Mobility and fluxes of trace elements and nutrients at the sediment–water interface of a lagoon under contrasting water column oxygenation conditions
The early diagenesis of the major carrier phases (Fe and Mn minerals), trace elements (As, Co, Cr, Hg, MeHg, Ni) and nutrients (RNO 3 , NH þ 4 , RPO 4) and their exchange at the sediment water/interface were studied in the Berre Lagoon, a Mediterranean lagoon in France, at one site under two contrasting oxygen-ation conditions (strictly anoxic and slightly oxic) and at an adjacent site with perennially well-oxygen-ated water. From the concentration profiles of the primary biogeochemical constituents and trace elements of the pore and bottom waters, as well as the total and reactive particulate phases, it was possible to locate and identify the diagenetic reactions controlling the mobility of trace elements in the sediments and quantify their rates by coupling one-dimensional steady-state transport-reaction modelling and thermodynamic speciation calculations. Under oxic conditions and in the absence of benthic organisms, the main redox reactions were well identified vertically in the surface sediments and followed the theoretical sequence of oxidant consumption: O 2 > ΣNO 3/MnO 2 > Fe(OH) 3 > SO4 2-. However, under anoxic conditions, only MnO 2 , Fe(OH) 3 and SO 4 2- reduction were present, and they all occurred at the interface. The main biogeochemical controls on the mobility of As, Cr, Hg, MeHg and Ni in the surface sediments were identified as the adsorption/ desorption on and/or coprecipitation/codissolution with Fe oxy-hydroxides. In contrast, Co mobility was primarily controlled by its reactivity towards Mn oxy-hydroxides. In sulphidic sediments, As, Hg and MeHg were sequestered along with Fe sulphides, whereas Co and Ni precipitated directly as metallic sulphides and Cr mobility was enhanced by complexation with dissolved organic ligands. The fluxes of trace elements at the sediment–water interface are essentially dependent on the localisation of their remobilisation and immobilisation reactions under the interface, which in turn is governed by the ben-thic water oxygenation conditions and kinetic competition among those reaction and diffusion processes. Under oxic conditions, the precipitation of Fe or Mn oxy-hydroxides in the surface sediments constitutes the most efficient mechanism to sequester most of the trace elements studied, thus preventing their diffusion to the water column. Under anoxic conditions the export of trace elements to the water column is dependent on the kinetic competition during the reductive dissolution of Fe and/or Mn oxy-hydroxides, diffusion and immobilisation with sulphides. It is also shown that benthic organisms in the perennially oxygenated site have a clear impact on this general pattern. Based on the extensive dataset and geochem-ical modelling, it is predicted that the planned re-oxygenation of the entire lagoon basin, if complete, will most likely limit or reduce the export of the trace elements from the sediments to the water column and therefore, limit the impact of the contaminated sediment.
(Applied Geochemistry. vol. 31, n° 0883-2927, pp. 35-51, 29/08/2026)
CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER, PROTEE, UTLN
Role of short and long-wave interaction on wave celerity in the surf zone of a low-sloping beach
A good prediction of wave celerity is essential for wave propagation modeling in the nearshore. Previous studies have been focusing on the analysis of wave celerities averaged over several waves, neglecting the intra-wave variability due to long-wave transformation for instance. This paper is devoted to a study of individual wave transformation in the surf zone of a low-sloping beach, based on the analysis of a high-resolution laboratory dataset. The variability of the individual wave celerity in the surf zone is quantified and is seen to relate with the local elevation of the long waves normalized by the mean water depth. Lastly, individual wave celerities are compared to the predictions given by several linear and non-linear models.
(pp. 1677 - 1686, 29/08/2026)
LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEGI, UJF, Grenoble INP, CNRS
Occurrence of selected micropollutants in treated wastewater and removal with optimised tertiary treatments
Two tertiary treatments were studied at pilot scale in three different plants. An advanced oxidation processes pilot was tested in two plants with two different upstream treatment processes: a membrane bioreactor and a low load activated sludge followed by a sand filter. An activated carbon pilot was tested in one plant, a low load activated sludge followed by a sand filter and an ozone reactor. 64 micropollutants were analysed in the samples of this study. The tertiary treatments studied, ozone, AOP and activated carbon, were efficient for the removal of most of the micropollutants analysed in this study, except metals.
(pp. 3 p., 29/08/2026)
CIRSEE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR MALY, IRSTEA
Contamination et physiologie des poissons exposés à des polluants
(29/08/2026)
LPGP, INRA, Biosit : Biologie - Santé - Innovation Technologique, IFREMER, UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UB, ULR, LIENSs, INSU - CNRS, ULR, CNRS, ULH, NU, BGMCD, IP, CNRS, PAnTher, Oniris VetAgroBio, INRAE
Direct exposure to PAH-spiked gravels induces developmental defects in Oncorhynchus mykiss early life stages
(29/08/2026)
UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPGP, INRA, Biosit : Biologie - Santé - Innovation Technologique, BE, IFREMER
Devenir des micropolluants dans les traitements tertiaires
Zone humide artificielle : un outil d’épuration et de préservation du milieu Vendredi 11 octobre 2013 de 13 h 30 à 17 h LabEx COTE – Séminaire commun avec le LyRE Salle de conférence de l’ISM – Université Bordeaux 1, bât. A12, 3ème étage Est Programme : Le séminaire est animé par Hélène Budzinski (CNRS, UMR EPOC), co-directrice du LabEx COTE • 13 h 30 accueil des participants • 14 h Introduction : o Les micropolluants : enjeux pour l’épuration, Hélène Budzinski (CNRS, UMR EPOC) • Présentations : o Les traitements tertiaires disponibles : analyse comparée, Jean-Marc Choubert (Irstea – Centre de Lyon, UR MAEP) o Les zones artificielles humides, Eric Blin (Lyonnaise des eaux) o Le devenir des micropolluants o Relations nappe/rivière ou zone humide/nappe : des échanges complexes, Alain Dupuy (ENSEGID, EA Géoressources et Environnement) o Le point de vue d’une collectivité, Sabine Jeandenand (Syndicat intercommunal du Bassin d'Arcachon) o Les leviers socio-économiques • 16 h : Discussion
(pp. 15, 29/08/2026)
UR MALY, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Qualité de l’eau : chapitre 8.2
Etat de l'art concernant les grandes ressources naturelles de la région Aquitaine.
(pp. 249-264, 29/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR REBX, IRSTEA, UPMC
Effets de mélanges environnementalement réalistes de pesticides sur des biofilms naturels ayant des historiques d'exposition différents
Localisée dans la région viticole du Beaujolais (Est de la France), la Morcille est soumise à une pression viticole forte conduisant à la contamination de la rivière par une gamme d'herbicides et de fongicides. L'objectif de cette étude est d'utiliser des extraits d'échantillonneurs passifs pour mettre en évidence les effets de mélanges réalistes de pesticides sur des biofilms naturels avec des antécédents d'exposition diversifiés. Les impacts chroniques et aigus des pesticides en mélange sur les biofilms ont été évalués à l'aide d'extraits de POCIS (Polar Organic Chemical Integrative Samplers) préalablement immergés à l'aval du cours d'eau (site le plus contaminé). Leurs effets sur des communautés issues de l'amont (site de référence) et de l'aval (contaminé) ont été étudiés en canaux artificiels, dans lesquels les biofilms ont été placés dans des conditions non contaminées pendant 13 jours, ou exposés à des extraits de POCIS afin de reproduire une pression toxique réaliste (observée in situ). Après 13 jours d'exposition, des impacts significatifs de la contamination ont été observés sur les paramètres liés à la biomasse, à la croissance et à la physiologie des biofilms. Une diminution significative de la densité de diatomées a été observée pour les biofilms exposés, par rapport aux témoins, quelle que soit l'origine du biofilm. Les analyses taxonomiques ont révélé des impacts des mélange de pesticides sur la composition des diatomées, la structure des communautés amont divergeant avec l'exposition ou non (avec des abondances accrues de Nitzschia palea et Eolimna minima pour la modalité contaminée). Les communautés aval, exposées ou non, se sont avérées présenter une composition, soulignant l'importance des processus d'immigration dans la récupération des assemblages de diatomées. Afin d'évaluer la tolérance initiale de biofilms au mélange de pesticides, des tests de toxicité aiguë ont été réalisés en début d'expérience, révélant une tolérance nettement plus élevée des biofilms originaires du site en aval, par rapport aux biofilms amont. Cette différence de tolérance aux extraits d'échantillonneurs passifs peut s'expliquer par les compositions taxonomiques très différentes selon l'origine du biofilm, elle reflète l'adaptation des communautés par les processus de sélection des espèces et illustre le concept PICT (Blanck et al, 1988.). Nos résultats soulignent des effets des mélange de pesticides marqués sur la croissance du biofilm, la composition diatomique, et sur la tolérance des biofilms naturels aux facteurs auxquels ils sont exposés. Cette étude met en évidence l'utilisation potentielle des extraits d'échantillonneurs passifs, combinés avec des tests de toxicité aiguë, pour l'expérimentation des impacts d'expositions chroniques plus réalistes sur les biofilms naturels, et offre des perspectives d'applications prometteuses pour l'évaluation du risque écologique lié aux pesticides.
(pp. 1, 29/08/2026)
UR REBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR MALY, IRSTEA
Climate-Caused Abrupt Shifts in a European Macrotidal Estuary
Although many consequences of climate change on marine and terrestrial ecosystems are well documented, the characterisation of estuarine ecosystems specific responses and the drivers of the changes are less understood. In this study, we considered the biggest Southwestern European estuary, the Gironde, as a model of a macrotidal estuary to assess the effects of both large- (i.e., North Atlantic basin-scale) and regional-scale climate changes. Using a unique set of data on climatic, physical, chemical and biological parameters for the period 1978–2009, we examined relations between changes in both the physical and chemical environments and pelagic communities (plankton and fish) via an end-to-end approach. Our results show that the estuary experienced two abrupt shifts (!1987 and !2000) over the last three decades, which altered the whole system. The timing of these abrupt shifts are in accordance with abrupt shifts reported in both marine (e.g., in the North Sea, the Mediterranean Sea and along the Atlantic) and terrestrial (e.g., in European lakes) realms. Although this work does not allow a full understanding of the dynamical processes through which climate effects propagate along the different compartments of the ecosystem, it provides evidence that the dynamics of the largest estuary of Southwest Europe is strongly modulated by climate change at both regional and global scales.
(Estuaries and Coasts. vol. 36, n° 1559-2723, pp. 1193-1205, 29/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], UR EPBX, IRSTEA
Physiological effects on zebrafish offspring following dietary parental exposure to a pyrolytic PAH mixture
(29/08/2026)
BE, IFREMER, UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ULR, LIENSs, INSU - CNRS, ULR, CNRS, LPGP, INRA, Biosit : Biologie - Santé - Innovation Technologique