Etude de la toxicité d’un produit virucide sur une espèce d’escargot aquatique Lymnaea stagnalis
Avec le contexte épidémique actuel, l’utilisation des biocides a connu un essor sans précédent qui risque de conduire à une augmentation de leur présence dans les écosystèmes aquatiques. Parmi eux, le chlorure de benzyldiméthyldodecylammonium (BAC 12), un biocide utilisé dans plus de la moitié des produits virucides conseillés par l'US EPA contre le SARS-CoV 2 soulève des questions. En effet, dans les rejets urbains les concentrations peuvent varier entre quelques ng/L à 170 µg/L tandis que la concentration maximale retrouvée dans l’environnement était de 6 mg /L dans les eaux usées d’un hôpital. Ce composé est connu pour être toxique pour de nombreux invertébrés aquatiques et très peu d’études se sont intéressées à son impact sur les mollusques d’eau douce. C’est pourquoi nous avons testé la toxicité aigüe et chronique du BAC 12 sur l’espèce Lymnaea stagnalis qui est un escargot aquatique ayant une distribution géographique large comprenant l’Europe, l’Amérique du Nord et l’Asie. Dans un premier temps nous nous sommes intéressés à la mortalité des escargots face au contaminant en les exposant à une gamme de concentration allant de 100 µg/L à 10 mg/L pendant une cinétique de 96h. Puis dans un second temps, nous avons prolongé l’exposition sur 21 jours pour les concentrations sublétales afin d’étudier les effets chroniques et la bioaccumulation du BAC 12 sur L. stagnalis. Les résultats de cette expérience sont en cours d’acquisition.
(15/03/2022)
UR EABX, INRAE, INRS - ETE, INRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UQAM
Sea ice changes in the southwest Pacific sector of the Southern Ocean during the last 140 000 years
(Climate of the Past. vol. 18, n° 1814-9324, pp. 465 - 483, 14/03/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Global biosphere primary productivity changes during the past eight glacial cycles
Global biosphere productivity is the largest uptake flux of atmospheric carbon dioxide (CO 2 ), and it plays an important role in past and future carbon cycles. However, global estimation of biosphere productivity remains a challenge. Using the ancient air enclosed in polar ice cores, we present the first 800,000-year record of triple isotopic ratios of atmospheric oxygen, which reflects past global biosphere productivity. We observe that global biosphere productivity in the past eight glacial intervals was lower than that in the preindustrial era and that, in most cases, it starts to increase millennia before deglaciations. Both variations occur concomitantly with CO 2 changes, implying a dominant control of CO 2 on global biosphere productivity that supports a pervasive negative feedback under the glacial climate.
(Science. vol. 375, n° 0036-8075, pp. 1145-1151, 11/03/2022)
LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, IPSL (FR_636), ENS-PSL, PSL, UVSQ, CEA, INSU - CNRS, X, IP Paris, CNES, SU, CNRS, UPCité, GEOPS, INSU - CNRS, CNRS, NBI, UCPH, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Holocene climate dynamics on the European scale: Insights from a coastal archaeological record from the temperate Bay of Biscay (SW France)
The main drivers of Europe's climate during the Holocene result from the coupling and interplay of external and internal radiative processes with the shifting patterns of many dynamic components (e.g. glaciers, ocean currents, wind fields, vegetation cover). Those driving forces were expressed across a range of geographical scales, from local to global, in a diverse set of records forming a patchwork of evidence as to the fundamental pacing effect of climate on past ecosystems. Various sedimentary deposits resulting from those complex forcing contexts bear climatic signatures that it is not always easy to disentangle especially with respect to local factors. The present paper focuses on a coastal archaeological site on the Medoc peninsula (the Lède du Gurp site in south-western France) that records Holocene palaeoenvironmental changes, decoded here century after century and integrated with ongoing events on a pan-North-Atlantic scale. Based on updated geoarchaeological approaches, thanks to new applications of proxies, especially X-ray fluorescence (XRF) core scanning methods for this article, continuous sedimentary records have been analysed in order to reconstruct a regional framework for past ecosystem events, including events potentially related to human activity. Our work identifies signals on various scales in the record under study, with both long- and short-term trends and local and global imprints, but all closely bound up with proximal North Atlantic Ocean dynamics. It highlights how western European environments (and so populations) were dependent upon the linearity of climate evolution at the key Northgrippian/Meghalayan transition.
(Quaternary International. vol. 613, n° 1040-6182, pp. 46-60, 10/03/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UBM, CNRS, UCM, IUEM, IRD, INSU - CNRS, UBO EPE, CNRS, GEO-OCEAN, UBS, IFREMER, INSU - CNRS, UBO EPE, CNRS, GEOPS, INSU - CNRS, CNRS
Calibration du proxy microcharbon préservé dans les sédiments marins et reconstruction des paléo-incendies en région Méditerranéenne Occidentale au cours de l'Holocene
Les microcharbons ont été analysés dans des sédiments marins de surface prélevés dans l’Océan Atlantique Est au large de la Péninsule Ibérique et en Mer Méditerranée Occidentale. Ils ont également été analysés dans un enregistrement sédimentaire du Golfe du Lion couvrant les derniers 8500 ans. Les paramètres de concentrations et de morphométries des microcharbons des sédiments de surface ont été comparés aux facteurs pouvant influencer la production, le transport et le dépôt de microcharbons dans l’océan. A l’échelle de la Péninsule Ibérique, les concentrations élevées de microcharbons fortement allongés dans les sédiments de surface indiquent des incendies rares, de grandes tailles et de forte intensité. Des concentrations faibles de microcharbons faiblement allongés indiquent des incendies fréquents, plus petits et de plus faible intensité. A l’échelle de la Méditerranée Occidentale, des concentrations fortes de microcharbons faiblement allongés indiquent des feux de forte intensité sous des conditions climatiques fraiches ou des feux de faible intensité se propageant dans une végétation fermée et arbustive sous des conditions climatiques chaudes et sèches. Des concentrations plus fortes de microcharbons fortement allongés indiquent des incendies dans une végétation ouverte et mixte sous des conditions chaudes et sèches. Les résultats observés à l’échelle de la Péninsule Ibérique ont été appliqués à un enregistrement sédimentaire marin couvrant l’Holocène dans le sud-ouest de la Péninsule Ibérique. Ainsi de rares et grands feux de forte intensité sont décrits depuis 8000 ans coïncidant avec l’ouverture progressive de la végétation. Les résultats observés à l’échelle de la Méditerranée, ont été appliqués à un enregistrement sédimentaire marin dans le sud-est de la France. Ainsi entre 8500 et 2700 ans de rares petits feux de forte intensité sont décrits tandis que depuis 2700 ans est décrite une alternance de rares petits feux de forte intensité et feux fréquents et larges de faible intensité. L’occurrence des feux dans le sud-est de la France pourraient être liée à des évènements froids, à la diminution de l’activité solaire et aux modes négatifs de l’Oscillation Nord Atlantique et de la condition atmosphérique de l’East Atlantic.
(10/03/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
One planet: one health. A call to support the initiative on a global science–policy body on chemicals and waste
The chemical pollution crisis severely threatens human and environmental health globally. To tackle this challenge the establishment of an overarching international science-policy body has recently been suggested. We strongly support this initiative based on the awareness that humanity has already likely left the safe operating space within planetary boundaries for novel entities including chemical pollution. Immediate action is essential and needs to be informed by sound scientific knowledge and data compiled and critically evaluated by an overarching science-policy interface body. Major challenges for such a body are (i) to foster global knowledge production on exposure, impacts and governance going beyond data-rich regions (e.g., Europe and North America), (ii) to cover the entirety of hazardous chemicals, mixtures and wastes, (iii) to follow a one-health perspective considering the risks posed by chemicals and waste on ecosystem and human health, and (iv) to strive for solution-oriented assessments based on systems thinking. Based on multiple evidence on urgent action on a global scale, we call scientists and practitioners to mobilize their scientific networks and to intensify science-policy interaction with national governments to support the negotiations on the establishment of an intergovernmental body based on scientific knowledge explaining the anticipated benefit for human and environmental health.
(Environmental Sciences Europe. vol. 34, n° 2190-4707, pp. 21, 08/03/2022)
UFZ, IRSTEA, CSIC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IRCCS, IRSTEA, INERIS, ZAG, DTU, MU, RECETOX / MUNI, SCI / MUNI, MU / MUNI, EAWAG, IBP, D-USYS, ETH Zürich, RWTH Aachen, UNSW, UCA, ECOSYS, INRAE, RIVM, NIVA, NILU, uni.lu, ISOE, NTU, UnB, UQ [All campuses : Brisbane, Dutton Park Gatton, Herston, St Lucia and other locations], NUS
PSDR4 AQUAVIT -Eléments pour une gestion territoriale des invasions biologiques. Le cas des plantes aquatiques sur les lacs de la façade atlantique en Aquitaine
Le projet AQUAVIT vise à accompagner l'évolution des modalités de gestion des lacs de la façade Atlantique, en Aquitaine, en tant qu'espaces supports d'activités récréatives et touristiques, confrontés à des enjeux environnementaux liés aux colonisations par les plantes aquatiques invasives. Une démarche pluridisciplinaire, associant les sciences humaines et sociales et les sciences de l'environnement, a été élaborée dans cette optique. Nos résultats invitent à s'éloigner d'une représentation univoque des conséquences potentielles de la présence d'herbiers denses de plantes aquatiques invasives, tout comme à contextualiser les problématiques socio-environnementales de leur développement. Sur cette base, nous dessinons plusieurs pistes pour une approche à caractère territorial de la gestion des phénomènes d'invasions biologiques.
(Innovations Agronomiques. vol. 86, n° 1958-5853, pp. 163-171, 01/03/2022)
UR ETTIS, INRAE, UR EABX, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, Bordeaux INP, UBM
Fossil pigments and environmental conditions in the oligotrophic Laja Lake in the Chilean Andes
Interactions among climate change, ozone depletion, and ultraviolet radiation affect aquatic ecosystems. Meteorological and biological monitoring is often too brief, however, to record the magnitudes of past changes in ultraviolet fluxes and their effects. This study presents an analysis of fossil pigments and environmental conditions in the oligotrophic Laja Lake in the Chilean Andes over a 60-year period. The age of the sediment core was determined using high-efficiency gamma spectrometry and dated with lead-210 (210Pb). Analysis of the total and specific fossil pigments from a sediment core utilized a combination of analytical methods, spectrophotometry, and high-performance liquid chromatography. Environmental variables, such as stratospheric ozone concentration, temperature, precipitation, and ultraviolet radiation explained changes in the fossil pigment scytonemin.. Results showed that low cloud cover over the high mountain lake predominated, with high ultraviolet radiation and temperature values during summer months. The most abundant group was Bacillariophyceae (diatoms). The highest concentrations of the pigments (canthaxanthin echinenone, myxoxanthophyll, aphanizophyll zeaxanthin and scytonemin) that represent the cyanobacteria groups were found in the upper part of the core (cm 0–15). The trend analysis further suggested that the influence of environmental features enabled generation of ultraviolet radiation-shielding pigment in the algae communities in the high mountain lake.This study advances understanding of the interactive effects of climate change, ozone depletion, and ultraviolet radiation on aquatic ecosystems. Fossil pigments proved to be good indicators of lake-ecosystem response to climate/environmental changes, which are necessary for predicting possible effects of future climate change.
(Anthropocene. vol. 37, n° 2213-3054, pp. 100321, 01/03/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Hydro-sedimentary dynamics of the Rance estuary : processes, evolution and management
The Rance estuary is a relatively small low-discharge steep-sided ria, located along the Brittany coast in northern France, with a maximum spring tidal range of 13.5 m. Taking advantage of this hyper-tidal regime, the first operational tidal power station (TPS) in the world (and currently the second largest) was built at the estuary’s mouth and has been in operation since the 1960s. In addition to the TPS, the Rance estuary is characterized by its complex morphology and the configuration of its uppermost limit (Chatelier lock).Net siltation and sediment accumulation were reported in the basin since the 1980s by various studies based on field measurements. However, the impact of the TPS on hydrodynamics, sediment transport and morphodynamic is still unquantified. In addition, the relevance of each physical processes driving hydrodynamics and sediment dynamics in this complex system is still unclear.This PhD thesis aims to better understand hydro-sedimentary dynamics in this highly engineered system by the presence of a tidal power plant on its mouth and a lock on its uppermost limit.To this goal, a complementary approach accounting for both field measurements and numerical modelling was deployed. On the one hand, field surveys of hydro-sedimentary variables were carried out to calibrate and validate the numerical models. On the other hand, 2D and 3D hydro-sedimentary numerical models were developed in the TELEMAC-MASCARET modelling system.Numerical results reveal that the TPS induces (i) a major decrease in tidal range and tidal prime along with the increase of submerged intertidal zones; (ii) a limitation of high-water level inside the estuary protecting it against marine flooding; and (iii) an overall decrease in currents except in the region close to the TPS. Moreover, the morphology of the estuary amplifies ebb currents in the narrowing at Saint-Hubert-Port. Furthermore, the TPS pushes the freshwater-saltwater interface roughly 5km upstream in the estuary. Its position is also sensitive to seasonal river discharge variation.The 3D hydro-sedimentary model shows that at the scale of a tidal cycle (i) peak suspended sediment concentrations (SSC) are noticed during the estuary's infilling phase; and (ii) sediment could be resuspended locally during the turbining phase (electricity production stage), but would not be transported further than 3km from the uppermost limit. At the scale of a fortnight, residual sediment flux is continuously oriented towards the upper estuary. Consequently, significant sedimentation rates were observed in the main upstream channel. This morphodynamic behavior was also captured by the model under natural tidal forcing (without TPS), but with lower sedimentation rates. At the time-scale of one year, 2D hydro-sedimentary numerical results assess the need to provide an accurate river discharge considering hydraulic flushes to correctly simulate long term morphodynamic processes.Furthermore, hydraulic flushes at the Chatelier lock and the opening of sluice gates during ebb prove their efficiency in decreasing sediment accumulation in the upper estuary. Finally, the complementary 2D and 3D numerical models showed to be invaluable tools to define a sustainable management plan of the Rance estuary.
(23/02/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Modelling past and future sandy shoreline change and the respective uncertainties : toward a holistic approach
Shoreline change along sandy coasts responds to a myriad of processes interacting at different spatial and temporal scales, making shoreline predictions challenging. Shoreline modelling inherits uncertainties from the primary driver boundary conditions (e.g. sea-level rise and wave forcing) as well as uncertainties related to model assumptions and/or misspecifications of the physics. Despite the recent progresses in addressing uncertainties related to sea-level rise (SLR), the uncertainties related to wave-driven shoreline response are still poorly understood. This thesis gathers wave-driven equilibrium shoreline models, SLRdriven recession models, and variance decomposition methods into a probabilistic framework to investigate the roles of several sources of uncertainty in modelled shoreline change. The framework is applied to analyse the uncertainties associated with past and future multi-decadal shoreline evolution at the cross-shore transport dominated sandy beach of Truc Vert (France). As the physics of the combined action of waves and sea-level rise has not yet been described in detail, the thesis also presents a novel physical interpretation of the beach response to sea-level rise to support the integration of SLR-driven recession into equilibrium shoreline models. Shoreline response under the coupled effects of waves and SLR reveals complex patterns and interplays of the several contributions of uncertainties to shoreline predictions. Overall, uncertainties on Truc Vert shoreline predictions across the 21st century are driven by the uncertain model free parameters and wave conditions over the first half of the century. Then, the uncertainties on SLR become the dominant driver over the last decades. When uncertainties on SLR are negligible, the uncertainties of wave conditions variability are responsible for up to 83% of the uncertainties in modelled shoreline. It is also observed that the uncertainties in modelled shoreline trajectories depend on the underlying physical assumptions of different equilibrium shoreline models and future climate scenario.
(10/02/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS