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International audience; Spectroscopic and imaging sensors are very useful methods in analytical chemistry because they are fast, cost effective, very informative analysis. Recent works search to fused them to create a new sensor with different spectral range to increase spectral and thus chemical information to create robust and precise prediction models. Remote sensing already used fusion methods to increase spatial resolution for spectral sensors. In this paper, we propose to use pixel level data fusion methods on laboratory sensors to check their availability to increase spatial information with low effect on both dimensions (spectral and spatial). The methodology presents two steps, first the registration to fit spatially the sensors and then the fusion step to estimate each sensor at the optimal resolution. The proposed method was used on three sediment cores, that are living sample which can move, crack. They are imaged sequentially with two sensors that do not overlap spectrally: visible near infrared VNIR (400-1000 nm, pixel size: 60 μm), short wave infrared SWIR (1000-2500 nm, pixel size: 190 μm). The registration step allows to have a correlation above 0.9 with still spatial defect bring by the samples that cannot be removed. The twenty-one state of the art pixel level data fusion methods seems to be less relevant than a bicubic interpolation for the case of the laboratory hyperspectral images of sediment cores.

International audience; The aim of this presentation is to overview some applications of hyperspectral imaging for sediment core analysis in paleo-environmental studies. The increase of the sensibility and the resolution of sensors, as well as the development of performant data processing methods allow the analyze of natural sample in a very informative (chemical, physical and biological) and time effective way. Hyperspectral imaging is a method at the interface of spectroscopy and imaging where a spectrum is obtained for each pixel in the sample image. In laboratory conditions, many spectroscopic range can use this kind of method, from the X-ray to the infrared, also fluorescence and Raman. The dataset obtains is called a datacube due to his three dimensions (two spatials and one spectral), a fourth temporal dimension can be added. For that, both methods of image processing and spectral processing methods (chemometrics) can be used independently or together to improve sample knowledge. Quantitative modelling allows to establish a relationship between the spectra and destructive analysis (Particle Size Distribution, RockEval). These supervised models can then theoretically use on other samples without any sampling. Known structures can be discriminating accurately with classification methods, for example lamina or floods, with the labeling of some pixels to a known group. Unknown ones defined by chemical, physical or biological compounds can be determinates with similar methods and then explained by environment hypothesis. For these chemometrics methods, discriminant spectral wavelengths are identified and therefore sediment properties (chemical, physical or biological). Image processing of the core image or of the quantitative or qualitative map can be used to reveal surface structures (instant event, lamina) or local anomalies (coal, grain). The image resolution allows to see structures that the eye cannot see precisely, as infra-millimeter lamina. The use of spectro-spatial methods together and a time model allow to have a chronicle of structural sediment compositions and events.In this study, we use visible and near infrared hyperspectral imaging (pixel sizes: 60 and 240 micrometers) and X-Ray Fluorescence spectroscopy (240 micrometer) to analyze the lake Le Bourget sediment core (Savoie, France). Quantitative prediction models have been made for LOI550, Particle Size Distribution and fractions, some RockEval variables with correlation coefficients of the model upper than 0.8 and consistent uncertainties. Lamination counting was also realized with spectral classification methods and image processing, and this is in agreement with eye counting. With these two methods, seasonal variations can be separated in the eutrophic part of the core and compare. Hyperspectral imaging can also be used to find the optimal sampling areas for routine destructive analysis and to create predictive models. The use of several sensors, with data fusion methods, has shown that the increase of the amount of spectro-chemical information allowed to improve the robustness of predictive models. Hyperspectral imaging present already many possibilities to improve our knowledge on natural sample.

For solids environmental samples, spectroscopic properties can be analyzed but their interpretation is difficult due to the lack of common referential. For the spectroscopic images, pixels are relatively spatially referenced but in most cases, each sensor has his own spatial resolution.The sample used in this work is the first 30cm of a sedimentary core from the Lake Le Bourget (Western Alps), characterized by a stratified area corresponding to last eutrophic conditions of the lake.The aim of this work is to combine four images, (1) two hyperspectral images (9x15cm²): VNIR (98 bands, pixel: 60µm) and SWIR (144 bands, pixel: 189µm), and (2) two fluorescence images (2x10cm²; sub-sample of the previous one) using excitation wavelengths of 266nm and 355nm (1024 bands each, pixel: 100µm). Each hyperspectral data can be resume with a structured grayscale image. With these, it is possible to calculate a micro-deformation model (digital image correlation) and registered them with the same spatial dimension. Applying ARSIS method [1], a pixel level data fusion model is created to fuse all the spectra in a unique spatial cube with the optimal resolution using wavelet spatial transform (decomposition in 4 images: details, vertical, horizontal and diagonal). The new cube can be used as a new instrument.The ARSIS method allows to create a correlation model between the wavelet functions for all the resolution images used. This correlation can be used to add spatial structures to the low spatial resolute data calculated with wavelet transform.

Poster; The aim of this presentation is to overview some applications of hyperspectral imaging for core sediment analysis in paleoenvironmental studies. Sampling methods (millimetre or centimetre) and routine analyses are destructive and non-spatially resolved methods that consume time and material. Hyperspectral Imaging is a way to have the advantages of spectroscopy (non-destructive, fast analysis) and of imaging (high resolution, information is spatially referenced). coupling hyperspectral imaging with data mining methods makes possible to study several proxies at micrometric scale in each area of the core.Two hyperspectral cameras are used, a Visible-Near InfraRed VNIR (spectral range: 400-1000nm, spatial resolution: 60μm) and a Short Wave InfraRed SWIR (spectral range: 1000-2500nm, spatial resolution: 189μm). The two datasets produced can be fused in a unique one used to model environmental proxies. This methodology was achieved on a core from the lake Le Bourget (Western Alps, 53cm long and 9cm width). Quantitative prediction models can be made with partial least squares regression PLSR. This method links spectra with a reference analysis by the creation of a regression model. Assuming a scale homogeneity, it can be spread to all the spectra of the hyperspectral image to predict high spatially resolved proxies. Total Organic Carbon and Grain Size class models have been developed with a validation determination coefficient of 0.86 for TOC and 0.85 for clay. Concentration maps are used to study variation inside each stratigraphic unit event at the scale of laminae.These datasets can be used for classification. Based on pattern recognition and artificial neural network, it is possible to classify the type of lithology defined by the user, for example: summer or winter lamina, floods with labelled areas of less than 1% of the image. For varved sediments, this method can be used to count the varve and apply statistics on them.

Poster; International audience; Dams represent favorable contexts for sediments accumulation in large volumes. In the caseof inorganic contamination, Metallic Elements (ME) may represent a great environmentalissue, as they constitute potential ME sinks and sources. Sedimentary archive records thetemporal evolution of the contamination, sediments transfers and the sediments-MEassociation that result from different mechanisms (punctual or exceptional events, naturallyoccuring or resulting from exploitation operations).

Poster; Sedimentary cores are used, thanks to their physical, chemical and biological properties, to infer past climate and environment. Sampling methods (millimetre or centimetre) and routine analysis are destructive and non-spatially resolved methods that consume time and material. The use of hyperspectral imaging makes it possible to have micrometric area in each point of the core. We use two hyperspectral cameras, the VNIR (spectral range: 400-1000nm, spatial resolution: 60μm) and the SWIR (spectral range: 1000-2500nm, spatial resolution: 189μm). Usually each camera is used separately. The goal of this work is to show the combination of sensor increase performance predictions. A pixel-level data fusion based on the ARSIS method [1] is applied to create a unique cube at the optimal resolution. This new cube can be used with a usual PLSR method to develop a model for the total organic carbon.Three cores from the lakes Le Bourget, Annecy and Geneva (Western Alps) are been tested (approximately 60cm long and 9cm width each). For both samples, the results show an increase prediction performance rather than data used separately. In the unique cube, the selected wavelength (chlorophyll area (nm), C-H bonds ( nm) and O-H bonds ( nm)) corresponds to those selected by each sensor. Although the analyzes were performed on bulk samples (5 mm x 90 mm x 45 mm slices), the prediction model provides access to the mapping of the surface with a micrometric resolution (the 60μm pixel can be interpreted as relevant information).

Sedimentary archives are used to infer past climate and environment thanks to their physical and chemical properties. Sampling methods (millimetric or centimetric) and routine analysis are time and material consuming. The use of some specific spectroscopic methods and data analysis, allow to develop and perform some robust methods capable of (i) fast high resolution (ii) performed at low costs (iii) non-destructive and (iv) monitor concentration variations of major sediment compounds. X-ray fluorescence spectroscopy is one of these techniques, but it is able to detect just mineral geochemistrys. Whereas hyperspectral imaging (VNIR 400-1000 nm, SWIR 1000-2500 nm) allow, behind each voxel (a pixel with several wavelengths), to define spectral fingerprint of organic or mineral chemical compounds. This type of data can be analyzed by statistical techniques. Many (pseudo-) univariate coefficients are available for the quantification of some molecules (RABD845 for BPhe a, RABD660-670 for chlr-a and chlorins). But in this study we choose to applied multivariate methods that take into account all spectra variations. To achieve such study we can use technic that usually applied in classical spectroscopy or for satellite data that can be unsupervised or supervised. For unsupervised techniques, without any prior knowledge of the sample, exploratory algorithms are used to determine groups in the data. Then, these groups can be interpreted with the comparison to other analytical methods. It is possible to find pure signal that corresponds to one or several organic or mineral sedimentary compounds by (i) endmembers techniques, (ii) spectral unmixing, or (iii) clustering. For supervised techniques, we can use the knowledge of sample chemical and physical properties to create prediction models, then it is possible to observe variations of a specific property along the core. To develop qualitative and quantitative model for focused spectral properties we can applied classification and regression techniques. They allow to discriminate spectral domains or some wavelengths for some interest property. In the present study, Lake Le Bourget (Savoie, France) and Black Sea (Northwest margin) sediment cores are used. From this two different environmental systems we could create and test several prediction models. The high-resolution acquisition is done with two hyperspectral cameras: VNIR (400-1000 nm) and SWIR (1000-2500 nm) with spatial resolution of several dozen micrometers. Both sensors are well designed to create predictive models for either physical or chemical properties. In order to improve prediction models and make them more robust, we can pair these two cameras and add XRF core scanner data. For the black sea sediment, we use unsupervised techniques to determine groups and define interesting spatial areas to take samples for analytic analysis. Whereas for the Lake le Bourget sediment, several previous studies allow us to have many available data, thus supervised techniques are used to observe along core variations. For some properties, we could try to use models of the Lake Le Bourget in the Black Sea data, for example if we create a grain-size model, chemical elements ratio or organic compounds.

Poster; International audience; Dams represent favorable contexts for sediments accumulation in large volumes (typical several cm.y-1 up to 200 cm.y-1 for some Asian streams). These sedimentary reservoirs may represent a great environmental issue as they may constitute sinks for Metallic Elements (ME). Dam contexts allow studying the temporal evolution of contaminated sediments transfers (and ME) by different mechanisms (e.g., flood events), notably by resuspension and homogenization processes.• This study has been focussed on a watershed mainly affected by past mining activities (± 6 t of Ag and ± 6000 t of Pb were extracted until the 19th century), where sediments have been accumulated

Poster; International audience; Recent paleo-studies revealed climatic southern high latitude climate evolution patterns that are crucial to understand the global climate evolution(1,2). Among others the strength and north-south shifts of westerlies wind appeared to be a key parameter(3). However, virtually no lands are located south of the 45th South parallel between Southern Georgia (60°W) and New Zealand (170°E) precluding the establishment of paleoclimate records of past westerlies dynamics. Located around 50°S and 70°E, lost in the middle of the sub-Antarctic Indian Ocean, Kerguelen archipelago is a major, geomorphologically complex, land-mass that is covered by hundreds lakes of various sizes. It hence offers a unique opportunity to reconstruct past climate and environment dynamics in a region where virtually nothing is known about it, except the remarkable recent reconstructions based on a Lateglacial peatbog sequence(4). During the 2014-2015 austral summer, a French-Norwegian team led the very first extensive lake sediment coring survey on Kerguelen Archipelago under the umbrella of the PALAS program supported by the French Polar Institute (IPEV). Two main areas were investigated: i) the southwest of the mainland, so-called Golfe du Morbihan, where glaciers are currently absent and ii) the northernmost Kerguelen mainland peninsula so-called Loranchet, where cirque glaciers are still present. This double-target strategy aims at reconstructing various independent indirect records of precipitation (glacier advance, flood dynamics) and wind speed (marine spray chemical species, wind-borne terrigenous input) to tackle the Holocene climate variability. Despite particularly harsh climate conditions and difficult logistics matters, we were able to core 6 lake sediment sites: 5 in Golfe du Morbihan and one in Loranchet peninsula. Among them two sequences taken in the 4km-long Lake Armor using a UWITEC re-entry piston coring system by 20 and 100m water-depth (6 and 7m-long, respectively). One sequence from the newly-named Lake Tiercelin (2m-long) was recovered using UWITEC gravity coring equipment operated from a portable rubber boat by 54m water-depth. Those three sequences cover the whole Holocene periods. The 3m-long sequence taken in Lake Guynemer, Loranchet peninsula, was taken using a homemade small platform and a Nesje piston corer by 50m water-depth and covers the last 5 ka cal. BP. Two additional lakes were cored in the vicinity of Lake Armor: Fougères and Poule from which short sequences were taken in order to study environmental changes since the arrival of humans in the 18th century and the subsequent introduction of exogenous plant and animal species. We present here preliminary results including the dating of all sediment sequences as well as their chemical logging and sedimentological description. This already revealed the recurrence of Holocene volcanic eruptions as well as erosion patterns that are comparable among different records. The recognition of tephra layers will further allow the synchronization of terrestrial records together and with marine records around Kerguelen Archipelago. Paleoclimate interpretations of acquired data as well as further measurements are still ongoing processes. However, one may already argue that we collected rare geological sequences of prime importance in the quest of understanding climate patterns affecting the southern high latitudes all along the Holocene. 1. Lamy. et al. 2015. in Integr. Anal. of Intergl. Clim. Dyn. Schulz & Paul eds., 75–81 (Springer) 2. Rebolledo et al. 2015. Quat. Res. 84, 21–36 3. Agosta et al. 2015. Clim. Res. 62, 219–240 4. Van der Putten et al 2015. Quat. Sci. Rev. 122, 142–157

Poster; International audience; The Polar-regions are changing rapidly as greenhouse warming is continuing with huge impact on e.g. sea ice extent and snow cover. This change triggers teleconnections to low latitude areas challenging societies and human activity. We have, however, very little quantitative information of past climate in the Polar-regions that can be used to evaluate the potential responses and the response patterns to forcing changes and changes in boundary conditions. Whatever anthropogenic changes may occur in the future, they will be superimposed on, and interact with, natural climate variations due to all the forcing we are aware of. This means we need to better document past climate/environmental variability of the Polar-regions. Especially in the Southern Ocean there are few time series recording past climate due to few suitable land areas and the few Sub-Antarctic Islands is remote and has cumbersome logistics. Continuous terrestrial records from this region are therefore urgently needed for constraining future scenarios from earth system models. Glaciers and ice caps are still ubiquitous in the Polar-regions, although they are rapidly shrinking due to the on-going warming. The continuous sedimentary records produced by glaciers, which are stored in downstream lakes, represent supreme archives of past variability wherefrom quantitative information of key climate system components can be extracted. Kerguelen Island is located within the Antarctic Circumpolar Current and the Southern Westerly wind belt and contains several glaciers and smaller ice caps. Terrestrial archives recording past history of the glaciers at Kerguelen thus have a unique potential to record past changes in oceanic and atmospheric circulation patterns from southern mid-latitudes. Here we present preliminary results from the first distal glacier-fed lake that is sampled from Kerguelen Island. A 2.8 m long sediment core was obtained from Lac Guynemer (121masl.) located at the Peninsule Loranchet at the northern part of Kerguelen Island. The lake receives glacial meltwater from Glacier Guynemer, a small cirque glacier at the Pic Guynemer (1188masl.). The sediment core was analyzed with high-resolution core scanning X-ray fluorescence (XRF), magnetic parameters, loss-on-ignition and dry bulk density, to reconstruct past glacier variability of Glacier Guynemer. The sediment record covers the last 5000 years and show a dynamic glacier responding to the changing boundary conditions during the Neoglacial.

International audience; ake La Thuile in the Massif des Bauges (874 m a.s.l. French Alps) provides a 18 meters sedimentary sequence.Due to its mid-altitude position, this lake is one of the first to be formed through the glacial retreat and documentsthe evolution of its catchment since the Late Glacial Maximum. The first 6 meters of the core cover the last 12000 years, and allowed to study human/climate/environment interactions in a carbonated environment. This studyis the first one to investigate a mid-altitude lake in the French Alps for paleoenvironment reconstruction fromlake sediment archive. Its altitudinal position presents the advantage to be very accessible to human activitiesand allows more developed agriculture than in higher altitude. This study aims to determined how and when isexpressed the erosive response of such an environment to human settlement.High resolution multiproxy analysis of the first 6 meters including sedimentological, palynological andgeochemical data associated to a well-constrained chronology over the Holocene period allows us to understandthe respective impacts of both climate and human on the evolution of Lake La Thuile environment.Five major phases of evolution have been highlighted over this period. From 12 000 to 10 000 yr cal. BP,the vegetation is developing with the onset of hardwood species and the disappearance of Pinus. From 10 000to 4500 yr cal. BP the warmer climatic conditions of the middle of the Holocene allows the forest to densifyand the very low sedimentation rate indicates that the forest stabilizes slopes and prevents from the erosionon the watershed. The climate cooling of the Neoglacial period triggers a first erosive phase with a decreasingof the forest around 3300 cal. BP. Human settlements are suggested at La Thuile from 2500 yr cal. BP bypalynological evidence of anthropic taxa. The triggered clearing is accompanied by a second erosive phase relatedto anthropic activities during the Roman period. Erosion intensified from 1600 cal. BP in a third erosive phase cor-responding to agriculture intensification during the Middle Ages. At the end of the Middle Ages, human footprintseems to decrease but the reason of this change is not resolved between social determination or/and climate forcing.These three erosive phases may have completely changed the catchment behavior until the agriculturalabandonment in the middle of the 20th century. Lake La Thuile sedimentary infill shows a landscape evolutionfirst controlled by climate and progressively, since 2500 years ago, human activities came to superimpose. Therole of human seems to be more important with abrupt and maybe irreversible modifications of the landscape

International audience; Organic matter (OM) sources and transfers are critical questions at the crossroad of ecology, hydrologyand paleoenvironmental studies in karst environments. Recently chemical or isotopic characterisationsof these organic matters have demonstrated their diversity in karst water and speleothems. However,knowledge of their origin and transfer from soil needs to be improved especially in karst environmentswhere a mosaic of soils occurs. Here we investigate the applicability of the Electron ParamagneticResonance (EPR) signature of OM to seek different soil fingerprints in speleothems. The positions andthe shapes of semiquinone-type radical’s EPR lines are considered as a robust signature of the organicmatter through the different compartment of karst ecosystems. We demonstrate that the combinationof EPR lines simulation constitutes a fingerprint that discriminates folic Leptosol developed on limestoneoutcrops from eutric Cambisols located in the dolines and topographical depressions. We also report theconservation of the thinner OM EPR lines after a water extraction of the organic matter from soils. Finally,OM EPR signatures were detected in two different speleothems sampled near each other: a stalagmiteand a subaqueous flowstone. An unexpected two-orders-of-magnitude discrepancy between the free radicalconcentrations of the subaqueous flowstone and the soils on one hand, and the low free radical concentrationof the stalagmite samples on the other, was ascribed to the kinetics of conformational changesin OM occurring during their transfer through karst either in fast or in slow water pathways. A folicLeptosol fingerprint was found in stalagmite and conversely, an eutric Cambisol fingerprint was foundin the flowstone sample. This unexpected difference between the EPR signatures of the flowstone sampleand stalagmite sample was ascribed to the masking of the Leptosol EPR signature (due to the low concentrationsof free radicals) in the case of the flowstone sample and to the fact that the EPR signature of thestalagmite sample clearly shows the Leptosol is the sole source of the OM. Finally, the folic Leptosolfingerprint remains steady over the last four centuries covered by the stalagmite demonstrating thatthe source of the OM is stable over the growth period strengthening the interest of OM entrapped inspeleothem for paleoenvironment studies.

Poster; A high-resolution sedimentological study of the large Lake Bourget (French Alps, 231m a.s.l., 45 45'55N,5 51'45E) was conducted to reconstruct the flood frequency and intensity (or magnitude) in the area over the last 350 years. Particular emphasis was placed on investigating the spatio-temporal distribution of flood deposits in this large lake basin. The thicknesses of deposits resulting from 30 flood events of the Rhône River were collected over a set of 24 short sediment cores. Deposit thicknesses were compared with instrumental data for the Rhône River discharge for the period from 1853 to 2010. The results show that flood frequency and intensity cannot be reliably reconstructed from a single core because of the inhomogeneous flood-deposit geometry in such a large lake. From all documented flood-deposit thicknesses, volumes of sediment brought into the lake during each flood event were computed through a kriging procedure and compared with the historical instrumental data. The results show that reconstructed sediment volumes are well correlated to maximal flood discharges. This significant correlation suggests that the increase of embankment and dam settlements on the Rhône River during the last 150 years has not significantly affected the transport of the smallest sediment fraction during major flood events. Hence, assessment of the flood-sediment volumes deposited in the large Lake Bourget allowed to reliably reconstruct the flood frequency and intensity of the past Rhône River floods.

Poster; Recent works showed Alpine lake sediment records can be used to reconstruct past extreme flood events chronologies. Reaching such a goal is crucial as the evolution of torrential flood patterns in the context of global warming is still poorly understood. In this study, we compare flood chronicles (frequency and intensity) acquired from two adjacent watershed-lake systems in the western French Alps. We hence aim at investigating the influence of local geomorphic and sedimentological settings on reconstructed chronicles. We studied sediment cores sampled from lake Lauvitel (1500 m a.s.l.) and lake Muzelle (2200 m a.s.l.) spanning the last 3500 and ca. 2000 last years, respectively. Their catchment areas are just separated by a ridge (3000 m a.s.l). Despite the vicinity of the lakes, their systems differ a lot from one to the other. Lauvitel catchment (15.1 km2) is more than three times larger than Muzelle one (5 km2); as well as lake surfaces. The surrounding vegetation is also greatly contrasting. However, the precipitation pattern is considered to be the same in both systems. Here, we focus on the most recent deposits covering the last 100 years, when sediment dating tie points and historical data are numerous, allowing to compare written archives and geological records. Flood deposits documented in sediment cores from both lakes have been dated through radionuclide-based geochronology (210Pb, 137Cs, 241Am). They were then investigated using high resolution sedimentological and geochemical analyses. The comparison of flood deposits with historical data of extreme precipitations in the nearby Vénéon river valley, allow us to determine the cause and effect of such events. We found that most sediment deposits are simultaneous with torrential floods or debris flows that impacted villages down in the valley. In total, five extreme events were recorded in both lakes and synchronous to historical records down the valley. However, some flood deposits are proper in each lakes. They certainly reflect the contrast between torrential activity and sediment sources of each catchment. The distinction of extreme and common deposits in the lake is imperative in order to extend the methodology to the whole sediment sequence.

Worldwide increase of pesticides uses in agriculture has been growing over the past decades but their long-term fate and effects on environment and ecosystem are poorly understood. Here, we present a retro-observation approach based on lake sediment record to monitor micropollutants and to evaluate the long term impact of pesticides treatments on a vineyard catchment in Savoie (France). In this study, we combined sedimentological and geochemical analyses to reconstruct the recent history of wine practices. The sediment sequence chronology, based on short-live radionuclides (210Pb/137Cs), provides a well constrain continuous age-depth relationship covering to the last century. Over this period, we reconstruct the succession of fungicides, insecticides and herbicides in relation to the appearance of new chemical substances and the banning of old ones. The first use of fungicide began at the end of the 19th century with the Bordeaux mixture (Cu). After the World War II, we observed an intensification of fungicides treatment against mildew, powdery mildew, Botrytis fungi and black rot with specific molecules succession. Insecticides used in vineyard treatment against tetranychid and eriophyid mites were observed since 1940 with a main increase in 1970. Dicofol, Bromopropylate, Bifenthrin succeed to DDT banning in 1972, but a secondary source of DDT appeared at the early of 90's. The first herbicides use was observed between 1960 and 1970 with the presence of Triazine metabolite (pre-emergence herbicide) and high value of AMPA (Glyphosate metabolite, Roundup® ), used as post-emergence herbicide, were found since 1990. Two sedimentation rate increases in 1973 and 1994 could be directly assigned to wine practices. In early 70's, heavy farm machinery associated to the first application of pre-emergence herbicide, induced a first increase of soil erosion. In early 90's, post-emergence herbicide (Roundup® ) treatment had a stronger impact on soil erosion with a huge contaminated sediment export. This latter, associated with high AMPA flux, is synchronous to the re-emergence of banned pesticides with the new source of DDT and its aerobic metabolites (DDE) probably stocked in vineyard soil. Over the last years, the decrease of pesticides concentration may be probably related to French and European policies against micropollutant substances in agriculture

Poster; Poster présenté à European Geoscience Union (EGU), Vienne, Autriche. Avril 2012; Organic matter (OM) entrapped in calcite is regularly used for environmental studies; however, incorporation mechanisms and types of interaction remain poorly understood. This study used a new methodology to investigate interactions between OM and the calcite matrix during crystallization processes using humic acid entrapment. A multi-method approach confirmed that OM is both adsorbed onto the calcite surface and incorporated into the calcite lattice during crystallization. Our results also confirm the log-linear correlation between fluorescence intensity and calcite matrix OM concentration. Fourier transform infrared spectroscopy (FTIR) showed that OM in colloidal conformation is adsorbed onto the calcite surface as a result of the structure of the OH stretching band. Based on synchrotron analysis (XRF and XANES), we also developed a new method in which sulfur is used as a tracer for entrapped humic acid and for locating? the OM electrostatically adsorbed onto the calcite surface. Changes in the sulfur environment, determined using XANES, indicated partitioning during calcite crystallization due to the effect of the matrix on OM incorporation. Desorption experiments revealed the stability of the OM atomic structure and the layered nature of that structure. These results have allowed us to devise a general model of OM incorporation into calcite.

International audience

International audience; This combines hydrochemical data, classically used to environmental tracing, and monitoring of different Dissolved Organic Matter (DOM) types. The studied area is karst system of Choranche caves in Vercors (Isère - France) because several previous works and measuring equipment allowed a good knowledge of its behaviour. thanks to daily sampling of Chevaline outlet, from August to November 2009, and usual hydrochemical analyses (alkalinity, hardness, TOC), knowledge about hydrogeological behaviour of system has been allowed to improve. Analytical methods of DOM characterization have been used simultaneously to observe their temporal evolution (UV-Vis absorbance spectrometry, pectrofluorescence). They allowed (i) a methodological development to monitor non-absorbent organic molecules, until then not easy to observe, and (ii) to show that, thanks to detailed DOM studies, complementary informations about karst aquifer behaviour can be obtained, when usual environmental tracing methods seem not to be enough distinguishing.

International audience

Poster; Poster présenté au 6th International Conférence, Climate Change- the Karst Record, Université de Birmingham, Angleterre. 26-29 Juin 2011; Organic matter (OM) entrapped in calcite is regularly used for environmental studies; however, insertion mechanisms and types of interaction remain poorly understood. The present study used a new methodology to investigate interactions between OM and the calcite matrix during crystallization processes with humic acid (Aldrich and natural) entrapment. As a first step, we conducted a detailed study of the effect of HS adsorption on calcite during crystallization processes, and the effect of this adsorption on the HS. We then investigated the ways in which the structure of the HS evolves as it is absorbed into the calcite matrix. We monitored the physico-chemical properties of the HS using fluorescence and x-ray absorption spectroscopy (XAS). Morphological and structural analyses at various scales combined with spectroscopic measurements confirmed that OM is both adsorbed onto the calcite surface and incorporated into the calcite lattice during crystallization. From a quantitative point of view, we showed that incorporation of HS is proportional to the HS concentration of the precipitating solution and, through the combined use of x-ray and FTIR spectroscopy, we demonstrated the partitioning of HS during crystallization. Structural investigations of the calcite matrix did not reveal any effect of OM insertion on calcite structure. Based on synchrotron analysis, we also developed a new method in which sulfur is used as a tracer element for entrapped humic acid and to localize the OM electrostatically adsorbed onto the calcite surface. Changes in the sulfur environment, determined using XANES, indicated partitioning during calcite crystallization due to the effect of the matrix on OM insertion. Desorption experiments showed the stability of the OM atomic structure and revealed the layered nature of that structure. These results allowed us to draw up a general model of OM insertion in calcite, and then a comparison between the behavior of Aldrich HS and natural HS could be given.

International audience; This study presents the measurement of streamflows by constant dilution of a yellow-orange food colorant (E110). Field measurements are carried out in the Doria River, a mountain torrent in the Savoie pre-Alps, France. A limnimetric station installed 12 years ago is periodically calibrated by mechanical and chemical measurements. Moreover, simultaneous mechanical and chemical methods allow the statistical validation of the proposed technique. The main advantages of this method are the lack of toxicity, the absence of visible river colouring, comparable to that of aquatic organic matter, and the low detection limit. This method allows high flow measurement under suitable conditions.; Cette étude présente la mesure de débits par jaugeage par dilution constante d'un colorant alimentaire jaune-orange (E110). Les mesures de terrain sont réalisées dans la Rivière Doria, un torrent montagnard des Préalpes de Savoie. Une station limnimétrique installée il y a 12 ans est régulièrement étalonnée à l'aide de jaugeages mécaniques et chimiques. La mise en œuvre simultanée de méthodes mécanique et chimique permet de plus la validation statistique de la technique proposée. Les principaux avantages de cette méthode sont l'absence de toxicité, l'absence de coloration visible de la rivière au-delà de celle de la matière organique aquatique, et une limite de détection basse. Cette méthode permet des mesures de forts débits dans de bonnes conditions.