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The timing of past glacier fluctuations is poorly constrained in Corsica island (Western Mediterranean Sea). Although several glacial landforms and deposits were described, there are no absolute glacial chronology. We will present 19 new 10Be cosmic-ray exposure ages (CRE) of boulders collected from 4 moraines located in the area of the Bastani Lake (Monte Renoso, Northern Corsica). For the first time on a Mediterranean island, mountain glacier fluctuations are documented from moraine CRE for the Lateglacial Period. Two main glacier advances since the Last Glacial Maximum are identified. 12 boulders of three moraines dated between 14.98 ± 0.89 ka BP and 18.88 ± 1.04 ka BP reveal a glacier extent during the Oldest Dryas (Heinrich Stadial 1 - HS1). 5 boulders of one moraine dated between 12.13 ± 0.69 ka BP and 13.93 ± 0.79 ka BP are attributed to the Late Glacial–Younger Dryas transition. Results and associated past Equilibrium Line Altitude will be compared with those in the Mediterranean mountain ranges. Implications for regional climatic conditions will be discussed.

The ocean's biological carbon pump (BCP) plays a major role in the global carbon cycle. A fraction of the photosynthetically fixed organic carbon produced in surface waters is exported below the sunlit layer as settling particles (e.g., marine snow). Since the seminal works on the BCP, global estimates of the global strength of the BCP have improved but large uncertainties remain (from 5 to 20 Gt C yr−1 exported below the euphotic zone or mixed-layer depth). The 234Th technique is widely used to measure the downward export of particulate organic carbon (POC). This technique has the advantage of allowing a downward flux to be determined by integrating the deficit of 234Th in the upper water column and coupling it to the POC∕234Th ratio in sinking particles. However, the factors controlling the regional, temporal, and depth variations of POC∕234Th ratios are poorly understood. We present a database of 9318 measurements of the POC∕234Th ratio in the ocean, from the surface down to >5500 m, sampled on three size fractions (∼>0.7 µm, ∼1–50 µm, ∼>50 µm), collected with in situ pumps and bottles, and also from bulk particles collected with sediment traps. The dataset is archived in the data repository PANGAEA® under https://doi.org/10.1594/PANGAEA.911424 (Puigcorbé, 2019). The samples presented in this dataset were collected between 1989 and 2018, and the data have been obtained from published papers and open datasets available online. Unpublished data have also been included. Multiple measurements can be found in most of the open ocean provinces. However, there is an uneven distribution of the data, with some areas highly sampled (e.g., China Sea, Bermuda Atlantic Time Series station) compared to some others that are not well represented, such as the southeastern Atlantic, the south Pacific, and the south Indian oceans. Some coastal areas, although in a much smaller number, are also included in this global compilation. Globally, based on different depth horizons and climate zones, the median POC∕234Th ratios have a wide range, from 0.6 to 18 µmol dpm−1.

Model simulations and remote sensing observations show that ocean dynamics at fine scales (1–100 km in space, day–weeks in time) strongly influence the distribution of phytoplankton. However, only a few in situ-based studies at fine scales have been performed, and most of them concern western boundary currents which may not be representative of less energetic regions. The PROTEVSMEDSWOT cruise took place in the moderately energetic waters of the western Mediterranean Sea (WMS), in the region south of the Balearic Islands. Taking advantage of nearreal-time satellite information, we defined a sampling strategy in order to cross a frontal zone separating different water masses. Multi-parametric in situ sensors mounted on the research vessel, on a towed vehicle and on an ocean glider were used to sample physical and biogeochemical variables at a high spatial resolution. Particular attention was given to adapting the sampling route in order to estimate the vertical velocities in the frontal area also. This strategy was successful in sampling quasi-synoptically an oceanic area characterized by the presence of a narrow front with an associated vertical circulation. A multiparametric statistical analysis of the collected data identifies two water masses characterized by different abundances of several phytoplankton cytometric functional groups, as well as different concentrations of chlorophyll a and O2. Here, we focus on moderately energetic fronts induced by fine-scale circulation. Moreover, we explore physical–biological coupling in an oligotrophic region. Our results show that the fronts induced by the finescale circulation, even if weaker than the fronts occurring in energetic and nutrient-rich boundary current systems, maintain nevertheless a strong structuring effect on the phytoplankton community by segregating different groups at the surface. Since oligotrophic and moderately energetic regions are representative of a very large part of the world ocean, our results may have global significance when extrapolated., This research has been supported by the Centre National d’Etudes Spatiales (grant no. BC 4500066497).

In the ocean, remineralisation rate associated with sinking particles is a crucial variable. Since the 90's, particulate biogenic barium (Baxs) has been used as an indicator of carbon remineralization by applying a transfer function relating Baxs to O2 consumption (Dehairs's transfer function, Southern Ocean-based). Here, we tested its validity in the Mediterranean Sea (ANTARES / EMSO-LO) for the first time by investigating connections between Baxs, prokaryotic heterotrophic production (PHP) and oxygen consumption (JO2-Opt; optodes measurement). We show that: (1) higher Baxs (409 pM; 100–500 m) in situations where integrated PHP (PHP100/500 = 0.90) is located deeper, (2) higher Baxs with increasing JO2-Opt, and (3) similar magnitude between JO2-Opt (3.14 mmol m−2 d−1; 175–450 m) and JO2-Ba (4.59 mmol m−2 d−1; transfer function). Overall, Baxs, PHP and JO2 relationships follow trends observed in the Southern Ocean. We believe that such transfer function could apply in the Mediterranean Sea with no restriction.

Runoff from rivers and coastal plains delivers significant amounts of nutrients to the Mediterranean Sea from the agricultural activities and urban waste waters. Several recent studies show that variations in rivers inputs may play a significant role on the marine biogeochemical cycles and planktonic food web in the entire basin. The aim of this study is to estimate the release of nutrients (N & P) to the Mediterranean Sea from basin-wide agriculture and urbanization through the implementation of the biogeochemical land-sea nutrient transfer processes within the agro-ecosystem model LPJmL. This is a contribution to the LaSeR-Med project (Towards an integrated prediction of Land & Sea Responses to global change in the Mediterranean Basin).A compilation of a new input data set of fertilizer, manure and wastewater nutrients content [1961-2005] has been added to the LPJmL forcing data set, with a new land use patterns produced by an econometric model. The representation of the nutrient transfer from land to sea has been introduced into LPJmL by considering the following processes: mineralization, denitrification, adsorption, remineralization, nitrification, and phytoplankton dynamics.First basin-wide LPJmL simulation at 1/12°, indicates that the model succeeds in simulating the temporal variations of water discharge for the main rivers flowing to the Mediterranean Sea, and shows a good consistency between the simulated nutrients concentration (NO3 and PO4) and available in-situ data. Preliminary results show that wastewater strongly contribute to the phosphorus fluxes (as PO4), while both agriculture and wastewater control the nitrogen fluxes (mainly as NO3). Alternative scenarios for land-use will allow to explore the future amounts of terrestrial nutrients that will reach the sea through rivers discharge and water runoffs and impact the marine ecosystems.

Cross-shelf processes drive the exchange of water between the continental shelf and western boundary currents, leading to the import and export of heat, freshwater, sediments, nutrients, plankton, fish larvae, and other properties. Upwelling is an important process which modulates those exchanges. It regulates primary productivity, which in turn promotes higher trophic levels and fisheries. In this paper, we investigate upwelling events in the East Australian Current (EAC) intensification zone off Southeast Queensland through the analysis of remotely-sensed Chlorophyll-a (Chl-a) and Sea Surface Temperature (SST) as well as wind and ocean reanalysis products. A particular focus is on identifying the likely mechanisms that drive upwelling events during the austral autumn to winter which are evident from cold SST and enhanced Chl-a concentrations. Four complementary Upwelling Indices (UIs) are derived. Chl-a (UIChla) and SST (UISST) based indices characterize the oceanic response to upwelling, while indices based on wind (UIw) and current (UIc) data capture the forcing of upwelling. The spatial and temporal variability of all UIs is examined over the continental shelf. It reveals distinct seasonal patterns. For the northern region, UIs identify the well-known Southeast Fraser Island Upwelling System. It prevails during the austral spring to early summer and is driven by current- and upwelling favourable wind. In contrast, upwelling is enhanced over the southern shelf during austral autumn to winter. About 70 % of all UISST and UIChla identified upwelling events occur during this period. A case study is presented that provides observational evidence for the existence of a shelf-break upwelling. Simultaneous downwelling favourable wind stress and upwelling favourable current-driven bottom stress establish a flow convergence in the bottom boundary layer (BBL). These convergent BBL flows force upwelling of cold and nutrient-rich slope waters as evident from negative SST anomaly and enhanced Chl-a in austral autumn to winter. It is evident from these results that the shelf region is characterised by two distinct seasonally reoccurring upwelling regimes.

The VAHINE mesocosm experiment in the oligotrophic waters of the Nouméa lagoon (New Caledonia), where high N2 fixation rates and abundant diazotroph organisms were observed, aimed to assess the role of the nitrogen input through N2 fixation in carbon production and export and to study the fate of diazotroph-derived nitrogen (DDN) throughout the planktonic food web. A 1-D vertical biogeochemical mechanistic model was used in addition to the in situ experiment to enrich our understanding of the dynamics of the planktonic ecosystem and the main biogeochemical carbon (C), nitrogen (N) and phosphate (P) fluxes. The mesocosms were intentionally enriched with ∼ 0.8 µmol L−1 of inorganic P to trigger the development of diazotrophs and amplify biogeochemical fluxes. Two simulations were run, one with and the other without the phosphate enrichment. In the P-enriched simulation, N2 fixation, primary production (PP) and C export increased by 201, 208 and 87 %, respectively, consistent with the trends observed in the mesocosms (+124, +141 and +261 % for N2 fixation, PP and C export, respectively). In total, 5–10 days were necessary to obtain an increase in primary and export productions after the dissolved inorganic phosphate (DIP) enrichment, thereby suggesting that classical methods (short-term microcosms experiments) used to quantify nutrient limitations of primary production may not be relevant. The model enabled us to monitor the fate of fixed N2 by providing the proportion of DDN in each compartment (inorganic and organic) of the model over time. At the end of the simulation (25 days), 43 % of the DDN was found in the non-diazotroph organisms, 33 % in diazotrophs, 16 % in the dissolved organic nitrogen pool, 3 % in the particulate detrital organic pool and 5 % in traps, indicating that N2 fixation was of benefit to non-diazotrophic organisms and contributed to C export.

In marine ecosystems, biological N-2 fixation provides the predominant external source of nitrogen (N; 140aEuro-+/- aEuro-50aEuro-TgaEuro-NaEuro-yr(-1)), contributing more than atmospheric and riverine inputs to the N supply. Yet the fate and magnitude of the newly fixed N, or diazotroph-derived N (hereafter named DDN) in marine ecosystems is poorly understood. Moreover, whether the DDN is preferentially and directly exported out of the photic zone, recycled by the microbial loop and/or transferred into larger organisms remains unclear. These questions were investigated in the framework of the VAHINE (VAriability of vertical and tropHIc transfer of diazotroph derived N in the south wEst Pacific) project. Triplicate large volume ( similar to aEuro parts per thousand aEuro-50aEuro-m(3)) mesocosms were deployed in the tropical south-west Pacific coastal ocean (New Caledonia). The mesocosms were intentionally fertilized with similar to aEuro parts per thousand aEuro-0.8aEuro-A mu M dissolved inorganic phosphorus (DIP) at the start of the experiment to stimulate diazotrophy. A total of 47 stocks, fluxes, enzymatic activities and diversity parameters were measured daily inside and outside the mesocosms by the 40 scientists involved in the project. The experiment lasted for 23 days and was characterized by two distinct and successive diazotroph blooms: a dominance of diatom-diazotroph associations (DDAs) during the first half of the experiment (days 2-14) followed by a bloom of unicellular cyanobacterial lineage C (UCYN-C during the second half of the experiment (days 15-23). These conditions provided a unique opportunity to compare the DDN transfer and export efficiency associated with different diazotrophs. Here we summarize the major experimental and modelling results obtained during the project and described in the VAHINE special issue, in particular those regarding the evolution of the main standing stocks, fluxes and biological characteristics over the 23-day experiment, the contribution of N-2 fixation to export fluxes, the DDN released to dissolved pool and its transfer to the planktonic food web (bacteria, phytoplankton, zooplankton). We then apply our Eco3M modelling platform to further infer the fate of DDN in the ecosystem and the role of N-2 fixation on productivity, food web structure and carbon export. Recommendations for future work are finally provided in the conclusion section.

The first KErguelen Ocean and Plateau compared Study (KEOPS1), conducted in the naturally iron-fertilised Kerguelen bloom, demonstrated that fecal material was the main pathway for exporting carbon to the deep ocean during summer (January–February~2005), suggesting a~limited role of direct export via phytodetrital aggregates. The KEOPS2 project re-investigated this issue during the spring bloom initiation (October–November 2011), when zooplankton communities may exert limited grazing pressure, and explored further the link between carbon flux, export efficiency and dominant sinking particles depending upon surface plankton community structure. Sinking particles were collected in polyacrylamide gel-filled and standard free-drifting sediment traps (PPS3/3), deployed at six stations between 100 and 400 m to examine flux composition, particle origin and their size distributions. Results revealed an important contribution of phytodetrital aggregates (49 ± 10% and 45 ± 22% of the total number and volume of particles respectively, all stations and depths averaged). This high contribution dropped when converted to carbon content (30 ± 16% of total carbon, all stations and depths averaged), cylindrical fecal pellets representing then the dominant fraction (56 ± 19%). At 100 and 200 m depth, iron and biomass enriched sites exhibited the highest carbon fluxes (maxima of 180 and 84 ± 27 mg C m−2 d−1; based on gel and PPS3/3 trap collection respectively), especially where large fecal pellets dominated over phytodetrital aggregates. Below these depths, carbon fluxes decreased (48 ± 21% decrease in average between 200 and 400 m), and mixed aggregates composed of phytodetritus and fecal matter dominated, suggesting an important role played by physical aggregation in deep carbon export. Export efficiencies determined from gels, PPS3/3 traps and 234Th disequilibria (200 m carbon flux/net primary productivity), were negatively correlated to net primary productivity with observed decreases from ~ 0.2 at low-iron sites to ~ 0.02 at high-iron sites. Varying phytoplankton communities and grazing pressure appear to explain this negative relationship. Our work emphasizes the need to consider detailed plankton community structure to accurately identify the controls on carbon export efficiency, which appear to include small spatio-temporal variations of ecosystem structure.

The pre-industrial millennium is among the periods selected by the Paleoclimate Model Intercomparison Project (PMIP) for experiments contributing to the sixth phase of the Coupled Model Intercomparison Project (CMIP6) and the fourth phase of the PMIP (PMIP4). The past1000 transient simulations serve to investigate the response to (mainly) natural forcing under background conditions not too different from today, and to discriminate between forced and internally generated variability on interannual to centennial timescales. This paper describes the motivation and the experimental set-ups for the PMIP4-CMIP6 past1000 simulations, and discusses the forcing agents orbital, solar, volcanic, and land use/land cover changes, and variations in greenhouse gas concentrations. The past1000 simulations covering the pre-industrial millennium from 850 Common Era (CE) to 1849 CE have to be complemented by historical simulations (1850 to 2014 CE) following the CMIP6 protocol. The external forcings for the past1000 experiments have been adapted to provide a seamless transition across these time periods. Protocols for the past1000 simulations have been divided into three tiers. A default forcing data set has been defined for the Tier 1 (the CMIP6 past1000) experiment. However, the PMIP community has maintained the flexibility to conduct coordinated sensitivity experiments to explore uncertainty in forcing reconstructions as well as parameter uncertainty in dedicated Tier 2 simulations. Additional experiments (Tier 3) are defined to foster collaborative model experiments focusing on the early instrumental period and to extend the temporal range and the scope of the simulations. This paper outlines current and future research foci and common analyses for collaborative work between the PMIP and the observational communities (reconstructions, instrumental data)., Geoscientific Model Development, 10 (11), ISSN:1991-9603, ISSN:1991-959X

We have measured Cd/Ca ratios of several benthic foraminiferal species and studied benthic foraminiferal assemblages on two cores from the northern Indian Ocean (Arabian Sea and northern Bay of Bengal, BoB), in order to reconstruct variations in intermediate-water circulation and paleo-nutrient content since the last deglaciation. Intermediate water Cdw records estimated from the benthic Cd/Ca reflect past changes in surface productivity and/or intermediate–bottom-water ventilation. The benthic foraminiferal assemblages are consistent with the geochemical data. These results suggest that during the last deglaciation, Cdw variability was primarily driven by changes in intermediate-water properties, indicating an enhanced ventilation of intermediate–bottom water masses during both Heinrich Stadial 1 and the Younger Dryas (HS1 and YD, respectively). During the Holocene, however, surface primary productivity appears to have influenced Cdw more than intermediate water mass properties. This is evident during the early Holocene (from 10 to 6 cal ka) when benthic foraminiferal assemblages indicate that surface primary productivity was low, resulting in low intermediate-water Cdw at both sites. Then, from ∼ 5.2 to 2.4 cal ka, surface productivity increased markedly, causing a significant increase in the intermediate-water Cdw in the southeastern Arabian Sea and the northeastern BoB. The comparison of intermediate-water Cdw records with previous reconstructions of past Indian monsoon evolution during the Holocene suggests a direct control of intermediate-water Cdw by monsoon-induced changes in upper-water stratification and surface primary productivity.

Soil carbon dynamics is strongly controlled by depth globally, with increasingly slow dynamics found at depth. The mechanistic basis remains however controversial, limiting our ability to predict carbon cycle-climate feedbacks. Combining radiocarbon and thermal analyses with long-term incubations in absence/presence of continuously 13C/14C-labelled plants, we show here that bioenergetic constraints of decomposers consistently drive the depth-dependency of soil carbon dynamics over a range of mineral reactivity contexts. The slow dynamics of subsoil carbon was tightly related to both its low energy density and high activation energy of decomposition, leading to an unfavorable ‘return-on-energy-investment’ for decomposers. We also observed strong acceleration of millennia-old subsoil carbon decomposition induced by roots (‘rhizosphere priming’), showing that sufficient supply of energy by roots is able to alleviate the strong energy limitation of decomposition. These findings demonstrate that subsoil carbon persistence results from its poor energy quality together with the lack of energy supply by roots due to their low density at depth. These findings provide insights into the bioenergetic control of SOC persistence and indicate that an increase in plant rooting depth induced by global change could threaten the storage of millennia-old SOC in deep layers.

Oxalic and other small dicarboxylic acids have been reported as important water-soluble organic constituents of atmospheric aerosols from different environments. Their molecular distributions are generally characterized by the predominance of oxalic acid (C2) followed by malonic (C3) and/or succinic (C4) acids. In this study, we collected marine aerosols from the Arctic Ocean during late summer in 2009 when sea ice was retreating. The marine aerosols were analyzed for the molecular distributions of dicarboxylic acids as well as ketocarboxylic acids and α-dicarbonyls to better understand the source of water-soluble organics and their photochemical processes in the high Arctic marine atmosphere. We found that diacids are more abundant than ketoacids and α-dicarbonyls, but their concentrations are generally low (< 30 ng m−3), except for one sample (up to 70 ng m−3) that was collected near the mouth of Mackenzie River during clear sky condition. Although the molecular compositions of diacids are in general characterized by the predominance of oxalic acid, a depletion of C2 was found in two samples in which C4 became the most abundant. Similar depletion of oxalic acid has previously been reported in the Arctic aerosols collected at Alert after polar sunrise and in the summer aerosols from the coast of Antarctica. Because the marine aerosols that showed a depletion of C2 were collected under the overcast and/or foggy conditions, we suggest that a photochemical decomposition of oxalic acid may have occurred in aqueous phase of aerosols over the Arctic Ocean via the photo dissociation of oxalate-Fe (III) complex. We also determined stable carbon isotopic compositions (δ13C) of bulk aerosol carbon and individual diacids. The δ13C of bulk aerosols showed −26.5‰ (range: −29.7 to −24.7‰, suggesting that marine aerosol carbon is derived from both terrestrial and marine organic materials. In contrast, oxalic acid showed much larger δ13C values (average: −20.9‰, range: −24.7‰ to −17.0‰) than those of bulk aerosol carbon. Interestingly, δ13C values of oxalic acid were higher than C3 (av. −26.6‰) and C4 (−25.8‰) diacids, suggesting that oxalic acid is enriched with 13C due to its photochemical processing (aging) in the marine atmosphere.

We studied a longitudinal transect in the Mediterranean Sea (MS) and along this transect, the influence of anticyclonic eddies at three long duration (LD) stations. The deep chlorophyll maximum depth, the euphotic layer depth and the top of the nitracline depth are clearly correlated outside of the eddies, and deepen from the oligotrophic western to the ultraoligotrophic eastern MS. We provide evidence that the locations of the three LD stations studied were near the axis of the eddies. Their diameters were close to 100 km and the studied areas were less than 10 km from the centre of the eddies. The positions of the LD stations are marked by an increase in the flux function and a decrease in apparent oxygen utilization (AOU) and in excess density σ), as expected for anticyclonic eddies. Integrated mean primary production measured in situ inside the three studied eddies confirms the previous conclusion that integrated primary production (IPP) about 150 mgC m−2 d−1 may appear as a lower limit for IPP during strong oligotrophic conditions. The mesoscale activity is strong enough to locally modify the very well-documented western-to-eastern gradient of trophic conditions in the MS. We proposed a new calculation for mixed layer depths (MLDs) enabling the determination of MLD to take into consideration processes occurring with time scales ranging from a few hours to several days, and also the winter MLD. Studying the main physical, chemical and dynamical characteristics of the three eddies enables us to consider that the vorticity barrier prevents any strong mixing and advection of outer water inside the eddy and explains why the depth range of eddies starts from the surface. As a first approximation, the anticyclonic eddies could be considered as closed systems dating back to the previous winter, making possible to draw first-order budgets. The daily new N-input in the photic zone is virtually identical to the N-export measured at 230 m by drifting traps. This means that the eddies are close to an equilibrium state where input is equal to loss. The annual N-input by winter convection, which is a fundamental criterion for new nutrient availability, may be extremely variable inside eddies, with W-MLD varying from 90.5 m at the western station to 396.5 m at the eastern station. W-MLDs are always deeper inside the eddies than outside where they are in keeping with climatological averages. AOU was low inside the eddies; this together with the near-identical export measured at 230 and 460 m seems to indicate that eddy cores are areas where low mineralisation of particulate organic matter occurs. "In" and "out" AOU comparisons indicate lower mineralisation inside the eddies suggesting a higher efficiency for CO2 sequestration via sedimentation of particulate organic matter. The three eddies are enriched in dissolved organic carbon (DOC). Sequestration of CO2 by vertical export of accumulated DOC therefore seems to be higher inside eddies. The relative importance of DOC transport in the biological pump is probably one of the main characteristics of low-P low chlorophyll (LPLC) areas, and it is likely to be reinforced inside anticyclonic eddies. The numerous anticyclonic eddies in the MS are likely to influence the water masses and their dispersion, and therefore have a strong impact on the biogeochemical properties at the scale of the MS.

Previous studies have provided some insight into the Saharan dust deposition at a few specific locations from observations over long time periods or intensive field campaigns. However, no assessment of the dust deposition temporal variability in connection with its regional spatial distribution has been achieved so far from network observations over more than 1 year. To investigate dust deposition dynamics at the regional scale, five automatic deposition collectors named CARAGA (Collecteur Automatique de Retombées Atmosphériques insolubles à Grande Autonomie in French) have been deployed in the western Mediterranean region during 1 to 3 years depending on the station. The sites include, from south to north, Lampedusa, Majorca, Corsica, Frioul and Le Casset (southern French Alps). Deposition measurements are performed on a common weekly period at the five sites. The mean dust deposition fluxes are higher close to the northern African coasts and decrease following a south-north gradient, with values from 7.4g m year in Lampedusa (35°31'N, 12°37'E) to 1g m year in Le Casset (44°59'N, 6°28'E). The maximum deposition flux recorded is of 3.2g m wk in Majorca with only two other events showing more than 1g m wk in Lampedusa, and a maximum of 0.5g m wk in Corsica. The maximum value of 2.1g m year observed in Corsica in 2013 is much lower than existing records in the area over the 3 previous decades (11 4g m year ). From the 537 available samples, 98 major Saharan dust deposition events have been identified in the records between 2011 and 2013. Complementary observations provided by both satellite and air mass trajectories are used to identify the dust provenance areas and the transport pathways from the Sahara to the stations for the studied period. Despite the large size of African dust plumes detected by satellites, more than 80% of the major dust deposition events are recorded at only one station, suggesting that the dust provenance, transport and deposition processes (i.e. wet vs. dry) of dust are different and specific for the different deposition sites in the Mediterranean studied area. The results tend to indicate that wet deposition is the main form of deposition for mineral dust in the western Mediterranean basin, but the contribution of dry deposition (in the sense that no precipitation was detected at the surface) is far from being negligible, and contributes 10 to 46% to the major dust deposition events, depending on the sampling site. ' Author(s) 2016., This study was funded by the PRIMEQUALADEME programme on “Pollution atmosphérique longue distance” through the research project “Mesure du dépôt atmosphérique et validation de sa représentation dans les modèles régionaux” (DEMO project, contract no. 0962c0067). This project was also funded by the MISTRALS (Mediterranean Integrated Studies at Local and Regional Scales) programme as part of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx) and by the Spanish Government project ChArMEx: aerosols deposition ref: CTM2011-14036-E.

Simulations of climate over the Last Millennium (850–1850 CE) have been incorporated into the third phase of the Paleoclimate Modelling Intercomparison Project (PMIP3). The drivers of climate over this period are chiefly orbital, solar, volcanic, changes in land use/land cover and some variation in greenhouse gas levels. While some of these effects can be easily defined, the reconstructions of solar, volcanic and land use-related forcing are more uncertain. We describe here the approach taken in defining the scenarios used in PMIP3, document the forcing reconstructions and discuss likely implications.

The analysis of biological and ecological traits has a long history in evolutionary and ecological research. However, trait data are often scattered and standardised terminology that transcends taxonomic and biogeographical context are generally missing. As part of the development of a global trait database of marine species, we collated trait information for European seaweeds and structured the data within the standardised framework of the World Register of Marine Species (WoRMS). We collected 45,175 records for 21 biologically and ecologically relevant traits of seaweeds. This resulted in a trait database for 1,745 European seaweed species of which more than half (56 %) of the records were documented at the species level, while the remaining 44 % was documented at a higher taxonomic level and subsequently inherited at lower levels. The trait database for European seaweeds will serve as a foundation for future research on diversity and evolution of seaweeds, and their responses to global changes. The data will contribute to developing detailed trait-based ecosystem models, and will be an important tool to inform marine conservation policies. The data is publicly accessible through the AlgaeTraits portal, algaetraits.org, doi: https://doi.org/10.14284/574, (AlgaeTraits, 2022).

1. IntroductionThe Fireball Recovery and Inter Planetary Observation Network (FRIPON) network [1] uses all-sky cameras in order to detect fireballs. The FRIPON network comprises over 150 cameras installed all over Europe [1]. In this work we focus on the results obtained by the Meteorite Orbits Reconstruction by Optical Imaging (MOROI) [2] component of the FRIPON network in Romania. As of May 2022, the MOROI network detects the events with the use of 13 all-sky cameras.2. MethodsThe method for computing the fireball trajectory used by FRIPON is presented in [3].The height, velocity and slope γ of the meteoroid are the input data for computing the ballistic coefficient α and the mass-loss parameter β. We select the candidates that are likely to produce meteorites of the ground using the α-β algorithm presented in [4], [5], [6], [7]. 3. Results Starting from January 2021 (the starting moment of data fusion of the MOROI network into the FRIPON network) until the present time (May 2022) over 100 meteors were detected. We present the most spectacular events that are likely to result on a meteorite production on the surface of the Earth. Figure 1: The outcome of the FRIPON (MOROI) detections in Romania In Figure 1 are represented the coordinates of the meteoroids with noticeable deceleration in the (ln(αsinγ),lnβ) coordinates system. The values of the shape parameter correspond to the cases when the meteoroid doesn’t rotate (µ=0) or rotates uniformly (µ=2/3). The boundaries (‘likely fall’, ‘possible fall’, ‘unlikely fall’) are represented for meteoroids with final mass of 50 g. We processed the 100 detections of the FRIPON (MOROI) network in Romania. From this amount of data, we found 15 fireball events with noticeable deceleration. We found one event in the ‘likely fall’ area and three events in the ‘possible fall’ area. The fireball that is likely to produce meteorites was detected by the MOROI network on 24.11.2021 at 19:20:57 UT. We model the dark flight trajectory of the meteoroids with the ‘likely fall’ and ‘possible fall’ outcomes and determine their strewn field with the model presented in [8], [9]. We use the wind model from the European Centre for Medium-Range Weather Forecasts (ECMWF). A meteorite recovery campaign will be organised to identify the strewn field area. Acknowledgement. The work of IB and MB was partially supported by a grant of the Romanian Ministry of Education and Research, CNCS-UEFISCDI, project number PN-III-P1-1.1-PD-2019-0784, within PNCDI III. The work of IB, MB, AN was partially supported by a grant of the Ministry of National Education and Scientific Research, PNIII-P2-1214/25.10.2021, program no. 36SOL/2021. JM and MG acknowledge the Academy of Finland project no. 325806 (PlanetS). References: [1] Colas F., Zanda B., Bouley S., Jeanne S., Malgoyre A., Birlan M., Blanpain C., Gattacceca J., Jorda L., Lecubin J., et al. (385 more) FRIPON: a worldwide network to track incoming meteoroids. Astronomy &. Astrophys. 644, A53. doi:10.1051/0004-6361/202038649. 2020. [2] Nedelcu D.A., Birlan M., Turcu V., Boaca I., Badescu O., Gornea A., Sonka A.B., Blagoi O., Danescu C., Paraschiv P. Meteorites Orbits Reconstruction by Optical Imaging (MOROI) Network. Romanian Astronomical Journal 28(1), 57 – 65. 2018. [3] Jeanne, S., Colas, F., Zanda, B., Birlan, M., Vaubaillon, J., Bouley, S., Vernazza, P., Jorda, L., Gattacceca, J., Rault, J. L., Carbognani, A., Gardiol, D., Lamy, H., Baratoux, D., Blanpain, C., Malgoyre, A., Lecubin, J., Marmo, C., Hewins, P. Calibration of fish-eye lens and error estimation on fireball trajectories: application to the FRIPON network. Astronomy and Astrophysics, 627:A78. 2019. [4] Gritsevich, M. I. The Pribram, Lost City, Innisfree, and Neuschwanstein falls: An analysis of the atmospheric trajectories. Solar System Research.42, 372–390. 2008. [5] Gritsevich, M.I., Stulov, V.P., Turchak, L.I. Consequences of collisions of natural cosmic bodies with the Earth's atmosphere and surface. Cosmic Research vol.50, no.1, 56-64. 2012. [6] Sansom, E.K., Gritsevich, M., Devillepoix, H.A.R., Jansen-Sturgeon, T., Shober, P., Bland, P.A., Towner, M.C., Cupák, M., Howie, R.M., Hartig, B.A.D. Determining Fireball Fates Using the α-β Criterion. Astrophysical Journal 885(2):115. 2019. [7] Boaca I., Gritsevich M., Birlan M., Nedelcu, A., Boaca, T., Colas, F., Malgoyre, A., Zanda, B., Vernazza P., to be submitted. 2022. [8] Moilanen, J., Gritsevich, M., Lyytinen, E., Determination of strewn fields for meteorite falls, Monthly Notices of the Royal Astronomical Society 503, 3337–3350. 2021. [9] Boaca I., Nedelcu A., Birlan M., Boaca T., Anghel S. Mathematical model for the dark-flight trajectory of a meteoroid, Romanian Astronomical Journal, Vol. 31, No. 2. 2021.

To examine the potentially competing influences of microzooplankton and calcite mineral ballast on organic matter remineralization, we incubated diatoms in darkness in rolling tanks with and without added calcite minerals (coccoliths) and microzooplankton (rotifers). Concentrations of particulate organic matter (POM in suspension or in aggregates), of dissolved organic matter (DOM), and of dissolved inorganic nutrients were monitored over 8 days. The presence of rotifers enhanced the remineralization of ammonium and phosphate, but not dissolved silicon, from the biogenic particulate matter, up to 40% of which became incorporated into aggregates early in the experiment. Added calcite resulted in rates of excretion of ammonium and phosphate by rotifers that were depressed by 67% and 36%, respectively, demonstrating the potential for minerals to inhibit the destruction of POM by zooplankton in the water column. Lastly, the presence of the rotifers and added calcite minerals resulted in a more rapid initial rate of aggregation, although not a greater overall amount of aggregation during the experiment.

The organic mass fraction from sea spray aerosol (SSA) is currently a subject of intense research. The majority of this research is dedicated to measurements in ambient air. However a number of studies have recently started to focus on nascent sea spray aerosol. This work presents measurements collected during a 5-week cruise in May and June 2017 in the central and western Mediterranean Sea, an oligotrophic marine region with low phytoplankton biomass. Surface seawater was continuously pumped into a bubble-bursting apparatus to generate nascent sea spray aerosol. Size distributions were measured with a differential mobility particle sizer (DMPS). Chemical characterization of the submicron aerosol was performed with a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) operating with 10 min time resolution and with filter-based chemical analysis on a daily basis. Using positive matrix factorization analysis, the ToF-ACSM non-refractory organic matter (OMNR) was separated into four different organic aerosol types, identified as primary OA (POANR), oxidized OA (OOANR), methanesulfonic acid type OA (MSA-OANR), and mixed OA (MOANR). In parallel, surface seawater biogeochemical properties were monitored providing information on phytoplankton cell abundance and seawater particulate organic carbon (1 h time resolution) and seawater surface microlayer (SML) dissolved organic carbon (DOC) (on a daily basis). Statistically robust correlations (for n>500) were found between MOANR and nanophytoplankton cell abundance, as well as between POANR, OOANR, and particulate organic carbon (POC). Parameterizations of the contributions of different types of organics to the submicron nascent sea spray aerosol are proposed as a function of the seawater biogeochemical properties for use in models.

Carbohydrates are important components of the carbon cycle and may be used as indicators of the origin and the diagenetic status of marine and terrestrial organic matter. Nevertheless, comprehensive studies of both particulate (PCHO) and dissolved (DCHO) carbohydrates in rivers are scarce, and the seasonal and interannual variability of these compounds in relationship to the bulk particulate (POM) and dissolved organic matter (DOM) is largely unknown. For the period 2007–2009, we sampled once per month POM and DOM and measured the total suspended matter (TSM), POM, DOM, PCHO, and DCHO for the Rhône River, which flows into the Mediterranean Sea. Using these measurements, we estimated for the above parameters annual fluxes for the period 2007–2009. The estimated carbohydrate fluxes averaged 0.064 ± 0.026 × 1010 moles C yr−1 for PCHO and 0.042 ± 0.008 × 1010 moles C yr−1 DCHO, representing 6 % and 7 % of the annual flux of POC and DOC, respectively. During flood and low-water periods, POM variations were reflected into the PCHO pool, whereas this was not observed for DOC and DCHO, indicating a decoupling between particulate and dissolved organic matter. Our results also showed that flood and low-water periods may be differentiated using the ratios PCHO/DCHO and POC/DOC, which had a significant relationship. Based on the carbohydrate abundances in both the PCHO and DCHO pools, we conclude that this material mainly derives from allochthonous sources (vascular plants, bacteria and soils). Moreover, during flood events, an enrichment in mannose in POM was observed, probably reflecting an angiosperm source (leaves or grasses). By expanding our results to the northwestern Mediterranean Sea (Gulf of Lions), we found that the total organic carbon (TOC) fluxes of the Rhône River accounted for ~1 % of the standing stock of seawater TOC. Considering that glucose is the most abundant carbohydrate in both particulate and dissolved organic matter pools (~33 %), its annual flux in the northwestern Mediterranean Sea was estimated to 3.8 × 108 moles glucose.

The Pliocene epoch (~2.6-5.3 million years ago) is one of the best resolved examples of a climate state in long-term equilibrium with current or predicted near-future atmospheric CO2 concentrations, characterised by a globally warmer climate, reduced continental ice volume, and reduced ocean/atmosphere circulation intensity compared to today. Towards the end of the Pliocene, there was a marked increase in glaciation in the northern hemisphere and atmospheric CO2 concentrations declined. The Past Global Changes (PAGES) PlioVAR working group aimed to co-ordinate a synthesis of terrestrial and marine data to characterise spatial and temporal variability of Pliocene climate, underpinned by high quality data sets supported by robust stratigraphies. Here we present some of the main findings of this synthesis effort, including new assessments of ocean temperatures during the KM5c interglacial, and recent work assessing orbital-scale climate variability across the late Pliocene-early Pleistocene northern hemisphere ice-sheet growth. We outline our approaches to integrating multi-proxy data recording ocean temperatures, d18O and sea-level variability from a globally distributed suite of marine sediment cores. We explore regional expressions of environmental change across this transition, identifying asynchronous trends and patterns in climate changes. We consider how these results might inform our understanding of past climate forcings and feedbacks during both warm intervals of the past and the development of larger ice sheets in the northern hemisphere.

The relative importance of river solid discharge, deposited sediment remobilisation, and atmospheric dust as sources of neodymium (Nd) to the ocean is the subject of ongoing debate, the magnitudes of these fluxes being associated with a significant uncertainty. The Mediterranean basin is a specific basin; it receives a vast amount of emissions from different sources and is surrounded by continental margins, with a significant input of dust as compared to the global ocean. Furthermore, it is largely impacted by the Atlantic water inflow via the Strait of Gibraltar. Here, we present the first simulation of dissolved Nd concentration ([Nd]) and Nd isotopic composition (εNd) using a high-resolution regional model (NEMO/MED12/PISCES) with an explicit representation of all Nd inputs, and the internal cycle, i.e. the interactions between the particulate and dissolved phases. The high resolution of the oceanic model (at ), essential to the simulation of a realistic Mediterranean circulation in present-day conditions, gives a unique opportunity to better apprehend the processes governing the Nd distribution in the marine environment. The model succeeds in simulating the main features of εNd and produces a realistic distribution of [Nd] in the Mediterranean Sea. We estimated the boundary exchange (BE, which represents the transfer of elements from the margin to the sea and their removal by scavenging) flux at 89.43 × 106 g(Nd) yr−1, representing ∼84.4 % of the total external Nd source to the Mediterranean basin. The river discharge provided 3.66 × 106 g(Nd) yr−1, or 3.5 % of the total Nd flow into the Mediterranean. The flux of Nd from partially dissolved atmospheric dusts was estimated at 5.2 × 106 g(Nd) yr−1, representing 5 % of the total Nd input, and 7.62 × 106 g(Nd) yr−1 comes from the Atlantic across the Strait of Gibraltar, i.e. 7.1 % of the total Nd input. The total quantity of Nd in the Mediterranean Sea was estimated to 7.28 × 109 g(Nd); this leads to a new calculated Nd residence time of ∼68 year. This work highlights that the impact of river discharge on [Nd] is localised near the catchments of the main rivers. In contrast, the atmospheric dust input has a basin-wide influence, correcting for a too-radiogenic εNd when only the BE input is considered and improving the agreement of simulated dissolved Nd concentration with field data. This work also suggests that εNd is sensitive to the spatial distribution of Nd in the atmospheric dust, and that the parameterisation of the vertical cycling (scavenging/remineralisation) considerably constrains the ability of the model to simulate the vertical profile of εNd. This research has been supported by the French National Research Agency (ANR) project MEDSENS ( grant no. ANR19-CE01-0019).

In the Western Alps, the Penninic frontal thrust (PFT) is the main crustal-scale tectonic structure of the belt. This thrust transported the high-pressure metamorphosed internal units over the non-metamorphosed European margin during the Oligocene (34–29 Ma). Following the propagation of the compression toward the European foreland, the PFT was later reactivated as an extensional detachment associated with the development of the High Durance extensional fault system (HDFS). This inversion of tectonic displacement along a major tectonic structure has been widely emphasized as an example of extensional collapse of a thickened collisional orogen. However, the inception age of the extensional inversion remains unconstrained. Here, for the first time, we provide chronological constraints on the extensional motion of an exhumed zone of the PFT by applying U–Pb dating on secondary calcites from a fault zone cataclasite. The calcite cement and veins of the cataclasite formed after the main fault slip event, at 3.6 ± 0.4–3.4 ± 0.6 Ma. Cross-cutting calcite veins featuring the last fault activity are dated at 2.6 ± 0.3–2.3 ± 0.3 Ma. δ13C and δ18O fluid signatures derived from these secondary calcites suggest fluid percolation from deep-seated reservoir at the scale of the Western Alps. Our data provide evidence that the PFT extensional reactivation initiated at least ∼ 3.5 Myr ago with a reactivation phase at ∼ 2.5 Ma. This reactivation may result from the westward propagation of the compressional deformation toward the external Alps, combined with the exhumation of external crystalline massifs. In this context, the exhumation of the dated normal faults is linked to the eastward translation of the HDFS seismogenic zone, in agreement with the present-day seismic activity.

Ocean circulation plays a central role on climate regulation. The paleoceanographic studies of the last decades have allowed to better document the variations in the production of the North Atlantic Deep Water (NADW). However, the role of intermediate water (IW) masses through time remains to be documented and is highly controversial. Indeed, some studies have highlighted the increased contribution of the Antarctic Intermediate Water (AAIW) in all ocean basins during the cold events recorded in the North Atlantic [1] while others suggest their absence [2]. Moreover, during the last deglaciation, the Southern Ocean played a fundamental role in the Carbon transfer from the deep ocean to the atmosphere via the increased upwelling associated to the AAIW production. In order to reconstruct the dynamics of IW masses, to better understand the relationships between variations in ocean circulation in the Atlantic and in the Southern Ocean, and the impact of these changes on the global carbon cycle during Termination I, we use two marine sediment cores from the Porcupine basin MD01-2461 (1153m) and the Iberian margin SU92-28 (997m). We combine the study of benthic foraminifera assemblages sensitive to variations in their environment (nutrient content, oxygen), and different geochemical proxies such as elemental ratios (Mg/Ca, Sr/Ca, Cd/Ca, Ba/Ca, B/Ca, Li/Ca and U/Ca), stable isotopes (δ18O and δ13C) and Neodymium isotopes records (eNd). On core SU92-28, past changes in the benthic foraminiferal content exhibit strong differences in the paleo-environments, with different ecological conditions from the LGM to the Holocene, as well as during the YD and H1 events. These differences are also observed in the δ13C, oxygen concentrations and elemental ratios records obtained from Uvigerina peregrina (or U.mediterranea), Cibicidoides mundulus and Melonis affinis. Changes in the Nd record allow to distinguish changes in the IW mass sources, reflecting the balance between Northern and Southern contributions. Future analysis (e.g., 14C reservoir ages) and the comparison with core MD01-2461 records will help to better constrain the North-South connections in the Atlantic Ocean at IW depths, and their impact on global climate changes.[1] Ma et al. (2019) Geochemistry, Geophysics, Geosystems, 20(3), 1592-1608[2] Gu, S., et al. (2017). Paleoceanography, 32, 1036-1053.

IntroductionMarl-limestone alternations are well known rhythmical inter-bedded deposits that commonly occur in many hemipelagic to pelagic deposits of the Phanerozoic. It is quite well established that the origin of these lithological variations are astronomically-driven climatic variations (22, 41, 100 and 405 ka being the main periods) e.g. [1]. However, the exact sedimentological control is not clear: several models attribute these alternations to cyclic changes in the carbonate flux, whereas the terrigenous silicoclastic flux remained relatively constant. On the opposite, some models suggest that the carbonate flux was constant while the silicoclastic flux changed cyclically.Material and methodsTo disentangle these different scenarios, we collected marlstone and limestone samples from two sedimentary successions of Bajocian, Middle Jurassic (3 marl-limestone- couplets over 3.5 m) and Valanginian, Lower Cretaceous (1 marl-limestone couplet over 1 m) age from the Southern French Alps (Barles). We measured their carbonate contents, the nannofossil proportion, as well as their extraterrestrial 3He (3HeET) concentrations in ~200 mg decarbonated aliquots.Results and discussionThe carbonate content ranges from 45% in marls to 86% in limestones. Importantly, for all samples, measured 3HeET concentrations are constant in the silicoclastic fractions, within uncertainties. Hence, our results indicate that sedimentation rates at the astronomical timescale in the examined examples were mainly controlled by large changes in the CaCO3 net fluxes, leading to variable dilution of the terrigenous and 3HeET fractions. Nannofossil counting shows that pelagic CaCO3 fluxes of coccolithophores are inversely correlated to the total CaCO3 along the marl-limestone alternations and represent less than 4% of the total carbonate content. Hence, in this setting, these marl-limestone alternations were more probably driven by variations in the CaCO3 supply from the nearby carbonate platform. Finally, assuming a constant 3HeET flux of 0.1 pcc/cm2/ka [2], and the whole thickness of Bajocian and Valanginian strata in this region, the measured 3HeET concentrations imply sedimentation rates that are broadly compatible with current duration estimates of these two stages. References:[1] Eldrett J. S. et al. (2015) Earth. Plan. Sci. Let., 423, 98-113.[2] Farley K.A. et al. (2012) GCA, 84, 314-328.

Calcium sulfates are the dominating salts but the respective sulfate sources are debated. In order to quantify the relative contribution and spatial distribution of sulfate sources and to identify biological sulfate recycling processes, we analyzed δ18OSO4, Δ17OSO4, 87Sr/86Sr, and δ34SSO4 of sulfate from Atacama Desert soils (Chile). Surface samples were taken along four W-E transects from the Pacific coast to the Pre-Andean Cordillera between 19.5°S and 25°S. Additionally, lacustrine gypsum and sulfate extracted from groundwater feeding the Salar de Llamará and sodium sulfates from the Salar del Huasco were analyzed.Sulfur from the ocean comprise high δ34SSO4 values compared with low δ34SSO4 volcanic sulfate allowing to estimate the marine sulfur contribution to the total sulfate sample. δ34SSO4 decreases with distance from the coast principally confirming previously published results [1]. Because Sr substitutes for Ca in Ca-Sulfates, 87Sr/86Sr follows similar systematics, at least for samples taken within the coastal fog zone (34SSO4 and 87Sr/86Sr of samples taken above 1200 m are decoupled indicating sulfate dissolution and re-precipitation or deposition of supra-regional Ca-rich aerosols with high 87Sr/86Sr values.Positive ∆17OSO4 values observed in all analyzed samples (0.1‰ to 1.1‰) suggest a significant contribution from secondary atmospheric sulfate (SAS) to Atacama Desert soils. Distinct mass-independent 17O anomalies of SAS originate from atmospheric oxidation of reduced sulfur species from volcanic or anthropogenic emissions, or biogenic sulfur gases such as dimethyl sulfide (DMS) by O3 or H2O2. Within our dataset we can distinguish between a SAS(DMS) endmember, comprising high ∆17OSO4 and δ34SSO4 and a SASAtacama endmember comprising moderate Δ17OSO4 and low δ34SSO4. Highest Δ17OSO4 values, interpreted to represent a pure SASAtacama endmember, are observed in samples from the Coastal Cordillera of the southernmost transect which is generally higher than the present maximum level of fog advection (1200 m). Lowering of Δ17OSO4 values results from 1) dilution of the positive Δ17OSO4 fromSAS by marine and/or terrestrial sulfate with Δ17OSO4 ≈ 0‰, and 2) resetting of Δ17OSO4 due to biological sulfate reduction and reoxidation. Lowest Δ17OSO4 values are observed in sulfates from salars and soils from alluvial fans.In general, Δ17OSO4 andδ18OSO4 of our data show an inverse relationship reflecting not only the source contributions but also biological sulfate cycling. Thus, large Δ17OSO4 anomalies (≈1‰) that suggest a dominant contribution from SASAtacama, also indicate the relative absence of biologically processed sulfate and thus, low water availability.[1] Rech et al. (2003), Geochim. Cosmochim. Acta 67, 575-586

Wind-blown sand and dust emissions shape singular landscapes in arid environments and globally impact climate, life and human activities. However, the accurate quantification of aeolian sediment fluxes are still subject to considerable uncertainties. Since extensive measurements are difficult to implement in the field, this quantification rely essentially on remote sensing data and transport laws that integrate a large number of parameters for the airflow and granular bed. However, confronted with all the sources of natural variability (wind regime, air recirculation, grain-size distribution, soil composition, etc.), a complete mass balance of aeolian transport remains challenging. Here we consider long time scales to smooth out such variability and integrate arid landscape dynamics into the source-to-sink assessment of aeolian mass transfers in the Lut Desert (Iran). Taking advantage of new remote sensing imagery and dating techniques, together with more accurate wind data and a deeper understanding of dune dynamics, we analyze major landforms of this desert to provide a comprehensive picture of aeolian transport on time scales from decades to millions of years. We map the modern sandflows, along which we evaluate the volume and chronology associated with the excavation of mega-yardangs upwind and the formation of giant dunes downwind. Sediment discharges deduced from long-term erosion and deposition are of the same order of magnitude (105 to 106 m3yr-1) as short and medium-term sand discharges derived from wind data and dune morphodynamics. At the scale of the internal aeolian sediment-routing system of the Lut, we establish an overall sediment budget constrained by the joint development of the erosional and depositional landforms. Our findings thus quantify the geomorphic controls of aeolian processes on arid landscapes at multiple length and time scales, while providing information on mass exchanges between continents and atmosphere.

Studies of karst denudation rates are great approach to provide an insight to karst landscape development. Traditionally, dissolution of carbonate rocks is considered to be the main process governing carbonate weathering, other processes should not be overlooked. Here we present research done in the North Dalmatian Plain, a carbonate erosive surface located in the Dinaric karst region. Although study site is composed of two different carbonate lithologies having different weathering style, there is no evident lithological impact on the topography of erosive surface. Analyses of 36Cl were performed in ten proximal samples from both lithologies resulted in denudation rates from 14.7 to 22.7 m/Ma. Since no statistical significance was found between samples from different lithologies (all samples belong to a single normal population) having same geomorphological context and climate features, variable denudation rates are attributed to local differences in denudation. In the study site there are no large outstanding rock residuals, or deep soil patches, thus in order to maintain the levelled erosive surface local differential denudation rates have to vary with time. We hypothesize that lichens and pedogenic carbonates have a significant role in modulating local differences in denudation rates. Our study shows that even at outcrop scale, differences in local denudation rate can be significant and study of large set of samples is preferred to properly characterize the overall denudation rates of carbonate surfaces. Thus, the long-term denudation rate of the North Dalmatian Plain, including local variability, is 18.55 ±0.79 m/Ma. Despite classical studies on karst terrains assume that dissolution is the main process responsible for denudation of these landscapes, our research highlights the importance of physical weathering in combination with dissolution of carbonates as main controls on the denudation of karst landscapes. Acknowledgements: This research is a part of the research project “Inter-comparison of karst denudation measurement methods” (KADEME) (IP-2018-01-7080) financed by Croatian Science Foundation.

Several episodes of strong climate change and environmental perturbation marked the Early Jurassic, and culminated during the Toarcian Oceanic Anoxic Event (T-OAE), characterised by widespread deposition of organic-rich shales. Exceptionally preserved fossils of marine vertebrates and invertebrates have been discovered in the Toarcian shales of NW Europe, but the potential links between the occurrences of these exceptionally preserved fossils and the T-OAE remain poorly investigated. Paleontological excavations realized in Toarcian strata near Lodève (Grands Causses Basin, southern France) have yielded several specimens of marine vertebrates and abundant invertebrate fauna. We have developed a multiproxy approach (ammonite biostratigraphy, X-ray diffraction-bulk mineralogy, Rock-Eval pyrolysis, stable isotopes, trace element, phosphorus and mercury contents) to place these findings in a well-defined temporal and paleoenvironmental context, and hence constrain the factors that led to their extraordinary preservation. The Jenkyns Event interval, unambiguously identified at the base of the Toarcian organic-rich shales by a 5‰ negative carbon isotope excursion, records higher mercury fluxes, which suggest a causal link with intense volcanic activity of the Karoo–Ferrar large igneous province. This interval is very condensed and unfossiliferous, and might have been deposited under abnormally low-salinity conditions. Our data exhibit that the deposition of the vertebrate-yielding horizons post-dated the T-OAE by several hundreds of ka, and took place during a prolonged period of widespread oxygen-deficiency and high carbon burial. Our results indicate that the unusual richness in vertebrates of the studied site can be explained by a combination of regional factors such as warming-induced, prolonged seafloor anoxia, and more local factors, such as extreme condensation owing to reduced dilution by carbonate and detrital input.

Since 2011, the distribution extent of pelagic Sargassum algae has substantially increased and now covers the whole Tropical North Atlantic Ocean, with significant inter-annual variability. The ocean colour imagery has been used as the only alternative to monitor such a vast area. However, the detection is hampered by cloud masking, sunglint, coastal contamination and others phenomena. All together, they lead to false detections that cannot be discriminated with classic radiometric analysis, but may be overcome by considering the shape and the context of the detections. Here, we built a machine learning model based on spatial features to filter false detections. More specifically, Moderate-Resolution Imaging Spectroradiometer (MODIS, 1 km) data from Aqua and Terra satellites were used to generate daily map of Alternative Floating Algae Index (AFAI). Based on this radiometric index, Sargassum presence in the Tropical Atlantic North Ocean was inferred. For every Sargassum detections, five spatial indices were extracted for describing their shape and surrounding context and then used by a random forest binary classifier. Contextual features were most important in the classifier. Trained with a multi-annual (2016-2020) learning set, the classifier performs the filtering of daily false detections with an accuracy of 90%. This leads to a reduction of detected Sargassum pixels of 50% over the domain. The method provides reliable data while preserving high spatial and temporal resolutions (1 km, daily). The resulting distribution on 2016-2020 is consistent with the literature for seasonal and inter-annual fluctuations, with maximum coverage in 2018 and minimum in 2016. In particular, it retrieves the two areas of consolidation in the western and eastern part of the Tropical Atlantic Ocean associated with distinct temporal dynamics. At full resolution, the dataset allowed us to semi-automatically extract Sargassum aggregations trajectories from successive filtered images. Using those trajectories will help to better quantify the drift of aggregations with respect to the currents, the wind and sea state. Overall, this new dataset will be useful for understanding the drivers of Sargassum dynamics at fine and large scale and validate future models.

After more than a century of research, the chronology of the deformation of the external part of the western Alpine belt (France) is still controversial for the Miocene epoch. In particular, the poor dating of the foreland basin sedimentary succession hampers a comprehensive understanding of the deformation kinematics. Here we focus on the Miocene molasse deposits of the northern subalpine massifs, southern Jura, Royans, Bas-Dauphiné, Crest, and La Bresse sedimentary basins through a multidisciplinary approach to build a basin-wide tectono-stratigraphic framework. Based on sequence stratigraphy constrained by biostratigraphical, chemostratigraphical (Sr isotopes), and magnetostratigraphical data between the late Aquitanian (∼ 21 Ma) and the Tortonian (∼ 8.2 Ma), the Miocene molasse chronostratigraphy is revised with a precision of ∼ 0.5 Ma. The Miocene molasse sediments encompass four different paleogeographical domains: (i) the oriental domain outlined by depositional sequences S1a to S3 (∼ 21 to ∼ 15 Ma), (ii) the median domain characterized by sequences S2 to S5 (∼ 17.8 to ∼ 12 Ma), (iii) the occidental domain in which sequences S2a to S8 (∼ 17.8 to ∼ 8.2 Ma) were deposited, and (iv) the Bressan domain where sedimentation is restricted to sequences S6 to S8 (∼ 12 to ∼ 8.2 Ma). A structural and tectono-sedimentary study is conducted based on new field observations and the reappraisal of regional seismic profiles, thereby allowing the identification of five major faults zones (FZs). The oriental, median, and occidental paleogeographical domains are clearly separated by FZ1, FZ2, and FZ3, suggesting strong interactions between tectonics and sedimentation during the Miocene. The evolution in time and space of the paleogeographical domains within a well-constrained structural framework reveals syntectonic deposits and a westward migration of the depocenters, allowing for proposing the succession of three deformation phases at the western Alpine front. (i) The first is a compressive phase (P1) corresponding to thrusting above the Chartreuse oriental thrust (FZ1), which was likely initiated during the Oligocene and rooted east of Belledonne. This tectonic phase generated reliefs that limited the Miocene transgression to the east. (ii) The second is a ∼ WNW–ESE-directed compressive phase (P2) lasting between 18.05 ± 0.25 Ma and ∼ 12 Ma, with thrusts rooted in the Belledonne basal thrust. Thrusts were activated from east to west: the Salève (SAL) and Gros Foug (GF) thrusts and then successively FZ2, FZ3, FZ4, and FZ5. Along two WNW–ESE balanced cross sections the amount of horizontal shortening is of ∼ 6.3 to 6.7 km, corresponding to average shortening rates of ∼ 1.2 km Myr−1 and migration of the deformation toward the west at a rate of ∼ 2.9 km Myr−1. During ∼ 6 Myr, the Miocene Sea was forced to regress rapidly westwards in response to westward migration of the active thrusts and exhumation of piggyback basins atop the fault zones. Phase P2 thus deeply shaped the Miocene paleogeographical evolution of the area and appears as a prominent compressive phase at the scale of the western Alps from the Swiss molasse basin to the Rhodano–Provencal one. (iii) The third is a ∼ 300 m phase of uplift in the Bas-Dauphiné (P3) of probable Tortonian age (∼ 10 Ma), which would have induced southward sea retreat and been coeval with the folding of the Jura in the north and possibly with back-thrusting east of the Chartreuse massif.

One of the most puzzling properties of silicon (Si) is its differential absorption by plants. Depending on the plant species, water and soil Si availability, environmental factors such as grazing and temperature, plant Si contents can vary from 0.1 % to 10 %(on a dry weight basis). Advances in genomics improved our understanding of biochemical and molecular mechanisms underlying plant Si uptake providing a framework to explain the variability of Si in plants and its distribution. Yet complex Si roles in plant strategies, its dependence on environmental factors and in mediating interactions with their environments and other organisms remain misunderstood. How is plant Si uptake affected by soil Si availability and how is Si distribution between tissue types controlled? It is hard for us to answer those questions even if Si plant traits are an indicator of the soil Si status. For example, a few studies showed that Si content and phytolith distribution are mainly controlled by Si availability. In this study, a pot experiment was conducted in a greenhouse where wheat (Triticum turgidum L.) was grown on three different soils: an aric podzol, an andosol and a calcosol. These soils are contrasted in term of clay size distribution, SiO2 concentrations and organic matter content and are presumed to reflect French soils variability in term of Si dynamics. Here, we focus on how plant Si patterns, both Si content and Si isotopes, are linked to soil Si availability leading to new insights to the mechanisms underlying the different Si uptake and translocation strategies. This work is supported by the BIOSiSOL project (ANR-14-CE01-0002).

Microbial communities on marine aggregates could be influenced by ambient water conditions; however, empirical data are scarce. In this study, we used fingerprint analysis of PCR-amplified 16S rRNA gene fragment to examine how microbial communities on aggregates change in response to different conditions of ambient water. We conducted two experiments using seawater cultures from surface waters of the lagoon and the anthropogenically influenced bay of Nouméa, New Caledonia: a transplant experiment in which the artificially produced aggregates from one station was added to ultra-filtered seawater culture of another station, and a water-flow experiment in which the artificially produced aggregates placed in the ultra-filtered seawater culture with or without water-flow. In a transplant experiment, bacterial community composition (BCC) on the bay and lagoon water aggregates were significantly different (p < 0.05, ANOSIM) at the beginning of experiment. After 11 days of incubation, BCC on the lagoon water aggregates were significantly different (p < 0.05) from transplanted communities. Transplantation effect was also observed in the bay water treatments. In a water-flow experiment, BCC on the bay and lagoon water aggregates were significantly different (p < 0.05) at the beginning of the experiment. BCC on the lagoon and bay water aggregates with and without water-flow treatments were significantly different (p < 0.05) at the end of incubation, and effect of water-flow on BCC were observed in the bay and lagoon water treatments. Our experimental studies suggest that changes in ambient water conditions potentially influence microbial communities on aggregates in the Bay of Nouméa.

N2O emission in soils is a consequence of the activity of nitrifying and denitrifying microorganisms and potentially abiotic processes. However, the large microscale variability of the soil characteristics that influence these processes and in particular the location of anoxic microsites, limits prediction efforts. Better understanding of denitrification activity on microscopic scales is required to improve predictions of N2O emissions.This study explored the role of soil microstructure on N2O emission. To fulfill this objective we sampled 24 soil columns (5 cm diameter, 6 cm height) in the surface layer of a same plot in a cultivated soil (Luvisol, La Cage, Versailles, France). The soil samples were saturated with a solution of ammonium nitrate (NH4NO3), and equilibrated at a matrix potential of -32 cm (pF 1.5). The emitted fluxes of N2O were measured during 7 days. At the end of the experiment, the soil columns were scanned in a X-ray micro tomograph, at the University of Poitiers. A 32 µm voxel resolution was achieved for the 3D reconstructed images.In order to reduce noise and segment the 3D images, the same protocol was implemented for all columns. The reduction of noise consisted of passing a non-local mean filter, a non-sharp mask and a radial correction. Such combination of steps succeeded in removing both ring artifacts and the radial dependence of the voxel values. Due to the variety of material densities in the soil, a local segmentation based on the watershed method was implemented to classify the soil constituents in four classes (based on its density value): air, water and organic matter (OM), soil matrix and minerals. This method is good for detecting thin pores and avoids missclassification of voxels undergoing partial volume effect, which can lead to false organic coatings around macropores.The soil columns exhibited a large variability of accumulated N2O after 7 days (from 107 to 1940 µgN kg-1 d.w. soil). The size of OM clusters varied between a couple and up to thousands of voxels. No correlation was found between the emission of N2O and the porosity, nor between the N2O emission and the connectivity of the air phase. Based on the premise that the less accessible is the oxygen to the OM, the bigger should be the N2O emission of the soil column, we proposed and computed a microscopic spatial descriptor, Igd, based on the notion of the geodesic distance between clusters of OM and air for each soil column 3D image. We expect to find a correlation between Igd and the N2O emission.

On December 29th, 2020, a strong Mw 6.4 earthquake hit central Croatia. The epicenter was located approximately 3 km southwest of Petrinja, and the intensity was estimated to VIII-IX EMS. The earthquake led to significant environmental effects related to earthquake magnitude, focal depth, and geological and geotechnical properties of the affected area.The Croatian Geological Survey (HGI-CGS) conducted extensive geological and geodetic surveys starting a few hours following the main shock to measure the earthquake’s effects,including those on infrastructures. Ten geologists from the Department of Geology carried out surveys from Decmber 31st, 2020 to January 7th, 2021 along the potential seismogenic source (inferred from geological maps and InSAR data) and in the wider epicentral area that suffered significant damage (e.g., Glina and Sisak).During a second phase, researchers from the University of Zagreb (PMF UniZG), Slovenia (GeoZS), Italy (INGV, ISPRA, U. Chieti) and France (CEREGE, IRSN) were mobilized to complete the observations. The collaboration with these geologists allowed to deepen the investigations and to bring further detail to quantify the effects. The surveys were then compiled based on data formats used by the European Community, namely those of the INGV EMERGEO team (Villani et al., 2017; for environmental effects including surface ruptures and liquefaction) and those of the SURE group (Baize et al., 2019 for surface ruptures).These observations revealed that the earthquake triggered a discontinuous, few km-long surface rupture with a maximum displacement of about 20 cm, which is consistent with the lower average of observations made on similar events (Wells and Coppersmith, 1994). Liquefaction spread over several tens of square kilometers mostly in river plains, the most distant being about 20 km from the epicenter (to be confirmed!). Other observed effects include lateral spreading, landslides, groundwater regime changes, rockfalls, and various infrastructure damage.The compilation of the acquired dataset into a unified database, consistent with database of other historical and recent events, is essential for establishing reliable empirical relations between geological effects and physical characteristics of earthquakes (magnitude, depth). This forms the basis for seismic hazard assessments, whether for “surface rupture”, “liquefaction”, or “ground-shaking” potential.

The Greenland Ice Sheet (GrIS) plays a key role in the global climate system. Its response to recent warming concerns the scientific community due to its potential contribution to the global sea-level rise, oceanographic changes and the related heat distribution in the atmosphere. Therefore, a better understanding of the GrIS response to past glacial oscillations can provide insights into its sensitivity to rapidly changing climates. Past natural GrIS dynamics are still poorly constrained, and there are important knowledge gaps in the spatio-temporal pattern of its past fluctuations, especially on the NE margins, in response to climate variability. Here, we present new records of past GRIS extents and a detailed space-time reconstruction of the deglaciation process in the Zackenberg Valley (74ºN, 20ºE), NE Greenland, based on geomorphological mapping combined with a new dataset of 39 10Be cosmic-ray exposure (CRE) ages of moraine boulders, polished surfaces, and erratic boulders. Our dataset records glacial oscillations from the Last Glacial Cycle to the Early Holocene. Geomorphic evidence at the summit surfaces reveal that glaciers were significantly thicker (>800 m) at ca. 80 ka, when valleys and fjords were ice-covered and only the highest peaks remained ice-free. The Zackenberg outlet glacier must have been slightly smaller during the Last Glacial Maximum, although no glacial records of this period were found. Samples from moraine boulders indicate rapid and massive deglaciation of the Zackenberg Valley slopes by ca. 14 ka, during the Bølling-Allerød interstadial. Ice thinning exposed the upper and intermediate slopes surrounding the valley floor, while stabilization phases within the long-term glacial retreat favoured the development of several moraine ridges. At the end of the Younger Dryas, by ca. 12 ka, a glacier readvance favoured the development of the lowest moraine ridges of the slopes, connected with the outermost moraine system on the valley floor. Within the limits of this moraine, a debris-covered glacier formed due to the intense paraglacial readjustment of rock slopes and moraines triggered by glacier thinning. This process favoured the degradation of the moraine ridges on the slopes, supplying large amounts of debris to the shrinking glacier. By ~10.5 ka, the last remnants of glacial ice disappeared from the Zackenberg Valley floor, exposing polished bedrock outcrops and leaving scattered erratic boulders. Higher temperatures also favoured the irregular collapse of the debris-covered glacier, transforming this area into a hummocky terrain. This deglaciation chronology shows a particularly intense recession during the Bølling-Allerød and Early Holocene, a path that is broadly similar to that observed in other sites across NE Greenland.

In the Central Apennines (Italy), up to now, no absolute dating directly based on the moraines has been carried out to constrain glacial oscillation. However, climatic constrains are often used in the Central Apennine to estimate long term (> 10 ka) fault slip rate. In addition slip rate assessments based on offset morphotectonic markers on the main branches of fault systems and encompassing several seismic cycles (> 10 ka) are sparse. This is particularly true for the Monte Vettore-Monte Bove fault system which triggered the 2016-2017 seismic sequence. We thus provide new assessment for the vertical slip rates along the Mt Vettore-Mt Bove fault system. Offset measurements were made using a 5-cm resolution DEM obtained through a drone survey and constrain a fault scarp height of 15.5 ± 1.4 m and a cumulative offset of 32-40.5 m. Samples were collected from the Valle Lunga terminal moraine at 1710 m asl and yield 36Cl exposure ages of 12.7 + 2.2/-1.9 ka while the flat, abraded surface located on top of the tectonic scarp yield 36Cl exposure ages of 23.4 + 5.3/-4.3 ka. Assuming the offset started to accumulate when climate conditions allow its preservation, thus once the surface was abandoned, we constrain a vertical slip rate of 1.2 ± 0.2 mm/yr along the master branch of the Mt Vettore normal fault. This rate is higher than the ones previously obtained from trenches along secondary splays of the Mt Vettore-Mt Bove and on the Norcia fault systems. Besides, the yielded chronology for the last glacial maximum in that area at ~23 ka is in good agreement with the timing previously proposed for the LGM in the Apennines.

Recent paleomagnetic data from early Late Cretaceous and late Eocene rocks from Myanmar (1,2) demonstrate that the Burma Terrane (BT) underwent an important northward translation alongside India in the Cenozoic. We present new paleomagnetic results from Paleocene to Eocene sediments that confirm the slightly southern to equatorial paleolatitudes during the Paleocene to mid Eocene. However, these paleomagnetic results imply a new paleogeography not compatible with the typical view of the geology of Myanmar as an andean-type margin above an active subduction of the Tethys/India oceanic crust below Sundaland. Most previous models proposed an active subduction below Myanmar during the Paleogene but a slab anchored in the mantle would impede the large northward motion of the BT implied by our paleomagnetic data. We thus review the geology of the BT in light of the new latitudinal constraints provided by the paleomagnetic data. The BT contains >10km thick Cenozoic basins (Central Myanmar Basins (CMBs)) recording the Cenozoic geological evolution of the BT. The CMBs were previously interpreted with sediment sources located within the Myanmar magmatic arc and to the east in Sibumasu. The numerous studies on detrital zircons from the Late Cretaceous - Paleogene sediments of the CMBs highlight a clear correlation in the distribution of the ages of the pre-Cretaceous zircons (~40% of the zircons in the sediments) with the one from the Triassic turbidites (Pane Chaung Formation) of the Indo-Burman Ranges and the Triassic sediments from the Tethyan Himalaya (Langjiexue Fm.). Thus, the source of sediments is unlikely to be in Sibumasu but proposed to be in an actively eroding north-western extension of the Indo-Burman ranges (Greater Burma block, (2)) possibly linked to the Tethyan Himalaya and consistent with a BT position within the India plate during the Cenozoic. In any case, we find little evidence for a nearby active magmatic arc in the detrital zircon record supporting the hypothesis of an active subduction below the BT. Thus this review of the geology of the BT supports a rapid northward moving BT alongside India during the Cenozoic. We will discuss the implication of this new paleogeography on the India-Asia collision models.(1) Westerweel et al. « Burma Terrane Part of the Trans-Tethyan Arc during Collision with India According to Palaeomagnetic Data ». Nature Geoscience 12, no 10 (octobre 2019): 863‑68. https://doi.org/10.1038/s41561-019-0443-2.(2) Westerweel et al. « Burma Terrane Collision and Northward Indentation in the Eastern Himalayas Recorded in the Eocene‐Miocene Chindwin Basin (Myanmar) ». Tectonics 39, no 10 (octobre 2020). https://doi.org/10.1029/2020TC006413.

Carbonate aquifers are known as a major source for drinking water in the Mediterranean region. Therefore, qualitative and quantitative estimation of the groundwater resource are crucial, especially in area with densely populated areas.In this study, geochemical and isotopic tracers (δ18O, δ2H and 87Sr/86Sr) have been used to discriminate different origins of groundwater and evaluate water-mass mixing in a Mediterranean carbonate environment. The case study, located in south-eastern France, offers an attractive geological context to explore strontium isotopic tracers: trias to cretaceous carbonate rocks, that have been eroded and locally resedimented in fluvial deposits during Oligocene extension and Quaternary periods. Moreover, many karst features act as sinking zones, generating fast infiltration. The 500 km² zone investigated has also a large range of elevation, from the sea to 1148m, giving an expected significant contrast in water isotopes. Monthly water samples have been collected in-situ for two years on ground and surface waters, in rivers, boreholes as well as karstic springs. Monthly rainwater samples provide the isotopic signal of the recharge at two distinct elevations and distance from the sea.The hydrogeochemical signatures allow to discriminate the end-members of two main waterbodies as well as a slight marine influence on one borehole. Nitrates concentrations (NO3-) highlight anthropogenic influence on groundwater resources. A multi-tracer approach taking in account water-rock interaction, mixing processes and recharge, coupled with hydrogeological conditions and dye-tracing tests, leads to a conceptual model of this complex hydrosystem.

Seismic hazard calculations are based on the assumption that seismicity rates are stable over time. In a given area, the seismicity recorded through historical archives and seismometers is considered a reliable indicator to model the occurrence of future high magnitude seismic events. But, to discuss this hypothesis regionally, it is essential to reconstruct long term seismicity.The junction between the Jura mountains and the Alps is seismically active, as shown by the occurrence of numerous seismic events and the presence of several active faults (De La Taille, 2015). Since the 15th century, more than twenty earthquakes of epicentral intensity greater than VII have been identified in this area. In addition, sedimentary sequences from Lake Annecy and Lake du Bourget have highlighted the capacity of these "natural archives" to record recurrent seismic activity (Beck 2009), with a potential major seismic event identified around 9900 cal. BP (Arnaud et al., 2012). Such lacustrine archives are key to better understand 1) the occurrence of major seismic events and 2) the evolution of seismicity rates through time, prior to historical and instrumental records.Here, we present two sedimentary sequences of 11 and 16 metres long respectively, sampled in the shallowest and deepest basins of Lake Aiguebelette (altitude: 374 m). We performed sedimentological, geochemical and paleomagnetic analyses combined with seismic profile analyses and radiocarbon dating to study processes of event layer deposition in this lake. Multi-proxy analyses allow a quantitative identification of event layers, contrasting with varved-sedimentation. In the deepest basin sequence, 33 homogenites are identified through variations of the laboratory induced isothermal remanent magnetization of sediments measured with a high-resolution fluxgate scanner (Demory et al., 2019) and high foliation (>2%) of the Anisotropy of Magnetic Susceptibility. These parameters are usually associated with seiche effect induced by seismic activity (Campos et al., 2013). Among these event layers, archived in the deep basin sequence, three of them occured synchronously in the shallow basin (at 3000 ± 100, 6900 ± 100 and 11400 ± 300 cal. BP, respectively).The oldest and thickest event layer recorded in Lake Aiguebelette was deposited at the transition between the Late Glacial and Holocene stages. In the deepest basin, this 1.15-meter-thick deposit is composed of an upward-graded base and a 0.84 meter-thick homogenite, which was also identified as a transparent facies on seismic profiles. In Lake Le Bourget, Lake Annecy, and central Swiss perialpine lakes, several seismic profiles analyses show transparent seismic facies interpreted as mass movement deposits occurring at the same period of time: the Late glacial-Holocene transition.Did this climatic transition influence the seismic activity in the Alps? If so, the impact of such climatic forcing on seismic hazard assessment should be evaluated. Arnaud et al (2012). Lake Bourget regional erosion patterns... QSR., 51, 81-92.Beck (2009). Late Quaternary lacustrine paleo-seismic... EarthSciRev., 96(4), 327-344.Campos et al (2013). Deciphering hemipelagites from homogenites... SedGeol., 292, 1-14.De La Taille et al (2015). Impact of active faulting... Tectonophysics, 664, 31-49.Demory et al (2019). A new high‐resolution magnetic scanner... Geochem,Geophy,Geosys., 20(7), 3186-3200. Keywords: Lake sediment, homogenites, paleo-earthquakes, seismic hazard, French Alps

The PMF receptor model was applied to a combined dataset using specific markers such as phospholipids and sugars together with other metals (e.g. Al, Pb, V) and ions (e.g. K+, Ca2+, SO42-, NO3-) as tracers of main aerosol sources in order to characterize the sources of P in atmospheric particles. The samples were collected from East Mediterranean; an oligotrophic region, strongly P-limited, with atmospheric nutrients deposition affecting its primary productivity. The results revealed that dominant sources of P compounds are the dust (43%) and the bioaerosols (34%). The coexistence of these sources in the spring period increased the organic P up to 53% of total P with more than a half to originate from bioaerosols. Dust is the major source of inorganic P forms with almost equal contribution to the phosphate ions and to the condensed P forms (e.g pyrophosphate or phosphorous minerals).Based on the results of source apportionment analysis and the atmospheric concentration of P species, the maximum annual deposition scaled to the East Mediterranean surface was 21.5 Gg P with almost equal deposition of org-P and phosphate ions. The soluble P content from dust aerosols is the similar magnitude of potential bioavailable organic P emitted from bioaerosols (~4 Gg P y-1), especially during the stratification period, when surface water is mostly nutrient starved. Anthropogenic pollution contributes slightly higher to organic P comparing with phosphate ions, while the latter is produced mainly secondary. Biomass burning emissions in the area are associated mainly with the more soluble P.

Oxygen Minimum Zones (OMZs) are oceanic areas largely depleted in dissolved oxygen, nowadays considered in expansion in the face of global warming. Their ecological and economic consequences are being debated. The investigation of past OMZ conditions allows us to better understand biological and physical mechanisms responsible for their variability with regards to climate change, carbon pump and carbonate system. To investigate the relationship between OMZ expansion and global climate changes during the late Quaternary, quantitative oxygen reconstructions are needed, but are still in their early development. Here, past bottom water oxygenation (BWO) was quantitatively assessed through a new, fast, semi-automated, and taxonfree morphometric analysis of benthic foraminiferal tests, developed and calibrated using Eastern North Pacific (ENP) and the Eastern South Pacific (ESP) OMZs samples. This new approach is based on an average size and circularity index for each sample. This method, as well as two already published micropalaeontological approaches based on benthic foraminiferal assemblages variability and porosity investigation of a single species, were here calibrated based on availability of new data from 23 core tops recovered along an oxygen gradient (from 0.03 to 1.79 mL.L−1) from the ENP, ESP, AS (Arabian Sea) and WNP (Western North Pacific, including its marginal seas) OMZs. Global calibrated transfer functions are thus herein proposed for each of these methods. These micropalaeontological reconstruction approaches were then applied on a paleorecord from the ENP OMZ to examine the consistency and limits of these methods, as well as the relative influence of bottom and pore waters on these micropalaeontological tools. Both the assemblages and morphometric approaches (that is also ultimately based on the ecological response of the complete assemblage and faunal succession according to BWO) gave similar and consistent past BWO reconstructions, while the porosity approach (based on a single species and its unique response to a mixed signal of bottom and pore waters) shown ambiguous estimations.

Marine Isotope Stage 5 deposits have been reported on many tropical Pacific islands. This paper presents a database compiled through the review of MIS 5e (last interglacial – LIG) coral reef records from islands belonging to French Polynesia (Anaa, Niau, Makatea, Moruroa, Takapoto, Bora Bora), the Hawaiian Islands (Oahu, Lanai, Midway Atoll), Tuvalu, Kiribati (Christmas Island, Tarawa), the Cook Islands (Mangaia, Atiu, Mitiaro, Mauke, Pukapuka, Rakahanga, Rarotonga), Tonga, Samoa, the Federal States of Micronesia, the Mariana Islands, the Marshall Islands (Enewetak, Bikini), New Caledonia, Papua New Guinea, the Solomon Islands, Vanuatu, Fiji and Niue. Studies reporting other sea-level indicators dated to other Pleistocene interglacials and Holocene sea-level indicators were not inserted in the database but are included in this data description paper for completeness. Overall, about 300 studies concerning Pleistocene and Holocene sea-level indicators have been reviewed, and finally 163 age data points and 94 relative sea-level (RSL) data points from 38 studies on the MIS 5e have been inserted in the database. An additional 155 age data points have been reviewed; i.e. the tropical Pacific islands database contains 318 age data points. The main sea-level indicators include emerged coral reef terraces, but also reef units recovered in drill cores from a few islands, thus reflecting the diversity of tectonic settings and sampling approaches. Future research should be directed towards better constrained RSL reconstructions, including more precise chronological data, more accurate elevation measurements and a better refinement of the palaeo-water-depth significance of coralgal assemblages. The database for tropical Pacific islands is available open access at this link: https://doi.org/10.5281/zenodo.3991672 (Hallmann and Camoin, 2020).

Understanding the degree of sensitivity of the Earth Surface to past climate changes is key to assess the strength of postulated links between weathering, denudation, rock uplift and climate. Numerous studies have investigated the response of surface processes to the evolution through time of temperature and precipitation, in various settings and over different time periods. In particular, an important question still actively debated concerns whether or not Late Cenozoic climate change had an effective impact on denudation rates. It is noteworthy that this Late Cenozoic climatic evolution is often described as a long-term cooling over several Ma. However, although it has been postulated to be an important control on this response, the impact of its orbitally-controlled high-frequency component has been less investigated.Studies focusing on climate-denudation links have often been carried out in regions of high tectonic activity. Therefore, they encountered associated significant limitations, such as: (1) high denudation rates that reach the analytical limits of many measurement methods; (2) stochastic events introducing a high degree of variability in the denudation signal; and, (3) high rates of tectonic uplift that can limit the sensitivity to the low-frequency component of the climatic boundary condition. Less active tectonic settings with lower denudation rates may thus provide conditions allowing to focus specifically on the coupling between climate variations and surface processes. Additionally, approaches combining different cosmogenic nuclides have proven to be very effective to unravel changes in surface processes over several time scales.We present a new cosmogenic nuclides dataset from the Sera do Cipo range in Minas Gerais, Brazil. The core of the range is made of resistant quarzite bedrock with a relief of 500 m with respect to the surrounding low lands, and reported denudation rates are 10Be and 26Al concentrations were measured in the collected samples, as in such slow denudation settings the ratio between the two nuclides is sensitive to changes in denudation rates through time. A high-resolution (1 m) Digital Elevation Models was also produced from tri-stereo Pléiades satellite images. This allows to compute high resolution metrics such as hilltop curvature at the sampling sites. Hilltop denudation rates display a strong positive correlation with curvature. 26Al/10Be values significantly departing from the theoretical steady state denudation ratio are interpreted at hilltop sites as reflecting the fluctuation of denudation through time. Concerning the catchments samples, the determined ratio can also be impacted by the sediment transport history along hillslopes. Combining cosmogenic nuclides and high-resolution topographic datasets, the measured concentrations were inverted to constrain the variation of denudation over the last 2 Ma. We observe a significant change in the denudation regime at 1 Ma, with different kind of responses between ridges and small catchments across the landscape.

This study aims at evaluating the information carried by the 17O-excess composition of precipitation in the sub-humid part of West Africa. Located at the southern border of the Sahelian band, the so-called “Sudanian Climatic Zone”, characterized by annual precipitation of 1200-1400mm, plays a crucial role in providing water to large African watersheds such as the Niger river’s one, and the Lake Chad catchment. Surface-atmosphere interactions were shown to influence convective processes in the semi-arid Sahelian band, with positive feedbacks between vegetation land cover and rainfall. Less focus has been put on the more humid Sudanian Zone, although surface-atmosphere interactions may have an important influence on the control of rainfall variations, and therefore on water resource availability in these watersheds.The stable isotope composition of precipitation reflects the combination of different processes associated with phase changes over the atmospheric water cycle, from the initial water vapor formation above the ocean to the raindrop on the ground surface. Classical tracers (δ18O, δ2H, and d-excess) are affected by multiple factors (i.e. Rayleigh process, temperature, humidity) changing during these successive steps. In contrast, 17O-excess variations mainly records evaporation processes controlled by the humidity conditions that prevail during phase change. There are few available 17O-excess studies focusing on precipitation in tropical and sub-tropical areas. They show that the 17O-excess in precipitation provides information on 1) relative humidity at oceanic moisture sources, and 2) secondary processes, such as raindrop re-evaporation. The contribution of vapor of continental origin, produced either by plant transpiration or soil water evaporation, should additionally affect the 17O-excess signature of precipitation, although no data are available so far to evaluate the magnitude of this process.For the study presented here, we collected precipitation from two sampling stations, both located in Benin and affected by a similar oceanic moisture source in the Gulf of Guinea. The first station (lat. 6°26’ N; long. 2°21’ E) is located along the coast and is essentially subject to oceanic influence. The second station (lat. 9°44’ N; long. 1°34’ E) is located 400 km inland and may be additionally affected by continental vapor recycling. The stable isotope composition of rainfall samples (δ2H, δ18O and δ17O) are measured on a WS-CRDS Picarro L2140-i, using three replicates per sample. Comparison between those two records allow to investigate how humidity at the oceanic source, raindrop re-evaporation and continental vapor­ contribute to the 17O-excess signature of precipitation.

Since the 1999 Izmit-Kocaeli earthquake, the Main Marmara Fault (MMF) of the North Anatolian Fault system in the Sea of Marmara has been considered at an imminent risk for a large earthquake. Land geodesy has difficulties characterizing the distribution of interseismic loading, and hence of slip deficit, on the offshore faults, and notably on the Istanbul-Silivri segment of the NAF. The need to clarify the status of offshore fault segments has motivated seafloor monitoring experiments and marine geophysical and sedimentological studies, notably in the framework of EMSO consortium and MARSITE and MAREGAMI projects. Results from cross-disciplinary projects have shown that aseismic creep, spatially correlated to active gas venting at the seafloor, occurs on the Western segment of the MMF. This segment is also capable to large earthquake ruptures such as the 1912 event. On the eastern part of the Sea of Marmara, the Istanbul-Silivri and Prince Island segments appear essentially locked. Moreover, the base of the seismogenic zone and locking depth appears to shallow (from 15-20 to 10-15 km) from west to east.On one hand, we propose to further evaluate fault slip rates and distribution of locking ratio on individual fault segments using an elastic block model constrained by land geodesy data and marine observations (long-term fault slip rate estimates, local acoustic ranging results). On the other hand, we evaluate the temperature at the seismogenic depths by basin modelling. Results suggest that spatial variations of fault behavior in the Sea of Marmara may result from a combination of factors. First, thermogenic gas generation within the > 6 km thick sedimentary cover in the Western Sea of Marmara may contribute to unlock the shallow part of the fault by generating overpressures. Second, heterogeneity of the crust composition could be a factor as the North Anatolian Fault system follows the intra-pontide ophiolitic suture. For instance, long term post-seismic creep onland at Ismet Paşa has been related to the presence of serpentinite in the fault zone. Moreover, high-density magnetic bodies have been identified along the MMF. Third, varying thermal regimes between the Western and Eastern parts of the Sea of Marmara may account for variations in the seismogenic depths. Seafloor heat flow in the Sea of Marmara is strongly affected by sediment blanketing and basin modeling considering this process suggests that the crustal heat flow is about 20 mW/m2 higher in the eastern part than in western part of the Sea of Marmara. This difference may be explained by a more spread out crustal extension in the western Sea of Marmara.

The oxygen isotope signature of leaf water is used to trace several processes at the soil-plant-atmosphere interface. During photosynthesis, it is transferred to the oxygen isotope signature of atmospheric CO2 and O2, which can be used for reconstructing past changes in gross primary production. The oxygen isotope signature of leaf water additionally imprints leaf organic and mineral compounds, such as phytoliths, used as paleoclimate and paleovegetation proxies when extracted from sedimentary materials.Numerous experimental and modelling studies were dedicated to constrain the main parameters responsible for changes in the δ18O of leaf water. Although these models usually correctly depict the main trends of 18O-enrichment of the leaf water when relative humidity decreases, the calculated absolute values often depart from the observed ones by several ‰. Moreover, the δ18O of leaf water absorbed by plants is dependent on the δ18O value of meteoric and soil waters that can vary by several ‰ at different space and time scales. These added uncertainties make our knowledge of the parameters responsible for changes in the δ18O of leaf water and phytoliths flawed.Changes in the triple oxygen isotope composition of leaf water, expressed by the 17O-excess, are controlled by fewer variables than changes in δ18O. In meteoric water the 17O-excess varies slightly as it is weakly affected by temperature or phase changes during air mass transport. This makes the soil water fed by meteoric water and the atmospheric vapour in equilibrium with meteoric water changing little from a place to another. Hence the 17O-excess of leaf water is essentially controlled by the evaporative fractionation. The latest depends on the ratio of vapor pressure in the air to vapor pressure in the stomata intercellular space, close to relative humidity. Leaf water evaporative fractionation can lead to 17O-excess negative values that can exceed most of surficial water ones.Here we present the outcomes of several recent growth chamber and field studies, for the purpose of i) refining the grass leaf water and phytoliths δ18O and 17O-excess modelling, ii) assessing whether the δ18O and 17O-excess of grass leaf water can be reconstructed from phytoliths, and iii) examining the precision of the 17O-excess of phytoliths as a new proxy for past changes in continental atmospheric relative humidity. Atmospheric continental relative humidity is an important climate parameter poorly constrained in global climate models. A model-data comparison approach, applicable beyond the instrumental period, is essential to progress on this issue. However, there is currently a lack of proxies allowing quantitative reconstruction of past continental relative humidity. The 17O-excess signature of phytoliths could fill this gap.

The term "fine scales" is generally used to refer to the ocean processes occuring on horizontal scales smaller than 10 km andcharacterized by a short lifetime (days/weeks). Fine scales have been predominantly studied with numerical simulations andsatellite observations which have highlighted their significant role on biological processes. Indeed, their short time scale is thesame as a lot of important processes in phytoplankton dynamics. Model simulations have shown that fine scales such as frontsand filaments strongly influence the distribution of phytoplankton species. Nowadays, the combination of in situ measurements,satellite observations and model simulations is a necessity to better understand these mechanisms. However these processesare particularly challenging to sample in situ because of their size and their ephemeral nature. The PROTEVSMED-SWOT cruise was performed in the Western Mediterranean Sea, in the southern region of the BalearicIslands, onboard BHO Beautemps-Beaupré, between April 30 th and May 14 th , 2018. In order to study the influence of finescales on the distribution of phytoplankton species, a satellite-based adaptive Lagrangian sampling strategy has been deployedin order to i) identify a fine scale structure of interest, ii) sample it at high spatial resolution the phytoplankton community, andiii) follow the evolution of this structure and the related distribution of phytoplankton. The SPASSO software package usessatellite altimetry, SST and surface Chl a concentration data to generate and provide near-real time daily maps of the dynamicaland biogeochemical structures present in the area. The sampling strategy was defined in order to cross a frontal zone separatingdifferent types of water. Multidisciplinary in situ sensors (hull-mounted ADCP, a Seasoar towed fish and an automated flowcytometer installed on the seawater supply of the Thermosalinograph) were used to sample at high spatial resolution physicaland biological variables. A particular attention was put in adapting the temporal sampling in different water masses to thebiological time scales in order to reconstruct the phytoplankton diurnal cycle. Such a strategy was successful in sampling two different water masses separated by a narrow front and characterized bydifferent aboundances of several phytoplankton species and functional groups. Consequently, our results highlight the role ofthe front on the physical and biological coupling confirming previous modelling and remote-sensing studies. The new generation of altimetric satellite, SWOT, will provide a 2D sea surface height at an unprecedented resolution andit will be a unique opportunity to better observe fine scale structures in the global ocean. Our methodology paves the way tofuture in situ experiments that are planned in 2022 during the SWOT fast-sampling phase, few months after its launch.

The Indian-Atlantic interocean exchange (IAIE), occurring through Agulhas current and its leakage around the southern tip of Africa, is one of the return flows of global thermohaline circulation that contributes to the temperate climate in Europe. The IAIE affects the transport of heat and salt to the zone of deep-water formation in the N Atlantic, influencing the variability of Atlantic Meridional Overturning Circulation (AMOC). During the last 600 kyr, significant climatic events took place such as the Mid-Bruhnes event (MBE) (~430 ka) that marks a transition towards more intense interglacial periods.The main objective of our study is to assess the impact of climate forcing on the strength of both surface and deep water IAIE during the last 600 kyr. For this purpose, we examined the variability of a group of warm-water planktonic foraminiferal species for tracing surface water circulation. We combined published and unpublished data from 3 cores along an Indian-Atlantic transect: two cores in the Indian Ocean, core MD96-2048 (26°10’S, 34°01’E, 660 m) in the source of the Agulhas current and our study core MD96-2077 (33º10’S, 31º14’E, 3781 m) in the middle of the Agulhas current; and one core in the Atlantic Ocean, core ODP1087 (31°27’S, 15°18’E 1372 m) recording the Agulhas leakage.Since Globorotalia menardii and Globorotalia tumida are frequently used to trace Agulhas leakage, their variability in Agulhas current in the Indian Ocean is of our interest. Therefore, we compared the relative abundances of the warm-water planktonic G. menardii and G. tumida species with a group of warm-water planktonic foraminiferal species to record the strength of Agulhas current in core MD96-2077. Our results show that the group of warm-water planktonic species reflects increased Agulhas current strength at glacial terminations coinciding with stronger Agulhas leakage (Atlantic core ODP1087) as observed in previous studies. However, in core MD96-2077, both G. menardii and G. tumida relative abundances increase during interglacial periods. This indicates that production of these species in the Agulhas current source region is unlikely to trace Agulhas leakage in the Atlantic Ocean. The analyses of deep-water circulation proxies (Nd isotopes, benthic O and C stable isotopes) are in progress, and they will allow us to assess the response of deep circulation to changes in Agulhas current and leakage over the last 600 kyr.