Tritiated thymidine induces developmental delay, oxidative stress and gene overexpression in developing zebrafish (Danio rerio)
Tritium is a betta emitter radionuclide. Being an isotope of hydrogen, it is easily transferred to different environmental compartments, and to human and non-human biota. Considering that tritium levels are expected to rise in the upcoming decades with the development of nuclear facilities producing tritium using fission processes, investigating the potential toxicity of tritium to human and non-human biota is necessary. Tritiated thymidine, an organic form of tritium, has been used in this study to assess its toxicity on fish embryo development. Zebrafish embryos (3.5 hpf; hours post fertilization) have been exposed to tritiated thymidine at three different activity concentrations (7.5; 40; 110 kBq/mL) for four days. These experiments highlighted that zebrafish development was affected by the exposure to organic tritium, with smaller larvae at 3 dpf after exposure to the two lowest dose rates (22 and 170 µGy/h), a delayed hatching after exposure to the two highest dose rates (170 and 470 µGy/h), an increase in the spontaneous tail movement (1 dpf) and a decrease in the heartbeat (3 dpf) after exposure to the highest dose rate. The results also highlighted an increase in ROS production in larvae exposed to the intermediate dose rate. A dysregulation of many genes, involved in apoptosis, DNA repair or oxidative stress, was also found after 1 day of exposure to the lowest tritium dose rate. Our results thus suggest that exposure to tritiated thymidine from a dose rate as low as 22 µGy/h can lead to sublethal effects, with an effect on the development, dysregulation of many genes and increase of the ROS production. This paper provides valuable information on toxic effects arising from the exposure of fish to an organic form of tritium, which was the main objective of this study.
(Aquatic Toxicology. vol. 265, n° 0166-445X, pp. 106766, 01/12/2023)
IRSN/PSE-ENV/SERPEN/LECO, IRSN/PSE-ENV/SERPEN, IRSN, IRSN/PSE-SANTE/SDOS/LDRI, IRSN/PSE-SANTE/SDOS, IRSN, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
First assessment of Rare Earth Element organotropism in Solea solea in a coastal area: The West Gironde Mud Patch (France)
Few studies exist on bioaccumulation and internal distribution of Rare Earth Elements (REEs) in marine fishes. REEs organotropism was determined in common sole (Solea solea) from the West Gironde Mud Patch (WGMP; N-E Atlantic Coast, France). The highest REEs concentrations occurred in liver (213 ± 49.8 µg kg -1 DW) and gills (119 ± 77.5 µg kg -1 DW) followed by kidneys (57.7 ± 25.5 µg kg -1 DW), whereas the lowest levels were in muscles (4.38 ± 1.20 µg kg -1 DW) of Solea solea. No significant age-or sex-related differences were observed.
The organotropism varied among groups of REEs. Light and heavy REEs preferentially accumulated in liver and gills, respectively. All considered organs showed different normalized REEs patterns, suggesting differences in internal distribution processes between organs. Further work should address: (1) baseline levels worldwide, and (2) factors controlling uptake and organ-specific bioaccumulation of REEs.
(Marine Pollution Bulletin. vol. 197, n° 0025-326X, pp. 115730, 01/12/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CNRS, Bordeaux INP, CCEM, IFREMER
Long-term trends and wave climate variability in the South Atlantic Ocean: the influence of climate indices
Linking wave climate variability and trends with climate indices is important to better understand and predict large-scale patterns of wave variability down to wave conditions at the coast. This study investigates such links in the South Atlantic Ocean using 72 years of ERA5 wave hindcast. Different wave parameters are computed, including storm wave statistics, and are further analyzed in terms of long-term trends and interannual changes. Our results indicate that, over the last decades, wave height has been significantly increasing across the entire domain, while extreme events statistics are also increasing, although with more complex spatial variability. The variations of these wave properties are primarily correlated, from low to high latitudes, with the Atlantic Multidecadal Oscillation (AMO), Tropical Southern Atlantic Index (TSA) and Southern Annular Mode (SAM), with different preferred timescales. We think that better understanding and predicting the evolution of these climate indices, including under climate change, will be critical to anticipate coastal hazards in this region.
(Regional Studies in Marine Science. vol. 66, n° 2352-4855, pp. 103131, 01/12/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Significant Impact of Hydrothermalism on the Biogeochemical Signature of Sinking and Sedimented Particles in the Lau Basin
Abstract Iron (Fe) is an essential micronutrient for diazotrophs, which are abundant in the Western Tropical South Pacific Ocean (WTSP). Their success depends on the numerous trace metals, particularly Fe, released from shallow hydrothermal vents along the Tonga Arc. This study aimed to explore the spatio‐temporal impact of hydrothermal fluids on particulate trace metal concentrations and biological activity. To identify the composition of sinking particles across a wide area of the WTSP, we deployed sediment traps at various depths, both close and further west of the Tonga Arc. Seafloor sediments were cored at these deployment sites, including at a remote location in the South Pacific Gyre. The sinking particles were composed of a large amount of biological material (up to 88 mg d −1 ), indicative of the high productivity of the region. A significant portion of this material (∼21 ± 12 wt.%) was lithogenic of hydrothermal origin, as revealed through Al‐Fe‐Mn tracing. The sinking material showed similar patterns between lithogenic and biogenic fractions, indicating that hydrothermal input within the photic layer triggered surface production. A hydrothermal fingerprint was suggested in the sediments due to the high sedimentation rates (>47 cm kyr −1 ) and the presence of large, heterogeneous, metal‐rich particles. The presence of nearby active deep hydrothermal sources was suspected near the Lau Ridge due to the large particle size (1–976 μm) and the significant excess of Fe and Mn (2–20 wt.%). Overall, this study revealed that hydrothermal sources have a significant influence on the biogeochemical signature of particles in the region.
(Journal of Geophysical Research. Oceans. vol. 128, n° 2169-9275, 30/11/2023)
LOV, INSU - CNRS, SU, CNRS, IMEV, INSU - CNRS, SU, CNRS, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, IMEV, INSU - CNRS, SU, CNRS, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEFREM, UPVD, INSU - CNRS, CNRS
Present and past biogeochemical functioning of the benthic ecosystem of the West Gironde Mud Patch (Bay of Biscay) : remineralization, recycling and burial processes of C and associated elements (O2, N, Mn, Fe, P, S)
In order to improve the understanding of the biogeochemical functioning of River-dominated Ocean Margins (RiOMars), the West Gironde Mud Patch (WGMP) was used as a model of a temperate non-deltaic system subjected to a high hydrodynamics. Measurements and sampling, carried out during eight cruises in different seasons between 2016 and 2021, allowed to characterize its biogeochemical functioning from seasonal to multi-century scales. Results showed that in the proximal area (i.e., < 42.5 m), the high hydrodynamics results in a sediment instability with a surface layer of transient sandy muds (< 10 cm) overlying relic muddy sediments. This induces a digenetic regime divided into two layers, a modern and a relic, having distinct biogeochemical functioning. In the superficial modern layer, organic matter is remineralized through aerobic respiration and suboxic degradation processes. Conversely, sulfate reduction is the main remineralization process occurring in relic deposits. Moreover, measurements of several particulate and dissolved compounds highlighted that the cycles of iron and sulfur differ between relic sediments and the rest of the WGMP. In the distal area, where a more continuous sedimentation occurs, the diagenetic sequence gradually expands seaward, likely due a decrease in organic matter lability and an increase in bioturbation. Seasonal measurements highlighted that aerobic respiration rates vary in response to seasonal events such as the spring blooms and bottom water deoxygenation. On a multi-decennial scale, more than half of the organic carbon deposited in the distal area is buried in sediments with a maximum burial rate of 45 gC m-2 y-1. The organic carbon load of the sediments shows that, this burial is less efficient on a multi-century scale and is mainly related to the grain-size of deposited particles. On this time scale, organic matter remineralization is limited by its lability and bioavailability. Results also highlighted that the WGMP is a sink through the precipitation of authigenic minerals (P, S, Fe, Si) and the adsorption on particles (C, Fe, Mn). Finally, this work has shown that, due to its non-deltaic nature, the biogeochemical functioning of the WGMP differs from that of previously studied high-energy RiOMars, suggesting that it could represent a new RiOMars model.
(27/11/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Role of Atmospheric Indices in Describing Shoreline Variability Along the Atlantic Coast of Europe
AbstractBeaches are highly variable environments and respond to changes in wave forcing, themselves modulated by climate variability. Here, we analyze three high‐quality beach profile data sets to robustly investigate, for the first time, the link between shoreline change, wave forcing and climate variability along the Atlantic coast of Europe. Winter wave conditions are strongly associated with North Atlantic Oscillation (NAO) and Western Europe Pressure Anomaly (WEPA), with WEPA explaining 50%–80% of the winter wave power variability. Shoreline variability during winter is also strongly linked to NAO and WEPA, with WEPA explaining 25% of the winter shoreline variability. Winter wave conditions and associated shoreline variability are both unrelated to El Nino Southern Oscillation. In addition to the atmospherically‐forced beach morphological response, shoreline change also depends strongly on the antecedent morphology as evidenced by significant correlations between summer/winter shoreline response and the shoreline position at the start of each season.
(Geophysical Research Letters. vol. 50, n° 0094-8276, 20/11/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Compréhension des interactions entre l'hydroclimat du Nord-Est du Brésil et l'Atlantique tropical de l'Ouest au cours des derniers 300 000 ans par une approche multi-traceurs organiques
La Terre est un système complexe aux multiples interactions et le lieu de vie d’innombrables espèces vivantes. Dès lors, de nombreux travaux ont permis depuis des décennies, d’améliorer notre compréhension du climat de la Terre. Toutefois de nombreuses zones d’ombre restent aujourd’hui inexplorées. La région du Nord-Est (NE) du Brésil et de l’Atlantique tropical de l’Ouest est à ce jour relativement peu étudiée. Pourtant, l’hydroclimat singulier du NE Brésil et le rôle de l’Atlantique tropical de l’Ouest dans le transport interhémisphérique de chaleur font de cette région une zone importante d’un point de vue climatique. Parmi les traceurs couramment employés pour reconstruire les paléoenvironnements, les biomarqueurs lipidiques sont de précieux supports d’information. De nombreuses propriétés environnementales telles que la température de l’océan, la composition du couvert de végétation ou les conditions hydroclimatiques peuvent être reconstruites à partir de l’abondance, de la distribution ou de la composition isotopique de ces molécules. Ce projet de thèse vise à reconstruire les variations hydroclimatiques passées dans la région de l’extrême NE du Brésil, en relation avec la circulation de surface de l’Atlantique tropical de l’Ouest par la caractérisation du matériel organique d’une carotte de sédiments marins prélevée sur la marge brésilienne qui couvre les derniers 305 000 ans. L’analyse de la matière organique (MO) aux échelles totale et moléculaire a, dans un premier temps, permis de caractériser les sources de MO et notamment la composition des végétations actuelles dans la région d’étude. Ensuite, les températures océaniques de surface et de subsurface, qui ont respectivement été reconstruites à partir de la distribution des alcénones à longues chaînes et des alkyl tétraéthers de glycérols isopréniques, mettent en lumière des réchauffements d’ampleur en subsurface lors des trois dernières déglaciations. L’action conjointe du ralentissement de la circulation océanique et de l’intensification de l’Agulhas Leakage pendant ces périodes est proposée pour expliquer le réchauffement de l’Atlantique tropical de l’Ouest. Enfin, les variations passées du couvert de végétation au NE Brésil, déduites des propriétés des n-alcanes à longues chaînes, sont apparues étroitement liées aux changements hydroclimatiques. La température de surface de l’Atlantique tropical et l’intensité des vents des alizés semblent jouer un rôle majeur dans le contrôle des variations passées de végétation et de l’hydroclimat du Nord-Est du Brésil. En résumé, ce travail a notamment permis d’une part de mieux comprendre le rôle de l’Atlantique tropical en tant que réservoir de chaleur pendant les déglaciations et d’autre part de mieux contraindre les influences contrôlant les variations hydroclimatiques passées au Nord-Est du Brésil.
(16/11/2023)
METIS, EPHE, PSL, INSU - CNRS, SU, CNRS
The Antarctic Ice Core Chronology 2023 (AICC2023) chronological framework and associated timescale for the European Project for Ice Coring in Antarctica (EPICA) Dome C ice core
Abstract. The EPICA (European Project for Ice Coring in Antarctica) Dome C (EDC) ice core drilling in East Antarctica reaches a depth of 3260 m. The reference EDC chronology, the AICC2012 (Antarctic Ice Core Chronology 2012), provides an age vs. depth relationship covering the last 800 kyr (thousands of years), with an absolute uncertainty rising up to 8000 years at the bottom of the ice core. The origins of this relatively large uncertainty are twofold: (1) the δ18Oatm, δO2/N2 and total air content (TAC) records are poorly resolved and show large gaps over the last 800 kyr, and (2) large uncertainties are associated with their orbital targets. Here, we present new highly resolved δ18Oatm, δO2/N2 and δ15N measurements for the EDC ice core covering the last five glacial–interglacial transitions; a new low-resolution TAC record over the period 440–800 ka BP (ka: 1000 years before 1950); and novel absolute 81Kr ages. We have compiled chronological and glaciological information including novel orbital age markers from new data on the EDC ice core as well as accurate firn modeling estimates in a Bayesian dating tool to construct the new AICC2023 chronology. For the first time, three orbital tools are used simultaneously. Hence, it is possible to observe that they are consistent with each other and with the other age markers over most of the last 800 kyr (70 %). This, in turn, gives us confidence in the new AICC2023 chronology. The average uncertainty in the ice chronology is reduced from 1700 to 900 years in AICC2023 over the last 800 kyr (1σ). The new timescale diverges from AICC2012 and suggests age shifts reaching 3800 years towards older ages over marine isotope stages (MISs) 5, 11 and 19. But the coherency between the new AICC2023 timescale and independent chronologies of other archives (Italian Lacustrine succession from Sulmona Basin, Dome Fuji ice core and northern Alpine speleothems) is improved by 1000 to 2000 years over these time intervals.
(Climate of the Past. vol. 19, n° 1814-9324, pp. 2257 - 2286, 10/11/2023)
LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GLACCIOS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, IGE, IRD, INSU - CNRS, CNRS, INRAE, Fédération OSUG, UGA, Grenoble INP, UGA, AARI, Roshydromet, TECLIM, ELI, UCLouvain, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, NBI, UCPH, OCCR, UNIBE, USTC
Distribution of Living Benthic Foraminifera in the Baffin Bay and Nares Strait in the Summer and Fall Periods: Relation with Environmental Parameters
Arctic climate warming leads to drastic changes in sea ice dynamics, hence impacting primary productivity but also the benthic communities. Therefore, to assess the response of living benthic foraminifera to contrasting Arctic environments, surface sediments from nine stations were collected during the summer of 2014 and fall of 2015 in the Baffin Bay and Nares Strait. Living standing stock are systematically low in the eastern and western Baffin Bay and much higher in the North Water Polynya and the Kane Basin located at the entrance and in the center of Nares Strait, respectively. High living benthic foraminiferal densities in the NOW reflect higher TOC while the highest density in the Kane Basin coincides with lower TOC but higher C/N and higher δ13Corg. The contribution of agglutinated species is on average very high for the whole study area and dominated by the species Adercotryma glomeratum, Lagenammina arenulata, and Reophax scorpiurus. Calcareous species, dominated by Nonionellina labradorica and Melonis barleeanus, are more abundant in the North Water Polynya and the Kane Basin. The very high living standing stock observed in the Kane Basin might be related to the northern position of the ice arch that summer during 2014 and therefore a particularly scarce sea ice cover might have allowed massive phytoplankton production during that season. In this study, the distribution of living benthic foraminifera is discussed according to several environmental parameters such as water masses, phytoplankton productivity, and organic matter fluxes.
(Journal of Marine Science and Engineering. vol. 11, n° 2077-1312, pp. 2049, 01/11/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BEEP, IFREMER, UBO EPE, CNRS
Comparison of the accumulation and effects of copper pyrithione and copper sulphate on rainbow trout larvae
(Environmental Toxicology and Pharmacology. vol. 104, n° 1382-6689, pp. 104308, 01/11/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS