Etude pluridisciplinaire d’une perturbation industrielle dans l’estuaire de la Gironde : implications du transport et de la dynamique de dégradation des débris végétaux sur le fonctionnement de la source froide du CNPE du Blayais
Jusqu’à présent, la dynamique des fractions végétales n’avait jamais été étudiée dans les estuaires macrotidaux en raison de leur faible quantité, par rapports aux fortes charges en matières en suspension fines, et du manque de protocoles d’étude et d’échantillonnage adéquats. Les débris végétaux sont toutefois à l’origine de perturbations d’activités économiques qui impliquent la filtration de larges volumes d’eau. L’objectif de cette thèse était ainsi de comprendre la dynamique d’apport et de transit de ces débris végétaux dans l’estuaire de la Gironde par la mise en oeuvre d’un suivi spatio-temporel de leur distribution et de techniques nouvelles pour un tel estuaire hyper-turbide (incubations in-situ litter-bag, caractérisation biogéochimique, identification des sources). Les résultats principaux sont la mise en évidence du contrôle du régime hydrologique sur leur distribution et la détermination des échelles de temps de leur persistance dans l’estuaire de la Gironde.
(24/01/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Amazon River carbon dioxide outgassing fuelled by wetlands
River systems connect the terrestrial biosphere, the atmosphere and the ocean in the global carbon cycle. A recent estimate suggests that up to 3 petagrams of carbon per year could be emitted as carbon dioxide (CO2) from global inland waters, offsetting the carbon uptake by terrestrial ecosystems. It is generally assumed that inland waters emit carbon that has been previously fixed upstream by land plant photosynthesis, then transferred to soils, and subsequently transported downstream in run-off. But at the scale of entire drainage basins, the lateral carbon fluxes carried by small rivers upstream do not account for all of the CO2 emitted from inundated areas downstream. Three-quarters of the world's flooded land consists of temporary wetlands, but the contribution of these productive ecosystems to the inland water carbon budget has been largely overlooked. Here we show that wetlands pump large amounts of atmospheric CO2 into river waters in the floodplains of the central Amazon. Flooded forests and floating vegetation export large amounts of carbon to river waters and the dissolved CO2 can be transported dozens to hundreds of kilometres downstream before being emitted. We estimate that Amazonian wetlands export half of their gross primary production to river waters as dissolved CO2 and organic carbon, compared with only a few per cent of gross primary production exported in upland (not flooded) ecosystems. Moreover, we suggest that wetland carbon export is potentially large enough to account for at least the 0.21 petagrams of carbon emitted per year as CO2 from the central Amazon River and its floodplains. Global carbon budgets should explicitly address temporary or vegetated flooded areas, because these ecosystems combine high aerial primary production with large, fast carbon export, potentially supporting a substantial fraction of CO2 evasion from inland waters.
(Nature. vol. 505, n° 0028-0836, pp. 395-398, 16/01/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], ULCO, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, UPCité, BOREA, MNHN, IRD, UPMC, CNRS, NIOZ
Investigating the response of cuproproteins from oysters (Crassostrea gigas) after waterborne copper exposure by metallomic and proteomic approaches
The pacific oyster (Crassostrea gigas), a good model for studying biomineralization and coastal environmental change, was used to study the expression of cuproproteins after waterborne Cu exposure (3 μg Cu L(-1)) similarly to the Arcachon Bay aquatic environment. Cuproproteins in oyster cytosols were analyzed by gel electrophoresis (non-denaturing PAGE and SDS 2-DE), laser ablation inductively coupled plasma mass spectrometry (LA-ICP MS) and electrospray ionization mass spectrometry (ESI-MS). The high molecular weight cuproproteins (identified as extracellular superoxide dismutase [Cu-Zn] (EC Cu/Zn-SOD) and l-ascorbate oxidase) in digestive glands of oysters were differentially expressed after Cu exposure. About 1.7 and 1.2-fold increase of the Cu level in EC Cu/Zn-SOD and l-ascorbate oxidase were, respectively, determined, although EC Cu/Zn-SOD was 1.6-1.9-fold down-regulated in the digestive gland of oysters after Cu exposure. At last, the role of EC Cu/Zn-SOD in protection against Cu exposure was discussed to propose possible mechanisms to better understand Cu homeostasis and/or detoxification mechanisms.
(Metallomics. vol. 6, n° 1756-5901, pp. 338, 15/01/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPREM, UPPA, INC-CNRS, CNRS
Improved Measurement Accuracy of Probe-Fed mm-Wave Antennas Using the Three Method
In this letter, we present a method to extract the scattering parameters of a microelectronic probe used to feed on-chip or in-package antennas at millimeter-wave frequencies. It is especially important to take into account these losses in the calibration procedure necessary for the extraction of the antenna gain. We are specifically demonstrating that these losses are positively or negatively impacted, depending on the impedance value of the input impedance of the antenna connected to the probe. Theory is detailed and examples are given to illustrate the importance of taking into account those losses with precision. From the S-parameters of the probe and the measurement of the reflection coefficient of the antenna, we can compute the gain from the measured realized gain. An accuracy improvement of 15% is shown for the gain of the presented antenna.
(IEEE Antennas and Wireless Propagation Letters. vol. 13, n° 1536-1225, pp. 103-105, 06/01/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEAT, UNS, CNRS, UniCA, ST-CROLLES
2000years of frequent turbidite activity in the Capbreton Canyon (Bay of Biscay)
Capbreton Canyon extends from 200 m water depth near the Aquitanian coast to 3000 m water depth before abruptly turning northward and merging with the Cap-Ferret systems. The Capbreton Canyon has been disconnected from the Adour River input since 1310 AD. Despite this situation, modern sedimentary activity is evident in the first kilometres from the head. Present sedimentation in the Capbreton Canyon was studied by combined analysis of acoustic data and cores. Cores from the topographic highs document moderate hemipelagic sedimentation and record the global climatic signal of the Bay of Biscay. Within the canyon, at±80 km from the head, on terraces bordering the thalweg at 1600 mwater depth, cores attest to recent turbidite activity.Massive medium sand is restricted to the thalweg floor, where sediment transfer dominates. Fine-grained turbidites are preferentially accumulated on the shallower terraces near the thalweg (the accumulation rate is 3 and 1 cm/year at 75 m and 125 m above the thalweg, respectively). On a higher terrace (225 m), turbidite sequences are absent or too thin to be preserved frombioturbation. The sedimentation rate is lower (approximately 0.17 cm/year) but still 10 times higher than the hemipelagic sedimentation outside the Capbreton Canyon. We demonstrate that frequent turbidity currents (1/year) are currently responsible for very high accumulation of dominantly fine-grained sediments on the terraces that are the nearest from the thalweg. We assume an impact of nepheloid layers on the sedimentation of the highest terraces. Looking for any impact on sediment supply of the disconnection of the Capbreton Canyon head from the Adour River mouth, it appears that the impact on the sedimentation affected the nature of the particles, which are less carbonate-rich, rather than the quantity of sediments. This result suggests that the longshore drift at the canyon head and hydrodynamic events are major factors in the sedimentation of Capbreton Canyon.
(Marine Geology. vol. 347, n° 0025-3227, pp. 136-152, 01/01/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Spatially Modulated Orthogonal Space-Time Block Codes with Non-Vanishing Determinants
This paper proposes a multiple-input multiple-output (MIMO) transmission scheme for M-ary modulations, called Spatially Modulated Orthogonal Space-Time Block Coding (SM-OSTBC), based on the concept of Spatial Constellation (SC) codewords introduced by Le at el. . In the proposed scheme, transmit codeword matrices are generated by multiplying SC matrices with codewords constructed from Orthogonal Space-time Block Codes (O-STBC). The maximum spectral efficiency of the proposed scheme is equal to (n_T-2+ log_2 M) bpcu, where n_T is the number of transmit antennas and M is the modulation order. The SC matrices provide a means of carrying information bits together with the O-STBC codewords and allow the SM-OSTBC scheme to achieve second-order transmit diversity by satisfying the non-vanishing determinant property. A systematic method to design the SC codewords for an even number of transmit antennas greater than 3 is presented. A single-stream maximum-likelihood (ML) decoder, which requires a low computational complexity thanks to the structure of the SM-OSTBC codewords and to the orthogonality of the O-STBCs, and a sphere decoder with further reduced signal processing complexity are developed. The bit error rate (BER) performance of the proposed scheme is studied by using both theoretical union bound analysis and computer simulations. Finally, simulation results are presented in order to compare BER performance, energy efficiency and decoding complexity of the proposed scheme with those of several existing MIMO transmission schemes.
(IEEE Transactions on Communications. vol. 62, n° 0090-6778, pp. 85 - 99, 01/01/2014)
HUST, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, L2S, UP11, CNRS
Neutralized Coupling Elements for MIMO Operation in 4G Mobile Terminals
A novel multiple-input-multiple-output (MIMO) dual-antenna system covering the low LTE700 and GSM850/900 communication standards is proposed for mobile terminals. The two-port antenna system is composed of two 3-D coupling elements, placed on the vertices of the short corner of a rectangular FR4 substrate. This rectangular shape emulates the printed circuit board of a modern mobile terminal. To achieve high port-to-port isolation, the neutralization technique is applied. Simulated reflection coefficients, total efficiencies, and envelope coefficient correlation are compared to measured data showing good agreement and competitive performance.
(IEEE Antennas and Wireless Propagation Letters. vol. 13, n° 1536-1225, pp. 141-144, 01/01/2014)
LEAT, UNS, CNRS, UniCA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Environmental effects of realistic pesticide mixtures on natural biofilm communities with different exposure histories
This study deals with the use of Polar Organic Chemical Integrative Sampler (POCIS) extracts to assess the impact of low-dose pesticide mixtures on natural biofilm communities originating from either a chronically contaminated or a reference field site. To investigate how natural biofilm communities, pre-exposed to pesticides in situ or not might respond to environmentally realistic changes in pesticide pressure, they were exposed to either clean water or to POCIS extracts (PE) in order to represent toxic pressure with a realistic pesticide mixture directly isolated from the field. The impacts of PE were assessed on structure, physiology and growth of biofilms. Initial levels of tolerance of phototrophic communities to PE were also estimated at day 0. PE exposure led to negative effects on diatom growth kinetics independently of in-field biofilm exposure history. In contrast, the impacts observed on dry weight, ash-free dry mass and algal fluorescence-related parameters followed different trends depending on biofilm origin. Exposure to PE induced changes in diatom assemblages for the biofilm originating from the reference field site with higher relative abundance of Eolimna minima and Nitzschia palea with PE exposure. Initial tolerance of phototrophic communities to PE was 8-fold higher for the biofilm originating from the chronically contaminated site compared to the reference field site. The use of POCIS extracts allowed us to highlight both chronic impacts of low doses of a mixture of pesticides on natural communities with regard to biofilm exposure history as well as initial levels of tolerance of phototrophic communities.
(Science of the Total Environment. vol. 473–474, n° 0048-9697, pp. 496-506, 23/04/2026)
UR EABX, IRSTEA, UR MALY, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
A chacun ses sciences participatives : Les conditions d’un observatoire participatif de la biodiversité sur le Bassin d’Arcachon
Cet article analyse les conditions préalables à la création d’un observatoire de sciences participatives de la biodiversité sur le Bassin d’Arcachon. L’enquête sociologique révèle les tensions entre finalités utilitaristes de recueil de données, nouveau mode collaboratif de construction des savoirs, instrument de communication politique, et démarche de vigilance citoyenne ; entre définition concertée de principes d’organisation des dispositifs et contrôle de positions de pouvoir sur le territoire. Loin du consensus apparent sur la protection de la biodiversité, le positionnement des acteurs du territoire redéfinit les enjeux environnementaux, précise les relations sciences - société et esquisse de nouvelles hiérarchies des priorités de gestion. / This paper considers the social and scientific requirements for a Citizen science monitoring programme on biodiversity in Arcachon Bay (France). The sociological study reveals tensions between different conceptions of what a Citizen science programme should be: a means for storing oriented-data; a new way to cocreate scientific knowledge; a political communication tool; a way to develop Citizen stewardship; or a place for expressing activist environmental demands. Citizen science programmes also tend to reveal tensions between participatory governance and classical management of environmental issues. Despite a seeming consensus amongst actors on biodiversity conservation, in practice contests over different citizen science conceptions have the potential to re-define environmental issues, to re-specify relationships between science and society and outline new management priorities.
(ESSACHESS – Journal for Communication Studies. vol. 7, n° 2066-5083, pp. p. 93 - p. 106, 23/04/2026)
UR ADBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Removal of Micropollutants from Secondary Effluents and Sludge by Various Processes in Rural and Peri-urban Areas
The present work details the results of a comprehensive study dealing with the fate of several families of micropollutants (with various physicochemical properties) through tertiary treatment processes of water and through sludge treatments. Powerful and sensitive analytical techniques were used: 16 metals and 39 organics (pharmaceuticals, polycyclic aromatic hydrocarbons, alkylphenols, pesticides) were analysed in wastewaters; 14 metals and 62 organic hydrophobic micropollutants were measured in sludge (estrogenic hormones, polychlorinated byphenyl, polybrominated diphenyl ethers, polycyclic aromatic hydrocarbons, alkylphenols and other organics). We studied treatment processes adapted for rural areas involving low energy-consumption: trench system, polishing pond, horizontal subsurface flow constructed wetlands with various adsorbing materials (i.e. expanded clay, zeolite, activated carbon, apatite, gravels) running at tertiary stage of water treatment; and sludge drying reed-bed operated at two different resting periods. Our results show that the trench system was not efficient for additional removal of refractory micropollutants. The polishing pond had higher removal efficiencies (between 30 and 70%) for some pharmaceuticals due to indirect photodegradation. The horizontal subsurface flow constructed wetland (HSSF-CW) built with activated carbon showed almost full-removal during more than 330 days for pharmaceuticals, pesticides, several metals and nonylphenoxyacetic acid. For the HSSF-CWs built with expanded clay or zeolite, we obtained removal efficiencies of 70% for half of studied pharmaceuticals and alkylphenols mono- and di-ethoxylates. The removal efficiencies of other substances were much lower than the ones measured with activated carbon, but they were still higher than the ones measured with gravel (filter designed for denitrification) or apatite (designed for phosphorus removal). Due to better oxygen conditions, the sludge drying reed-bed with low frequency of sludge input resulted in better removal for organic micropollutants than the sludge drying reed-bed with high frequency of sludge input.
(pp. 5 p., 23/04/2026)
UR MALY, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CIRSEE