (DOM) constitutes a key component of the carbon cycle controlling the transport, speciation, bioavailability, and toxicity of trace metals. In this work, we study the spatiotemporal variability of the MO in terms of both quality and quantity from upstream to downstream the Parisian conurbation. Urban discharges which are the main source of allochthonous organic matter into the Seine at low-water periods were also investigated. The DOM collected was fractionated according to polarity criteria into five fractions: hydrophobic, transphilic, hydrophilic acid, hydrophilic basic, and hydrophilic neutral. Due to urban discharges, a strong enrichment in the hydrophilic (HPI) fraction was observed for downstream sites. This hydrophilic fraction presented stronger binding capacities for copper than hydrophobic fraction from less urbanized site (upstream from Paris) and Suwannee river fulvic acid (SRFA). Furthermore, biotests highlighted a significant copper bioavailability decrease in presence of hydrophilic DOM. \textcopyright 2013 Zhejiang University Press and Springer Science+Business Media Dordrecht. All rights are reserved.
(. vol. 9789400756342, pp. 517--521, 30/08/2026)
LEESU, UPEM, ENPC, UPEC UP12, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR HBAN, IRSTEA, CEREVE, ENPC, UPEC UP12
Polychlorinated Biphenyls, Polybrominated Diphenyl Ethers, and Phthalates in Roach from the Seine River Basin (France): Impact of Densely Urbanized Areas
Endocrine disruptors (EDs) from three chemical classes—polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and phthalates—were investigated in the Seine River and one tributary, the Orge River, upstream and downstream of urban areas. The impact of urban areas was characterized by a concentration increase of all compounds in the Seine River and for phthalates and PBDEs in the Orge River. In the Seine River, from upstream (Marnay) to downstream (Triel) of urban areas, water concentration increases were greater for diethylhexyl phthalate (DEHP) (6 times, p < 0.05) and ∑tri-hexa BDE (5 times [p < 0.05]) than for ∑7PCBi (2.6 times). Simultaneously, sediments displayed a strong accumulation of contaminants downstream and compared with upstream values, their concentrations increased greatly: 202-fold for DEHP, 69-fold for BDE209, 25-fold for ∑tri-hexa-BDE, and 11-fold for ∑7PCBi. Variations of fish ED concentrations gave an indication of their habitat contamination increase observed downstream of densely urbanized areas of the Seine River, especially for PBDEs (∑tri-hexa-PBDEs = 14-fold increase ≤15.7 ± 6.9 ng g−1 dry weight [dw; p < 0.001]) and for PCBs (∑7PCBi eightfold increase ≤211 ± 55 ng g−1 dw [p < 0.01]). PCA results highlighted relationships between the different ED classes. A correlation (p < 0.05) was observed between PCB and PBDE fish concentrations, suggesting common sources and similar absorption mechanisms. For PCBs, which were poorly biodegraded, the bioaccumulation factor was strongly correlated (p < 0.001) to molecular hydrophobicity, whereas for PBDEs a negative correlation (p < 0.05) was observed related active debromination processes. This multichemical study investigates for the first time the occurrence of a wide range of EDs in roach, which was chosen as a sentinel species for this survey of surface water contamination.
(Archives of Environmental Contamination and Toxicology. vol. 66, n° 0090-4341, pp. 41-57, 30/08/2026)
SISYPHE, UPMC, EPHE, PSL, PSL, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Study of the optical properties of dissolved organic matter in the Seine river catchment (France)
In this study, the optical properties of dissolved organic matter (DOM) were investigated using UV/visible photometry and excitation emission matrix (EEM) fluorescence spectroscopy. Differences in quality and quantity of organic carbon were observed and highlighted discrimination of organic matter typologies between the four studied areas in the catchment of the Seine river. \textcopyright 2013 Zhejiang University Press and Springer Science+Business Media Dordrecht. All rights are reserved.
(. vol. 9789400756342, pp. 219--223, 30/08/2026)
LEESU, UPEM, ENPC, UPEC UP12, IPGP, INSU - CNRS, UPD7, UR, IPG Paris, CNRS, IPGP, INSU - CNRS, UPD7, UR, IPG Paris, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Differences in fluorescence properties between humic acid and its size fractions separated by preparative HPSEC
We applied three dimensional excitation-emission-matrix (3D-EEM) spectrofluorometry to investigate the fluorescence properties of a humic acid (HA) solution at different pH values and its size-fractions separated by preparative high performance size exclusion chromatography (HPSEC). 3D-EEM fluorescence spectra revealed peak maxima in the bulk HA which were assigned to protein-like, phenol-like and naphthol-like components. Moreover, changes of peak maxima with pH showed that phenol-like and naphthol-like molecular classes were composed of sub-components with different acidities, and, thus, different structures. The 3D-EEM spectra of three size-fractions separated by HPSEC showed similar peak maxima as for the bulk HA, with additional components, such as highly condensed aromatic systems, which had not been visible in the bulk HA. Furthermore, the fluorescence intensity of peak maxima in 3D-EEM spectra of size-fractions appeared invariably greater than that for the bulk HA. This phenomenon as well as the appearance of new maxima in size-fraction spectra is explained by the reduced self-quenching effect in the less complex and conformationally looser size-fractions. In fact, the close mutual proximity of fluorescent humic molecules in the tight supramolecular association of the bulk HA decreased or even inhibited their fluorescence quantum yield. This work shows that, due to self-quenching of humic molecules, fluorescence spectroscopy cannot be used to characterise the molecular complexity of humic matter and, thus, differentiate its environmental origin. \textcopyright 2012 Elsevier B.V.
(Journal of Geochemical Exploration. vol. 129, n° 0375-6742, pp. 23--27, 30/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Investigations into the differential reactivity of endogenous and exogenous mercury species in coastal sediments
Stable isotopic tracer methodologies now allow the evaluation of the reactivity of the endogenous (ambient) and exogenous (added) Hg to further predict the potential effect of Hg inputs in ecosystems. The differential reactivity of endogenous and exogenous Hg was compared in superficial sediments collected in a coastal lagoon (Arcachon Bay) and in an estuary (Adour River) from the Bay of Biscay (SW France). All Hg species (gaseous, aqueous, and solid fraction) and ancillary data were measured during time course slurry experiments under variable redox conditions. The average endogenous methylation yield was higher in the estuarine (1. 2 %) than in the lagoonal sediment (0. 5 %), although both methylation and demethylation rates were higher in the lagoonal sediment in relation with a higher sulfate-reducing activity. Demethylation was overall more consistent than methylation in both sediments. The endogenous and exogenous Hg behaviors were always correlated but the exogenous inorganic Hg (IHg) partitioning into water was 2. 0-4. 3 times higher than the endogenous one. Its methylation was just slightly higher (1. 4) in the estuarine sediment while the difference in the lagoonal sediment was much larger (3. 6). The relative endogenous and exogenous methylation yields were not correlated to IHg partitioning, demonstrating that the bioavailable species distributions were different for the two IHg pools. In both sediments, the exogenous IHg partitioning equaled the endogenous one within a week, while its higher methylation lasted for months. Such results provide an original assessment approach to compare coastal sediment response to Hg inputs.
(Environmental Science and Pollution Research. vol. 20, n° 0944-1344, pp. 1292--1301, 30/08/2026)
IPREM, UPPA, INC-CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Potential role of giant marine diatoms in sequestration of atmospheric CO2 during the Last Glacial Maximum: δ13C evidence from laminated Ethmodiscus rex mats in tropical West Pacific
Giant marine diatoms, blooming or aggregating within deep chlorophyll maxima under stratified conditions, can generate substantial production and a large export flux of organic carbon from surface waters. However, their role in regulating glacial-interglacial variation in atmospheric pCO 2 remains unclear. Here, we report the organic carbon isotopic compositions of Ethmodiscus rex diatoms (δ 13 C E. rex) and bulk sediments (δ 13 C org) from a sediment core in the eastern Philippine Sea dated to ~19.5-31.0 kyr B.P. and consisting of (from youngest to oldest) (1) laminated E. rex diatom mats (LDM), (2) diatomaceous clay (DC), and (3) pelagic clay (PC). Our results suggest that δ 13 C E. rex provides a better record of palaeoceanographic processes during LDM and DC deposition than δ 13 C org because of reduced differential vital effects in near-monospecific E. rex fractions. We used the isotopic composition of the coarse E. rex fraction (δ 13 C E. rex (>154 μm)) to calculate the CO 2 partial pressure of eastern Philippine Sea surface waters (pCO 2-sw) during the Last Glacial Maximum (LGM). Our pCO 2-sw records suggest that the eastern Philippine Sea switched from being a strong CO 2 source during DC deposition to a weak CO 2 sink during LDM deposition. The role of the eastern Philippine Sea as a CO 2 sink during the LGM was promoted by elevated primary production and, to a lesser extent, intensified water-column stratification. These observations highlight the potential role of giant marine diatoms in the sequestration of atmospheric CO 2 during the LGM and, hence, support changes in biogenic silica fluxes as a potential cause of lower glacial atmospheric CO 2. Our findings are consistent with an eolian source of silica, as proposed by the 'silica hypothesis' and the 'silicon-induced alkalinity pump hypothesis' but not by the 'silicic acid leakage hypothesis.
(Global and Planetary Change. vol. 108, n° 0921-8181, pp. 1-14, 30/08/2026)
IOCAS, CAS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UC
L'adaptation au changement climatique : contraintes et opportunités
Éléments issus de la synthèse sur la biodiversité en Aquitaine, réalisée pour le Conseil Régional d'Aquitaine sur les thématiques Biodiversité et Ressources exploitées.
(pp. 14, 30/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EPBX, IRSTEA, LERAR, COAST, IFREMER, IFREMER, IRSTEA, MNHN
Etude intégrée de l’effet des apports amont et locaux sur le fonctionnement de la Garonne estuarienne (ETIAGE) : Rapport année 3 Avril 2012 - Mars 2013
Le programme ETIAGE a été mis en place avec pour objectif de répondre aux questions suivantes : que représentent les apports des effluents de la Communauté Urbaine de Bordeaux (CUB) par rapport à ceux venant de l’amont en termes de charge organique et de micro-polluants ? Quels rôles sur le devenir des effluents jouent la présence du bouchon vaseux et la stagnation résiduelle des eaux (déplacement net entre mouvement de flot et de jusant) au niveau de l’estuaire fluvial amont en période d’étiage estival ? Réciproquement, à quels moments et jusqu’où s’étend l’impact de ces effluents sur la qualité des eaux de la Garonne estuarienne ? Quelles incidences des effluents sur le comportement des populations biologiques en place ou migratoires dans la Garonne estuarienne ? Quelle tendance évolutive va connaître l’oxygénation des eaux ? Quel sera l’impact sur le comportement des micro-polluants et des populations biologiques ? Quelles recommandations de gestion pourraient être préconisées à partir de la synthèse des pressions exercées sur les eaux de la Garonne estuarienne ? Le programme est divisé en 5 axes, dont les bilans de travail sont présentés axe par axe.
(pp. 53, 30/08/2026)
UR EPBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS