Simulation of future Geostationnary Ocean Color Images
no abstract
(IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. vol. 5, n° 1939-1404, pp. 173-182, 01/02/2012)
Le2i, UB, ENSAM, CNRS, LOV, OOVM, UPMC, INSU - CNRS, CNRS, UPMC, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, TAS
Mapping coastal habitats over the Arcachon Lagoon using high-resolution optical and SAR
This study explores the potential of high-resolution spaceborne Synthetic Aperture Radar data for mapping intertidal coastal areas as a complement of high-resolution optical imagery (e.g. SPOT, Formosat-2). Classification algorithms based on optical imagery alone fail to accurately discriminate a series of relevant habitats, in particular seabeds of benthic fauna (oysters), low-density Zostera noltii seabed and salt-marsh vegetation species. Firstly, the benefits from TerraSAR-X data by investigating SAR signatures over intertidal wetlands which have been poorly described in the literature were addressed. Secondly, a supervised classification algorithm is run based on the fused SAR-optical bands. A statement of the mapping performance is finally carried out using field observations.
(17/01/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR TETIS, Cirad, IRSTEA
Biodiversity and bio-evaluation methods in transitional waters: a theoretical challenge
1 - This paper addresses the question of the weaknesses of the methodologies developed based on the analysis of the composition of benthic invertebrate communities in transitional waters.2 - Benthic communities are an important element of the bio-evaluation methodologies suggested for the Ecological Quality status of the European transitional and coastal waters in the context of the Water Framework Directive. It is argued that the assessment of Ecological Quality status requires both fundamental and applied science.3 - The lack of performance of many biotic indices under varying and highly fluctuating environmental conditions may well be related to weakness in theory supporting marine biodiversity.4 - We propose some possible approaches for future development in the field of biotic indices and marine biodiversity theory.
(Transitional Waters Bulletin, 01/01/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The impact of African aridity on the isotopic signature of Atlantic deep waters across the Middle Pleistocene Transition
A high resolution analysis of benthic foraminifera as well as of aeolian terrigenous proxies extracted from a 37 m-long marine core located off the Mauritanian margin spanning the last ~1.2 Ma, documents the possible link between major continental environmental changes with a shift in the isotopic signature of deep waters around 1.0-0.9 Ma, within the so-called Mid-Pleistocene Transition (MPT) time period. The increase in the oxygen isotopic composition of deep waters, as seen through the benthic foraminifera δ 18 O values, is consistent with the growth of larger ice sheets known to have occurred during this transition. Deep-water mass 2 δ 13 C changes, also estimated from benthic foraminifera, show a strong depletion for the same time interval. This drastic change in δ 13 C values is concomitant with a worldwide 0.3‰ decrease observed in the major deep oceanic waters for the MPT time period. The phase relationship between aeolian terrigeneous signal increase and this δ 13 C decrease in our record, as well as in other paleorecords, supports the hypothesis of a global aridification amongst others processes to explain the deep-water masses isotopic signature changes during the MPT. In any case, the isotopic shifts imply major changes in the end-member δ 18 O and δ 13 C values of deep waters.
(Quaternary Research. vol. 77, n° 0033-5894, pp. 182-191, 01/01/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GEOPS, UP11, CNRS, CLIMAG, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], CNRS
A 2500 year record of natural and anthropogenic soil erosion in South Greenland
The environmental impact of the Norse landnám (colonization) in Greenland has been studied extensively. But to date, no study has quantified the soil erosion that Norse agricultural practices are believed to have caused. To resolve this problem, a high resolution sedimentary record from Lake Igaliku in South Greenland is used to quantitatively reconstruct 2500 years of soil erosion driven by climate and historical land use. An accurate chronology, established on 18 AMS 14C, and 201Pb and 137Cs dates, allows for the estimation of detritic fluxes and their uncertainties. Land clearance and the introduction of grazing livestock by the Norse around 1010 AD caused an acceleration of soil erosion up to ∼8 mm century-1 in 1180 AD which is two-fold higher than the natural pre-landnám background. From 1335 AD to the end of the Norse Eastern Settlement (in the mid-fifteenth century), the vegetation began to recover from initial disturbance and soil erosion decreased. After an initial phase of modern sheep breeding similar to the medieval one, the mechanization of agriculture in the 1980s caused an unprecedented soil erosion rate of up to ∼21 mm century-1, five times the pre-anthropogenic levels. Independently, a suite of biological and geochemical proxies (including Ti and diatom concentrations, C:N ratio, δ13C and δ15N of organic matter) confirm that the medieval and modern anthropogenic erosion far exceeds any natural erosion over the last 2500 years. Our findings question the veracity of the catastrophic scenario of overgrazing and land degradation considered to have been the major factor responsible for Norse settlement demise. They also shed light on the sustainability of modern practices and their consequences for the future of agriculture in Greenland.
(Quaternary Science Reviews. vol. 32, n° 0277-3791, pp. 119 - 130, 01/01/2012)
LCE, CNRS, UFC, UBFC, BGS, UB, CNRS, ArScAn, UP1, UP8, UPN, MCC, CNRS, ARTeHiS, MCC, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LISA (UMR_7583), INSU - CNRS, UPEC UP12, CNRS, UPCité
The chemokine CCL2 protects against methylmercury neurotoxicity.
Industrial pollution due to heavy metals such as mercury is a major concern for the environment and public health. Mercury, in particular methylmercury (MeHg), primarily affects brain development and neuronal activity, resulting in neurotoxic effects. Because chemokines can modulate brain functions and are involved in neuroinflammatory and neurodegenerative diseases, we tested the possibility that the neurotoxic effect of MeHg may interfere with the chemokine CCL2. We have used an original protocol in young mice using a MeHg-contaminated fish-based diet for 3 months relevant to human MeHg contamination. We observed that MeHg induced in the mice cortex a decrease in CCL2 concentrations, neuronal cell death, and microglial activation. Knock-out (KO) CCL2 mice fed with a vegetal control food already presented a decrease in cortical neuronal cell density in comparison with wild-type animals under similar diet conditions, suggesting that the presence of CCL2 is required for normal neuronal survival. Moreover, KO CCL2 mice showed a pronounced neuronal cell death in response to MeHg. Using in vitro experiments on pure rat cortical neurons in culture, we observed by blockade of the CCL2/CCR2 neurotransmission an increased neuronal cell death in response to MeHg neurotoxicity. Furthermore, we showed that sod genes are upregulated in brain of wild-type mice fed with MeHg in contrast to KO CCL2 mice and that CCL2 can blunt in vitro the decrease in glutathione levels induced by MeHg. These original findings demonstrate that CCL2 may act as a neuroprotective alarm system in brain deficits due to MeHg intoxication.
(Review of Economic Dynamics. vol. 125, n° 1094-2025, pp. 209-18, 01/01/2012)
UPMC, INSERM, CNRS, UNIL, UPMC, INSERM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SU, CRICM, UPMC, INSERM, CNRS
Natural and anthropogenic trace metals in sediments of the Ligurian Sea (Northwestern Mediterranean)
(Chemical Geology. vol. 291, n° 0009-2541, pp. 141-151, 01/01/2012)
MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, IFREMER, LEP, EEP, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOV, OOVM, UPMC, INSU - CNRS, CNRS, UPMC, INSU - CNRS, CNRS
Quantitative reconstruction of sea-surface conditions over the last ∼150 yr in the Beaufort Sea based on dinoflagellate cyst assemblages: the role of large-scale atmospheric circulation patterns
Dinoflagellate cyst (dinocyst) assemblages have been widely used over the Arctic Ocean to reconstruct sea-surface parameters on a quantitative basis. Such reconstructions provide insights into the role of anthropogenic vs natural forcings in the actual climatic trend. Here, we present the palynological analysis of a dated 36 cm-long core collected from the Mackenzie Trough in the Canadian Beau-fort Sea. Dinocyst assemblages were used to quantitatively reconstruct the evolution of sea-surface conditions (temper-ature, salinity, sea ice) and freshwater palynomorphs fluxes were used as local paleo-river discharge indicators over the last ∼ 150 yr. Dinocyst assemblages are dominated by au-totrophic taxa (68 to 96 %). Cyst of Pentapharsodinium dalei is the dominant species throughout most of the core, except at the top where the assemblages are dominated by Op-erculodinium centrocarpum. Quantitative reconstructions of sea-surface parameters display a series of relatively warm, lower sea ice and saline episodes in surface waters, alternately with relatively cool and low salinity episodes. Variations of dinocyst fluxes and reconstructed sea-surface conditions may be closely linked to large scale atmospheric circulation patterns such as the Pacific Decadal Oscillation (PDO) and to a lesser degree, the Arctic Oscillation (AO). Positive phases of the PDO correspond to increases of dinocyst fluxes, warmer and saltier surface waters, which we associate with upwelling events of warm and relatively saline water from Pacific origin. Freshwater palynomorph fluxes increased in three phases from AD 1857 until reaching maximum values in AD 1991, suggesting that the Mackenzie River discharge followed the same trend when its discharge peaked between AD 1989 and AD 1992. The PDO mode seems to dominate the climatic variations at multi-annual to decadal timescales in the western Canadian Arctic and Beaufort Sea areas.
(Biogeosciences. vol. 9, n° 1726-4170, pp. 5391 - 5406, 19/04/2026)
ISMER, UQAR, LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, PALEOPROXUS, LOCEAN, IPSL, ENS-PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ULaval, INSU - CNRS, CNRS
Use of optical and radar data in synergy for mapping intertidal flats and coastal salt-marshes (Arcachon lagoon, France)
This paper explores the potential of high-resolution spaceborne Synthetic Aperture Radar data for mapping intertidal coastal areas as a complement of high-resolution optical imagery (e.g. SPOT, Formosat-2). Classification algorithms based on optical imagery alone fail to accurately discriminate a series of relevant habitats, in particular seabeds of benthic fauna (oysters), low-density Zostera noltii seabeds and salt-marsh vegetation species. Firstly, the paper addresses the benefits from TerraSAR-X data by investigating SAR signatures over intertidal wetlands which have been poorly described in the literature. Secondly, a supervised classification algorithm is run based on the fused SAR-optical bands. A statement of the mapping performance is finally carried out using field observations.
(pp. 4, 19/04/2026)
IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR TETIS, Cirad, IRSTEA
Les cartes auto-organisantes de Kohonen appliquées à l’étude des communautés de micro-algues des cours d’eau
Depuis une quinzaine d’années, les diatomées sont utilisées en routine afin d'évaluer l'état écologique des hydrosystèmes. Toutefois les indices diatomiques classiques ne permettent pas de diagnostiquer finement les différents types de pollution, et intègrent mal les variations naturelles, temporelles ou spatiales des communautés. Le but de ce travail est donc d'utiliser de nouvelles méthodologies biomathématiques et de tester leur pertinence dans un diagnostic de qualité écologique.
(pp. 43, 19/04/2026)
UR REBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS