Intégration de pics de contamination d’intensité et de durée variables par le « Polar Organic Chemical Integrative Sampler »
Compte tenu de l’efficacité des produits phytosanitaires face aux parasites animaux et végétaux, une augmentation croissante de l’utilisation de ces composés s’est fait ressentir à partir des années cinquante. Cette utilisation massive provoque une contamination des trois compartiments de l’environnement (eau, air, sol) avec des conséquences préoccupantes pour l’homme et son écosystème. Ainsi, la pollution quasi généralisée des masses d’eau françaises et européennes a conduit l’Union Européen a adopté en 2000, la Directive Cadre sur l’Eau (DCE, 2000/60/EC), dans le but de préserver et restaurer l’état des milieux aquatiques. Dans cette optique, des institutions telles que les Agences de l’Eau sont chargées d’assurer la surveillance de la qualité des eaux au moyen de prélèvements d’eau 4 à 12 fois par an. Seulement, il se pose la question de la représentativité spatiale et temporelle de ce type d’échantillonnage. Pour cause, le niveau de contamination d’un cours d’eau peut varier brutalement en fonction de la saisonnalité des applications et de l’hydrologie du moment. Ainsi, des pics de contamination peuvent passer inaperçus aux regards des réseaux de mesure, ce qui engendrerait une image partielle de la qualité des milieux aquatiques. Pour remédier à ce manque de représentativité, notamment dans le but d’estimer de façon plus robuste une concentration moyenne dans le temps, intégrant l’ensemble des évènements dont les pics de contamination, des techniques d’échantillonnage passif, ont été développées. Dans cette étude, seul le Polar Organic Chemical Integrative Sampler (POCIS) a été considéré. Cet outil, largement utilisé pour l’échantillonnage des pesticides polaires (0 < log Kow < 4) (Alvarez et al. 2004), permet la pré-concentration in-situ des analytes, et dispose d’une capacité intégrative sur plusieurs semaines. Son domaine d’application, ainsi que ses limitations techniques sont maintenant assez bien documentées (Mazzella et al. 2010, Lissalde et al. 2011). De plus, il a été démontré que ce dispositif était capable d’échantillonner convenablement des pics de contaminations relativement long (3 jours) pour des composés modérément polaires (log Kow = 2-3) (Mazzella et al. 2008). Toutefois, des interrogations demeurent sur sa réactivité face à des pics de contamination plus brefs (quelques heures à quelques jours), ce qui peut être le cas lors de pollutions ponctuelles ou d'un apport brutal dans un cours d'eau (lessivage des sols et crue succédant un épisode de pluie par exemple). C'est dans ce contexte qu’a été réalisée une expérimentation en laboratoire, ayant pour objectif, d’étudier la réactivité du POCIS face à trois typologies de pics de contamination, d’intensité et de durée variables sur une période d’exposition totale de 14 jours. Pour ce faire quinze pesticides, couvrant différentes polarités (log Kow=0-5) et familles (herbicides, fongicides et insecticides) ont été sélectionnés. Au terme de celle-ci, les données acquises montrent des profils de cinétiques d’accumulation différents en fonction des caractéristiques physico-chimiques des substances et de la durée d’exposition. En effet, pour certains composés des phénomènes de retard à l’accumulation (« lag effect ») ou au contraire d’accumulation trop rapide (« burst effect ») apparaissent au cours des premiers jours d’exposition. Malgré cela, pour sept composés de l’étude, le POCIS intègre correctement les pics de contamination simulés, ce qui montre que cet outil est capable de prendre en compte des événements parfois assez fugaces.
(pp. 40, 22/06/2026)
UR EABX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Caractérisation du standard d’eau de rivière slrs-6 (nrc-cnrc) compilation interlaboratoire du silicium, des terres rares et de 21 autres éléments en trace
L’analyse des eaux nécessite, généralement, des matériaux de référence certifiés afin d’assurer la qualité des mesures. En Géosciences, il existe peu de standards d’eau de rivière naturelle ayant un nombre important d’éléments certifiés. Or, depuis plusieurs années, une dizaine de laboratoires étudient les éléments majeurs et en traces dans les solutions naturelles (groupe de travail de l’atelier du CNRS ”Isotrace”) et valident leurs mesures avec les 19 éléments certifiés de l’eau de rivière d’Ottawa SLRS produit par le NRC-CNRC. D’autres éléments non certifiés de cette eau sont régulièrement analysés par ces laboratoires à l’aide d’ICP-MS (Inductively Coupled Plasma Mass-Spectrometry) et d’ICP-OES (Inductively Coupled Plasma Optical-Emission Spectrometry). Ces travaux ont fait l’objet de deux publications sur les lots SLRS- 4 et SLRS-5. Le nouveau lot SLRS-6 est disponible depuis fin 2015 et le groupe de travail propose, dès à présent, les valeurs pour une vingtaine d’éléments en traces non certifiés par le producteur. Comme pour les lots précédents, il a été vérifié que les résultats obtenus étaient cohérents pour les éléments certifiés par le producteur. Ensuite, des valeurs moyennes et leurs incertitudes associées sont proposées pour des éléments non certifiés par NRC-CNRC tels que le silicium et une vingtaine d’éléments en traces dont les terres rares. L’ensemble des valeurs obtenues est comparé au lot SLRS-5 précédent : SLRS-6 est caractérisé par des teneurs généralement plus faibles que SLRS-5 ce qui en fait un matériau plus difficile à étudier, proches des limites de détection des techniques utilisées. Enfin, pour comprendre les biais éventuels observés dans les laboratoires, il est aussi discuté individuellement des variations pour chaque élément.
(pp. 334, 22/06/2026)
CRPG, INSU - CNRS, UL, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GR, UR, INSU - CNRS, CNRS, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS
Seasonal and subseasonal climate changes recorded in laminated diatom ooze sediments, Adélie Land, East Antarctica
A 40 m long sediment core covering the 1000-9600 years BP period was retrieved from the Dumont d'Urville Trough off Adélie Land, East Antarctica, during the MD 130-Images X-CADO cruise. This sedimentary sequence allows the documentation of changes in climate seasonality during the Holocene. Here we show preliminary results of diatom communities, lithic grain distribution and titanium content measured on two 30 cm long sequences of thin sections. The two sequences originate from two different climate regimes, the colder Neoglacial and the warmer Hypsithermal. Proxies were measured at microscale resolution on 25 laminations for the Neoglacial and 14 laminations for the Hypsithermal. The two sequences reveal alternating light-green and dark-green laminae. Light laminae result from low terrigenous input and high sea-ice edge diatom fluxes and are interpreted to represent the spring season. Dark laminae result from high terrigenous input mixed with a diversified open ocean diatom flora and are interpreted to represent the summer-autumn season. The two sequences therefore resolve annual couplets composed of one light plus one dark lamina. Variations in the relative thickness of laminations and annual couplets, associated with diatom assemblage changes, are observed in each sequence and between the two sequences giving information on interannual to millennial changes in environmental conditions.
(The Holocene. vol. 16, n° 0959-6836, pp. 1137-1147, 22/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GM, IFREMER
Reconstructions of biomass burning from sediment-charcoal records to improve data-model comparisons
The location, timing, spatial extent, and frequency of wildfires are changing rapidly in many parts of the world, producing substantial impacts on ecosystems, people, and potentially climate. Paleofire records based on charcoal accumulation in sediments enable modern changes in biomass burning to be considered in their long-term context. Paleofire records also provide insights into the causes and impacts of past wildfires and emissions when analyzed in conjunction with other paleoenvironmental data and with fire models. Here we present new 1000-year and 22 000-year trends and gridded biomass burning reconstructions based on the Global Charcoal Database version 3 (GCDv3), which includes 736 charcoal records (57 more than in version 2). The new gridded reconstructions reveal the spatial patterns underlying the temporal trends in the data, allowing insights into likely controls on biomass burning at regional to global scales. In the most recent few decades, biomass burning has sharply increased in both hemispheres but especially in the north, where charcoal fluxes are now higher than at any other time during the past 22 000 years. We also discuss methodological issues relevant to data-model comparisons and identify areas for future research. Spatially gridded versions of the global data set from GCDv3 are provided to facilitate comparison with and validation of global fire simulations.
(Biogeosciences. vol. 13, n° 1726-4170, pp. 3225-3244, 22/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LCE, CNRS, UMLP, UBFC
Extreme wave activity during 2013/2014 winter and morphological impacts along the Atlantic coast of Europe
Studies of coastal vulnerability due to climate change tend to focus on the consequences of sea level rise, rather than the complex coastal responses resulting from changes to the extreme wave climate. Here we investigate the 2013/2014 winter wave conditions that severely impacted the Atlantic coast of Europe and demonstrate that this winter was the most energetic along most of the Atlantic coast of Europe since at least 1948. Along exposed open-coast sites, extensive beach and dune erosion occurred due to offshore sediment transport. More sheltered sites experienced less erosion and one of the sites even experienced accretion due to beach rotation induced by alongshore sediment transport. Storm wave conditions such as were encountered during the 2013/2014 winter have the potential to dramatically change the equilibrium state (beach gradient, coastal alignment, and nearshore bar position) of beaches along the Atlantic coast of Europe.
(Geophysical Research Letters. vol. 43, n° 0094-8276, pp. 2135–2143, 22/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LETG - Brest, LETG, UNICAEN, NU, UA, EPHE, PSL, UBO EPE, UR2, CNRS, IGARUN, UN, LDO, INSU - CNRS, UBO EPE, CNRS
Norwegian fjord sediments reveal NAO related winter temperature and precipitation changes of the past 2800 years
The North Atlantic Oscillation (NAO) is the leading mode of atmospheric circulation variability in the North Atlantic region. Associated shifts of storm tracks, precipitation and temperature patterns affect energy supply and demand, fisheries and agricultural, as well as marine and terrestrial ecological dynamics. Long-term NAO records are crucial to better understand its response to climate forcing factors, and assess predictability and shifts associated with ongoing climate change. A recent study of instrumental time series revealed NAO as main factor for a strong relation between winter temperature, precipitation and river discharge in central Norway over the past 50 years. Here we compare geochemical measurements with instrumental data and show that primary productivity recorded in central Norwegian fjord sediments is sensitive to NAO variability. This observation is used to calibrate paleoproductivity changes to a 500-year reconstruction of winter NAO (Luterbacher et al., 2001). Conditioned on a stationary relation between our climate proxy and the NAO we establish a first high resolution NAO proxy record (NAO TFJ) from marine sediments covering the past 2800 years. The NAO TFJ shows distinct co-variability with climate changes over Greenland, solar activity and Northern Hemisphere glacier dynamics as well as climatically associated paleo-demographic trends. The here presented climate record shows that fjord sediments provide crucial information for an improved understanding of the linkages between atmospheric circulation, solar and oceanic forcing factors.
(Earth and Planetary Science Letters. vol. 435, n° 0012-821X, pp. 84-93, 22/06/2026)
UiT, UiT, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Palaeohydrological changes over the last 50 ky in the central Gulf of Cadiz: complex forcing mechanisms mixing multi-scale processes
New dinoflagellate cyst (dinocyst) analyses were carried out at high resolution in core MD99-2339, retrieved from a contouritic field in the central part of the Gulf of Cadiz, for the Marine Isotope Stage (MIS) 3 interval, allowing for discussion of palaeohydrological changes over the last 50 ky in the subtropical NE Atlantic Ocean. Some index dinocyst taxa, according to their (palaeo)ecological significance, shed light on significant sea-surface changes. Superimposed on the general decreasing pattern of dinocyst export to the seafloor over the last 50 ky, paralleling the general context of decreasing aeolian dust fertilization, a complex variability in dinocyst assemblages was detected at the millennial timescale. Enhanced fluvial discharges occurred during Greenland Interstadials (GIs), especially GI 1, 8 and 12, while enhanced upwelling cell dynamics were suggested during the Last Glacial Maximum and Heinrich Stadials. Finally, during the early Holocene, and more specifically during the Sapropel 1 interval (around 7-9 ka BP), we evidenced a strong decrease in dinocyst fluxes, which occurred synchronously to a strong reduction in Mediterranean Outflow Water strength and which we attributed to an advection of warm and nutrient-poor subtropical North Atlantic Central Waters. Over the last 50 ky, our study thus allows for capturing and documenting the fine tuning existing between terrestrial and marine realms in North Atlantic subtropical latitudes, in response to not only the regional climate pattern but also monsoonal forcing interfering during precession-driven Northern Hemisphere insolation maxima. This mechanism, well expressed during the Holocene, is superimposed on the pervasive role of the obliquity as a first major trigger for explaining migration of dinocyst productive centres in the NE Atlantic margin to the subtropical (temperate) latitudes during glacial (interglacial) periods.
(Biogeosciences. vol. 13, n° 1726-4170, pp. 5357-5377, 22/06/2026)
LDO, INSU - CNRS, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Atmospheric particulate mercury in the megacity Beijing: Efficiency of mitigation measures and assessment of health effects
Atmospheric particulate mercury (HgP) was studied before, during, and after the Olympic Summer Games in Beijing, China, in August 2008 in order to investigate the efficiency of the emission control measures implemented by the Chinese Government. These source control measures comprised traffic reductions, increase in public transportation, planting of vegetation, establishment of parks, building freeze at construction sites, cleaner production techniques for industries and industry closures in Beijing and also in the surrounding areas. Strictest measures including the ;odd-even ban; to halve the vehicle volume were enforced from the 20th of July to the 20th of September 2008. The Olympic period provided the unique opportunity to investigate the efficiency of these comprehensive actions implemented in order to reduce air pollution on a large scale. Therefore, the sampling period covered summer (August, September) and winter (December and January) samples over several years from December 2005 to September 2013. Average HgP concentrations in total suspended particulates (TSP) sampled in August 2008 were 81 ± 39 pg/m3 while TSP mass concentrations were 93 ± 49 μg/m3. This equals a reduction by about 63% for TSP mass and 65% for HgP, respectively, compared to the previous two years demonstrating the short-term success of the measures. However, after the Olympic Games, HgP concentrations increased again to pre-Olympic levels in August 2009 while values in August 2010 decreased again by 30%. Moreover, winter samples, which were 2- to 11-fold higher than corresponding August values, showed decreasing concentrations over the years indicating a long-term improvement of HgP pollution in Beijing. However, regarding adverse health effects, comparisons with soil guideline values and studies from other cities highlighted that HgP concentrations in TSP remained high in Beijing despite respective control measures. Consequently, future mitigation measures need to be tailored more specifically to further reduce HgP concentrations in Beijing.
(Atmospheric Environment. vol. 124, n° 1352-2310, pp. 396-403, 22/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Climate change and ecosystems dynamics over the last 6000 years in the Middle Atlas, Morocco
The present study aims at reconstructing past climate changes and their environmental impacts on plant ecosystems during the last 6000 years in the Middle Atlas, Morocco. Mean January temperature (Tjan), annual precipitation (Pann), winter (Pw) and summer (Ps) precipitation, and a seasonal index (SI) have all been quantified from a fossil pollen record. Several bio- and geo-chemical elements have also been analysed to evaluate the links between past climate, landscape, and ecosystem changes. Over the last 6000 years, climate has changed within a low temperature and precipitation range with a trend of aridity and warming towards the present. Tjan has varied within a ca. 2 °C range, and Pann within less than 100 mm yr-1. The long-term changes reconstructed in our record between 6 ka cal BP and today are consistent with the aridity trend observed in the Mediterranean basin. Despite the overall limited range of climate fluctuation, we observe major changes in the ecosystem composition, the carbon isotopic contents of organic matter (δ13C), the total organic carbon and nitrogen amount, and the carbon to nitrogen ratio (C / N) after ca. 3750 cal BP. The main ecosystem changes correspond to a noticeable transition in the conifer forest between the Atlas cedar, which expanded after 3750 cal BP, and the pine forest. These vegetation changes impacted the sedimentation type and its composition in the lake. Between 5500 and 5000 cal BP, we observe an abrupt change in all proxies which is coherent with a decrease in Tjan without a significant change in the overall amount of precipitation.
(Climate of the Past. vol. 12, n° 1814-9324, pp. 1029-1042, 22/06/2026)
URAC 45, UCD, LGR, UCA, UMR ISEM, Cirad, IRD, EPHE, PSL, UM, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
To boldly climb: behavioural and cognitive differences in migrating European glass eels
European eel (Anguilla anguilla) is a catadromous fish species that received substantial attention as its population has markedly declined in the last three decades. The possible causes of this decline include habitat fragmentation factors such as dams and weirs. In some cases, these obstacles are equipped with fish friendly passage devices that may select young eels according to their climbing behaviour. We tested how individual climbing tendency was related to the event of fishway passage experienced in the field and classified fish climbing profiles as climbing ‘leaders', ‘followers', ‘finishers' and ‘no climbers'. Moreover, we analysed the brain transcription level of genes related to neurogenesis and synaptic plasticity and compared it to climbing profiles.We found that fish from the upstream segments of an impounded river had a higher climbing propensity. Their behaviour was also more repeatable throughout the whole test than the obstacle-naive fish from the downstream segment. Moreover, we found that boldly climbing ‘leaders' had lower levels of transcription of synapse-related genes than the climbing ‘followers'. These differences could be related to coping styles of fish, where proactive ‘leaders' express a routine and risky behaviour, whereas reactive fish need an environmental assessment before exploratory behaviour. Our study showed that differences in climbing propensity exist in glass eels separated by water obstacles. Moreover, eels could adopt climbing different strategies according to the way they deal with environmental stress and to the cognitive abilities they possess.
(Royal Society Open Science. vol. 3, n° 2054-5703, pp. 150665, 22/06/2026)
UR EABX, IRSTEA, SETE, UT3, Comue de Toulouse, CNRS, EDF R&D STEP, EDF R&D, EDF [E.D.F.], EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS