Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
This paper presents a multicontinuum approach to model fractal temporal scaling of catchment response in hydrological systems. The temporal scaling of discharge is quantified in frequency domain by the transfer function HðxÞ, which is defined as the ratio between the spectra of catchment response and recharge time series. The transfer function may scale with frequency x as HðxÞ x2b. While the classical linear and Dupuit models predict exponents of b52 and b51, observations indicate scalings with noninteger exponents b. Such behaviors have been described by multifractal models, which, however, often lack a relation to the medium characteristics. We revisit and extend the classical linear Dupuit aquifer models and discuss their physical meanings in the light of the resulting aquifer dynamics. On the basis of these classical models, we derive a multicontinuum approach that provides physical recharge models which are able to explain fractal behaviors with exponents 1=2 < b < 2. Furthermore, this approach allows to link the fractal dynamics of the discharge process to the physical aquifer characteristics as reflected in the distribution of storage time scales. We systematically analyze the catchment responses in the proposed multicontinuum models, and identify and quantify the time scales which characterize the dynamics of the catchment response to recharge.
ISSN: 0043-1397

insu-00952537
https://hal-insu.archives-ouvertes.fr/insu-00952537
https://hal-insu.archives-ouvertes.fr/insu-00952537/document
https://hal-insu.archives-ouvertes.fr/insu-00952537/file/russian.pdf
DOI : 10.1002/2013WR014255

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Evidence of a changing environment in the catchment area of a small pond (Lansquenet, Lorraine, France) during the last millennium was provided by coupling palynology data and organic ratios [terrestrial to aquatic ratio: TAR(HC); the C29 vs. C27 sterols, C29/C27(ST); average chain length, ACL and aquatic/macrophytes ratio, Paq]. The depositional and alteration conditions of organic matter (OM) were provided by the 5α(H)-stanols/Δ5-sterols ratio. This study shows that quite simple organic ratios clearly allow identification of the different evolution steps of a watershed, from a swamp to the progressive settlement of a pond. During the swampy period, the C/N(at) (ca. 11.1), TAR(HC) (ca. 36.8), C29/C27(ST) (ca. 8.7) and Paq (<0.3) show a high contribution of allochthonous OM associated with the presence of particular aquatic and mesohygrophilous species. A woody level dated to the XIIIth century reflects the period of the settlement of the pond in a more oxic environment [5α(H)-stanol/Δ5sterol ratio <0.2]. Then, the progressive increase in aquatic input and the development of submerged and floating macrophytes are evidenced by low C/N(at) (<7.6), TAR(HC) (ca. 2.7), C29/C27(ST) (ca. 2) and high Paq (ca. 0.5), suggesting an increase in the water level and eutrophication of the pond. A second oxic event [5α(H)-stanols/Δ5sterols ratio averaging 0.16], associated with extensive OM degradation, corresponds to the most recent dredging in 2002 and reflects an important disturbance of sediments due to pond management.
ISSN: 0146-6380

hal-00758066
https://hal.archives-ouvertes.fr/hal-00758066
DOI : 10.1016/j.orggeochem.2012.06.004

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Mass balances are often used to calculate sediment fluxes in foreland basins and denudation rates in adjacent mountain ranges on intermediate to long timescales (from a few tens of thousand to a million years). Here, we study the simple Quaternary catchment-alluvial fan system of the Kuitun River, in northern Tian Shan, to discuss some ideas about sediment storage, release, and bypass in relatively short (100 km long) sediment routing systems. This study shows that the Kuitun catchment and piedmont areas clearly present evidence of a significant and temporary storage of sediments during the Pleistocene. These sediments were then excavated and delivered farther into the foreland basin during the Holocene. The difference between the volumes of materials released from the catchment and piedmont areas (5.5 ± 1.7 km3) and the volume stored in a contemporaneous fan downstream (2.6 ± 0.6 km3) indicates that the latter did not trap the whole sediment load transported by the river. The alluvial fan was bypassed by 27 to 78% of this load toward its distal alluvial plain. If this value is well estimated, it implies a major volumetric partitioning of the deposits between the fan and the alluvial plain, with a very high sedimentation rate in the fan (1.97 ± 0.52 mm*y− 1) and a much lower one downstream (0.11 ± 0.11 mm*y− 1). However, this volumetric partitioning might only occur during periods with a very specific hydrological regime such as the Holocene deglaciation. Eventually, the peculiar sediment storage and release pattern within the Kuitun catchment and piedmont areas during the Pleistocene and Holocene complicates the calculation of mean paleodenudation rates using either sediment budgets or in situ produced cosmogenic nuclides.
ISSN: 0169-555X

insu-00985283
https://hal-insu.archives-ouvertes.fr/insu-00985283
https://hal-insu.archives-ouvertes.fr/insu-00985283/document
https://hal-insu.archives-ouvertes.fr/insu-00985283/file/jolivet-et_al-2014_HAL.pdf
DOI : 10.1016/j.geomorph.2014.01.024

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The dating of alluvial landforms by cosmogenic nuclides requires distinguishing the pre-deposition inheritance from the post-deposition history of the clasts in the studied marker. Moreover, estimating catchment-scale erosion rates from the concentrations of cosmogenic nuclides in active alluvia requires a good knowledge of the local/regional relationships between rock exhumation and transport through space and time. This is still poorly known for timescales of tens of thousand years. In order to document the evolution of clast exhumation and transport rates through time, we analyze in situ 10Be concentrations in boulders and cobbles from hillslopes to outlet of an arid mountainous catchment located in Gobi-Altay, Mongolia, strongly affected by global climatic changes during the Pleistocene-Holocene period. Samples were collected on bedrock, abandoned alluvial deposits, active colluvia and alluvia. Our results show a large 10Be scattering in the active river bed, consistent with a low and discontinuous catchment erosion rate dominated by mass wasting and fluvial incision. On the contrary, pre-exposure signal within abandoned terraces is much more homogeneous, consistent with climatic pulses responsible of strong erosional events on hillslopes and rapid fluvial transport. These results show that exhumation/transport processes at the catchment scale vary in style and intensity through time as a consequence of climatic oscillations. The occurrence of abrupt climatic changes during short periods of time recorded by 10Be concentrations in abandoned alluvia raise questions about the temporal applicability of catchment erosion rates derived from cosmogenic nuclide concentrations measured in sediments of active rivers. On the other hand, strong and short erosion events limit and homogenize the pre-exposure 10Be signal in associated deposits like debris-flows, making them particularly suitable markers for dating in active tectonic and paleoclimatic studies.
ISSN: 0169-555X

hal-00626702
https://hal.archives-ouvertes.fr/hal-00626702
https://hal.archives-ouvertes.fr/hal-00626702/document
https://hal.archives-ouvertes.fr/hal-00626702/file/GEOMOR-2485R1_corrected.pdf
DOI : 10.1016/j.geomorph.2011.07.023

Éditeur(s) : HAL CCSD The Royal Society
Résumé : International audience
Conservation commonly requires trade-offs between social and ecological goals. For tropical small-scale fisheries, spatial scales of socially appropriate management are generally small— the median no-take locally managed marine area (LMMA) area throughout the Pacific is less than 1 km 2. This is of particular concern for large coral reef fishes, such as many species of grouper, which migrate to aggregations to spawn. Current data suggest that the catchment areas (i.e. total area from which individuals are drawn) of such aggregations are at spatial scales that preclude effective community-based management with no-take LMMAs. We used acoustic telemetry and tag-returns to examine reproductive migrations and catchment areas of the grouper Epinephelus fuscoguttatus at a spawning aggregation in Papua New Guinea. Protection of the resultant catchment area of approximately 16 km 2 using a no-take LMMA is socially untenable here and throughout much of the Pacific region. However, we found that spawning migrations were skewed towards shorter distances. Consequently, expanding the current 0.2 km 2 no-take LMMA to 1–2 km 2 would protect approximately 30–50% of the spawning population throughout the non-spawning season. Contrasting with current knowledge, our results demonstrate that species with moderate reproductive migrations can be managed at scales congruous with spatially restricted management tools.
ISSN: 2054-5703

Droits : http://creativecommons.org/licenses/by/
hal-01297717
https://hal-univ-perp.archives-ouvertes.fr/hal-01297717
https://hal-univ-perp.archives-ouvertes.fr/hal-01297717/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01297717/file/150694.full.pdf
DOI : 10.1098/rsos.150694

Éditeur(s) : HAL CCSD
Résumé : Karstic aquifers represent the most important fresh water reservoirs in many regions of the world like the Mediterranean Basin. However, because of complex processes of karstification, those aquifers are highly heterogeneous at all spatial scales and vulnerable to contamination. In this dissertation, we studied the potential of gravimetry and ambient seismic noise for hydrological modeling in karstic areas.The dolomitic area surrounding the “GEK” observatory in the Durzon catchment on the Larzac plateau, in France, is the preferred site for these studies. Inside the observatory, a superconducting gravimeter dedicated to hydrology has continuously measured gravity changes since 2011 with high precision, undertaken for the first time on a karst. From this gravity monitoring, we made conceptual hydrological models which laid the foundation of 1-D flow physical models. Indeed, gravimetry is an integrative hydro-geophysical method which allows 1) to consider the epikarst, locally heterogeneous as an equivalent tabular medium and 2) to define the types of transfer (fast & slow) occurring at the site. Especially, the lack of fast transfer through the GEK epikarst was precisely quantified for the first time at the field scale (~100m). Gravity-driven water mass balance with local meteorological data (evapotranspiration from a flux tower and precipitation) allowed setting the bottom outlet of the model to 1 mm.day-1. This flow has proved to be representative of the low-flow discharge at the only spring which represents all groundwater outflows from the catchment. This result supposes the homogeneity of the dolomitic epikarst almost at the basin scale. Model parameters were next calibrated using one year of ambient seismic noise monitored at two stations. Phase velocity changes obtained by cross-correlating the noise between 6 and 8 Hz were used as a ”timer” to follow the water infiltration between a depth of 30 and 60 meters. Thus, monitoring seismic velocity changes using ambient seismic noise demonstrates great potential for the study of deep and complex critical zones and could fill the instrumental gap currently existing in hydrology.Time-lapse gravity measurements with a spring-based portable gravimeter have also demonstrated the different behavior of two epikarsts and their variability at the scale of a few hundred meters. Monthly measurements around the observatory revealed the spatial homogeneity of this dolomitic epikarst: all the stations showed the same water storage changes. On the contrary, seasonal surface to depth gravity measurements along the underground passage of the Saint-Ferréol sinkhole, in limestone, have shown fast transfer and strong spatial variability of water storage. Lithology is then expected to play a part in the epikarst capacity to retain water. The precision needed to measure the weak hydrological induced signals during those surveys required robust methodology and an ambient temperature effect on measurements with spring-based gravimeter was observed in the field and quantified in the laboratory.
Les aquifères karstiques représentent des ressources en eau essentielles dans de nombreuses régions du monde comme le bassin Méditerranéen. Cependant, de par les processus complexes de karstification, ces aquifères sont hétérogènes à de nombreuses échelles et vulnérables. Dans cette thèse, nous étudions le potentiel de la gravimétrie et du bruit sismique ambiant pour la modélisation hydrologique en milieu karstique.Le site dolomitique de l’observatoire « GEK », sur le bassin du Durzon dans le Larzac, est le site d’étude privilégié de ces travaux. Dans l’observatoire, un gravimètre supraconducteur dédié à l’hydrologie mesure depuis 2011 les variations de gravité en continu et à une très haute précision, pour la première fois sur un karst. Des modèles hydrologiques conceptuels ont été réalisés à partir de cette surveillance gravimétrique et ont permis de poser les bases de modèles physiques d’écoulements 1-D. En effet la gravimétrie, intégratrice, permet 1) de considérer l’épikarst localement hétérogène comme un milieu tabulaire équivalent et 2) de définir les types de transfert à l’œuvre sur le site. En particulier, l’absence de transfert rapide dans l’épikarst a été quantifiée avec précision pour la première fois à l’échelle du terrain (~100m). A l’aide de données météorologiques locales, un bilan de masse précis a permis de définir le flux en limite inférieure du modèle à 1 mm.jour-1. Ce flux s’est montré représentatif du débit de basses-eaux de la source drainant l’ensemble du bassin. Ce résultat suppose une homogénéité de l’épikarst dolomitique quasiment à l’échelle du bassin. Les paramètres des modèles physiques ont ensuite pu être calibrés à l’aide d’un an d’intercorrélation du bruit sismique ambiant entre deux stations. Les variations de vitesses de phase obtenues entre 6 et 8Hz nous ont servi de « chronomètre » pour suivre l’infiltration entre 30 et 60m de profondeur. La surveillance passive des variations de vitesses sismiques par intercorrélation du bruit sismique ambiant montre ainsi un fort potentiel pour l’étude des zones critiques profondes et complexes à l’échelle du terrain et peut combler la lacune instrumentale qui existe actuellement en hydrologie.Des campagnes répétées de mesures avec un gravimètre portable à ressort ont également mis en évidence le fonctionnement différent de deux épikarsts et leur variabilité à l’échelle de la centaine de mètres. Des mesures mensuelles autour de l’observatoire ont mis en évidence l’homogénéité spatiale de cet épikarst dolomitique : toutes les stations ont les mêmes variations temporelles de stock d’eau. Au contraire, des mesures saisonnières en surface et en profondeur le long de la galerie souterraine calcaire de l’abîme de Saint-Ferréol ont montré une variabilité spatiale forte du stockage ainsi que du transfert rapide. La lithologie de l’épikarst est donc suspectée de jouer un rôle dans sa capacité de stockage. Lors de ces campagnes, la faiblesse du signal recherché a nécessité une méthodologie précautionneuse et un effet de température sur les mesures des gravimètres relatifs à ressort a été observé sur le terrain et quantifié en laboratoire.
https://tel.archives-ouvertes.fr/tel-01649606

NNT : 2016MONTT128
tel-01649606
https://tel.archives-ouvertes.fr/tel-01649606
https://tel.archives-ouvertes.fr/tel-01649606/document
https://tel.archives-ouvertes.fr/tel-01649606/file/2016_FORES_archivage.pdf

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
We studied the patterns, rates and evolution of fluvial terraces and fault system during the building process of an intracontinental transpressional mountain in the Gobi-Altay (Mongolia). By analyzing incisions and offsets of fluvial terraces and alluvial fans, we show that the massif has grown by outward migration of thrust faults through time. On the northern flank, the present bounding thrust fault began its activity ~600 ka ago, while a more internal sub-parallel fault was still active until ~200-100 ka. Vertical offset of an alluvial fan abandoned ~100 ka ago allows an estimate of 0.1 mm/yr Upper Pleistocene - Holocene uplift rate. The morphology of the catchment-piedmont system strongly suggests a periodical formation of the alluvial surfaces, controlled by the climatic pulses, at the beginning of the wet interglacial periods. The abandonment of the alluvial terraces lags by several thousand years the abandonment of the alluvial fans, showing a diachronous incision propagating upstream. The incision rate deduced from the different elevations of straths exceeds of one order of magnitude the rock uplift rate. This excess is mostly due to ongoing drainage network growth at the core of the massif, and incision due to alluvial apron entrenchment near the outlet. This implies that fluvial response is mainly controlled by drainage growth, interaction with piedmont and cyclic climatic variations, rather than by rock uplift.
ISSN: 0278-7407

hal-00323558
https://hal.archives-ouvertes.fr/hal-00323558
https://hal.archives-ouvertes.fr/hal-00323558v2/document
https://hal.archives-ouvertes.fr/hal-00323558/file/Vassallo2007.pdf
DOI : 10.1029/2006TC002081

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : In this paper we present the potential of a new compact superconducting gravimeter (GWR iGrav) designed for groundwater monitoring. At first, 3 yr of continuous gravity data are evaluated and the performance of the instrument is investigated. With repeated absolute gravity measurements using a Micro-g Lacoste FG5, the calibration factor (−894.8 nm s−2 V−1) and the long-term drift of this instrument (45 nm s−2 yr−1) are estimated for the first time with a high precision and found to be respectively constant and linear for this particular iGrav. The low noise level performance is found similar to those of previous superconducting gravimeters and leads to gravity residuals coherent with local hydrology. The iGrav is located in a fully instrumented hydrogeophysical observatory on the Durzon karstic basin (Larzac plateau, south of France). Rain gauges and a flux tower (evapo-transpiration measurements) are used to evaluate the groundwater mass balance at the local scale. Water mass balance demonstrates that the karst is only capacitive: all the rainwater is temporarily stored in the matrix and fast transfers to the spring through fractures are insignificant in this area. Moreover, the upper part of the karst around the observatory appears to be representative of slow transfer of the whole catchment. Indeed, slow transfer estimated on the site fully supports the low-flow discharge at the only spring which represents all groundwater outflows from the catchment. In the last part of the paper, reservoir models are used to characterize the water transfer and storage processes. Particular highlights are done on the advantages of continuous gravity data (compared to repeated campaigns) and on the importance of local accurate meteorological data to limit misinterpretation of the gravity observations. The results are complementary with previous studies at the basin scale and show a clear potential for continuous gravity time-series assimilation in hydrological simulations, even on heterogeneous karstic systems.
ISSN: 0956-540X

hal-01526965
https://hal.archives-ouvertes.fr/hal-01526965
https://hal.archives-ouvertes.fr/hal-01526965/document
https://hal.archives-ouvertes.fr/hal-01526965/file/fores2016.pdf
DOI : 10.1093/gji/ggw396

Éditeur(s) : HAL CCSD European Geosciences Union (EGU)
Résumé : International audience
Climate models project that rising atmospheric carbon dioxide concentrations will increase the frequency and the severity of some extreme weather events. The flood events represent a major risk for populations and infrastructures settled on coastal lowlands. Recent studies of lagoon sediments have enhanced our knowledge on extreme hydrological events such as palaeo-storms and on their relation with climate change over the last millennium. However, few studies have been undertaken to reconstruct past flood events from lagoon sediments. Here, the past flood activity was investigated using a multi-proxy approach combining sedimentological and geochemical analysis of surfaces sediments from a southeastern Tunisian catchment in order to trace the origin of sediment deposits in the El Bibane Lagoon. Three sediment sources were identified: marine, fluvial and aeolian. When applying this multi-proxy approach on core BL12-10, recovered from the El Bibane Lagoon, we can see that finer material, a high content of the clay and silt, and a high content of the elemental ratios (Fe ∕ Ca and Ti ∕ Ca) characterise the sedimentological signature of the palaeo-flood levels identified in the lagoonal sequence. For the last century, which is the period covered by the BL12-10 short core, three palaeo-flood events were identified. The age of these flood events have been determined by 210Pb and 137Cs chronology and give ages of AD 1995 ± 6, 1970 ± 9 and 1945 ± 9. These results show a good temporal correlation with historical flood events recorded in southern Tunisia in the last century (AD 1932, 1969, 1979 and 1995). Our finding suggests that reconstruction of the history of the hydrological extreme events during the upper Holocene is possible in this location through the use of the sedimentary archives.
ISSN: 1814-9324

hal-01571962
https://hal.archives-ouvertes.fr/hal-01571962
https://hal.archives-ouvertes.fr/hal-01571962/document
https://hal.archives-ouvertes.fr/hal-01571962/file/affouri2017.pdf
DOI : 10.5194/cp-13-711-2017

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
Background: The evaluation of geographical healthcare accessibility in residential areas provides crucial information to public policy. Traditional methods - such as Physician Population Ratios (PPR) or shortest travel time - offer only a one-dimensional view of accessibility. This paper developed an improved indicator: the Index of Spatial Accessibility (ISA) to measure geographical healthcare accessibility at the smallest available infra-urban level, that is, the Ilot Regroupe pour des Indicateurs Statistiques. Methods: This study was carried out in the department of Nord, France. Healthcare professionals are geolocalized using postal addresses available on the French state health insurance website. ISA is derived from an Enhanced Two-Step Floating Catchment Area (E2FCA). We have constructed a catchment for each healthcare provider, by taking into account residential building centroids, car travel time as calculated by Google Maps and the edge effect. Principal Component Analyses (PCA) were used to build a composite ISA to describe the global accessibility of different kinds of health professionals. Results: We applied our method to studying geographical healthcare accessibility for pregnant women, by selecting three types of healthcare provider: general practitioners, gynecologists and midwives. A total of 3587 healthcare providers are potentially able to provide care for inhabitants of the department of Nord. On average there are 92 general practitioners, 22 midwives and 21 gynecologists per 100,000 residents. The composite ISA for the three types of healthcare provider is 39 per 100,000 residents. A comparative analysis between ISA and physician-population ratios indicates that ISA represents a more even distribution whereas the physician-population ratios show an 'all-or-nothing' approach. Conclusion: ISA is a multidimensional and improved measure, which combines the volume of services relative to population size with the proximity of services relative to the population's location, available at the smallest feasible geographical scale. It could guide policy makers towards highlighting critical areas in need of more healthcare providers, and these areas should be earmarked for further knowledge-based policy making.
ISSN: 1475-9276

hal-01359567
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01359567
DOI : 10.1186/s12939-016-0411-z
PUBMED : 27485740

Résumé : Spiny lobsters are an important component of the coastal fisheries around the Martinique island. This study aimed to assess the contamination by kepone of the two main species Panulirus argus and P. guttatus in the main fishery area laying along the eastern coast of Martinique. The objectives of the study were to describe the distribution of the spiny lobster contamination in the area, to explore possible relationships with some biological parameters such as individual size, sex and colour of tegument, as well as characterize difference of kepone concentration between the muscle and soft flesh of the head, in view of helping the definition of further fishery management measures. The analyses were done from chemical analyses of 125 samples of spiny lobsters gathered from 2008 to 2010 all around the island, and from a specific set of 200 new observations from a specific survey carried out in 2011 in the study area. For both species, the results show a diffusion of the contamination all over the coral shoals, close to contaminated catchment basins, with a strong decrease just outside these areas. For the Caribbean spiny lobster, a strong relationship between kepone concentration and individual size was identified, and less for the Spotted spiny lobster. For the two species, the concentration of kepone found in soft flesh of the head was more than twice as in the muscle. Finally, the difference of contamination between the two species appeared strongly linked with their biology.
La langouste blanche Panulirus argus et la langouste brésilienne P. guttatus représentent environ 25 % du chiffre d’affaires des pêcheurs professionnels de Martinique. Une part très importante des captures de ces espèces proviennent du platier continental de la zone centre-atlantique de l’île. L’étude réalisée en 2011 visait à approfondir les connaissances sur la distribution de la contamination par la chlordécone des langoustes dans la zone centre- atlantique de la Martinique, d’explorer d’éventuelles relations entre cette contamination et des paramètres biologiques des individus comme la taille, le sexe et leur pigmentation tégumentaire, et d’analyser la différence de contamination entre la queue et les chairs molles du céphalothorax, en vue d’aider à la définition de mesures de réglementation de la pêche dans ce secteur. L’étude s’appuie sur un ensemble de 125 échantillons rassemblés de 2008 à 2010 pour les deux espèces autour de la Martinique, complétés par 200 échantillons constitués pour la présente étude dans la zone centre-atlantique en 2011. Le rapport est précédé d’un rappel d’éléments sur la biologie et sur l’état de la pêche des langoustes en Martinique. Pour les deux espèces, l’étude met en évidence une extension de la contamination à l’ensemble du platier corallien au pied des bassins versants contaminés, puis une nette diminution au-delà. Pour la langouste blanche, cette contamination est en relation avec la taille des individus, en liaison avec leur plongée progressive vers le large. Cette relation avec la taille est moins marquée pour la langouste brésilienne, espèce beaucoup plus inféodée aux eaux littorales. Pour les deux espèces, les chairs molles du céphalothorax apparaissent plus de deux fois plus contaminées que le muscle caudal. Les différences de contamination observées entre langouste blanche et la langouste brésilienne sont cohérentes avec les connaissances sur la biologie de chaque espèce.

Droits : Délégation Antilles
http://archimer.ifremer.fr/doc/00088/19971/17638.pdf
http://archimer.ifremer.fr/doc/00088/19971/

Résumé : Kepone contamination of French West Indies marine environments is scarcely known. Contaminated soils particles are carried by rivers from terrestrial zones to the coastal marine sediments where they settle. Thus coastal sediments potential function as a sink for them, but also as a source of contamination for the marine biota. Therefore, they can be of major importance both in relation with the origin of the catchment area contamination and with the potential impact of this contamination on the benthic ecosystems. The objectives of this study are to characterize the marine deposits in order to define the spatial extent of the contamination and to determine the temporal stages of this contamination in the superficial sedimentary column (about one half-meter deep). Two neighbouring bays were chosen along the south-atlantic coasts of the Martinique Island, the Robert Bay, where different previous studies have been already performed, and the Galion Bay, which also present important environmental concerns. The results (i) confirm the general low rate of kepone contamination in the Robert Bay superficial sediments, while the influence of the river is more pronounced in the Galion Bay for which sediment samples from the proximity of the river outfall are more contaminated, (ii) relativize the role of organic matter associated to the finer particle in the little contaminated marine sediments (iii) and at last, differentiate strongly the contamination of the two bays due to specific characteristic parameters. So, it apparears that the sedimentary dynamics and mineralogical cohorts undoubtedly should explain the discrepancies in the contamination of the sediments between the two bays, also characterized by very different humus-clayed compounds in the soils of each catchment basin.
La connaissance de la contamination des milieux marins antillais par la chlordécone est fragmentaire. Or, la fonction potentielle de ‘puits’, mais également de ‘source’, qu’assurent les sédiments littoraux suite au transfert de la molécule des sols terrestres jusqu’aux fonds marins devrait leur confèrer un rôle majeur dans leur relation avec les écosystèmes benthiques comme dans leur connexion avec les bassins versants correspondants. Du fait de la méconnaissance sédimentologique de ces milieux, le double objectif de la présente étude était de caractériser ces fonds afin de cerner l’extension spatiale de la contamination en chlordécone et de déterminer les phases temporelles de cette dernière dans la colonne sédimentaire superficielle (environ quarante premiers centimètres). Les zones d’étude choisies sont deux baies sud-atlantiques martiniquaises adjacentes, le havre du Robert, déjà retenu comme zone-atelier pour des études antérieures sur la dynamique du bassin versant, et la baie du Galion faisant l’objet de préoccupations environnementales et de travaux scientifiques prévus sur le bassin versant attenant. Les résultats obtenus conduisent à : (i) confirmer le faible taux de contamination générale des sédiments du havre du Robert, alors que l’influence de la rivière à débit significatif de la baie du Galion marque en ce sens les sédiments proches de son exutoire ; (ii) relativiser le rôle de la matière organique liée aux particules les plus fines dans cette faible contamination marine des sédiments et enfin (iii) différencier fortement la contamination des deux baies à partir de paramètres caractéristiques. Les dynamiques sédimentaires et les cortèges minéralogiques constituent sans aucun doute des pistes explicatives aux différences de contamination des sédiments entre les deux baies dont les bassins versants sont également caractérisés par des sols présentant des composés argilo-humiques très différents.

Droits : 2012 Ifremer
http://archimer.ifremer.fr/doc/00071/18247/15810.pdf
http://archimer.ifremer.fr/doc/00071/18247/

Éditeur(s) : HAL CCSD MDPI
Résumé : International audience
The issue of drinking water quality compliance in small and medium scale water services is of paramount importance in relation to the 98/83/CE European Drinking Water Directive (DWD). Additionally, concerns are being expressed over the implementation of the DWD with respect to possible impacts on water quality from forecast changes in European climate with global warming and further anticipated reductions in north European acid emissions. Consequently, we have developed a decision support system (DSS) named ARTEM-WQ (AwaReness Tool for the Evaluation and Mitigation of drinking Water Quality issues resulting from environmental changes) to support decision making by small and medium plant operators and other water stakeholders. ARTEM-WQ is based on a sequential risk analysis approach that includes consideration of catchment characteristics, climatic conditions and treatment operations. It provides a holistic evaluation of the water system, while also assessing human health risks of organic contaminants potentially present in treated waters (steroids, pharmaceuticals, pesticides, bisphenol-a, polychlorobiphenyls, polycyclic aromatic hydrocarbons, petrochemical hydrocarbons and disinfection by-products; n = 109). Moreover, the system provides recommendations for improvement while supporting decision making in its widest context. The tool has been tested on various European catchments and shows a promising potential to inform water managers of risks and appropriate mitigative actions. Further improvements should include toxicological knowledge advancement, environmental background pollutant concentrations and the assessment of the impact of distribution systems on water quality variation.
ISSN: 1660-4601

hal-01122233
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01122233
PUBMED : 25046634
DOI : 10.3390/ijerph110707354
PUBMEDCENTRAL : PMC4113881

Éditeur(s) : HAL CCSD
Résumé : National audience
Mass balances are often used to calculate sediment fluxes in sedimentary basins and denudationrates in adjacent topographies on intermediate to long timescales (from a few tens ofthousand to a million years). In this study, we focus on simple Quaternary catchment–alluvial fansystems in the northern Tian Shan Range and its foreland basin to discuss some ideas about sedimentproduction, storage, release, and bypass in relatively short (100 km long) sediment routing systems.Based on a geometrical reconstruction of the fans, we estimated the volumes of sediments exportedout of the range and deposited in its alluvial piedmont during the Middle- Late Pleistocene andthe Holocene. This work shows that the two areas clearly present evidence of a temporary butsignificant storage of sediments during the Pleistocene. These sediments were then excavated anddelivered farther into the foreland basin during the Holocene. The difference between the volumesof materials released from the range and piedmont areas and the volume stored in thecontemporaneous fans downstream indicates that the latter did not trap the whole sediment loadtransported by the rivers. The alluvial fans were bypassed by 27 to 78% of this load toward thedownstream alluvial plain. It implies a major volumetric partitioning of the deposits between thefans and the alluvial plain, with a sedimentation rate about twenty times higher in the fans thanin the plain. However, this volumetric partitioning might only occur during periods with a veryspecific hydrological regime such as the Holocene deglaciation. Eventually, the peculiar sedimentstorage and release pattern within the range and piedmont areas during the Pleistocene and Holocenecomplicates the calculation of mean paleodenudation rates using either sediment budgets or in situproduced cosmogenic nuclides.
Association des Sédimentologistes Français. 15ème congrès français de sédimentologie
Chambéry, France

hal-01252100
https://hal.archives-ouvertes.fr/hal-01252100

Éditeur(s) : HAL CCSD
Résumé : International audience
Diffuse contamination of surface water by veterinary pharmaceuticals (VP) has been poorly studied in intensive breeding context. Recycling animal waste on soil is supported to fertilize crops and reduce utilization of mineral fertilizer but may have some environmental impact by recycling pollutants on soils and transferring pollutants from soils to rivers. Most of pharmaceuticals are consumed indifferently by human and animal, especially antibiotics. This study aims to quantify veterinary pharmaceuticals (VP) in superficial water in two agricultural catchments. One is dedicated to the production of drinkable water. Agriculture but also waste water treatment plant may contribute to the contamination of water and it is difficult to distinguish animal versus human source of contamination
1ere conférence internationale sur l’évaluation des risques des résidus de médicament dans l’environnement
Paris, France

insu-01467591
https://hal-insu.archives-ouvertes.fr/insu-01467591

Éditeur(s) : HAL CCSD
Résumé : International audience
Mass balances are often used to calculate sediment fluxes in sedimentary basins and denudationrates in adjacent topographies on intermediate to long timescales (from a few tens ofthousand to a million years). In this study, we focus on simple Quaternary catchment–alluvialfan systems in the northern Tian Shan Range and its foreland basin to discuss some ideasabout sediment production, storage, release, and bypass in relatively short (100 km long) sedimentrouting systems. Based on a geometrical reconstruction of the fans, we estimated thevolumes of sediments exported out of the range and deposited in its alluvial piedmont duringthe Middle-Late Pleistocene and the Holocene. This work shows that the two areas clearlypresent evidence of a temporary but significant storage of sediments during the Pleistocene.These sediments were then excavated and delivered farther into the foreland basin during theHolocene. The difference between the volumes of materials released from the range and piedmontareas and the volume stored in the contemporaneous fans downstream indicates thatthe latter did not trap the whole sediment load transported by the rivers. The alluvial fans werebypassed by 27 to 78% of this load toward the downstream alluvial plain. It implies a majorvolumetric partitioning of the deposits between the fans and the alluvial plain, with a sedimentationrate about twenty times higher in the fans than in the plain. However, this volumetricpartitioning might only occur during periods with a very specific hydrological regime suchas the Holocene deglaciation. Eventually, the peculiar sediment storage and release patternwithin the range and piedmont areas during the Pleistocene and Holocene complicates thecalculation of mean paleodenudation rates using either sediment budgets or in situ producedcosmogenic nuclides.
Source to Sink: a long term perspective of sediment budgets and sources characterization, Abstracts
Rennes, France

insu-01406440
https://hal-insu.archives-ouvertes.fr/insu-01406440

Éditeur(s) : HAL CCSD Elsevier
Résumé : Fire-history reconstructions inferred from sedimentary charcoal records are based on measuring sieved charcoal fragment area, estimating fragment volume, or counting fragments. Similar fire histories are reconstructed from these three approaches for boreal lake sediment cores, using locally defined thresholds. Here, we test the same approach for a montane Mediterranean lake in which taphonomical processes might differ from boreal lakes through fragmentation of charcoal particles. The Mediterranean charcoal series are characterized by highly variable charcoal accumulation rates. Results there indicate that the three proxies do not provide comparable fire histories. The differences are attributable to charcoal fragmentation. This could be linked to fire type (crown or surface fires) or taphonomical processes, including charcoal transportation in the catchment area or in the sediment. The lack of correlation between the concentration of charcoal and of mineral matter suggests that fragmentation is not linked to erosion. Reconstructions based on charcoal area are more robust and stable than those based on fragment counts. Area-based reconstructions should therefore be used instead of the particle-counting method when fragmentation may influence the fragment abundance.
ISSN: 0033-5894

hal-00903607
https://hal.archives-ouvertes.fr/hal-00903607
DOI : 10.1016/j.yqres.2013.01.003

Éditeur(s) : HAL CCSD Springer
Résumé :  
Nineteen novel microsatellite loci were isolated from Adenomera andreae, a widespread Amazonian frog considered to be a species complex. Three multiplex kits were optimized. Genetic diversity was assessed in 66 individuals sampled in three populations along the West of the Approuague River catchment (French Guiana). We also tested the multiplex kits in four other Adenomera and nine Leptodactylus species with 43.4 and 17.5% success respectively.
ISSN: 1877-7252

hal-01032133
https://hal.archives-ouvertes.fr/hal-01032133
DOI : 10.1007/s12686-009-9053-4

Éditeur(s) : HAL CCSD Institute of Oceanography and Fisheries, Split
Résumé : International audience
This study deals with temporal variations in eel Anguilla anguilla diet, sampled seasonally in the Languedocian Mauguio lagoon (Gulf of Lion), from Autumn 1998 to Summer 1999. Eel mainly feeds on benthic organisms, primarily small Amphipoda, Crustacea (mainly Gammarus gr. locusta), Polychaeta, insect larvae (Chironomidae) and small fish. Based on variations in the eels feeding regime, seasonal influence is illustrated by decreased feeding activity in summer, which progressively increases during the following seasons. The trophic quality available to eels in the Mauguio lagoon depends more on allochtonous inputs from the catchment area than on its own hydrodynamics on which water of marine origin has little influence due to its long distance from the sea. Variations observed during the four seasons illustrate the opportunist type feeding behaviour of eels. They consume the most available benthic preys at a given moment without using a particular feeding strategy like specialisation or generalisation. Eel adapts its diet according to the available resources offered by the ecosystem. Because of this eel, as an amphihaline migrant species, can be characterised as an obvious indirect bioindicator of the trophic capacity and very marked level of confinement in the brackish lagoon ecosystem of Mauguio.
ISSN: 0001-5113

hal-00750416
https://hal.univ-antilles.fr/hal-00750416
https://hal.univ-antilles.fr/hal-00750416/document
https://hal.univ-antilles.fr/hal-00750416/file/Acta_Adriatica_2009_50_2_.pdf