Trajectory, fate, and magnitude of continental microplastic loads to the inner shelf: A case study of the world's largest coastal shallow lagoon
The Patos Lagoon estuary is a highly significant ecosystem where freshwater from a vast and densely populated area continuously flows into the Atlantic Ocean by coastal plumes, exporting not only freshwater but also sediment, nutrients, plastics, and other contaminants. In this work, numerical modeling tools together with field data were used to assess for the first time the capacity of the coastal plume to export microplastics (MPs) to the inner shelf under different hydrodynamic conditions. Two field surveys were conducted during plume events to quantify MP concentrations and validate the model approach. A bottom-up approach was employed to estimate the potential MP export from the estuary's domain to the Atlantic Ocean. MP concentration in surface plume waters ranged from 0.20 items m−3 to 1.37 items m−3, confirmed by FTIR as synthetic polymers in a 90 %, being Polypropylene (PP) and Polyethylene (PE) the most abundant in a 73 %. The accumulation pattern was observed on the plume's frontal system, consistent with simulation results. The estimated average MP potential export rate attained 9.0 million items day−1 during moderate plume events and 47.5 million items day−1 during high discharge plume events. Strong discharge events, coupled with intense northeast winds, facilitated rapid southwestward export of MPs. Conversely, moderate to weak discharge events retained MPs closer to the estuary's mouth, enabling either longer trajectories or earlier deposition. Significant MP accumulation hotspots were identified in the gyre between the jetties and Cassino beach, as well as in the saline front within the plume boundaries. These accumulation zones may function as reservoirs for MP particles, potentially posing threats to local ecosystems. Understanding these dynamics is crucial for ongoing monitoring efforts to assess potential harmful interactions over time.
(Science of the Total Environment. vol. 948, n° 0048-9697, pp. 174791, 01/10/2024)
INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Physicochemical behavior and impact of CO2 and CH4 plumes during gas-rich water leakage in a shallow carbonate freshwater aquifer
Carbon capture and storage (CCS) is a promising technology for reducing CO2 emissions. Significant concerns have emerged about the potential leakage of CO2 into shallow aquifers, highlighting the risk to water quality and environmental safety. This underscores the importance of finding monitoring tools suitable for different geological scenarios. If leakage occurs in the context of depleted reservoirs being used for CO2 storage, residual CH4 from the storage complex will likely be entrained together with CO2. However, few studies have addressed the implications of CH4 presence and its potential as a monitoring parameter during CO2 leakage. To address this gap, we simulated a leakage event by injecting water enriched with CO2 and CH4 into a shallow limestone aquifer. The impact of the injection was monitored using a combination of laboratory measurements on water samples and in-situ sensors located downstream from the injection well. All parameters were affected by the simulated leakage. Some monitoring tools allowed us to differentiate the leakage event from natural variations. A key finding of this study was that at 7 m from the injection well, the CH4 breakthrough occurred roughly one day before the CO2 breakthrough, highlighting the potential of CH4 as an early indicator of CO2 leakage and suggesting interesting prospectives for industrial-scale sites. However, further research is needed to confirm the potential of CH4 as a CO2 leakage indicator at industrial scales, due to potential methane oxidation and loss of the signal with longer times and distances. This study contributes to a better understanding of the potential risks and effective monitoring strategies associated with CO2-CH4 leakage in carbonate aquifers.
(Applied Geochemistry. vol. 172, n° 0883-2927, pp. 106122, 01/10/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFPEN
Late Miocene transformation of Mediterranean Sea biodiversity
Understanding deep-time marine biodiversity change under the combined effects of climate and connectivity changes is fundamental for predicting the impacts of modern climate change in semi-enclosed seas. We quantify the Late Miocene–Early Pliocene [11.63 to 3.6 million years (Ma)] taxonomic diversity of the Mediterranean Sea for calcareous nannoplankton, dinocysts, foraminifera, ostracods, corals, molluscs, bryozoans, echinoids, fishes, and marine mammals. During this time, marine biota was affected by global climate cooling and the restriction of the Mediterranean’s connection to the Atlantic Ocean that peaked with the Messinian salinity crisis. Although the net change in species richness from the Tortonian to the Zanclean varies by group, species turnover is greater than 30% in all cases, reflecting a high degree of reorganization of the marine ecosystem after the crisis. The results show a clear perturbation already in the pre-evaporitic Messinian (7.25 to 5.97 Ma), with patterns differing among groups and subbasins.
(Science Advances. vol. 10, n° 2375-2548, 27/09/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Influence of estuarine physical processes in the transport of microplastics: a modelling study in the Gironde estuary
(23/09/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SIAME, UPPA, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS
Estimating CaCO3 Content Based on Natural Gamma Ray (NGR) in Deep-Ocean Sediment Cores
We present a simple, quick, and high-resolution (approx.10 cm) method for calculating almost continuous calciumcarbonate (CaCO3) proxy records in deep-marine sediment cores based on the well-known dependence of NGR (natural gamma ray) on sediment clay content. The method used in this study is based on the assumption that sediment composition along the SAT (South Atlantic Transect) consists of two components: carbonate and clay. This assumption is reasonably accurate for the region under investigation. At carbonate-rich Site U1583 (66–97 wt% CaCO3), calculated CaCO3 wt% contents are within 4.18% at 1 standard deviation (r) of geochemical analyses of the CaCO3 wt% contents of discrete samples (measured using a coulometer), while at the more lithologically variable Site U1557 (0.1–92 wt% CaCO3), they are within 15.6% at 1r. Results indicate good to excellent correlations between the NGR- and coulometry-derived datasets, supporting the use of this method for carbonate stratigraphy, paleoceanography, and paleoclimate reconstructions. We provide an equation to derive CaCO3 wt% from NGR based on the SAT datasets. The procedure described below can be used to construct the higher resolution proxy CaCO3 records at other sites worldwide compared to discrete CaCO3 values. This method can assist with shipboard lithology determination and can guide core sampling.
(Stratigraphy. vol. 21, pp. 225-242, 20/09/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Ecodynamique des Terres Rares dans les écosystèmes aquatiques : approches pluridisciplinaire et multi-échelle
Les écosystèmes aquatiques sont soumis à de nombreux contaminants, y compris les Terres Rares (REEs), qui forment un groupe cohérent d'éléments aux propriétés physico-chimiques similaires. Au cours des deux dernières décennies, la production et la consommation accrues des REEs pour les technologies modernes ont conduit à leur présence croissante dans les milieux aquatiques. Cependant, des lacunes significatives subsistent qui nécessitent des approches pluridisciplinaires combinant Géochimie et Ecotoxicologie afin de : i) évaluer les cycles géochimiques (distribution, réactivité et devenir) des REEs dans les écosystèmes aquatiques ; et ii) identifier les facteurs et processus contrôlant leurs concentrations dans les organismes aquatiques (biodisponibilité, bioaccumulation). La première partie de ce travail s'est concentrée sur la distribution spatiale et le comportement géochimique des REEs à l'interface continent-océan, principalement en milieu estuarien. L’analyse des concentrations en REEs dissoutes le long d’un profil estuarien dans l’estuaire de la Gironde par condition d’étiage a permis de caractériser le comportement géochimique dans le gradient de salinité avec : (i) un abattement des REEs à faible salinité (S<5), plus importante pour les REEs légères (La, Ce, Pr, Nd) ; (ii) une augmentation des concentrations dissoutes aux salinités intermédiaires (5 (10/09/2024) EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The effects of a neonicotinoid insecticide, imidacloprid, on the embryo-larval stages of the sterlet sturgeon, Acipenser ruthenus
(03/09/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EABX, INRAE
The contribution of near surface geophysics to measure soil related terroir factors in viticulture: A review
Wine quality is affected by environmental factors in the location where the vines are cultivated, in particular the soil and the climate. Major soil-related factors influencing vine development, yield, and berry composition (and thus wine quality) include soil water availability, soil temperature, and soil nutrients, particularly nitrogen. These can be impacted by soil depth and soil compaction. Mapping these factors with classical field-based methods is constraining and expensive. Near surface geophysics (NSG) can be useful in increasing the resolution of data acquisition and, possibly, its cost. Among these techniques, many are already commercially available, but some of them, including Magnetic Resonance Sounding, Induced Polarization and Spectral Analysis of Surface Waves, require a high degree of expertise for acquisition and processing. These should be further developed in order to enlarge the application possibilities. This article reviews soil-related parameters relevant to terroir expression in vineyards and how these can be measured with NSG techniques.
(Geoderma. vol. 449, n° 0016-7061, pp. 116983, 01/09/2024)
UMR EGFV, UB, Bordeaux Sciences Agro, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Biogeochemical cycling of manganese and iron in a macrotidal and hyperturbid estuary subject to flow-driven sedimentation
The study of manganese (Mn) and iron (Fe) cycling in early diagenetic processes in estuaries is crucial for understanding the functioning of these vital ecosystems and predicting their responses to environmental change. The present study investigates the dynamic interplay of Mn and Fe in early diagenetic processes at highly contrasted hydrosedimentary conditions in the Loire estuary, which is very rare and allows a comprehensive framework to understand diagenetic processes in a very dynamic environment. One campaign took place in the Brillantes intertidal mudflat in March 2015 (PV1), while 3 others took place in a muddy riverbed along the navigation channel off the city of Paimboeuf during a decennial flood in February (RR1–4), under moderate discharge in June (RRK-4) and low in August 2021 (RR2–4). The monitored riverbed station was upstream, under and downstream the maximum turbidity zone, respectively. By combining sequential extraction techniques for Mn and Fe in solid phases and pore-water analysis, the study provides insights into the behaviour of these elements in sedimentary environments and reveals their speciation and association with specific mineral phases and forms during different diagenesis stages. The remobilization of Mn and Fe in the surface sediments of the Brillantes mudflat (PV1) allows iron sulphide formation within the upper 50 cm of the sediment column (above the sulphate penetration depth). The deeper layers show other authigenic phases formation, such as the probable precipitation of vivianite below the sulphate depletion depth and progressive precipitation of carbonate at depth, leading to definitive burial and accumulation. At the muddy riverbed, following the exceptional flood in February 2021 (RR1–4), significant sediment erosion occurred unveiling to the water column old and reduced sediments. Sharp pore-water gradients for dissolved Mn, Fe and sulphate indicated the sudden exposure of the old 7Be-free and anoxic sediment to low-salinity, well‑oxygenated water. Despite its dark colour, this sediment showed no authigenic FeS/FeS2 phases. Four months later, changes in the estuarine environment (low river discharge) and the presence of a maximum turbidity zone (TMZ) led to a new deposition of a sediment layer (RRK-4) triggering transient diagenetic reactions. The freshly deposited sediment layer developed important recycling of dissolved Mn, Fe and sulphate above the precedent sediment water interface (SWI) generating a double peak, accompanied by consistently low concentrations of solid Mn and Fe phases specially FeS/FeS2 and Mn bound to FeS/FeS2 compared to PV1. Six months after the flood event, in August (RR2–4), the discernible attenuation of dissolved Mn and Fe peaks and sulphate concentration, indicated a gradual recovery of characteristic sediment profiles with the well-known redox layer succession. Overall, despite important sulphate reduction within sediments from both the river and its adjacent mudflats, pyritization is not a major process for Mn and Fe burial. The intense hydrodynamics of the mid estuary prevents thermodynamical equilibrium between pore-water chemistry and solid phases not allowing pyrite formation while in the calmer conditions of intertidal mudflats, pyrite accumulates in intermediate depths but carbonates and phosphates seem to be the preferential phases of burial probably related to methane production and phosphate availability.
(Chemical Geology. vol. 661, n° 0009-2541, pp. 122182, 01/09/2024)
LPG, UM, UA, INSU - CNRS, CNRS, Nantes univ - UFR ST, Nantes Univ, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ISTOM, IPREM, UPPA, INC-CNRS, CNRS, CHROME, UNIMES
Tout comprendre (ou presque) sur l'eau
L'eau douce est vitale. Elle est essentielle dans l'espace domestique, pour les cultures et l'alimentation, les activités industrielles et la production d'énergie. Elle est la condition de vie de la faune et de la flore, et de la bonne santé humaine. Elle peut inonder des territoires comme venir à manquer gravement. Pour la partager au bénéfice de tous, il faut prendre en compte l'évolution de sa disponibilité, de sa qualité et des incertitudes associées, notamment en raison du changement climatique. Pour mieux comprendre et appréhender l'eau douce sous touts ses formes, et ainsi pour mix la protéger, des scientifiques de disciplines variées ont été mobilisées pour apporter des réponses à 20 questions essentielles. Cet ouvrage mettant en image des textes scientifiques permet de découvrir des enjeux fondamentaux et rend compte de ce que l'on sait vraiment.
(01/09/2024)
LATTS, ENPC, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GEDI, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EVS, ENS de Lyon, Mines Saint-Étienne MSE, IMT, UL2, UJML, INSA Lyon, INSA, UJM, ENTPE, ENSAL, CNRS, ALLHiS, UJM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CRBE, IRD, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse, LEHNA, UCBL, ENTPE, CNRS, OSUR, UR, INSU - CNRS, UR2, CNRS, INRAE, UMR ART-Dev, Cirad, UPVM, UPVD, CNRS, UM, LGENS, INSU - CNRS, CNRS, ENS-PSL, PSL, IODE, UR, CNRS, CRPG, INSU - CNRS, UL, CNRS, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE, UM6P, LEEISA, IFREMER, UG, CNRS, CREDA, CNRS, CLERSÉ, CNRS