Predicting the impact of land use on the major element and nutrient fluxes in coastal Mediterranean rivers: The case of the Teˆt River (Southern France)

This study presents a detailed discrimination between the natural and anthropogenic sources of dissolved major elements in the Teˆt River, a typical small coastal river in the south of France. The main objectives were to quantify the materials that were released by human activities in the basin, and to determine the specific element inputs for the major land use forms. The dissolved material fluxes were estimated by weekly monitoring over a hydrological year (2000–2001) along the major water gauging stations, and the flux relationships were examined in the context of anthropogenic and natural basin characteristics as determined by a Geographical Information System (GIS). Intensive agricultural land use in the form of fruit tree cultures and vineyards has a strong control on the dissolved element fluxes in the river. Area specific element releases for these cultures are greatest for SO4, with an estimated average of about 430 ± 18 keq km2 a1. This is P11 times the natural SO4 release by rock weathering. Also for K, NO3, PO4 and Mg, the specific releases were P6 times the natural weathering rates (respectively about 44, 60, 4 and 265 keq km2 a1). Waste-waters are the other major source of anthropogenic elements in the river. They have an important role for the fluxes of inorganic P and N, but they are also a considerable source of Cl and Na to the river. For example, the average annual release of Cl is around 150 moles/inhabitant in the rural basin parts. Further downstream, however, where population density strongly increases, industrial effluents can enhance this value (>300 moles/inhabitant). The waste-waters contribute more than 70% of the dissolved inorganic N export to the sea, although their contribution to the average DOC export is almost negligible (3%)

Lipoxygenase-induced autoxidative degradation of terrestrial particulate organic matter in estuaries: A widespread process enhanced at high and low latitude

International audienceThere exists a substantial amount of research on abiotic (e.g. photochemical) degradation pertaining to organic matter (OM) in the marine realm. While recent research has shown its importance in the degradation of terrestrial particulate OM (TPOM), the mechanisms involved in the induction of autoxidation in estuaries remain unclear. In this study, we propose for the first time the involvement of lipoxygenase (LOX) activity in the induction of autoxidation in mixed waters. The observation of unusual profiles of palmitoleic acid oxidation products and the presence of jasmonic acid in suspended particulate matter (SPM) collected close to the Rhône River, as well as in samples from the Mackenzie and Amazon rivers, is attributed to strong LOX activity. We show the role played by salinity in the induction of this LOX activity and provide an explanation for the differences in estuarine autoxidation level. At high latitude, lower temperatures and irradiance favor photooxidative damage to higher plant debris and, consequently, hydroperoxide production. High hydroperoxide content strongly contributes to LOX activation in mixed waters. The high resulting LOX activity enhances alkoxyl radical production and thus autoxidation. On the contrary, at low latitude, photooxidative effects are limited, and riverine autoxidation is favored. The higher hydroperoxide content of TPOM may, as a consequence, thereby also contribute to a high level of LOX activity and autoxidation in estuaries. In temperate zones, land and riverine photooxidative and autoxidative damage is limited, unlike estuaries where we observed significant LOX-induced and autox-idative damage.

L'impôt et le prélevement seigneurial au Moyen Âge, fin XIIe-début XVIe siècle

International audienc

Suspended particle dynamics and fluxes in an Arctic fjord (Kongsfjorden, Svalbard)

International audienceAn experiment was carried out during summer 2015 in the inner part of the Kongsfjorden to study the inputs of meltwater and behaviour of associated suspended particles. We used a wide range of oceanographic instruments to assess the hydrological and hydrodynamic characteristics of coastal waters. The transfer of suspended particles occurs from a large surface plume fed by two main sources: the most important one is the upwelling of fresh and turbid water coming from a tide-water glacier: the Kronebreen, and the second one from a continental glacier: the Kongsvegen. We estimated that these two sources discharged about 2.48 ± 0.37 × 10⁶ t of suspended sediments during the two months of melting. The major part of these sediments is deposited within the first kilometre due to flocculation phenomena. Flocculation is initiated below the surface turbid plume and is mainly caused by the salinity gradient and high suspended particle concentration. Finally, our estimates of suspended particle fluxes by a typical Arctic coastal glacier showed the need to consider suspended sediment fluxes from high-latitude areas into global budgets in the context of climate change

CMOS fully integrated reconfigurable power amplifier with efficiency enhancement for LTE applications

International audienceA fully integrated power amplifier (PA) using power cell switching (PCS) technique, implemented in 65 nm CMOS technology is presented. The main objective of the proposed architecture is to significantly improve the efficiency at high power back-off. To do so, distributed active transformers (DATs) are used as splitter, combiner and DC bias feed to partition the power requirements among the parallelized power cells. Individual cell can be dynamically turned ON/OFF according to the desired output power. At 2.5GHz, measured maximum output power is 28.2dBm and PAE is improved for low level, +3.2% and +4.9% for 18dBm and 23.7dBm respectivel

Ingested Microplastics in 18 Local Fish Species from the Northwestern Mediterranean Sea

Plastic waste and its fragments (microplastics, <5 mm) are a global, persistent, and ubiquitous threat for land and marine ecosystems. We have investigated the occurrence and composition of microplastics within 18 coastal fish species of the northwestern Mediterranean Sea. Digestive tracts were digested using hydrogen peroxide, and residues were observed under a stereo-microscope. Suspected microplastics were analyzed with a Fourier Transform InfraRed (FTIR) spectrometer to confirm its plastic nature and to identify the polymer type. A rigorous blank control and FTIR correction was applied, leading to the removal of 78% of the initially sorted and suspected particles. Corrected concentrations range from 0.00 to 5.15 items per fish, a result within the same range than this has been reported for other coastal species previously investigated in this area. Fibers, made of polyester (PES), polyamide (PA), acrylic (A) and polypropylene (PP), largely dominate the microplastic shapes (91%). A single driving force could not be identified, but several species traits (morphology, feeding, and habitat) may influence the number of ingested microplastics

Depositional Processes of Organic Matter in the Rhône River Delta (Gulf of Lions, France) Traced by Density Fractionation Coupled with Δ 14 C and δ 13 C

International audienceAs a main source of freshwater and particles, the Rhône River plays a major role in the biogeochemical cycle of organic carbon (OC) in the Mediterranean Sea. To better understand the origin of organic matter and the processes leading to its export to the coastal sea near the Rhône River, we measured radiocarbon (Δ14C) and stable carbon isotopes (δ13C) in the sediments of the delta, after density fractionation. In April 2007, 3 sites located along an offshore transect (A, C, and E) were sampled for surface sediments, and bulk sediment was separated into 4 fractions of different densities (2.5 g cm−3). In order to better understand the evolution of the OC along the transect, we investigated the OC sources and their evolution for each density fraction. Bulk OC shows a large increase in δ13C from −27.2′ nearshore to −24.5′ at offshore stations while Δ14C decreased from 59′ to −320′. The distribution of δ13C with density displayed a convex pattern at all stations. Except for fraction >2.5 g cm−3, δ13C increases by 2.5′ between stations A and E, indicating a loss of terrestrial signature. The distribution of Δ14C versus density had a concave pattern at all stations: at a single station, it showed a large heterogeneity with a difference of 500–600′ between the 2.5 g cm−3 had less variability, with an average δ13C of −24.6 ± 0.4′ and Δ14C of −370 ± 115′. Several processes may explain this distribution: retention in the prodelta of large particles; mineralization of all fractions during the transport and deposition in the delta and shelf sediments; and dilution of terrestrial particles in continental shelf pool

Characterization of trophic niche partitioning between carp (Cyprinus carpio) and roach (Rutilus rutilus) in experimental polyculture ponds using carbon (δ13C) and nitrogen (δ15N) stable isotopes

In temperate fish polyculture, common carp (Cyprinus carpio) and roach (Rutilus rutilus) are two fish species commonly reared in the same ponds. In the natural environment, these two species are considered omnivorous and may compete for food sources. However, few is known about their trophic behavior in polyculture ponds. The aim of our study was to use carbon and nitrogen stable isotope analysis to characterize trophic niche partitioning between both fish species reared in semi-intensive (fed) and extensive (non-fed) ponds. Fish growth performance was higher in semi-intensive than in extensive ponds. In semi-intensive ponds, δ13C and δ15N values of fish indicated that carp consumed mainly formulated feed, whereas roach also consumed natural food sources. In extensive ponds, δ13C and δ15N values of carp and roach indicated that both fish species did not use the same food sources. Regardless of the type of pond, standard ellipse areas, proxies of the estimated trophic niche size, were significantly smaller for carp than for roach and did not overlap, confirming that roach had more trophic plasticity than carp. Results of this study confirmed that carp and roach are good candidates to be rear in the same pond because they are able to adapt their trophic behavior to reduce trophic competition

Les Chambres des comptes en France aux xive et xve siècles

Fruit de la collaboration de plusieurs historiens, ce recueil a été conçu comme un complément aux actes du colloque de Moulins d'avril 1995 publiés par le Comité pour l'histoire économique et financière de la France, en 1996, sous le titre : La France des principautés. Les Chambres des comptes aux xive et xve siècles. Sans prétendre être un inventaire documentaire stricto sensu, il propose, sous forme de dossiers consacrés à plusieurs Chambres des comptes du royaume de France (Chambres des comptes de Paris, de Bourgogne, de Bretagne, de Normandie, de Bourbonnais, de Beaujolais, de Forez) et extérieures au royaume (Chambres des comptes de Savoie et de Provence), une sélection de textes et de documents pour la plupart inédits et commentés. Ce livre espère ainsi contribuer à mieux faire connaître des institutions qui ont joué un rôle essentiel à la fin du Moyen Âge dans le processus de mise en place de l'État moderne

Spatio-temporal variation in benthic function in two high Arctic fjords (Kongsfjorden and Rijpfjorden, Svalbard)

International audienc