Qualité des Milieux Naturels
Qualité des Milieux Naturels
(pp. 96 p., 01/09/2026)
IC2MP [Poitiers], UP, INC-CNRS, CNRS, LIENSs, INSU - CNRS, ULR, CNRS, IPREM, UPPA, INC-CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IC2MP [Poitiers], UP, INC-CNRS, CNRS, P3F, INRA, ECOSYS, INRA
Modulation of the vertical particle transfer efficiency in the oxygen minimum zone off Peru
The fate of the organic matter (OM) produced by marine life controls the major biogeochemical cycles of the Earth's system. The OM produced through photosynthe-sis is either preserved, exported towards sediments or degraded through remineralisation in the water column. The productive eastern boundary upwelling systems (EBUSs) associated with oxygen minimum zones (OMZs) would be expected to foster OM preservation due to low O 2 conditions. But their intense and diverse microbial activity should enhance OM degradation. To investigate this contradiction, sediment traps were deployed near the oxycline and in the OMZ core on an instrumented moored line off Peru. Data provided high-temporal-resolution O 2 series charac-terising two seasonal steady states at the upper trap: sub-oxic ([O 2 ] < 25 µmol kg −1) and hypoxic-oxic (15 < [O 2 ] < 160 µmol kg −1) in austral summer and winter-spring, respectively. The OMZ vertical transfer efficiency of particulate organic carbon (POC) between traps (T eff) can be classi-Published by Copernicus Publications on behalf of the European Geosciences Union. 5094 M. Bretagnon et al.: Modulation of the vertical particle transfer efficiency fied into three main ranges (high, intermediate, low). These different T eff ranges suggest that both predominant preservation (high T eff > 50 %) and remineralisation (intermediate T eff 20 < 50 % or low T eff < 6 %) configurations can occur. An efficient OMZ vertical transfer (T eff > 50 %) has been reported in summer and winter associated with extreme limitation in O 2 concentrations or OM quantity for OM degradation. However, higher levels of O 2 or OM, or less refractory OM, at the oxycline, even in a co-limitation context, can decrease the OMZ transfer efficiency to below 50 %. This is especially true in summer during intraseasonal wind-driven oxygenation events. In late winter and early spring, high oxy-genation conditions together with high fluxes of sinking particles trigger a shutdown of the OMZ transfer (T eff < 6 %). Transfer efficiency of chemical elements composing the majority of the flux (nitrogen, phosphorus, silica, calcium car-bonate) follows the same trend as for carbon, with the lowest transfer level being in late winter and early spring. Regarding particulate isotopes, vertical transfer of δ 15 N suggests a complex pattern of 15 N impoverishment or enrichment according to T eff modulation. This sensitivity of OM to O 2 fluctuations and particle concentration calls for further investigation into OM and O 2-driven remineralisation processes. This should include consideration of the intermittent behaviour of OMZ towards OM demonstrated in past studies and climate projections .
(Biogeosciences. vol. 15, n° 1726-4170, pp. 5093-5111, 01/09/2026)
LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, LOV, INSU - CNRS, SU, CNRS, IMEV, INSU - CNRS, SU, CNRS, IMARPE, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, CAU, UABC, CICESE, IGP, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IMARPE, IMAGO, INSU - CNRS, LOPS, IRD, IFREMER, INSU - CNRS, UBO EPE, CNRS
Antimony in the Lot–Garonne river system: a 14-year record of solid–liquid partitioning and fluxes
Antimony is a trace element ubiquitously present in the environment, but data are lacking on its spatio-temporal distribution in aquatic environments. Long-term records serve as essential tools to decipher temporal patterns, historical sources and sinks and background concentrations in an area. We characterise the temporal concentrations, transport and behaviour of antimony in the Garonne River watershed, the main tributary to the Gironde Estuary, the largest estuary in south-west Europe. AbstractKnowledge of the environmental chemistry of antimony (Sb) in aquatic systems is limited, and a better understanding of its geochemical behaviour is needed. Based on a fourteen-year survey (2003–2016) with monthly measurements of dissolved and particulate Sb at five sites in the Lot–Garonne river system, combined with daily measurements of water discharge and suspended particulate matter, this work characterises Sb behaviour in the upstream major river watershed of the Gironde Estuary. The survey provides a first regional geochemical Sb background in the Garonne River watershed for dissolved (~0.2 µg L−1) and Th-normalised particulate Sb (Sbp/Thp ~0.25) concentrations. Observed decreasing temporal trends (<1 ng L−1 in dissolved and <0.02 mg kg−1 in particulate concentrations per month) at sites representing natural concentrations probably reflect global atmospheric Sb dynamics at the watershed scale. Regular seasonal cycles of solid/liquid partitioning, with higher solubility in summer (matching high dissolved and low particulate concentrations), reflect water-discharge and suspended particulate matter transport dynamics and possibly seasonal (bio)geochemical processes. Furthermore, this coefficient decreases from the river to the estuarine reaches (from average log10Kd 4.3 to minimum 3.7 L kg−1), suggesting an increased solubility of Sb in estuarine systems. Flux estimates indicate the relevance of the dissolved fraction in Sb transport (with negligible influence of the colloidal fraction) and a total flux (dissolved + particulate) entering the Gironde Estuary of 5.66 ± 2.96 t year−1 (~50 % particulate). These results highlight the importance of timescales and environmental parameters for understanding and prediction of future Sb biogeochemistry.
(Environmental Chemistry. vol. 15, n° 1448-2517, pp. 121, 01/09/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Nature-Based Tourism Elicits a Phenotypic Shift in the Coping Abilities of Fish
Nature-based tourism is gaining extensive popularity, increasing the intensity and frequency of human-wildlife contacts. As a consequence, behavioral and physiological alterations were observed in most exposed animals. However, while the majority of these studies investigated the effects of punctual exposure to tourists, the consequences of constant exposition to humans in the wild remains overlooked. This is an important gap considering the exponential interest for recreational outdoor activities. To infer long-term effects of intensive tourism, we capitalized on, a short-lived sedentary Tetra fish who spends its life close to humans, on which it feeds on dead skin. Hence, those fish are constantly exposed to tourists throughout their lifecycle. Here we provide an integrated picture of the whole phenomenon by investigating, for the first time, the expression of genes involved in stress response and neurogenesis, as well as behavioral and hormonal responses of animals consistently exposed to tourists. Gene expression of the mineralocorticoid (and cortisol) receptor () and the neurogenic differentiation factor () were significantly higher in fish sampled in the touristic zone compared to those sampled in the control zone. Additionally, after a simulated stress in artificial and controlled conditions, those fish previously exposed to visitors produced more cortisol and presented increased behavioral signs of stress compared to their non-exposed conspecifics. Overall, nature-based tourism appeared to shift selection pressures, favoring a sensitive phenotype that does not thrive under natural conditions. The ecological implications of this change in coping style remain, nevertheless, an open question.
(Frontiers in Physiology. vol. 9, n° 1664-042X, pp. 13, 01/09/2026)
UFMT, UMR MARBEC, IRD, IFREMER, UM, CNRS, Biosit : Biologie - Santé - Innovation Technologique, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UnB
Steps to improve gender diversity in coastal geoscience and engineering
Robust data are the base of effective gender diversity policy. Evidence shows that gender inequality is still pervasive in science, technology, engineering and mathematics (STEM). Coastal geoscience and engineering (CGE) encompasses professionals working on coastal processes, integrating expertise across physics, geomorphology, engineering, planning and management. The article presents novel results of gender inequality and experiences of gender bias in CGE, and proposes practical steps to address it. It analyses the gender representation in 9 societies, 25 journals, and 10 conferences in CGE and establishes that women represent 30% of the international CGE community, yet there is under-representation in prestige roles such as journal editorial board members (15% women) and conference organisers (18% women). The data show that female underrepresentation is less prominent when the path to prestige roles is clearly outlined and candidates can self-nominate or volunteer instead of the traditional invitation-only pathway. By analysing the views of 314 survey respondents (34% male, 65% female, and 1% ‘‘other’’), we show that 81% perceive the lack of female role models as a key hurdle for gender equity, and a significantly larger proportion of females (47%) felt held back in their careers due to their gender in comparison with males (9%). The lack of women in prestige roles and senior positions contributes to 81% of survey respondents perceiving the lack of female role models in CGE as a key hurdle for gender equality. While it is clear that having more women as role models is important, this is not enough to effect change. Here seven practical steps towards achieving gender equity in CGE are presented: (1) Advocate for more women in prestige roles; (2) Promote high-achieving females; (3) Create awareness of gender bias; (4) Speak up; (5) Get better support for return to work; (6) Redefine success; and, (7) Encourage more women to enter the discipline at a young age. Some of these steps can be successfully implemented immediately (steps 1–4), while others need institutional engagement and represent major societal overhauls. In any case, these seven practical steps require actions that can start immediately.
(Humanities and Social Sciences Communications. vol. 4, 01/09/2026)
UoN, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Réflexions sur deux pendentifs à “dent de requin” trouvés à Burdigala (Bordeaux)
(Aquitania, n° 0758-9670, pp. 357-364, 01/09/2026)
UBM, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Photodegradation of novel oral anticoagulants under sunlight irradiation in aqueous matrices
Kinetics of photodegradation of novel oral anticoagulants dabigatran, rivaroxaban, and apixaban were studied under simulated solar light irradiation in purified, mineral, and river waters. Dabigatran and rivaroxaban underwent direct photolysis with polychromatic quantum yields of 2.2 × 10−4 and 4.4 × 10−2, respectively. The direct photodegradation of apixaban was not observed after 19 h of irradiation. Kinetics of degradation of rivaroxaban was not impacted by the nature of the aqueous matrix while photosensitization from nitrate ions was observed for dabigatran and apixaban dissolved in a mineral water. The photosensitized reactions were limited in the tested river water (Isle River, Périgueux, France) certainly due to the hydroxyl radical scavenging effect of the dissolved organic matter. The study of photoproduct structures allowed to identify two compounds for dabigatran. One of them is the 4-aminobenzamidine while the second one is a cyclization product. In the case of rivaroxaban, as studied by very high field NMR, only one photoproduct was observed i.e. a photoisomer. Finally, seven photoproducts were clearly identified from the degradation of apixaban under simulated solar light.
(Chemosphere. vol. 193, n° 0045-6535, pp. 329-336, 01/09/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CBMN, UB, ENITAB, INC-CNRS, CNRS, INERIS, UR MALY, IRSTEA
Wilkes Land Late Pleistocene diatom age model: From bio-events to quantitative biostratigraphy
A new method merges conventional and quantitative biostratigraphic approaches, supported by magnetic polarity data, to develop a chronological framework for sediment core MD03-2595 retrieved on the continental rise off Wilkes Land, East Antarctica before proceeding to paleoceanographic and paleoclimatic analysis. This combined method helped to identify climatic cycles, highlight stratigraphic discontinuities and reworking, and assess regional sedimentological and diatom biostratigraphic evolution. Core MD03-2595 spans the last 0.8 Ma, from the Mid Pleistocene Transition (MPT) to the Early Holocene. A hiatus including Marine Isotope Stages (MIS) 19, 18 and 17 was identified, and a decreasing trend in sediment accumulation rates from MIS 16 to the Holocene was observed. This quantitative diatom biostratigraphic dataset, placed in its own sedimentological and paleomagnetic context, provides new information regarding the paleobiogeographic distribution and ecological responses of biostratigraphically significant diatom species, such as Thalassiosira elliptipora and T. fasciculata, for the Matuyama-Brunhes (M-B) transition, and Actinocyclus ingens, Hemidiscus karstenii and Rouxia spp. for the middle and late Pleistocene diatom biozonation.
(Revue de Micropaléontologie. vol. 61, n° 0035-1598, pp. 81-96, 01/09/2026)
UniGe, INGV, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Bref panorama scientifique de l'estuaire de la Gironde 2018
L'intérêt pour cette synthèse s'est développé en réponse au constat partagé avec les acteurs de la société d'un besoin de bilan des connaissances. Ce document est le fruit d'une démarche pluridisciplinaire des « Sciences du milieu» et des « Sciences humaines et sociales». Cet ouvrage de synthèse des connaissances s'inscrivant dans une démarche globale de partage des connaissances (et des interrogations), nous espérons qu'il permettra d'identifier de nouvelles réponses, mais aussi des lacunes, qui conduiront à des développements ultérieurs tant du point de vue de la recherche que de la gestion.
(pp. 55, 01/09/2026)
UB, IRSTEA, UR ETBX, IRSTEA, UR EABX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Refining uptake and depuration constants for fluoroalkyl chemicals in Chironomus riparius larvae on the basis of experimental results and modelling
The aims of this study were to determine depuration rates for a range of per- and polyfluoroalkyl substances (PFASs) using Chironomus riparius, and to test a concentration-dependency hypothesis for the long-chain perfluorotridecanoic acid (PFTrDA) for this species. Midge larvae were exposed to field sediments collected downstream of a fluorotelomer plant, and to the same sediment spiked with PFTrDA. Elimination kinetics results indicated complete elimination of all PFASs by chironomids after 42 h. These data were used to develop two PFTrDA bioaccumulation models accounting for chironomid growth and for compound concentration dependency or not. There was much better agreement between observed and simulated data under the concentration-dependency hypothesis than under the alternative one (passive diffusion). The PFTrDA uptake rate derived from the concentration-dependency model equaled 0.013 ± 0.008 goc gww h−1, and the depuration rate 0.032 ± 0.009 h−1.
(Ecotoxicology and Environmental Safety. vol. 149, n° 0147-6513, pp. 284-290, 01/09/2026)
IRSTEA, EPFL, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INERIS, ECOSYS, INRA