Observation and Modeling of the Equilibrium Slope Response of a High-Energy Meso-Macrotidal Sandy Beach
Beach slope is a critical parameter to, e.g., beach safety, wave reflection at the coast and longshore transport rate. However, it is usually considered as a time-invariant and profile-average parameter. Here, we apply a state-of-the-art equilibrium model to hindcast beach slope variability from the time scales of days to years at the high-energy meso-macrotidal sandy beach of Truc Vert, southwest France. We use 9 years of bimonthly beach surveys to compute beach slope time series at different elevations. Results show that beach slope exhibits an equilibrium response with contrasting behaviors along two distinct areas of the beach profile. From 0 to 2 m above mean sea level, which is located under the berm crest, a slope response predominantly at the storm time scale is observed. The beach slope steepens under low energy waves, with the equilibrium model explaining up to 40% of the observed beach slope variability. In contrast, from 2.5 to 4 m above mean sea level, which is above the berm crest, the beach slope steepens under high-energy waves. Within this region of the beach profile, the response time scale increases upwards from seasonal (~2.5 m) to seasonal (~4 m), with the model explaining up to 65% of the observed beach slope variability. Such behaviors are found to be enforced by the berm dynamics developing from the end of the winter to early autumn, providing new perspectives to model and predict beach slope on sandy beaches.
(Journal of Marine Science and Engineering. vol. 11, n° 2077-1312, pp. 584, 09/03/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Développement d’échantillonneurs passifs pour la surveillance des pesticides dans l’air
Une des conséquences environnementales majeures de l'agriculture intensive actuelle est la dégradation de la qualité de l'environnement, du fait de la dissémination des intrants agricoles, notamment les pesticides. Le développement de la surveillance des milieux met en évidence l'ampleur de la dispersion des pesticides dans l'environnement : une présence quasi généralisée de pesticides dans les eaux françaises et une contamination chronique de l'air par les pesticides, pour laquelle la signature agricole est généralement très claire, en particulier dans les régions viticoles comme la Gironde. La viticulture bordelaise est d'ailleurs désormais sous la pression grandissante d'associations et de riverains, qui dénoncent les effets toxiques d'herbicides et fongicides de synthèse. Les pesticides peuvent se retrouver dans l'air ambiant, soit lors de lors application sur les cultures, soit après traitement, en se volatilisant à partir du sol et de la végétation. Ainsi, de 25 à 90% des pesticides appliqués seraient transférés vers l'atmosphère selon les propriétés physico-chimiques des pesticides, les modes d'application et les conditions climatiques. Dans ce contexte, l’objectif de cette thèse vise notamment à caractériser les niveaux et les variations saisonnières des pesticides dans l'air de milieux hétérogènes (viticoles, urbains, péri-urbains). Pour cela, des échantillonneurs passifs en mousse de polyuréthane (PUF) ont été déployés sur 8 sites d’études et changés entre 3 et 6 semaines sur les années 2020 et 2021. Ainsi, les axes de travail ont été d’établir une liste de suivi de 39 molécules étant emblématiques, utilisées actuellement ou venant d’être interdites et appartenant à plusieurs familles chimiques ; de mettre au point une technique d’extraction fiable et efficace, construire un protocole expérimental simple et robuste, puis bâtir des filières analytiques dédiées, spécifiques et sensibles. Ceci dans l’objectif final de développer et facilité l’usage des PUF pour le suivi de pesticides. L’évaluation du potentiel de ce type d’échantillonneur passif pour décrire la présence de contaminants a été posée, afin de décrire son adéquation entre sa facilité d’usage et le fait de pouvoir caractériser les niveaux de contamination dans l’atmosphère en Gironde en lien avec la dualité agricole et urbaine afin d’identifier les sources et la provenance des pesticides. Des miniaturisations et diverses expérimentations ont permis d’étudier, de décrire et améliorer le mode de fonctionnement de ces échantillonneurs passifs. En parallèle, des échantillonneurs actifs bas, moyen- et haut-débit, fonctionnant à des débits de prélèvement connus, ont été également installés sur le terrain afin de calibrer les échantillonneurs passifs et permettre des déterminations semi-quantitatives des pesticides sur ces derniers. Ces échantillonneurs passifs ont permis un suivi environnemental à grande échelle de par leur moindre coût et le développement effectué d’un protocole d’extraction, de préparation et d’analyse d’échantillons adapté aux pesticides dans l’air. Jusqu’à 33 molécules différentes ont pu être identifiées avec des fréquences de détection de 100% pour le métolachlore-(S) ou le chlorpyrifos-éthyl. Une dynamique spatio-temporelle a été démontrée avec des pics de contamination sur l’ensemble des sites durant les épandages en zones viticoles comme le folpel ou en zone agricole avec le prosulfocarbe. Des molécules non appliquées à proximité ont été retrouvées avec par exemple le métolachlore-(S), montrant un transport des molécules par le compartiment aérien et atteignant les zones urbaines.
(03/03/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Spectral wave dissipation over a roughness‐varying barrier reef
The present paper reports on a field experiment performed over a shallow, roughness-varying barrier reef at Maupiti island, French Polynesia. The spectral wave energy balance is examined, outside the breaking zone and accounting for non-linear transfers and mean current, to estimate the wave friction factor. This latter varies from 0.05 to 4, with dependence on the ratio between near-bed orbital amplitude and roughness height well predicted by an adjusted parameterization from Madsen (1995). The present results are discussed with respect to other field data recovered on coral and rocky grounds.
(Geophysical Research Letters. vol. 50, n° 0094-8276, pp. e2022GL102104, 02/03/2023)
SIAME, UPPA, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UNSW, LIENSs, INSU - CNRS, ULR, CNRS, TU Delft, INSU - CNRS, CNRS, UA, UM, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE
Late Cenozoic sea-surface-temperature evolution of the South Atlantic Ocean
At present, a strong latitudinal sea surface temperature (SST) gradient of ~16°C exists across the Southern Ocean, maintained by the Antarctic Circumpolar Current (ACC) and a set of complex frontal systems. Together with the Antarctic ice masses, this system has formed one of the most important global climate regulators. The timing of the onset of the ACCsystem, its development towards modern-day strength, and the consequences for e.g., the latitudinal SST gradient around the southern Atlantic Ocean, are still uncertain. Here we present new TEX$_{86}$-biomarker records, calibrated to SST, from two sites located east of Drake Passage (southern South Atlantic) to assist in better understanding two critical time intervals of prominent climate transitions during the Cenozoic: The Late Eocene-Early Oligocene (ODP Site 696) and Middle-Late Miocene (IODP Site U1536) transitions. Our results overall show rather temperate conditions (20-11°C) during the Late Eocene to Early Oligocene interval, with a weaker latitudinal SST gradient (~8°C) across the Atlantic sector of the Southern Ocean compared to present day (~16°C). We ascribe the regional similarity in SSTs across the Late Eocene-Early Oligocene South Atlantic to a persistent, strong Subpolar Gyre circulation, connecting all sites, which can only exist in absence of a strong throughflow across the Drake Passage. Surprisingly, the southern South Atlantic records show comparable SSTs (~12-14°C) during both the Earliest Oligocene Oxygen Isotope Step (EOIS, ~33.65 Ma) and the Miocene Climate Optimum (MCO, ~16.5 Ma). Apparently, maximum Oligocene Antarctic ice volume could coexist with warm ice-proximal surface ocean conditions, while at similar ocean temperatures, the Middle Miocene Antarctic ice sheet was strongly reduced. Southern South Atlantic SSTs cooled to ~5°C at the onset of the Middle Miocene Climate Transition (MMCT, 14 Ma), making it the coldest oceanic region recorded around Antarctica and the likely main location for deep water formation. The already cold southern South Atlantic conditions at MMCT meant it experienced little cooling during the latter part of the Miocene, which contrasts the profound cooling due to northward expansion of the Southern Ocean frontal systems in the lower latitudes and other sectors of the Southern Ocean.
(Climate of the Past. vol. 19, n° 1814-9324, pp. 1931-1949, 01/03/2023)
UGR, EPHE, PSL, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOCEAN-VOG, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité, IACT, CSIC, UGR, NIOZ
Evidence of separate influence of moon and sun on light synchronization of mussel’s daily rhythm during the polar night
(iScience. vol. 26, pp. 106168, 01/03/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IMR, IMR, UiB, NIVA, UiT
The Norfolk Ridge: A Proximal Record of the Tonga‐Kermadec Subduction Initiation
Norfolk Ridge bounds the northeastern edge of the continent of Zealandia and is proximal to where Cenozoic Tonga-Kermadec subduction initiation occurred. We present and analyze new seismic reflection, bathymetric and rock data from Norfolk Ridge that show it is composed of a thick sedimentary succession and that it was formed and acquired its present-day ridge physiography and architecture during Eocene to Oligocene uplift, emergence and erosion. Contemporaneous subsidence of the adjacent New Caledonia Trough shaped the western slope of Norfolk Ridge and was accompanied by volcanism. Neogene extension along the eastern slope of Norfolk Ridge led to the opening of the Norfolk Basin. Our observations reveal little or no contractional deformation, in contrast to observations elsewhere in Zealandia, and are hence significant for understanding the mechanics of subduction initiation. We suggest that subduction nucleated north of Norfolk Ridge and propagated rapidly along the ridge during the period 40-35 Ma, giving it a linear and narrow shape. Slab roll-back following subduction initiation may have preserved the ridge and created its eastern flank. Our observations suggest that pre-existing structures, which were likely inherited from Cretaceous Gondwana subduction, were well-oriented to propagate rupture and create self-sustaining subduction.
(Geochemistry, Geophysics, Geosystems. vol. 24, pp. 1-23, 01/03/2023)
SGNC DIMENC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GEO-OCEAN, UBS, IFREMER, INSU - CNRS, UBO EPE, CNRS, UniCA, EMMAH, AU, INRAE, BRGM, NPU, iSTeP, INSU - CNRS, SU, CNRS
An overview of marine non-indigenous species found in three contrasting biogeographic metropolitan French regions: Insights on distribution, origins and pathways of introduction
Biological invasions are one of the main global threats to biodiversity in terrestrial, freshwater and marine ecosystems worldwide, requiring effective inventorying and monitoring programs. Here, we present an updated list of non-indigenous species in French marine and transitional waters. Focused on eukaryote pluricellular species found throughout the three metropolitan French marine regions (Western Mediterranean Sea, Bay of Biscay and the Northern Seas), a total of 342 non-indigenous, including 42 cryptogenic, species are listed as having been introduced since the 13th century. The majority of the species originated from the temperate Northern Pacific. They mainly arrived through both ballast and hull fouling and also are associated with shellfish farming activities. Most of them have been introduced since the 1970s, a time when maritime and aquaculture trade intensified. Despite important human-aided opportunities for species transfer between the three marine regions (for instance, via recreational boating or aquaculture transfers), only a third of these NIS are common to all regions, as expected due to their environmental specificities.
(Diversity. vol. 15, n° 1424-2818, pp. 161, 23/02/2023)
PatriNat, MNHN, IRD, CNRS, OFB - DSUED, OFB, UMR ISEM, Cirad, EPHE, PSL, CNRS, UM, LITTORAL, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], LEMAR, IRD, IFREMER, UBO EPE, CNRS, DGD.REVE, MNHN, DYNECO, IFREMER, DECOD, IFREMER, INRAE, Institut Agro, Institut Agro, IFREMER, LIENSs, INSU - CNRS, ULR, CNRS, ECOSEAS, CNRS, UniCA, LECOB, SU, CNRS, OOB, SU, CNRS, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, SBR, SU, CNRS, IUEM, IRD, INSU - CNRS, UBO EPE, CNRS, OFB, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS
Pesticide Exposure of Residents Living in Wine Regions: Protocol and First Results of the Pestiprev Study
The PESTIPREV study has been designed to investigate residential exposure to pesticides applied to vines and ultimately propose mitigation measures. A feasibility study was carried out to validate a protocol for measuring six pesticides in three houses located near vineyards in July 2020. Samples included indoor and outdoor surfaces sampled with wipes (n = 214), patches on the resident's skin (n = 7), hand or foot washing (n = 5), and pets sampled using wipes (n = 2). Limits of quantification for wipes ranged between 0.02 ng for trifloxystrobin and 1.50 ng for pyraclostrobin. Tebuconazole and trifloxystrobin were quantified in nearly 100% of the surface samples, whereas the other fungicides were less frequently found (from 39.7% for pyraclostrobin to 55.1% for boscalid). The median surface loadings ranged from 3.13 ng/m(2) for benalaxyl to 82.48 ng/m(2) for cymoxanil. The pesticides most frequently quantified in hand washing, patch samples, and pet wipes were the same as those quantified on surfaces. Finally, the analyses proved to be successful. The tools developed to collect information on determinants were well completed. The protocol was well received by the participants and appeared to be feasible and relevant to the objective of the PESTIPREV study, although some improvements have been identified. It was applied on a larger scale in 2021 to study the determinants of pesticide exposure.
(International Journal of Environmental Research and Public Health. vol. 20, n° 1661-7827, 22/02/2023)
BPH, UB, INSERM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ECOSYS, INRAE
Upside down sulphate dynamics in a saline inland lake
The sulphur cycle has a key role on the fate of nutrients through its several interconnected reactions. Although sulphur cycling in aquatic ecosystems has been thoroughly studied since the early 70's, its characterisation in saline endorheic lakes still deserves further exploration. Gallocanta Lake (NE Spain) is an ephemeral saline inland lake whose main sulphate source is found on the lake bed minerals and leads to dissolved sulphate concentrations higher than those of seawater. An integrative study including geochemical and isotopic characterization of surface water, porewater and sediment has been performed to address how sulphur cycling is constrained by the geological background. In freshwater and marine environments, sulphate concentration decreases with depth are commonly associated with bacterial sulphate reduction (BSR). However, in Gallocanta Lake sulphate concentrations in porewater increase from 60 mM at the water-sediment interface to 230 mM at 25 cm depth. This extreme increase could be caused by dissolution of the sulphate rich mineral epsomite (MgSO 4 •7H 2 O). Sulphur isotopic data was used to validate this hypothesis and demonstrate the occurrence of BSR near the water-sediment interface. This dynamic prevents methane production and release from the anoxic sediment, which is advantageous in the current context of global warming. These results underline that geological context should be considered in future biogeochemical studies of inland lakes with higher potential availability of electron acceptors in the lake bed compared to the water column.
(Scientific Reports. vol. 13, n° 2045-2322, pp. 1845 - 1856, 21/02/2023)
iEES Paris, IRD, SU, UPEC UP12, CNRS, INRAE, IPREM, UPPA, INC-CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
PHANGS–JWST First Results: Multiwavelength View of Feedback-driven Bubbles (the Phantom Voids) across NGC 628
We present a high-resolution view of bubbles within the Phantom Galaxy (NGC 628), a nearby (∼10 Mpc), starforming (∼2 M e yr -1 ), face-on (i ∼ 9°) grand-design spiral galaxy. With new data obtained as part of the Physics at High Angular resolution in Nearby GalaxieS (PHANGS)-JWST treasury program, we perform a detailed case
(The Astrophysical Journal Letters. vol. 944, n° 2041-8205, pp. L22, 16/02/2023)
MPIA, AlfA, CRAL, ENS de Lyon, UCBL, INSU - CNRS, CNRS, ESO, RIDI - UPR 9022, IBMC, UNISTRA, CNRS, UNISTRA, INSERM, CNRS, OSU, UC San Diego, UC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UniCA, LAGRANGE, UNS, INSU - CNRS, UniCA, CNRS, UniCA, LAM, AMU, INSU - CNRS, CNES, CNRS, AIM (UMR7158 / UMR_E_9005 / UM_112), CEA, INSU - CNRS, UPD7, CNRS, UW, ANU, LIVE, UNISTRA, CNRS, CfA, IRAM, CNRS, LERMA (UMR_8112), INSU - CNRS, CNRS, PSL, UCP, SU, CNRS