Alongshore variability in crescentic sandbar patterns at a strongly curved coast
(Journal of Geophysical Research: Earth Surface. vol. 124, n° 2169-9003, pp. 2877– 2898, 23/11/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Une chronologie étendue des crues de la Garonne entre ca. 500 et 1500 AD. : apports croisés et comparés des sources historiques et sédimentaires
(21/11/2019)
LIENSs, INSU - CNRS, ULR, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UBM, CNRS, LASCARBX, UB, UBM, GEODE, UT2J, Comue de Toulouse, CNRS
A drop does not fall in a straight line: a rationale for the width of stalagmites
(Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. vol. 475, n° 1364-5021, pp. 20190556, 20/11/2019)
IS2M, Université de Haute-Alsace (UHA), INC-CNRS, CNRS, MNGE, UNISTRA, Université de Haute-Alsace (UHA), INSERM, INC-CNRS, CNRS, UNISTRA, Université de Haute-Alsace (UHA), CNRS, UM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM
Comparing the efficiency of hypoxia mitigation strategies in an urban, turbid tidal river via a coupled hydro-sedimentary-biogeochemical model
Coastal-water hypoxia is increasing globallydue to global warming and urbanization, and the need todefine management solutions to improve the water quality ofcoastal ecosystems has become important. The lower tidalGaronne River (TGR; southwestern France), characterizedby the seasonal presence of a turbidity maximum zone(TMZ) and urban water discharge, is subject to episodichypoxia events during low river flow periods in the summer.Future climatic conditions (higher temperature and summerdroughts) and increasing urbanization could enhance hy-poxia risks near the city of Bordeaux in the coming decades.A 3-D model of dissolved oxygen (DO) that coupleshydrodynamics, sediment transport and biogeochemicalprocesses was used to assess the efficiency of differentmanagement solutions for oxygenation of the TGR duringsummer low-discharge periods. We ran different scenarios ofreductions in urban sewage overflows, displacement of urbandischarges downstream from Bordeaux and/or temporaryriver flow support during the summer period. The modelshows that each option mitigates hypoxia, but with variableefficiency over time and space. Sewage overflow reductionimproves DO levels only locally near the city of Bordeaux.Downstream relocation of wastewater discharges allows forbetter oxygenation levels in the lower TGR. The support ofow river flow limits the upstream TMZ propagation anddilutes the TGR water with well-oxygenated river water.Scenarios combining wastewater network management andlow-water replenishment indicate an improvement in waterquality over the entire TGR. These modelling outcomesconstitute important tools for local water authorities todevelop the most appropriate strategies to limit hypoxia inthe TGR.
(Natural Hazards and Earth System Sciences. vol. 19, n° 1561-8633, pp. 2551-2564, 19/11/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EDF [E.D.F.], BOREA, UNICAEN, NU, MNHN, IRD, SU, CNRS, UA
Detection of adsorbed chlordecone on microplastics in marine sediments in Guadeloupe: a preliminary study
Plastic pollution in the oceans is recognized as a worldwide problem. Since the 1950s, the production of plastics has been increasing and the first reports of microplastics (particles < 500 μm) in the marine environment began to appear in the 1970s. These particles represent a growing environmental problem due to their dispersion in seawater and marine organisms. Additionally, microparticles in general can adsorb pollutants that will then become bioavailable to organisms by being desorbed during digestion, which could be an important pathway for the contamination of organisms. In Guadeloupe and Martinique, an organochlorine pesticide called “chlordecone” was used from 1972 to 1993 in banana plantations and this very persistent pollutant contaminates soils, rivers, and coastal marine areas and accumulates in marine foodwebs. To examine these issues, we had two goals: 1) to assess the contamination of marine sediments by microplastics surrounding Guadeloupe; and 2) to determine the ability of microplastics to adsorb chlordecone, as has been demonstrated for other organochlorine pollutants. To do so, marine sediments were collected in triplicate from 12 sites in coral reef environments around the island. Microplastics from each sample were then enumerated by size, color and shape under a binocular microscope. The results indicate that microplastics are found in all the studied sites and that their distribution could be linked to marine currents or proximity to areas of significant human activities (port activities, agglomeration, etc.). Finally, our preliminary results indicated that chlordecone could be adsorbed onto microplastics, with a concentration ranging from 0.00036—0.00173 µg/µg of microfilter.
(Gulf and Caribbean Research. vol. 30, n° 1528-0470, pp. GCFI 8-GCFI 14, 13/11/2019)
BOREA, UNICAEN, NU, MNHN, IRD, SU, CNRS, UA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Vers des traitements des eaux usées plus durables : Prise en considération des Produits de Transformation des contaminants chimiques organiques - TRANSPRO
La préservation de la qualité de l'eau est un enjeu majeur à la fois pour l'environnement et pour la santé humaine. Dans le contexte de la Directive Cadre sur l'Eau (DCE, 2000/60/CE), de nombreux travaux ont étudié les micropolluants organiques, et les connaissances concernant leur présence, voies d'introduction, sources et impacts sur les écosystèmes aquatiques ont considérablement augmenté. Les eaux usées étant des sources importantes de micropolluants en lien avec la consommation de produits manufacturés, l'application de la DCE a conduit au renforcement de la réglementation sur le traitement des eaux usées urbaines et à la généralisation des procédés biologiques tels que les boues activées à aération prolongée ou les biofiltres, permettant d'éliminer significativement les micropolluants organiques. Les processus d'oxydation impliqués consistent en une dégradation qui peut ne pas être complète, générant des produits de transformation (TP) relativement stables et toxiques susceptibles de se retrouver à la fois dans les boues et effluents liquides. Jusqu'à présent, les données sur les TP restent rares et se limitent à quelques composés. Ainsi, il apparaît essentiel que les futurs projets de recherche portent sur la question des TP afin d'élucider leur présence, formation et devenir tout au long du système de traitement des eaux usées jusqu'à leur entrée potentielle dans le milieu aquatique par le biais des rejets d'effluents des stations d'épuration (STEP). Objet ou objectifs TRANSPRO étudie la formation des TP, en développant des méthodes innovantes de screening utilisant des outils à la fois chimiques (Spectrométrie de Masse Haute Résolution) et biologiques (tests in vitro). Il étudie l'ensemble du système de traitement des eaux usées (des entrées de STEP) jusqu'aux écosystèmes aquatiques naturels, en se concentrant sur différents types de procédés de traitement par rapport à leur capacité à générer des TP ainsi que sur les procédés naturels (biodégradation, photo-oxydation) pouvant donner lieu à des transformations dans le milieu lui-même. Méthode TRANSPRO est un projet financé par l'agence nationale de la recherche (ANR) sur la période 2019-2022. Il est porté par un consortium de partenaires publics. C'est un projet collaboratif impliquant un partenariat solide basé sur une expertise pluridisciplinaire, associant chimistes analyticiens (EPOC), physico-chimistes (EPOC, LGC), chimistes de l'environnement (EPOC, Irstea), spécialistes en génie des procédés et modélisation (Irstea, LGC), (éco) toxicologues (EPOC), spécialistes des systèmes de traitement des eaux usées (LGC, Irstea), tous rassemblés pour aborder une question commune: quels processus génèrent des TP, que sont ces TP et quels sont ceux pertinents d'un point de vue environnemental ? Résultats TRANSPRO va permettre d'améliorer nos connaissances sur la nature, l'origine et la dynamique des TP. Il permettra également de classifier les procédés de traitement des eaux usées par rapport à leur tendance à générer des TP et d'aider à sélectionner le processus le plus efficace en termes de dégradation des contaminants parents mais minimisant la formation des TP. TRANSPRO fournira ainsi des connaissances qui contribueront à améliorer les traitements des eaux usées pour concevoir les systèmes d'assainissement de demain. Tout savoir sur le projet TRANSPRO : https://lnkd.in/dkZnUyS
(pp. 1, 07/11/2019)
UR REVERSAAL, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LGC, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse, IUT Toulouse Auch Castres, UT3, Comue de Toulouse
Chemical Heterogeneity of Mg, Mn, Na, S, and Sr in Benthic Foraminiferal Calcite
The chemical composition of fossil foraminiferal shells (tests) is widely used as tracers for past ocean chemistry. It is, therefore, important to understand how different (trace) elements are transported and incorporated into these tests from adjacent seawater. The elemental distribution within the walls of foraminiferal tests might be used to differentiate between proposed transport mechanisms. Here, the microdistribution of Mg, Mn, Na, S, and Sr in tests of three species of foraminifera, known to have contrasting test chemistry, is investigated by a combination of electron probe microanalysis (EPMA) and nanoscale secondary ion mass spectrometry (nanoSIMS), micro-X-ray fluorescence (µXRF), and micro-X-ray absorption near-edge structure (µXANES) analyses. The three investigated species are the symbiont-barren Ammonia sp. T6 and Bulimina marginata, which precipitate a low-Mg calcite test, and the symbiont-bearing species Amphistegina lessonii, which produces a test with intermediate Mg content. Because all analyzed tests were formed under controlled and identical laboratory conditions, the observed distributions of elements are not due to environmental variability but are a direct consequence of the processes involved in calcification or, in the case of A. lessonii, possibly symbiont activity. Despite some variability in elemental microdistribution between specimens from a given species, our combined dataset shows species-specific distributions of the elements (e.g., peak heights and/or band-widths) and also a systematic colocation of Mg, Na, S, and Sr for all three species, suggesting a coupled or simultaneous uptake, transport, and incorporation of these elements during chamber addition. The observed trace element patterns generally reflect a laminar calcification model, suggesting that heterogeneity of these elements is intrinsically linked to chamber addition. Although the incorporation of redox-sensitive Mn depends on the Mn concentration of the culture medium, the Mn distribution observed in Ammonia sp. suggests that Mn transport is similarly linked to laminar calcification dynamics. However, for B. marginata, Mn banding was sometimes anticorrelated with Mg banding, suggesting that (bio)availability, uptake, and transport of Mn differ from those forAmmonia sp. Our results from symbiont-bearing A. lessonii suggest that the activity of symbionts (i.e., photosynthesis/respiration) may influence the incorporation of Mn owing to alternation of the chemistry in the microenvironment of the foraminifera, an iimportant consideration in the development of this potential proxy for past oxygenation of the oceans.
(Frontiers in Earth Science. vol. 1, n° 2296-6463, 07/11/2019)
LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ESRF, LAMS, UPMC, INC-CNRS, SU, CNRS, UACH
Drinking water quality in areas impacted by oil activities in Ecuador: Associated health risks and social perception of human exposure
The unregulated oil exploitation in the Northern Ecuadorian Amazon Region (NEAR), mainly from 1964 to the 90's, led to toxic compounds largely released into the environment. A large majority of people living in the Amazon region have no access to drinking water distribution systems and collects water from rain, wells or small streams. The concentrations of major ions, trace elements, PAHs (polycyclic aromatic hydrocarbons) and BTEX (benzene, toluene, ethylbenzene, xylenes) were analyzed in different water sources to evaluate the impacts of oil extraction and refining. Samples were taken from the NEAR and around the main refinery of the country (Esmeraldas Oil Refinery/State Oil Company of Ecuador) and were compared with domestic waters from the Southern region, not affected by petroleum activities. In most of the samples, microbiological analysis revealed a high level of coliforms representing significant health risks. All measured chemical compounds in waters were in line with national and international guidelines, except for manganese, zinc and aluminum. In several deep-water wells, close to oil camps, toluene concentrations were higher than the natural background while PAHs concentrations never exceeded individually 2 ng·L−1. Water ingestion represented 99% of the total exposure pathways for carcinogenic and non-carcinogenic elements (mainly zinc) in adults and children, while 20% to 49% of the Total Cancer Risk was caused by arsenic concentrations. The health index (HI) indicates acceptable chronic effects for domestic use according the US-EPA thresholds. Nevertheless, these limits do not consider the cocktail effects of metallic and organic compounds. Furthermore, they do not include the social determinants of human exposure, such as socio-economic living conditions or vulnerability. Most (72%) of interviewed families knew sanitary risks but a discrepancy was observed between knowledge and action: religious beliefs, cultural patterns, information sources, experience and emotions play an important role front to exposure.
(Science of the Total Environment. vol. 690, n° 0048-9697, pp. 1203-1217, 01/11/2019)
GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, OMP, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, LPTC, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR ECOFOG, Cirad, INRA, UG, CNRS, UA, CERTOP, UT2J, Comue de Toulouse, UT3, Comue de Toulouse, CNRS, LCBI, CUFR
Uncertainties associated with in situ high-frequency long-term observations of suspended particulate matter concentration using optical and acoustic sensors
Measurement of suspended particulate matter concentration (SPMC) spanning large time and geographical scales have become a matter of growing importance in recent decades. At many places worldwide, complex observation platforms have been installed to capture temporal and spatial variability over scales ranging from cm (turbulent regimes) to whole basins. Long-term in situ measurements of SPMC involve one or more optical and acoustical sensors and, as the ground truth reference, gravimetric measurements of filtered water samples. The estimation of SPMC from optical and acoustical proxies generally results from the combination of a number of independent calibration measurements, as well as regression or inverse models. Direct or indirect measurements of SPMC are inherently associated with a number of uncertainties along the whole operation chain, the autonomous field deployment, to the analyses necessary for converting the observed proxy values of optical and acoustical signals to SPMC. Controlling uncertainties will become an important issue when the observational input comprises systems of sensors spanning large spatial and temporal scales. This will be especially relevant for detecting trends in the data with unambiguous statistical significance, separating anthropogenic impact from natural variations, or evaluating numerical models over a broad ensemble of different conditions using validated field data. The aim of the study is to present and discuss the benefits and limitations of using optical and acoustical backscatter sensors to acquire long-term observations of SPMC. Additionally, this study will formulate recommendations on how to best acquire quality-assured SPMC data sets, based on the challenges and uncertainties associated with those long-term observations. The main sources of error as well as the means to quantify and reduce the uncertainties associated with SPMC measurements are also illustrated.
(Progress in Oceanography. vol. 178, n° 0079-6611, pp. 102162, 01/11/2019)
DYNECO, IFREMER, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, GéHCO, UT, SHOM, IRSNB / RBINS, GKSS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Speciation of organic fractions does matter for aerosol source apportionment. Part 3: Combining off-line and on-line measurements
he present study proposes an advanced methodology to refine the source apportionment of organic aerosol (OA). This methodology is based on the combination of offline and online datasets in a single Positive Matrix Factorization (PMF) analysis using the multilinear engine (ME-2) algorithm and a customized time synchronization procedure. It has been applied to data from measurements conducted in the Paris region (France) during a PM pollution event in March 2015. Measurements included OA ACSM (Aerosol Chemical Speciation Monitor) mass spectra and specific primary and secondary organic molecular markers from PM10 filters on their original time resolution (30 min for ACSM and 4 h for PM10 filters). Comparison with the conventional PMF analysis of the ACSM OA dataset (PMF-ACSM) showed very good agreement for the discrimination between primary and secondary OA fractions with about 75% of the OA mass of secondary origin. Furthermore, the use of the combined datasets allowed the deconvolution of 3 primary OA (POA) factors and 7 secondary OA (SOA) factors. A clear identification of the source/origin of 54% of the total SOA mass could be achieved thanks to specific molecular markers. Specifically, 28% of that fraction was linked to combustion sources (biomass burning and traffic emissions). A clear identification of primary traffic OA was also obtained using the PMF-combined analysis while PMF-ACSM only gave a proxy for this OA source in the form of total hydrocarbon-like OA (HOA) mass concentrations. In addition, the primary biomass burning-related OA source was explained by two OA factors, BBOA and OPOA-like BBOA. This new approach has showed undeniable advantages over the conventional approaches by providing valuable insights into the processes involved in SOA formation and their sources. However, the origins of highly oxidized SOA could not be fully identified due to the lack of specific molecular markers for such aged SOA.
(Science of the Total Environment. vol. 690, n° 0048-9697, pp. 944-955, 01/11/2019)
INERIS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA