Caractérisation intégrée de la matière organique dissoute d'eaux résiduaires
La MO des milieux aquatiques soumis à des pressions urbaines importantes possède des propriétés physico-chimiques différentes de la MO des eaux de surface pas ou peu impactées par les rejets anthropiques : plus faible proportion d'acides fulviques et humiques, molécules de tailles plus petites, plus faible aromaticité, enrichissement en azote (Imai et al., 2002 ; Pernet-Coudrier et al., 2011). De même, les caractéristiques de la MO d'origine anthropique peuvent varier en fonction de l'origine des eaux (e.g. domestique, industrielle, pluviale, ruissellement) et du type de traitement appliqué ou non (Michael-Kortadou et al., 2015). Les différences de nature entre MO naturelle et anthropique sont aussi observées au travers de leurs interactions avec certains métaux qui sont plus complexés par la MO d'origine anthropique (e.g. Louis et al., 2014 ; Matar et al., 2015). Cependant, les connaissances sur la nature et les propriétés physico-chimiques de la MO d'origine anthropique, ainsi que sa réactivité et son devenir sont limitées. En effet : - de nombreuses études sur la MO d'origine anthropique traitent des rendements épuratoires à partir d'analyses globales (type DCO ou DBO) qui sont limitées pour décrire la nature de la MO ; - la MO est souvent représentée par les substances humiques qui représentent en moyenne 40 à 60% de la MO naturelle mais qui sont peu représentatives de la MO anthropique (Pernet-Coudrier et al., 2008) ; - la MO est souvent analysée après des étapes d'extraction et de purification qui permettent de séparer la MO selon certaines propriétés mais qui sont longues à mettre en oeuvre et ne permettent pas l'analyse d'échantillons en grande quantité. Nous proposons d'initier une étude sur l'établissement de relations entre les différentes sources de MO anthropique et sa nature ou ses propriétés physico-chimiques. Le potentiel de la combinaison de différentes techniques analytiques complémentaires est étudié au travers du développement d'une stratégie de caractérisation intégrée de la MO basée sur la combinaison de descripteurs pertinents. Pour cela, des eaux usées brutes et traitées (n=26) ont été collectées en amont et aval de différentes stations de traitement d'eaux usées et de traitements tertiaires (traitements par boues activées, filtres plantés de roseaux, biofiltres, zones de rejets végétalisées...). La MO dissoute de ces échantillons a été caractérisée par des techniques permettant des analyses sans prétraitements de l'échantillon : spectrophotométrie UV-visible, fluorescence 3D, chromatographie liquide couplée à la spectrométrie de masse haute résolution, chromatographie d'exclusion stérique couplée à détection UV. La variabilité de la composition/nature de la MO anthropique et de ses propriétés physico-chimiques est mise en évidence. Ce travail préliminaire permettra de commencer la constitution d'une base de données inédite à partir d'un jeu d'échantillons couvrant une très large gamme de types de rejets urbains.
(pp. 1, 04/02/2018)
IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Phenolic chemistry of the seagrass Zostera noltei Hornem. Part 1: First evidence of three infraspecific flavonoid chemotypes in three distinctive geographical regions
The flavonoid content of Zostera noltei leaves was investigated over a broad spatial scale using chromatographic and spectroscopic techniques (HPLC-DAD, LC/MS and NMR). Samples were collected at fifteen localities covering Mediterranean Sea and NE Atlantic coast, and representative of three types of coastal ecosystems: mesotidal bays, coastal lagoons, and open-sea. Three geographically distinct flavonoid chemotypes were identified on the basis of their respective major compound. One is characterized by apigenin 7-sulfate (Eastern part of Gulf of Cadiz), one by diosmetin 7-sulfate (French Atlantic coast and Mediterranean Sea), and the third contained similar quantities of the above two compounds (Mauritania and South Portugal). Our results show that metabolomic profiling using a combination of analytical techniques is a tool of choice to characterize chemical phenotype accurately. This work emphasizes for the first time the spatial variability in the flavonoid chemistry of Z. noltei throughout Atlantic and Mediterranean range, and constitutes the first report of chemical races in the Zosteraceae family. This infraspecific chemical differentiation should be considered when dealing with the role of Z. noltei in coastal ecosystems or in the selection of the best population donor for Z. noltei beds restoration. Combined with molecular identification, phenolic fingerprinting might be helpful to elucidate the evolutionary history of Z. noltei.
(Phytochemistry. vol. 146, n° 0031-9422, pp. 91-101, 01/02/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Infragravity waves: From driving mechanisms to impacts
(Earth-Science Reviews. vol. 177, n° 0012-8252, pp. 774 - 799, 01/02/2018)
LIENSs, INSU - CNRS, ULR, CNRS, DELTARES, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INSU - CNRS, UM, CNRS, UA, IPGP, INSU - CNRS, UPD7, UR, IPG Paris, CNRS, LETG - Brest, LETG, UNICAEN, NU, UA, EPHE, PSL, UBO EPE, UR2, CNRS, IGARUN, UN, SHOM, BRGM, UF, UNESCO, IMAU, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS
Tracing platinum accumulation kinetics in oyster Crassostrea gigas, a sentinel species in coastal marine environments
Platinum Group Elements (PGEs) are extremely scarce in the Earth's Crust and of strong interest for high-end technologies due to their specific properties. They belong to the Technology Critical Elements (TCEs) for which use is forecast to increase, implying growing emissions into the environment in the following years. In particular, with the intensive use of platinum (Pt) in car catalytic converters, the anthropogenic geochemical cycle of this element has surpassed the natural cycle. Yet, environmental Pt levels are still in the sub picomolar range, making its analytical detection a challenge. Few studies cover the behavior of Pt in marine waters in terms of speciation, reactivity and possible transfer to the biota. In this study, oysters (Crassostrea gigas) from an unpolluted estuary were exposed to the stable isotope 194Pt in seawater at a range of concentrations during 35 days. Seawater was renewed daily and spiked to three nominal Pt concentrations (50, 100, and 10,000 ng·L− 1) for two replicate series. In addition, control conditions were monitored. Five oysters from each tank were dissected after 3, 7, 14, 21, 28, 35 days of Pt exposure, and analyzed by ICP-MS. Accuracy of this analytical method applied to biological matrix was checked by an inter-method comparison with a voltammetrical technique. A concentration-dependent accumulation of Pt in oysters increasing with exposure time occurred. After 28 days, oyster Pt accumulation from low and intermediate exposure conditions reached a plateau. This was not the case of the highest exposure condition for which oyster tissues showed increasing concentrations until the last day of the experiment. A linear correlation exists between seawater concentrations and Pt content in oysters for low and intermediate exposure concentrations i.e. closer to environmental concentrations. By showing high Pt accumulation potential, oysters may serve as sentinels, ensuring biomonitoring of Pt concentrations in marine coastal waters.
(Science of the Total Environment. vol. 615, n° 0048-9697, pp. 652-663, 01/02/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UPV / EHU, IIM, CSIC
Eemian estuarine record forced by glacio-isostasy (southern Iceland)—link with Greenland and deep sea records
(Canadian journal of earth sciences. vol. 55, n° 0008-4077, pp. 154-171, 01/02/2018)
LGO, UBS, IFREMER, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Monitoring Sea Level and Topography of Coastal Lagoons Using Satellite Radar Altimetry: The Example of the Arcachon Bay in the Bay of Biscay
Radar altimetry was initially designed to measure the marine geoid. Thanks to the improvement in the orbit determination from the meter to the centimeter level, this technique has been providing accurate measurements of the sea surface topography over the open ocean since the launch of Topex/Poseidon in 1992. In spite of a decrease in the performance over land and coastal areas, it is now commonly used over these surfaces. This study presents a semi-automatic method that allows us to discriminate between acquisitions performed at high tides and low tides. The performances of four radar altimetry missions (ERS-2, ENVISAT, SARAL, and CryoSat-2) were analyzed for the retrieval of sea surface height and, for the very first time, of the intertidal zone topography in a coastal lagoon. The study area is the Arcachon Bay located in the Bay of Biscay. The sea level variability of the Arcachon Bay is characterized by a standard deviation of 1.05 m for the records used in this study (2001-2017). Sea surface heights are very well retrieved for SARAL (R~0.99 and RMSE < 0.23 m) and CryoSat-2 (R > 0.93 and RMSE < 0.42 m) missions but also for ENVISAT (R > 0.82 but with a higher RMSE >0.92 m). For the topography of the intertidal zone, very good estimates were also obtained using SARAL (R~0.71) and CryoSat-2 (R~0.79) with RMSE lower than 0.44 m for both missions.
(Remote Sensing. vol. 10, n° 2072-4292, pp. 297, 01/02/2018)
LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], ULCO
Temperature and metal exposure affect membrane fatty acid composition and transcription of desaturases and elongases in fathead minnow muscle and brain
(Ecotoxicology and Environmental Safety. vol. 148, n° 0147-6513, pp. 632-643, 01/02/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INRS - ETE, INRS
Role of the floodplain lakes in the methylmercury distribution and exchanges with the Amazon River, Brazil
Seasonal variability of dissolved and particulate methylmercury (F-MeHg, P-MeHg) concentrations was studied in the waters of the Amazon River and its associated Curuai floodplain during hydrological year 2005–2006, to understand the MeHg exchanges between these aquatic systems. In the oxic white water lakes, with neutral pH, high F-MeHg and P-MeHg concentrations were measured during the rising water stage (0.70 ± 0.37 pmol/L, n = 26) and flood peak (14.19 ± 9.32 pmol/g, n = 7) respectively, when the Amazon River water discharge into the lakes was at its maximum. The lowest mean values were reported during the dry season (0.18 ± 0.07 pmol/L F-MeHg, n = 10 and 1.35 ± 1.24 pmol/g P-MeHg, n = 8), when water and suspended sediments were outflowing from the lakes into the River. In these lakes, the MeHg concentrations were associated to the aluminium and organic carbon/nitrogen changes. In the black water lakes, with acidic pH and reducing conditions, elevated MeHg concentrations were recorded (0.58 ± 0.32 pmol/L F-MeHg, n = 16 and 19.82 ± 15.13 pmol/g P-MeHg, n = 6), and correlated with the organic carbon and manganese concentrations. Elevated values of MeHg partition coefficient (4.87 < Kd < 5.08 log (L/kg) indicate that MeHg is mainly transported associated with the particulate phase. The P-MeHg enrichment detected in all lakes suggests autochthonous MeHg inputs from the sediments into the water column. The MeHg mass balance showed that the Curuai floodplain is not the source of P-MeHg for the Amazon River.
(Journal of Environmental Sciences. vol. 68, n° 1001-0742, pp. 24-40, 01/02/2018)
UnB, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, IPREM, UPPA, INC-CNRS, CNRS, UGA [2016-2019], EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Pollen from the Deep-Sea: A Breakthrough in the Mystery of the Ice Ages
Pollen from deep-sea sedimentary sequences provides an integrated regional reconstruction of vegetation and climate (temperature, precipitation, and seasonality) on the adjacent continent. More importantly, the direct correlation of pollen, marine and ice indicators allows comparison of the atmospheric climatic changes that have affected the continent with the response of the Earth’s other reservoirs, i.e., the oceans and cryosphere, without any chronological uncertainty. The study of long continuous pollen records from the European margin has revealed a changing and complex interplay between European climate, North Atlantic sea surface temperatures (SSTs), ice growth and decay, and high- and low-latitude forcing at orbital and millennial timescales. These records have shown that the amplitude of the last five terrestrial interglacials was similar above 40 N, while below 40 N their magnitude differed due to precessionmodulated changes in seasonality and, particularly, winter precipitation. These records also showed that vegetation response was in dynamic equilibrium with rapid climate changes such as the Dangaard-Oeschger (D-O) cycles and Heinrich events, similar in magnitude and velocity to the ongoing global warming. However, the magnitude of the millennial-scale warming events of the last glacial period was regionally-specific. Precession seems to have imprinted regions below 40 N while obliquity, which controls average annual temperature, probably mediated the impact of D-O warming events above 40 N. A decoupling between high- and low-latitude climate was also observed within last glacial warm (Greenland interstadials) and cold phases (Greenland stadials). The synchronous response of western European vegetation/climate and eastern North Atlantic SSTs to D-O cycles was not a pervasive feature throughout the Quaternary. During periods of ice growth such as MIS 5a/4, MIS 11c/b and MIS 19c/b, repeated millennial-scale cold-air/warm-sea decoupling events occurred on the European margin superimposed to a long-term air-sea decoupling trend. Strong air-sea thermal contrasts promoted the production of water vapor that was then transported northward by the westerlies and fed ice sheets. This interaction between long-term and shorter timescale climatic variability may have amplified insolation decreases and thus explain the Ice Ages. This hypothesis should be tested by the integration of stochastic processes in Earth models of intermediate complexity.
(Frontiers in Plant Science. vol. 9, n° 1664-462X, 26/01/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Biostratigraphy of the last 50 kyr in the contourite depositional system of the Gulf of Cádiz
This paper proposes a biostratigraphic framework for the last 50 kyr in the contourite depositional system (CDS) of the Gulf of Cádiz with a solid and independent age control, and tests the reliability of faunal-based analyses in a bottom current-dominated environment related to high current velocities. The distribution of planktonic foraminifera and pteropods has been studied in twenty-two piston cores of the Holocene and Late Pleistocene age from the Gulf of Cádiz. A detailed correlation between the cores has been made possible by a large radiocarbon and isotopic data set and a high degree of similarity of frequency changes within several species by coiling direction changes of Globorotalia truncatulinoides and Globorotalia hirsuta and by occurrences of the polar species Neogloboquadrina pachyderma and Limacina retroversa. Occurrences of these polar species are clearly related to paleoclimatic oscillations and reflect rapidly changing surface water conditions in the Gulf of Cádiz during the latest Pleistocene that have been observed regardless of sedimentation rates and sedimentary environments (contouritic drifts vs slope without bottom current influence).
(Marine Geology. vol. 395, n° 0025-3227, pp. 285-300, 01/01/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS