Revival of ancient marine dinoflagellates using molecular biostimulation
The biological processes involved in the preservation, viability, and revival of long‐term dormant dinoflagellate cysts buried in sediments remain unknown. Based on studies of plant seed physiology, we tested whether the revival of ancient cysts preserved in century‐old sediments from the Bay of Brest (France) could be stimulated by melatonin and gibberellic acid, two molecules commonly used in seed priming. Dinoflagellates were revived from sediments dated to approximately 150 years ago (156 ± 27, 32 cm depth), extending the known record age of cyst viability previously established as around one century. A culture suspension of sediments mixed with melatonin and gibberellic acid solutions as biostimulants exhibited germination of 11 dinoflagellate taxa that could not be revived under controlled culture conditions. The biostimulants revived some dinoflagellates from century‐old sediments, including the potentially toxic species Alexandrium minutum. The biostimulants showed positive effects on germination on even more ancient cysts, showing dose‐dependent effects on the germination of Scrippsiella acuminata. Concentrations of 1, 10, and 100 µM melatonin and gibberellic acid promoted germination. In contrast, 1000 µM solutions, particularly for melatonin, drastically decreased germination, suggesting a potential noxious effect of high doses of these molecules on dinoflagellate revival. Our findings suggest that melatonin and gibberellic acid are involved in the stimulation of germination of dinoflagellate cysts. These biostimulants can be used to germinate long‐term stored dinoflagellate cysts, which may promote studies of ancient strains in the resurrection ecology research field.
(Journal of Phycology. vol. 56, n° 0022-3646, pp. 1077-1089, 01/06/2020)
LEMAR, IRD, IFREMER, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GM, IFREMER, DYNECO, IFREMER
Biogenic volatile organic compounds (BVOCs) reactivity related to new particle formation (NPF) over the Landes forest
Atmospheric particles play a major role in both air quality and climate change. Formation of secondary particles in the atmosphere has been observed over many different environments and is believed to provide up to half of the atmospheric cloud condensation nuclei (CCN) at a global scale. However, high uncertainties are still remaining in the description of mechanisms involved in new particle formation (NPF). Especially, more evidences of the implication of biogenic volatile organic compounds (BVOCs) in NPF from field studies are still needed. To investigate this question, two field campaigns have been set up during July 2014 and July 2015, in the French Landes forest (south west of France). Summer 2015 was characterized by a strong hydric stress, whereas summer 2014 was rainy. In 2015, frequent nocturnal NPF was observed, reaching a frequency of occurrence of similar to 55% of the nights, while only one event was observed in 2014. In July 2015, monoterpene mixing ratios (dominated by alpha- and beta-pinene) were higher, mostly due to high ambient temperatures and drought. A focus was made on the 2015 field campaign, where NPF was mostly observed. The mean diurnal variation of the ratio between alpha- and beta-pinene mixing ratios highlighted in-canopy reactivity of monoterpenes with ozone in the early night. This hypothesis was reinforced by the increasing gas phase levels of pinonaldehyde and nopinone, the main first-generation products arising from alpha- and beta-pinene ozonolysis, at night, before NPF started. It strongly suggests that monoterpene oxidation further generated very-low volatility gases involved in NPF. This finding is also supported by the high concentrations of the SOA traditional biogenic tracers, e.g. pinic and pinonic acids, quantified in the particulate phase. The role of BVOCs in NPF is thus highlighted, as well as the importance of nighttime NPF.
(Atmospheric Research. vol. 237, n° 0169-8095, pp. 1-11, 01/06/2020)
UMR ISPA, Bordeaux Sciences Agro, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ECOSYS, INRAE
Spatial variability of arsenic speciation in the Gironde Estuary: Emphasis on dynamic (potentially bioavailable) inorganic arsenite and arsenate fractions
(Marine Chemistry. vol. 223, n° 0304-4203, pp. 103804, 01/06/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Presentation and evaluation of the IPSL‐CM6A‐LR climate model
This study presents the global climate model IPSL-CM6A-LR developed at Institut Pierre-Simon Laplace (IPSL) to study natural climate variability and climate response to natural and anthropogenic forcings as part of the sixth phase of the Coupled Model Intercomparison Project (CMIP6). This article describes the different model components, their coupling, and the simulated climate in comparison to previous model versions. We focus here on the representation of the physical climate along with the main characteristics of the global carbon cycle. The model's climatology, as assessed from a range of metrics (related in particular to radiation, temperature, precipitation, and wind), is strongly improved in comparison to previous model versions. Although they are reduced, a number of known biases and shortcomings (e.g., double Intertropical Convergence Zone [ITCZ], frequency of midlatitude wintertime blockings, and El Niño–Southern Oscillation [ENSO] dynamics) persist. The equilibrium climate sensitivity and transient climate response have both increased from the previous climate model IPSL-CM5A-LR used in CMIP5. A large ensemble of more than 30 members for the historical period (1850–2018) and a smaller ensemble for a range of emissions scenarios (until 2100 and 2300) are also presented and discussed.
(Journal of Advances in Modeling Earth Systems. vol. 12, n° 1942-2466, pp. e2019MS002010, 28/05/2020)
LMD, INSU - CNRS, X, IP Paris, ENPC, SU, CNRS, ENS-PSL, PSL, MERMAID, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LOCEAN-NEMO R&D, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LATMOS, UVSQ, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, PSL, UVSQ, CEA, INSU - CNRS, X, IP Paris, CNES, SU, CNRS, UPCité, CLIM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CALCULS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LOCEAN-VARCLIM, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité, isac, CNR, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, METIS, EPHE, PSL, INSU - CNRS, SU, CNRS, MOSAIC, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, IGE, IRD, INSU - CNRS, CNRS, Fédération OSUG, UGA, Grenoble INP, UGA, UvA, CNRM, INSU - CNRS, CNRS, Comue de Toulouse, BRGM
Coastal Dune Morphology Evolution Combining Lidar and UAV Surveys, Truc Vert beach 2011-2019
In the context of climate change, coastal dunes, which provide significant ecosystem services, are one of the most vulnerable coastal environments. Moreover, the lack of high resolution and large spatial scale data limits our understanding of coastal dunes, which are subject to important morphological variations over a wide range of spatial and temporal scales. This study is focused on combining non-intrusive remote sensing methods including a series of historical aerial photographs, airborne Lidar and UAV surveys in order to better understand the coastal dune morphodynamic on a wide range of spatial and temporal scales. On the time scale of decades, aerial photos indicate a reasonably stable coastal dune position, with large anthropogenic reprofiling and vegetation planting resulting in a reasonably alongshore-uniform morphology. On shorter time scales, the combination of Lidar and UAV 4-km surveys between 2011 and 2019 shows a quasi-steady dune volume increase by approximately 64 m3/m, associated with a foredune crest growth and a landward migration reaching 1.1 m and 0.54 m in average, respectively. On the other hand, the dune foot shows a more complex dynamics, dominated by a large landward migration (shoreline erosion) of approximately 20 m during the outstanding winter of 2013/2014 followed by a slow seaward migration (recovery). This study provides new insight into coastal dune morphological changes driven by both Aeolian and marine processes from the time scale of storm to approximately a decade, highlighting the relevance of UAV surveys for such applications.
(Journal of Coastal Research. vol. 95, n° 0749-0208, pp. 163, 26/05/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Analysis of Two Contrasting Seasonal Recovery Periods of an Open Sandy Beach, using High Frequency DGPS Surveys
Biausque, M. and Senechal, N., 2020. Analysis of two contrasting seasonal recovery periods of an open sandy beach, using high frequency DGPS surveys. High frequency DGPS surveys were undertaken for 2.5 years (November 2015 until April 2018) on an open sandy double barred beach in the SW of France (Biscarrosse Beach) covering three winter and two summer periods. On those latitudes, summers are usually described as seasonal recovery periods. The morphological response of the beach during two consecutive summer periods (2016 and 2017) has been analyzed to identify processes involved in seasonal recovery. Analysis of alongshore mean profiles indicates that the summer 2016 is marked by a progressive berm reconstruction, manly driven by cross-shore sediment transport. The beach recovery in 2016 can be characterized as complete with a stable berm through the summer season associated with steady beach cusps, and a seaward dune foot migration. During this summer the variations in volume of each section of the beach (intertidal/supratidal beach and dune) show sediment transport firstly orientated from the intertidal beach toward the supratidal one, and, later, driven from the supratidal beach to the dune. This cycle is coherent with recent observations described by Philips (2017). In contrast, the summer 2017 is characterized by an incomplete recovery, an unstable berm and so, a much more complex dynamic: the berm, rapidly rebuild (by the end of June), started to erode in July. Six sequences of cross-shore sediment exchanges are measurable along the season between the intertidal and the supratidal beach, inducing successive erosion/ accretion of both sections of the beach. Thus, according to those results summers 2016 and 2017 present variable spatial and temporal dynamics. Moreover, analysis of hydrodynamic and environmental factors indicate that recovery periods not only depend on hydrodynamic conditions, such as wave energy and tide, but also on winter/summer morphological coupling, and sandbar/beach coupling.
(Journal of Coastal Research. vol. 95, n° 0749-0208, pp. 377, 26/05/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Wave and Tide Controls on Rip Current Activity and Drowning Incidents in Southwest France
The meso-macrotidal sandy surf beaches of southwest France are a popular destination visited by millions of tourists each summer, who potentially expose themselves to surf zone hazards and particularly to rip currents flowing through the inner-bar rip channels. 281 non-fatal and fatal drowning incidents, most of them caused by rip currents, recorded by lifeguards during the summer 2007, 2009 and 2015 were combined with measured and hindcast wave and tide data. Results show that drownings occur disproportionally near neap low tide, under shore-normal incident waves and average to above-average height and period, with drowning incidents tending to occur in clusters with particular days of mass incidents. An XBeach model is implemented on measured rip-channelled bathymetries to address the influence of offshore wave conditions and tidal elevation on rip flow dynamics and resulting hazard. Simulations show that rip flow increases with increasing wave height, increasing wave period and increasingly shore-normal incidence, which is consistent with the increased number of drowning incidents for such conditions. Although more incidents also tend to occur on warm sunny days with light winds, presumably driving more exposure to the rip current hazard, this highlights the dominance of the physical hazard on the life risk along this stretch of coast.
(Journal of Coastal Research. vol. 95, n° 0749-0208, pp. 769, 26/05/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ISPED, BPH, UB, INSERM, BRGM
3D variability of Sediment Granulometry in Two Tropical Environments: Nha Trang (Vietnam) and Saint-Louis (Sénégal)
The sediment variability of two tropical beaches was studied in order to provide the input data of the COASTVAR project's morphodynamic models. The longshore, cross-shore and vertical sediment organization of the first decimeters seems important to take into account in modeling. In particular, the presence of coarser underlying sediments, very frequently observed at all latitudes, may be at the origin of the slope of the beach. And these coarser sediments can also cause significant changes in sedimentary dynamics, when the most energetic events come to set them in motion. But the 3D characterization of beach sediments is not easy and the methods to achieve it are presented here.
(Journal of Coastal Research. vol. 95, n° 0749-0208, pp. 495, 26/05/2020)
SHOM, LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Polychlorinated Biphenyls (PCB) indicators in sediments from the main French Rivers from 1945 to 2018 (Garonne, Loire, Rhône, Seine)
We collected PCB analysis results from multiple sources (French Water Basin Agencies, Port Authorities, Research Laboratories) to produce a spatio-temporal database of PCB contamination in sediments along the main French Rivers (source-estuary) from 1945 to 2018. This database contains data from bed and flood deposits, cores, suspended particulate matter and dredged sediments. It presents sediment concentrations of PCB indicators (PCB28, 52, 101, 118, 138, 153, 180; µg/kg) and their sum or reconstructed sum according to the porportion of highly chlorinated congeners (PCB 138, 153 and 180).
(pp. https://doi.pangaea.de/10.1594/PANGAEA.904277, 20/05/2020)
LEHNA, UCBL, ENTPE, CNRS, GéHCO, UT, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS
Spatio-temporal assessment of the polychlorinated biphenyl (PCB) sediment contamination in four major French river corridors (1945-2018)
Environmental pollution by polychlorinated biphenyls (PCBs) is a key cause for concern about river quality because of their low degradation rates leading to their accumulation in sediments and living organisms. An original interdisciplinary work was conducted along the four main French rivers (Seine, Rhône, Loire and Garonne rivers), which flow into major European seas. We completed a dataset based on sediment analyses provided by monitoring agencies, port authorities and research teams on different solid matrices (sediment cores, bed and flood deposits, suspended particulate matter and dredged sediments). This dataset focused on the seven indicator PCBs and their sum (PCBi) from 1945 to 2018 (n PCBi = 1416). Special effort was put into the quality control to provide robust spatio-temporal information. Taking into account hydrological and human drivers, we outlined two main pollution trends: (1) from 1945 to 1975, a quick increase in PCBi (up to 4 mg kg −1 dry weight, dw) and a sharp decrease in the 1980s on the Seine and Loire rivers and (2) increasing but moderate PCBi levels (50 to 150 µg kg −1 dw) followed by a decline after the 1990s on the Rhône and Garonne rivers. In addition to these patterns, PCB emissions from urban and industrial areas or accidental events were significant in each river. Finally, when calculating specific flux, the Rhône exhibited the uppermost PCBi load (up to 12 µg m −2 yr −1 in 1977-1987), at least 25 % higher than those of the Seine and Loire rivers, while the Garonne showed a very low flux. In western Europe, we confirmed that the Rhône, Seine and Loire rivers contribute significantly to the PCB contamination of the seas, while French specific PCBi fluxes are 2 orders of magnitude lower than those found in American or Asian rivers. The dataset is available at https://doi.org/10.1594/PANGAEA.904277 (Dendievel et al., 2019).
(Earth System Science Data. vol. 12, n° 1866-3508, pp. 1153-1170, 20/05/2020)
LEHNA, UCBL, ENTPE, CNRS, LEHNA IAPHY, LEHNA, UCBL, ENTPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GEDI, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, COBRA, IRCOF, UNIROUEN, NU, INSA Rouen Normandie, INSA, NU, CNRS, UNIROUEN, NU, INSA Rouen Normandie, INSA, NU, INC3M, UNICAEN, NU, ENSICAEN, NU, ULH, NU, UNIROUEN, NU, INSA Rouen Normandie, INSA, NU, INC-CNRS, CNRS, INC-CNRS, CNRS, GéHCO, UT