Possible impact des changements environnementaux sur les derniers néandertaliens et de l’implantation de l’homme anatomiquement moderne dans le sud-ouest de la France (48 000 et 35 000 ans avant le présent)
Une des questions qui se pose conjointement en archéologie et en paléoenvironnement est le possible impact des changements climatiques sur les populations humaines et leurs moyens d’adaptation. Répondre à cette question reste difficile et on peut seulement l’aborder si on trouve un synchronisme entre un événement climatique et un changement culturel. Cependant, l’identification d’une synchronie est limitée par les incertitudes inhérentes aux chronologies des sites archéologiques et à celles des enregistrements paléoclimatiques, mais aussi en raison des résolutions des archives environnementales. Pour pallier au dernier problème, notre étude se focalise sur l’amélioration de la résolution temporelle des données environnementales dans le sud-ouest de la France, lors de la période-charnière entre le Paléolithique moyen/supérieur entre environ 48 000 et 35 000 ans avant le présent. Cette région du sud-ouest de la France a été l’objet de nombreuses études archéologiques sur les traditions culturelles du Paléolithique moyen et Paléolithique supérieur. Nous avons analysé à très haute résolution (100-300 ans)), les pollens et spores préservés dans une carotte sédimentaire marine prélevée dans le Golfe de Gascogne (France). Cette analyse a permis d’identifier des expansions et contractions de la forêt atlantique dans le sud-ouest de la France, qui sont synchrones respectivement des réchauffements et refroidissements des températures des eaux de surface de l’Atlantique Nord-Est. Ces événements climatiques peuvent être associés aux cycles de Dansgaard-Oeschger (D-O) 11 au D-O 8 et à l’événement d’Heinrich 4. De plus, nous avons pu identifier plusieurs phases au cours du stadiaire d’Heinrich 4. La comparaison de nos résultats avec la chronologie des transitions culturelles de cette région semble montrer, malgré les difficultés chronologiques évoquées plus haut, une concomitance entre changements environnementaux et changements culturels.
(03/02/2020)
IRAMAT-CRP2A, IRAMAT, UTBM, UO, UBM, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EPHE, PSL, PACEA, UB, CNRS
Livret-guide de l'Excursion Géologique de l’AGSO en MARTINIQUE, 19 au 25 avril 2020
L’objectif de cette excursion géologique organisée par l’AGSO (Association des Géologues du Sud-Ouest) sur 7 jours est de découvrir (ou redécouvrir) quelques aspects du volcanisme de l’île de la Martinique. La Martinique appartient à l'arc volcanique des Petites Antilles qui résulte de la subduction, toujours active, de la plaque Atlantique sous la plaque Caraïbe. Ce volcanisme d'arc insulaire se caractérise par la production de magmas de chimisme calco-alcalin qui donnent lieu à une activité éruptive effusive (coulées de laves andésitiques dominantes, et basaltiques subordonnées) et explosive (dômes et écoulements pyroclastiques, coulées de ponces, dans lesquelles les compositions andésitiques à dacitiques dominent). L'île de la Martinique (1080 km²) est essentiellement d'origine volcanique. Les formations volcaniques et volcano-sédimentaires y prédominent très largement, accompagnées de formations calcaires liées à des épisodes de sédimentation marine restreinte aux périodes de submersion. L'activité volcanique sous-marine initiale, qui a formé le substratum de l'île, entrecoupée de phases de sédimentation calcaire, est devenue progressivement aérienne et a édifié de grands ensembles volcaniques qui constituent les principaux reliefs actuels de la Martinique. L’histoire géologique de la Martinique est complexe et se divise en trois grands cycles éruptifs qui sont respectivement liés aux activités des arcs dits ancien, intermédiaire et récent. Ce livret-guide est organisé en quatre parties. La première partie présente rapidement les caractéristiques des magmas, de leurs produits et la diversité des mécanismes éruptifs qui accompagnent leur arrivée en surface. La seconde partie propose une synthèse générale sur le volcanisme associé au contexte de la marge active des Petites Antilles. La troisième partie détaille les spécificités de l’île de la Martinique. La quatrième partie, enfin, dresse l’inventaire des sites visités chaque jour sur le terrain. Bon terrain !
(03/02/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM
An environmentally realistic pesticide and copper mixture impacts embryonic development and DNA integrity of the Pacific oyster, Crassostrea gigas
Frequent occurrences of pesticides in the environment have raised concerns that combined exposure to these chemicals may result in enhanced toxicity through additive or synergistic interaction between compounds. Spermatozoa and embryos of the Pacific oyster, Crassostrea gigas, were exposed to different concentrations of a pesticide mixture with and without copper, mimicking the cocktail of pollutants occurring in the oyster culture area of Arcachon Bay. For the 1× exposure condition, measured concentration corresponds to a total concentration of 1.083 μg L−1 for the mixture of 14 pesticides and to 6.330 μg L−1 for copper (Cu). Several endpoints including larval abnormalities, DNA damage to spermatozoa and embryo and gene expression in D-larvae were investigated. Results demonstrated that pesticide mixtures in combination with or without copper induced a dose-dependent increase in embryotoxic and genotoxic effects on D-larvae from the lowest tested dose of 0.1×. Transcription of genes involved in anti-oxidative stress (cat), respiratory chain (coxI), metal detoxification (mt1 and mt2), and cell cycle arrest and apoptosis (p53) was found to be significantly downregulated while the xenobiotic biotransformation gene gst was significantly upregulated in embryos exposed to pesticide mixture with and without Cu. These findings raise the question of the possible impacts of mixtures of pesticides and metals on wild or farmed oyster populations from polluted coastal marine areas.
(Environmental Science and Pollution Research. vol. 27, n° 0944-1344, pp. 3600-3611, 01/02/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EABX, INRAE
Influence of Macrophyte and Gut Microbiota on Mercury Contamination in Fish: A Microcosms Study
The freshwater lakes of southwestern France are subject to the development of invasive macrophytes which are associated with mercury (Hg) contamination of the food web. The aim of this study was to determine the bioavailability of methylmercury (MeHg) produced by plant roots in aquatic ecosystems. A microcosm experiment was performed using isotopically enriched inorganic Hg at environmental concentrations (1 μg 199IHg L-1). For all conditions, total Hg in fish as well as Hg species associated with different compartments (water, sediments, plant roots, fish) were analyzed by gas chromatography-inductively coupled plasma-mass spectrometry (GC-ICP-MS). In addition, sediment, plants, and fish gut microbiota were studied by MiSEQ sequencing. Some strains were isolated and tested for their ability to methylate Hg. The results revealed 199MeHg production in plant roots and the presence of this form in fish (tissues and gut), highlighting a MeHg trophic transfer. Moreover, methylator bacteria were identified from the gut contents of the fish when they were in the presence of plants. Some of them were related to bacteria found in the plant roots. On the basis of these results, the transfer of MeHg and bacteria from plants to fish is highlighted; in addition, Hg methylation is strongly suspected in the fish gut, potentially increasing the Hg bioaccumulation.
(Applied Sciences. vol. 10, n° 2076-3417, pp. 1500, 01/02/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPREM, UPPA, INC-CNRS, CNRS, IMS, UB, CNRS, IMS, UB, CNRS, ENSC, Bordeaux INP
Contrasts in chemical composition and oxidative potential in PM10 near flares in oil extraction and refining areas in Ecuador
For decades, oil extraction in rural sites in the North Amazon Region (NAR) in Ecuador, have generated mixtures of potentially toxic compounds, such as polycyclic aromatic hydrocarbons (PAHs) and metal(loid)s. The main national refinery and the thermal power plant located in Esmeraldas, on the North Pacific Coast (NPC), are also considered as important sources of air contamination. Particulate matter (PM10) emitted at both sites could induce the formation of reactive oxygen species (ROS) in the lungs upon inhalation and could be associated with respiratory diseases. In this study, PM10 mass composition was monitored over a two-year period in both regions: NAR (close to oil platforms and open flares) and NPC (in a public school close to the refinery). PM10 composition was assessed in terms of metal(loid)s, organic and elementary carbon (OC, EC), monosaccharides (levoglucosan, mannosan, galactosan), glucose, polyols (sorbitol, mannitol, arabitol), water soluble ions and polycyclic aromatic compounds (PAHs, oxy-PAHs and nitro-PAHs). Additionally, three complementary biochemical and acellular tests were performed to evaluate the oxidative potential (OP).Results show that the PM10 mass and elemental concentrations were higher in NPC than in NAR. Barium and Mo concentrations, commonly used in oil operations, were up to 1000-fold higher than values recorded in other regions of Ecuador. OC/EC ratios and polyols concentrations were higher in NAR than in NPC, indicating a larger biogenic contribution to the PM mass in this region. In NAR, the main sources associated with ROS burden were biogenic emissions and oil production, as indicated by positive correlations between OP, sugars, Ba, some PAHs and oxy-PAHs. On the other hand, in NPC, associations between NH4+, Ba, As and Ni imply that oil refining and industrial activities are the main contributors to the OP of PM10.
(Atmospheric Environment. vol. 223, n° 1352-2310, pp. 117302, 01/02/2020)
GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, IGE, IRD, INSU - CNRS, CNRS, Fédération OSUG, UGA, Grenoble INP, UGA, UMSA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UASB
Glacial-interglacial flux and size variability of Fragilariopsis kerguelensis and Thalassiosira lentiginosa from the Indian sector of the Southern Ocean
(Deep Sea Research Part II: Topical Studies in Oceanography, n° 0967-0645, pp. 104746, 01/02/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Oceanic versus continental influences over the last 7 kyrs from a mid-shelf record in the northern Bay of Biscay (NE Atlantic)
We discuss paleoenvironments of north-western France over the last 7 kyrs in terms of: i) long-term changes (relative sea-level rise and boreal summer insolation), ii) rapid climate changes (millennial-scale Bond events and multi-decadal regimes of the North Atlantic Oscillation: NAO) and iii) growing human impacts in watersheds. Our study focuses on the CBT-CS11 core, retrieved in the northern Bay of Biscay, with new high-resolution (70 years) palynological data (dinoflagellate cysts and pollen), combined with sedimentological and oxygen stable isotopic records. This multiproxy approach enabled us to gain a better understanding of the influence of varying Middle to Late Holocene climate regimes on marine, coastal and terrestrial ecosystems as well as on human coastal societies. We especially show that the slowdown of the relative sea-level rise, starting at around 5.9 ka BP, led to the stabilization of tidal flats in estuarine environments. Subsequently, increasing river flows to the ocean resulted in a progressive seasonal stratification of the shelf under increasing winter precipitations and establishment of the modern winter thermohaline front at 3.3 ka BP. In addition, within the 4–2 ka BP interval, palynological and sedimentological evidence suggests increasing river discharges in north-western France, in a context of a weakened Atlantic subpolar gyre and recurrent negative “NAO-like” conditions. Finally, we identified a major transition at around 1.2 ka BP (Early Middle-Ages) that appears to be linked to a period of maximal anthropogenic landscape opening and soil erosion, implying stronger primary productivity in coastal surface waters of the studied region.
(Quaternary Science Reviews. vol. 229, n° 0277-3791, pp. 106135, 01/02/2020)
LGO, UBS, IFREMER, UBO EPE, CNRS, LARA, UN, CReAAH, UM, UR, UR2, CNRS, UFR HHAA, UN, MC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GM, IFREMER, LETG - Brest, LETG, UNICAEN, NU, UA, EPHE, PSL, UBO EPE, UR2, CNRS, IGARUN, UN, LOPS, IRD, IFREMER, INSU - CNRS, UBO EPE, CNRS, Inrap, UP1, CNRS, LHEEA, ECN, CNRS, GEOTOP, EPM, UdeM, UQAT, UQAR, UQAM, LPG-ANGERS, LPG, UM, UA, INSU - CNRS, CNRS, Nantes univ - UFR ST
Ecotoxicity of polyethylene nanoplastics from the North Atlantic oceanic gyre on freshwater and marine organisms (microalgae and filter-feeding bivalves)
Each year, 5 to 10 million tons of plastic waste is dumped in the oceans via freshwaters and accumulated in huge oceanic gyres. Under the effect of several abiotic factors, macro plastic wastes (or plastic wastes with macro sizes) are fractionated into microplastics (MP) and finally reach the nanometric size (nanoplastic NP). To reveal potential toxic impacts of these NPs, two microalgae, Scenedemus subspicatus (freshwater green algae), and Thalassiosira weissiflogii (marine diatom) were exposed for up to 48 h at 1, 10, 100, 1000, and 10,000 μg/L to reference polyethylene NPs (PER) or NPs made from polyethylene collected in the North Atlantic gyre (PEN, 7th continent expedition in 2015). Freshwater filter-feeding bivalves, Corbicula fluminea, were exposed to 1000 μg/L of PER and PEN for 48 h to study a possible modification of their filtration or digestion capacity. The results show that PER and PEN do not influence the cell growth of T. weissiflogii, but the PEN exposure causes growth inhibition of S. subspicatus for all exposure concentrations tested. This growth inhibition is enhanced for a higher concentration of PER or PEN (10,000 μg/L) in S. subspicatus. The marine diatom T. weissiflogii appears to be less impacted by plastic pollution than the green algae S. subspicatus for the exposure time. Exposure to NPs does not lead to any alteration of bivalve filtration; however, fecal and pseudo-fecal production increased after PEN exposure, suggesting the implementation of rejection mechanisms for inedible particles.
(Environmental Science and Pollution Research. vol. 27, n° 0944-1344, pp. 3746-3755, 01/02/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GR, UR, INSU - CNRS, CNRS, UMR ECOFOG, Cirad, INRA, UG, CNRS, UA, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, IMRCP, ICT, IRD, UT3, Comue de Toulouse, INC-CNRS, CNRS, Toulouse INP, Comue de Toulouse, INEE-CNRS, CNRS, UT3, Comue de Toulouse, INC-CNRS, CNRS, IMRCP - SMODD, IMRCP, ICT, IRD, UT3, INC-CNRS, CNRS, Toulouse INP, INEE-CNRS, CNRS, UT3, Comue de Toulouse, INC-CNRS, CNRS
Mercury contamination levels in the bioindicator piscivorous fish Hoplias aïmara in French Guiana rivers: mapping for risk assessment
In French Guiana, native populations present high level of mercury contamination, which has been linked to the consumption of contaminated fishes. The goal of this study is to undertake a cartography of mercury contamination levels in fishes from the six main Guiana rivers. The selected species for this study is the ubiquitous piscivorous fish Hoplias aimara. A total number of 575 fishes from 134 discrete fishing sites are regrouped into 51 river sectors. Results from this study permits to rank the six main Guiana rivers by their mean level of contamination: Oyapock (0.548 mg kg−1), Comté (0.624 mg kg−1), Maroni (0.671 mg kg−1), Approuague (0.684 mg kg−1), Mana (0.675 mg kg−1), and Sinnamary (1.025 mg kg−1). The contamination is however not spatially homogenous along each river, and a map of the different levels of mercury contamination in fishes is provided. Sectors of low mean Hg contamination are observed both upstream (0.471 mg kg−1) and downstream (0.424 mg kg−1), corresponding to areas without any influence of gold mining activities and areas under the influence of estuarine dilution, respectively. Anoxia and gold mining activities are found to be the two main factors responsible for the high mercury concentration in fish muscles. While mean levels of mercury contaminations are higher in anoxia areas (1.029 mg kg−1), contaminations induced by gold mining activities (0.717 mg kg−1) present the most harmful consequences to human populations. No significant differences in Hg concentrations are observed between 2005 and 2014 for neither a pristine nor a gold mining area, while Hg concentration differences are observed between former (0.550 mg kg−1) and current gold mining sites (0.717 mg kg−1).
(Environmental Science and Pollution Research. vol. 27, n° 0944-1344, pp. 3624-3636, 01/02/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM, LMBA, UBS, UBO EPE, CNRS
Juvenile fish caging as a tool for assessing microplastics contamination in estuarine fish nursery grounds
Estuaries serve as nursery grounds for many marine fish species. However, increasing human activities within estuaries and surrounding areas lead to significant habitat quality degradation for the juveniles. In recent years, plastic pollution has become a global environmental issue as plastic debris are found in all aquatic environments with potential adverse impacts on marine biota. Given the important ecological role of estuaries and implications of microplastics (MP) in ecosystems, here we assess the occurrence, number, size and polymer types of MP ingested by wild and caged juveniles European flounder (Platichthys flesus). We deployed caged fish for one month at five sites in three estuaries in the Eastern English Channel. The Seine estuary, heavily impacted by manmade modifications and one of the most contaminated estuaries in Europe, was compared to two smaller estuaries (Canche and Liane) less impacted by industrial activities. We found that juvenile flounders (7- 9 cm) were vulnerable to plastic ingestion. 75% of caged fish and 58% of wild caught fish had the presence of MP items in their digestive tract. Fibers (69%) dominated in the fish’s digestive tract at all sites. An average of 2.04 ± 1.93 MP items were ingested by feral juveniles flounder and 1.67 ± 1.43 by caged juveniles flounder. For the caged fish, the three sites impacted by wastewater treatment plant (Liane, Le Havre Harbor and Rouen) were those with the highest percentage of individuals that have ingested MP items. Most of the isolated items were fibers and blue in color. Polymers identified by micro Raman spectroscopy were Polycaprolactam, Polyethylene Terephtalate and Polyurethane. Although other environmental factors may have affected caged fish condition and mortality, we found no significant correlation with the number of ingested MP. However, the high occurrence of MP ingested by juvenile fish on nursery grounds raises concerns on their potential negative effects for fish recruitment success and population renewal. Finally, this study describes, for the first time, the feasibility of using caged juvenile fish as an assessing tool of MP contamination in estuarine nursery grounds.
(Environmental Science and Pollution Research. vol. 27, n° 0944-1344, pp. 3548-3559, 01/02/2020)
LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], ULCO, CNRS-L, IFREMER, LSAl, ANSES, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS