Des biofilms témoins et acteurs du fonctionnement de la rivière
Des biofilms phototrophes complexes (multi espèces) se développent dans certains tronçons de rivière. Ils participent au fonctionnement de la rivière et peuvent être utilisés comme bioindicateurs pour la gestion des cours d'eau.
(pp. 3, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CNRS, UR REBX, CEMAGREF
Antarctic climate change and the environment
The Antarctic climate system varies on timescales from orbital, through millennial to sub-annual, and is closely coupled to other parts of the global climate system. We review these variations from the perspective of the geological and glaciological records and the recent historical period from which we have instrumental data (, the last 50 years). We consider their consequences for the biosphere, and show how the latest numerical models project changes into the future, taking into account human actions in the form of the release of greenhouse gases and chlorofluorocarbons into the atmosphere. In doing so, we provide an essential Southern Hemisphere companion to the Arctic Climate Impact Assessment.
(Antarctic Science. vol. 21, n° 0954-1020, pp. 541, 10/04/2026)
BAS, NERC, GSFC, CNR, AWI, SCAR, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Holocene glacier and deep water dynamics, Adélie Land region, East Antarctica
This study presents a high-resolution multi-proxy investigation of sediment core MD03-2601 and documents major glacier oscillations and deep water activity during the Holocene in the Adé lie Land region, East Antarctica. A comparison with surface ocean conditions reveals synchronous changes of glaciers, sea ice and deep water formation at Milankovitch and sub-Milankovitch time scales. We report (1) a deglaciation of the Adé lie Land continental shelf from 11 to 8.5 cal ka BP, which occurred in two phases of effective glacier grounding-line retreat at 10.6 and 9 cal ka BP, associated with active deep water formation; (2) a rapid glacier and sea ice readvance centred around 7.7 cal ka BP; and (3) five rapid expansions of the glacier-sea ice systems, during the Mid to Late Holocene, associated to a long-term increase of deep water formation. At Milankovich time scales, we show that the precessionnal component of insolation at high and low latitudes explains the major trend of the glacier-sea ice-ocean system throughout the Holocene, in the Adé lie Land region. In addition, the orbitally-forced seasonality seems to control the coastal deep water formation via the sea ice-ocean coupling, which could lead to opposite patterns between north and south high latitudes during the Mid to Late Holocene. At sub-Milankovitch time scales, there are eight events of glacier-sea ice retreat and expansion that occurred during atmospheric cooling events over East Antarctica. Comparisons of our results with other peri-Antarctic records and model simulations from high southern latitudes may suggest that our interpretation on glacier-sea ice-ocean interactions and their Holocene evolutions reflect a more global Antarctic Holocene pattern.
(Quaternary Science Reviews. vol. 28, n° 0277-3791, pp. 1291-1303, 10/04/2026)
UP1, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, VU, PBDS, INSU - CNRS, CNRS, LMGM, CNRS, CBI, UT3, Comue de Toulouse, CNRS
Erosion and impact of human disturbance on sediment transport in the Red River, Vietnam
Mechanical erosion and sediment transfers depend strongly on many natural parameters related to topography, climate and land cover [1]. Additionally, anthropogenic activities may affect sediment supplies to estuaries, deltas and the coastal zone [2]. The Red River (China/Vietnam, A=155 000 km²) is a typical tropical humid river originating from the mountainous area of the Yunnan Province in China. Based on daily discharges (Q) and suspended particulate matter (SPM) concentrations between 1960-2007 at SonTay gauging station (outlet of the river and entry to the Delta) provided by the national institute IMHE-MONRE, the mean annual SPM fluxes was estimated to 90 Mt/yr, corresponding to a sediment yield of 600 t/km²/yr, similar to the Ganges/Brahmaputra system [3], and probably due to same controlling factors. The temporal variability of annual SPM fluxes (ranging from 24 to 200 Mt/yr) is strongly related to the interannual hydrological conditions. However, some years of high water flow did not account for high sediment fluxes, especially after 1989 when the HoaBinh dam was operated. Sediment rating curves (power law-type; SPM=aQb) were fitted for both periods (1960-1989; 1990-2007). The analysis of the pre- and post-1989 sediment rating parameters (a, b) suggests a downshift of a-parameter values after 1989, attributed to decreased sediment supply [4]. A single sediment rating curve derived from 1960-1989 data was used to simulate the annual variability of former sediment delivery, generating excellent cumulative flux estimates (error <-5%). In contrast, applying the same rating curve to the 1986-2007 data resulted in systematic, important (up to 97%) overestimation. This suggests that the HoaBinh dam reduces annual SPM delivery to the delta by half, implying changes in nutrient and contaminant transport.
(Geochimica et Cosmochimica Acta. vol. 13, n° 0016-7037, pp. A260, 10/04/2026)
Bioemco, ENS-PSL, PSL, IRD, INRA, UPMC, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IWMI-SEA, IWMI, CGIAR, SFRI, VAAS, ICH/VAST
La dimension biogéographique de l'évolution de la Vie.
Le rôle de la composante biogéographique dans les mécanismes de l’évolution biologique fait l’objet de discussions entre les évolutionnistes. Dans ce travail, les idées de Darwin dans le contexte de la biogéographie sont discutées après avoir rappelé le rôle de l’élément géographique dans les processus de spéciation et résumé les notions de base et les modèles théoriques classiques de la biogéographie. Le modèle de Darwin, ou de la dispersion à partir d’un « centre d’origine », fut proposé lorsque les preuves de la mobilité continentale n’étaient pas encore concluantes. Le modèle de la vicariance, qui s’oppose à celui de la dispersion, est maintenant soutenu par la dérive continentale et l’expansion des fonds océaniques. Ces deux modèles classiques de la biogéographie pourraient s’appliquer dans les cas de convergence et divergence biogéographique, en relation avec des changements paléogéographiques
(Comptes Rendus. Palevol. vol. 8, n° 1631-0683, pp. 119-132, 10/04/2026)
CR2P, MNHN, UPMC, CNRS
Evidence for obliquity forcing of glacial Termination II
Variations in the intensity of high-latitude Northern Hemisphere summer insolation, driven largely by precession of the equinoxes, are widely thought to control the timing of Late Pleistocene glacial terminations. However, recently it has been suggested that changes in Earth's obliquity may be a more important mechanism. We present a new speleothem-based North Atlantic marine chronology that shows that the penultimate glacial termination (Termination II) commenced 141,000 T 2500 years before the present, too early to be explained by Northern Hemisphere summer insolation but consistent with changes in Earth's obliquity. Our record reveals that Terminations I and II are separated by three obliquity cycles and that they started at near-identical obliquity phases.
(Science, n° 0036-8075, pp. 1527-1531, 10/04/2026)
SUERC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, PACEA, UB, CNRS, AWI
Contrasting intrainterstadial climatic evolution between high and middle North Atlantic latitudes: A close-up of Greenland Interstadials 8 and 12
Three highly resolved pollen and sea surface temperature records from the Iberian margin (36-42°N) reveal the local evolution of vegetation and climate associated with the rapid climatic variability of marine isotope stage 3. The comparison of the climate at these midlatitudes with dD and d excess from Greenland ice cores shows that the north-south climatic gradient underwent strong variations during the long Greenland Interstadials (GIs) 8 and 12. After the Northern Hemispheric rapid warming at the Greenland Stadial (GS)-GI transition, the trend during the first part of the GI is a Greenland cooling and an Iberian warming. This increase of the North Atlantic climatic gradient led to moisture transportation to Greenland from midlatitudes (lightest d excess) and to a drying episode in Iberia. The subsequent temperature decrease in Greenland and Iberia associated with the precipitation increase in the latter region occurred when the major source of Greenland precipitation shifted to lower latitudes (d excess increase).
(Geochemistry, Geophysics, Geosystems. vol. 10, pp. n/a-n/a, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GLACCIOS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, UB
Dynamics of the turbidity maximum zone in a macrotidal estuary (the Gironde, France): Observations from field and MODIS satellite data
Over a 1-year period, field and satellite measurements of surface water turbidity were combined in order to study the dynamics of the turbidity maximum zone (TM) in a macrotidal estuary (the Gironde, France). Four fixed platforms equipped with turbidity sensors calibrated to give the suspended particulate matter (SPM) concentration provided continuous information in the upper estuary. Full resolution data recorded by the moderate resolution imaging spectroradiometer (MODIS) sensors onboard the Terra and Aqua satellite platforms provided information in the central and lower estuary twice a day (depending on cloud cover). Field data were used to validate a recently developed SPM quantification algorithm applied to the MODIS `surface reflectance' product. The algorithm is based on a relationship between the SPM concentration and a reflectance ratio of MODIS bands 2 (near-infrared) and 1 (red). Based on 62 and 75 match-ups identified in 2005 with MODIS Terra and Aqua data, the relative uncertainty of the algorithm applied to these sensors was found to be 22 and 18%, respectively. Field measurements showed the tidal variations of turbidity in the upper estuary, while monthly-averaged MODIS satellite data complemented by field data allowed observing the monthly movements of the TM in the whole estuary. The trapping of fine sediments occurred in the upper estuary during the period of low river flow. This resulted in the formation of a highly concentrated TM during a 4-month period. With increasing river flow, the TM moved rapidly to the central estuary. A part of the TM detached, moved progressively in the lower estuary and was finally either massively exported to the ocean during peak floods or temporary trapped (settled) on intertidal mudflats. The massive export to the ocean was apparently the result of combined favorable environmental conditions: presence of fluid mud near the mouth, high river flow, high tides and limited wind speeds. The mean SPM concentration within surface waters of the whole estuary showed strong seasonal variations but remained almost unchanged on a 1-year-basis. These observations suggest that the masses of suspended sediments exported toward the ocean and supplied by the rivers were almost equivalent during the year investigated (2005). Results show the usefulness of information extracted from combined field and current ocean color satellite data in order to monitor the transport of suspended particles in coastal and estuarine waters. (c) 2008 Elsevier Ltd. All rights reserved.
(Estuarine, Coastal and Shelf Science. vol. 81, n° 0272-7714, pp. 321-332, 10/04/2026)
LOV, INSU - CNRS, SU, CNRS, IMEV, INSU - CNRS, SU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOV, OOVM, UPMC, INSU - CNRS, CNRS, UPMC, INSU - CNRS, CNRS
New outcomes from spatial remote sensing during the ECORS experiment : towards validation of ocean color products and large-scale bathymetry mapping in a coastal zone
(Journal of Coastal Research, n° 0749-0208, pp. SI56(2), 1756-1760, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CRC, UB, CNRS
Millennial-scale climatic variability between 340 000 and 270 000 years ago in SW Europe: evidence from a NW Iberian margin pollen sequence
We present a new high-resolution marine pollen record from NW Iberian margin sediments (core MD03-2697) covering the interval between 340 000 and 270 000 years ago, a time period centred on Marine Isotope Stage (MIS) 9 and characterized by particular baseline climate states. This study enables the documentation of vegetation changes in the northwestern Iberian Peninsula and therefore the terrestrial climatic variability at orbital and in particular at millennial scales during MIS 9, directly on a marine stratigraphy. Suborbital vegetation changes in NW Iberia in response to cool/cold events are detected throughout the studied interval even during MIS 9e ice volume minimum. However, they appear more frequent and of higher amplitude during the 30 000 years following the MIS 9e in-terglacial period and during the MIS 9a-8 transition, which correspond to intervals of an intermediate to high ice volume and mainly periods of ice growth. Each suborbital cold event detected in NW Iberia has a counterpart in the Southern Iberian margin SST record. High to moderate amplitude cold episodes detected on land and in the ocean appear to be related to changes in deep water circulation and probably to iceberg discharges at least during MIS 9d, the mid-MIS 9c cold event and MIS 9b. This work provides therefore additional evidence of pervasive millennial-scale climatic variability in the North Atlantic borderlands throughout past climatic cycles of the Late Pleistocene, regardless of glacial state. However, ice volume might have an indirect influence on the amplitude of the millennial climatic changes in Southern Europe.
(Climate of the Past. vol. 5, n° 1814-9324, pp. 53-72, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, WHOI, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA