Cultural changes and adaptations to climatic and environmental changes of the last Neanderthals in southern France
(Quaternaire, n° 1142-2904, pp. 139-142, 01/07/2023)
UB, UBM, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Riverine Particulate Matter Enhances the Growth and Viability of the Marine Diatom Thalassiosira weissflogii
Riverine particulates dominate the transport of vital nutrients such as Si, Fe or P to the ocean margins, where they may increase primary production by acting as slow-release fertilizer. Furthermore, the supply of particulate surface area to the ocean is considered to be a major control of organic carbon burial. Taken together, these observations suggest a close link between the supply of riverine particulate material and the organic carbon cycle. To explore this link, we conducted microcosm experiments to measure the growth of the marine diatom Thalassiosira weissflogii in the presence and absence of different types and concentrations of riverine particulate material. Results demonstrate a strong positive effect of riverine particulate material on diatom growth with increased total diatom concentrations and slowed post-exponential death rates with increasing particulate concentration. Moreover, SEM and optical microscope investigations confirm that riverine particulates facilitate organic carbon burial through their role in the aggregation and sedimentation of phytoplankton. The supply of riverine particulate material has been shown to be markedly climate sensitive with their fluxes increasing dramatically with increasing global temperature and runoff. This pronounced climate sensitivity implies that riverine particulates contribute substantially in regulating atmospheric CO2 concentrations through their role in the organic carbon cycle.
(Minerals. vol. 13, n° 2075-163X, pp. 183, 26/06/2023)
GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, TSU, FECIAR UrB RAS, RAS, UCL
Chronic exposure to tebuconazole alters thyroid hormones and plumage quality in house sparrows (Passer domesticus)
Triazoles belong to a family of fungicides that are ubiquitous in agroecosystems due to their widespread use in crops. Despite their efficiency in controlling fungal diseases, triazoles are also suspected to affect non-target vertebrate species through the disruption of key physiological mechanisms. Most studies so far have focused on aquatic animal models, and the potential impact of triazoles on terrestrial vertebrates has been overlooked despite their relevance as sentinel species of contaminated agroecosystems. Here, we examined the impact of tebuconazole on the thyroid endocrine axis, associated phenotypic traits (plumage quality and body condition) and sperm quality in wild-caught house sparrows (Passer domesticus). We experimentally exposed house sparrows to realistic concentrations of tebuconazole under controlled conditions and tested the impact of this exposure on the levels of thyroid hormones (T3 and T4), feather quality (size and density), body condition and sperm morphology. We found that exposure to tebuconazole caused a significant decrease in T4 levels, suggesting that this azole affects the thyroid endocrine axis, although T3 levels did not differ between control and exposed sparrows. Importantly, we also found that exposed females had an altered plumage structure (larger but less dense feathers) relative to control females. The impact of tebuconazole on body condition was dependent on the duration of exposure and the sex of individuals. Finally, we did not show any effect of exposure to tebuconazole on sperm morphology. Our study demonstrates for the first time that exposure to tebuconazole can alter the thyroid axis of wild birds, impact their plumage quality and potentially affect their body condition. Further endocrine and transcriptomic studies are now needed not only to understand the underlying mechanistic effects of tebuconazole on these variables, but also to further investigate their ultimate consequences on performance (i.e. reproduction and survival).
(Environmental Science and Pollution Research, n° 0944-1344, 26/06/2023)
CEBC, ULR, CNRS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BOREA, UNICAEN, NU, MNHN, IRD, SU, CNRS, UA, LIENSs, INSU - CNRS, ULR, CNRS, LCE, CNRS, UFC, UBFC
Étude expérimentale de l’érodabilité des microplastiques en milieux vaseux
(26/06/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, HydEE, Département FTC, PPrime [Poitiers], UP, ISAE-ENSMA, CNRS, PPrime [Poitiers], UP, ISAE-ENSMA, CNRS
Characterization of the infiltration in the cave of Villars (Dordogne) by geophysical and isotopic methods : Importance for paleo-climatic studies based on speleothems as well as for the conservation of heritage sites
The geometry of caves and infiltration zones as well as the rainfall infiltration processes in karst areas are complex and still not completely understood. This knowledge is, however, crucial for the interpretation of speleothem-based climatic reconstructions, water sustainability, and heritage conservation. In order to deepen our knowledge on this topic, we choose a typical shallow cave (Villars Cave, SW-France) that has been monitored for decades and where numerous studies have been already made on both present-day environment and speleothem studies. The first question that we worked on was about the rainfall “input” signal above the Villars Cave. What is the source of the rainfall above the cave, and how does it vary? For that, we used a backtracking (HYSPLIT) model to better understand the rainfall original oxygen isotopic sources (δ18O) of the seepage water. Results revealed a well-marked seasonality of the rainfall sources and long-term trends, depending on the distance between Villars Cave and moisture source regions, expressed in the percentage of initial moisture sources (PIMS). The second question concerns the characterization of the infiltration and its time evolution using isotopic composition from the rainfall to the stalactite dripping water that feeds stalagmites. We used both a very long monitoring (>20 years) isotopic data set (of rainfall and dripping rates at a different level in this cave) combined with a conceptual model (KarstFor) that mixes water flows and isotopes to better understand the process of karst infiltration. Results showed that the modeled output variations in the quantity of storage water and infiltration flow coincide with the observed dripping discharge rates made under stalactites at two different gallery levels in the cave. The fact that the model strikingly simulates the small, but constant, isotopic difference between the upper and the lower galleries of Villars Cave, not only reinforces the model itself but also reveals the impact of multiple infiltration routes and karst reservoir dynamics on the drip-water δ18O. The third question focused on the geometry of the infiltration zone: water reservoirs and preferential flow routes. For that, we applied a 2D ERT (Electrical resistivity tomography) method above the Villars Cave at a one-two monthly interval during three years (February 2020 and January 2023). With the help of a multidimensional statistical approach (Hierarchical agglomerative clustering, HAC), ERT monitoring images revealed the seasonal variation of resistivity in different ERT regions. This allowed us to visualize specific karst zones characterized by their resistivity and their variability in resistivity, leading to the identification of cave galleries, water storage reservoirs, wetting fronts, soil layers and potential preferential flow paths as deep as 30 m. By combining ERT, hydrology and isotopic methods, we have significantly improved our understanding of the source and variability of the water flow above Villars Cave, as well as the mixing processes in the reservoirs that feed the stalactites. This knowledge is invaluable for the preservation of the cave environment and for speleothem- based paleoclimatic research.
(26/06/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Variabilité de la mousson indienne d’été pendant les périodes interglaciaires des derniers 800 000 ans : étude des changements de végétation à partir des sédiments du Golfe du Bengale
Bien qu’elle affecte la vie quotidienne d’un sixième de la population mondiale ainsi que les écosystèmes continentaux, la compréhension du phénomène de la mousson d’été indienne (ISM pour Indian Summer Monsoon) n’est pas aboutie. Puisque les expériences de modélisation actuelles ne s’accordent pas sur l’évolution future de l’ISM en relation avec le réchauffement climatique, l’étude des interglaciaires passés fournit un moyen stratégique d’examiner la réponse et le forçage de la mousson pendant les grandes périodes chaudes du passé. L’objectif principal de cette thèse est de contribuer au débat qui existe depuis plus d’une décennie sur les forçages et les processus qui contrôlent en particulier le timing et l’intensité de l’ISM lors des périodes interglaciaires. Dans ce travail, l’étude des grains de pollen contenus dans la carotte sédimentaire du Site IODP U1446 localisé au large du fleuve Mahanadi dans le nord-est de la péninsule indienne a permis la constitution des changements de la végétation au cours des trois périodes interglaciaires : les MIS 1, MIS 5e, et MIS 19c. Le choix de ces intervalles a été réalisé en mettant à profit leur diversité de forçage afin d’examiner comment était l’intensité de la mousson dans un monde plus chaud (le MIS 5e) que notre interglaciaire actuel (MIS 1), et dans un monde plus frais (MIS 19c). Des changements de végétation de très grande amplitude ont été observés pour chacun des intervalles étudiés, marqués par le passage d’une steppe semi-aride lors de la fin de périodes glaciaires au développement d’une forêt tropicale -plus ou moins dense- lors des périodes interglaciaires. Si l’évolution à long terme de la forêt totale est en accord avec les autres traceurs du Site U1446 et les enregistrements régionaux de l’ISM, le développement d’un marqueur d’humidité basé sur la composition de cette forêt tropicale a permis la discrimination de différentes phases d’évolution de l’ISM au cours du temps que ni la forêt tropicale totale, ni les autres traceurs du Site U1446 ne discriminaient. Associés à une révision du modèle d’âge par rapport à ceux précédemment publiés, les données polliniques ont permis de définir les périodes humides indiennes pour chacun de ces trois intervalles, contraints de 11,8 à 5,1 ka cal BP pour le MIS 1, de 127 à 120 ka BP pour le MIS 5e et de 787,5 à 782,5 ka BP pour le MIS 19c. En comparaison relative, nous montrons que l’intensité des pluies de mousson étaient la plus forte lors des périodes humides du MIS 5e et MIS 19c par rapport à celle du MIS 1, elle-même plus humide que les conditions actuelles. La confrontation des données polliniques avec les résultats d’expériences de simulations transitoires et instantanées (LOVECLIM1.3 et HadCM3) a conduit à la conclusion que le forçage orbital, en particulier la précession, constituait le principal forçage de contrôle sur le timing de l’ISM lors des trois périodes étudiées. Bien que largement minoritaire par rapport au forçage orbital, une influence non négligeable du volume de glace sur le renforcement de la mousson a été identifié en particulier lors des terminaisons, pouvant induire un retardement du début des périodes humides de 2 à 3 ka par rapport à l’insolation. L’effet des gaz à effet de serre sur les changements à long terme de l’ISM en période interglaciaire est négligeable comparé au forçage orbital et au volume de glace. Le forçage orbital a également été identifié que le principal forçage à l’origine des différences d’intensité de l’ISM lors des périodes humides des MIS 1 et MIS 5e. En revanche, si le forçage orbital ne peut expliquer l’intensité étonnamment forte de l’ISM au MIS 19c, nous proposons que la localisation plus proximale des calottes en Eurasie ait généré des conditions inattendues sur l’ISM en amplifiant le contraste thermique continent-océan.
(20/06/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Contribution of soil structure and colloidal particles to the dynamics of PFAS leaching from a firefighting contaminated site
The topic of per- and polyfluoroalkyl substances (PFAS) is a late-breaking issue due to its high environmental relevance (toxicity, persistence and bio accumulation) and due to the detection of PFAS as contaminants in various environmental compartments including groundwater, surface water and soil. PFAS enter the environment via different pathways such as industrial, agricultural, and house-hold activities but as well through firefighting activities using aqueous fire-fighting foams (AFFF) which contain a high variety of PFAS molecules. Especially firefighting training zones are therefore highly exposed to PFAS contamination in soil and ground water and can even pollute other regions since PFAS can be carried away from the source within the soil pore water. Previous studies have shown that the transport and retention of PFAS in soils depend on various factors such as the PFAS type (e.g. molecular structure and carbon chain length), the soil properties (e.g. amount of organic carbon, surface charge), and the pore water (e.g. degree of saturation, pH). Still, the retention and release mechanisms of PFAS on soil constituents are not completely elucidated, and an official, universal protocol for the determination of PFAS concentrations in the subsoil is not existing yet. PFAS are commonly analyzed in the ground water or/and in the soil assuming that PFAS transport only occurs directly by desorption into solution and not considering the co-transport due to strong adsorption of PFAS to eroded particles as a possible solid carrier phase next to the liquid phase. Still, this assumption might not be correct including the already observed spatial and temporal interactions between the soil and the soil pore water like e.g. soil particle mobilization caused by wetting and drying cycles or macro pore flow. Especially with regard to the surfactant characteristic of PFAS, particle mediated transport of PFAS should be further investigated since only few projects on this topic have been carried out so far. Based on the findings of enhanced leaching of one PFAS molecule because of its adsorption to released particles in artificially contaminated, homogenously compacted soil columns, we now increased the complexity to more real-life conditions working with undisturbed soil columns from a firefighting training site contaminated by various PFAS through the use of AFFF. We expose these columns to simulated rain falls of different rain intensities and dry periods and afterwards analyze the drained effluent water for PFAS once in the liquid phase and once adsorbed to eroded soil particles. In preliminary tests we were already able to detect even long-chain PFAS in the collected leachate (although their mobility in soil is expected to be low) which could be attributed to colloid leaching and colloidal particles as a carrier phase for long-chain PFAS. The separated analysis of PFAS in the liquid and the solid phase will help us to better understand the contribution of soil particles to the transport of PFAS in the soil pore water and therefore possibly point out the risk of higher pollutions of remote areas, and whether this contribution should also be taken into account in the determination of PFAS in the subsoil in the future.
(13/06/2023)
GERS-LEE, EMMAH, AU, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Impacts of urban stressors on freshwater biofilms
Abstract In urban areas, aquatic ecosystems and their communities are exposed to numerous stressors of various natures (chemical and physical), which impacts are often poorly documented. In epidemic context such as the COVID 19 pandemic, the use of biocides such as the dodecylbenzyldimethylammonium chloride (BAC 12) increased, resulting in an expectable increase in their concentrations in urban aquatic ecosystems. This compound is known to be toxic to most aquatic organisms. Besides, artificial light at night (ALAN) is increasing globally, especially in urban areas. ALAN may have a negative impact on photosynthetic cycles of periphytic biofilms, which in turn may result in changes in their metabolic functioning. Moreover, studies suggest that exposure to artificial light could increase the biocidal effect of BAC 12 on biofilms. The present study investigates the individual and combined effects of BAC 12 and/or ALAN on the functioning and structure of photosynthetic biofilms. We exposed biofilms to a nominal concentration of 30 mg.L-1 of BAC 12 and/or ALAN for 10 days. BAC 12 had a negative impact on biofilm functioning by decreasing the amount and the quality of photosynthetic pigments, resulting in a >90% decrease in photosynthetic efficiency after 2 days of exposure. We also noted a strong decrease in glycolipids that resulted in a shift in lipid profiles. We found no significant effect of ALAN on the endpoints assessed and no interaction between the two stress factors. Graphical abstract
(11/06/2023)
UR EABX, INRAE, INRS, UB, CNRS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UQAM
Locomotion behavior of juveniles of the freshwater pearl mussel Margaritifera margaritifera: A new non-invasive tool for the evaluation of stress effects
(Chemosphere. vol. 327, n° 0045-6535, pp. 138521, 01/06/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Precession and obliquity forcing of the South African monsoon revealed by sub-tropical fires
While the influence of precession on monsoon at low latitudes through insolation forcing is well-known, the role of obliquity is still debated since its influence on the distribution of incoming solar radiation is small in these regions. In southern Africa, long marine and terrestrial sedimentary records attest of a precessional influence on the South African monsoon at orbital time scale. The obliquity signal is occasionally observed in the geological records although modeling results suggest an influence of precession and obliquity on summer monsoon. Here, we present a record of microscopic charcoal from core MD96-2098 located off Namibia covering the past 184,000 years. Our record of fire activity reveals cyclic changes at frequencies of 23, 58 and 12 kyr À1 and lacks the obliquity signal at 41 kyr À1. Changes in fire over southern Africa are interpreted as shifts in large and intense fires spreading in open-grassland savanna as a result of orbitally-driven changes in rainfall intensity associated with the South African monsoon. We show that, despite the absence of a 41 kyr obliquity imprint, the presence of 23, 58 and 12 kyr À1 frequencies likely stems from a nonlinear response of fire to precipitation controlled by a combination of precession and obliquity frequencies, supporting the influence of obliquity on the South African monsoon.
(Quaternary Science Reviews. vol. 310, n° 0277-3791, pp. 108128, 01/06/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UCL, AWI, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CLIM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, IRAP, UT3, Comue de Toulouse, INSU - CNRS, CNRS