Characterization and migration of atmospheric REE in soils and surface waters

Rainwater and snow collected from three different sites in France (Vosges Mountains, French Alps and Strasbourg) show more or less similar shapes of their REE distribution patterns. Rainwater from Strasbourg is the most REE enriched sample, whereas precipitations from the two mountainous, less polluted catchments are less REE enriched and have concentrations close to seawater. They are all strongly LREE depleted. Different water samples from an Alpine watershed comprising snow, interstitial, puddle and streamwater show similar REE distributions with LREE enrichment (rainwater normalized) but MREE and HREE depletion. In this environment, where water transfer from the soil to the river is very quick due to the low thickness of the soils, it appears that REE in streamwater mainly originate from atmospheric inputs. Different is the behaviour of the REE in the spring- and streamwaters from the Vosges Mountains. These waters of long residence time in the deep soil horizons react with soil and bedrock REE carrying minerals and show especially significant negative Eu anomalies compared to atmospheric inputs. Their Sr and Nd isotopic data suggest that most of the Sr and Nd originate from apatite leaching or dissolution. Soil solutions and soil leachates from the upper soil horizons due to alteration processes strongly depleted in REE carrying minerals, have REE distribution patterns close to those of lichens and throughfall. Throughfall is slightly more enriched especially in light REE than filtered rainwater probably due to leaching of atmospheric particles deposited on the foliage and also to leaf excretion. Data suggest that Sr and Nd isotopes of the soil solutions in the upper soil horizons originate from two different sources: 1) An atmospheric source with fertilizer, dust and seawater components and 2) A source mainly determined by mineral dissolution in the soil. These two different sources are also recognizable in the Sr and Nd isotopic composition of the tree’s throughfall solution. The atmospheric contributions of Sr and Nd to throughfall and soil solution are of 20 to 70 and 20%, respectively. In springwater, however, the atmospheric Sr and REE contribution is not detectable

Understanding nitrogen transfer dynamics in a small agricultural catchment: Comparison of a distributed (TNT2) and a semi distributed (SWAT) modeling approaches

The coupling of an hydrological and a crop model is an efficient approach to study the impact of the interactions between agricultural practices and catchment physical characteristics on stream water quality. We analyzed the consequences of using different modeling approaches of the processes controlling the nitrogen (N) dynamics in a small agricultural catchment monitored for 15 years. Two agro-hydrological models were applied: the fully distributed model TNT2 and the semi-distributed SWAT model. Using the same input dataset, the calibration process aimed at reproducing the same annual water and N balance in both models, to compare the spatial and temporal variability of the main N processes. The models simulated different seasonal cycles for soil N. The main processes involved were N mineralization and denitrification. TNT2 simulated marked seasonal variations with a net increase of mineralization in autumn, after a transient immobilization phase due to the burying of the straw with low C:N ratio. SWAT predicted a steady humus mineralization with an increase when straws are buried and a decrease afterwards. Denitrification was mainly occuring in autumn in TNT2 because of the dynamics of N availability in soil and of the climatic and hydrological conditions. SWAT predicts denitrification in winter, when mineral N is available in soil layers. The spatial distribution of these two processes was different as well: less denitrification in bottom land and close to ditches in TNT2, as a result of N transfer dynamics. Both models simulate correctly global trend and inter-annual variability of N losses in small agricultural catchment when a sufficient amount data is available for calibration. However, N processes and their spatial interactions are simulated very differently, in particular soil mineralization and denitrification. The use of such tools for prediction must be considered with care, unless a proper calibration and validation of the different N processes is carried out

Technologie plasma triphasée pour la synthèse de fullerenes en continu

International audienceDepuis une quinzaine d'années, il est développé au Centre Energétique et Procédés (CEP) de MINES ParisTech en partenariat avec la société TIMCAL une technologie plasma triphasée permettant la synthèse de fullerènes et de suie fullerénique en continue à une échelle industrielle. Le procédé est basé sur la vaporisation de particules de carbone solide au moyen d'un plasma triphasé haute température. Les produits synthétisés sont très fortement dépendants des conditions opératoires et plus particulièrement des champs de températures obtenus dans le réacteur de synthèse et des espèces chimiques présentes dans le plasma ainsi que du rapport carbone solide injecté / débit de gaz plasma

Mobility and bioavailability of trace elements in the Touch catchments(Haute-Garonne, France)

In the Touch catchment (South-West of France), samples of sediment and water were collected to evaluate the mobility and bioavailability of some potentially toxic elements (Cr, Co, Ni, Cu, Zn, As, Pb and Cd) for ecosystems. In addition to these trace elements, certain compounds of the dissolved phase (pH, major ions, and dissolved organic carbon) were also studied. The results show two groups of trace elements in the Touch aquatic environment. We distinguish the elements associated with more than 50% in the residual phase (Cr, Zn, Ni and Cu) and those whose non residual fractions are dominant more than 60% (As, Cd, Co and Pb). In the non-residual phases, the trace elements have a significant association with the iron oxides, with the exception of Cd which is controlled to about 50% by the carbonate phases. The first two phases of the sequential extraction (water soluble and exchangeable) are insignificant in the pollutants controlling. Arsenic despite its very high proportion of non-residual phase (about 90%) is relatively less mobile than certain elements such as Cd, Co and Pb that have non residual proportions less important. Trace elements more stable in relation to physico-chemical conditions prevailing in the Touch aquatic environments are Cr, Zn and As, and most mobile are Cd, Co and Pb. The availability of these elements is particularly sensitive to the Physico–chimical conditions of this environment. Their presence in solution increases with the concentrations of inorganic ligands such as chlorides and organic ligands (DOC), while it decreases with increasing pH and alkalinity (in particular Cd and Pb because of their relative abundance in the carbonate phases)

Caractéristiques géochimiques des eaux de surface dans un environnement agricole : cas des bassins versants de la Gascogne (Région Midi Pyrénées, S-W de la France)

La région de la Gascogne, située dans le Sud-Ouest de la France, est une région marquée par une forte activité agricole, avec plus de 75% de terres cultivées. Pour évaluer l’impact des activités anthropiques sur la qualité des eaux de surface drainant cette région, 75 échantillons d’eau de rivières ont été prélevés. Les éléments majeurs, le COD, la silice et le pH ont été mesurés dans la phase dissoute de ces échantillons. Les résultats obtenus montrent que la composition géochimique des cours d’eau de la Gascogne, reflète globalement les caractéristiques lithologiques régionales. Cependant à certains endroits, très fortement cultivés, ces apports lithologiques sont accentués par les activités agricoles. Seuls Cl*, Na+, COD et à un degré moindre SO4*, sont influencés par les activités urbaines, plus particulièrement aux abords des grandes agglomérations. Les eaux de surface de la Gascogne sont marquées par un pH alcalin (pH-7,47, pH-8,11). Les ions dominants dans ces eaux de surface sont HCO3* et Ca2+. Ces deux éléments représentent environ 70% du total des sels dissous (TDS) et présentent des concentrations évoluant respectivement de 0,61 à 6,55 meq.l-1 et de 0,74 à 6,25 meq.l-1. Les teneurs Na+, Clet Mg2+, varient respectivement de 0,14 à 3,24 meq.l-1, de 0,17 à 5,23 meq.l-1 et de 0,14 à 2,62 meq.l-1. Les éléments les moins abondants (K+, NO3* et SO4*), ont des teneurs inférieures à 1,5 meq.l-1. Les concentrations en COD sont comprises entre 1,04 mg.l-1 et 7,96 mg.l-1. Celles de la silice varient de 1,29 à 5,87 mg.l-1 avec une moyenne de 2,87 mg.l-1

Ressources numériques en bibliothèque publique et scolaire: Etude pour la Suisse romande (Les)

C\u27est dans un contexte de dématérialisation des supports et d\u27une volonté pour les bibliothèques suisses de continuer à garantir à leurs usagers un accès libre et démocratique aux contenus que le comité romand de la Communauté de travail des bibliothèques suisses de lecture publique (CLP) a constitué un groupe de travail (GT). Celui-ci a été chargé de réfléchir à l’offre numérique des bibliothèques et en particulier à ce qui pourrait être mis en commun au niveau de la Suisse romande pour créer un portail d’accès à des ressources électroniques dédié aux bibliothèques publiques ou scolaires, quelle que soit leur taille. Ce rapport se veut avant tout un état des lieux des ressources offertes actuellement par les bibliothèques de lecture publique suisses permettant une réflexion pour le futur

NDR Kinases Are Essential for Somitogenesis and Cardiac Looping during Mouse Embryonic Development

Studies of mammalian tissue culture cells indicate that the conserved and distinct NDR isoforms, NDR1 and NDR2, play essential cell biological roles. However, mice lacking either Ndr1 or Ndr2 alone develop normally. Here, we studied the physiological consequences of inactivating both NDR1 and NDR2 in mice, showing that the lack of both Ndr1/Ndr2 (called Ndr1/2-double null mutants) causes embryonic lethality. In support of compensatory roles for NDR1 and NDR2, total protein and activating phosphorylation levels of the remaining NDR isoform were elevated in mice lacking either Ndr1 or Ndr2. Mice retaining one single wild-type Ndr allele were viable and fertile. Ndr1/2-double null embryos displayed multiple phenotypes causing a developmental delay from embryonic day E8.5 onwards. While NDR kinases are not required for notochord formation, the somites of Ndr1/2-double null embryos were smaller, irregularly shaped and unevenly spaced along the anterior-posterior axis. Genes implicated in somitogenesis were down-regulated and the normally symmetric expression of Lunatic fringe, a component of the Notch pathway, showed a left-right bias in the last forming somite in 50% of all Ndr1/2-double null embryos. In addition, Ndr1/2-double null embryos developed a heart defect that manifests itself as pericardial edemas, obstructed heart tubes and arrest of cardiac looping. The resulting cardiac insufficiency is the likely cause of the lethality of Ndr1/2-double null embryos around E10. Taken together, we show that NDR kinases compensate for each other in vivo in mouse embryos, explaining why mice deficient for either Ndr1 or Ndr2 are viable. Ndr1/2-double null embryos show defects in somitogenesis and cardiac looping, which reveals their essential functions and shows that the NDR kinases are critically required during the early phase of organogenesis

Mutation update and genotype-phenotype correlations of novel and previously described mutations in TPM2 and TPM3 causing congenital myopathies

Mutations affecting skeletal muscle isoforms of the tropomyosin genes may cause nemaline myopathy, cap myopathy, core-rod myopathy, congenital fiber-type disproportion, distal arthrogryposes, and Escobar syndrome. We correlate the clinical picture of these diseases with novel (19) and previously reported (31) mutations of the TPM2 and TPM3 genes. Included are altogether 93 families: 53 with TPM2 mutations and 40 with TPM3 mutations. Thirty distinct pathogenic variants of TPM2 and 20 of TPM3 have been published or listed in the Leiden Open Variant Database (http://www.dmd.nl/). Most are heterozygous changes associated with autosomal-dominant disease. Patients with TPM2 mutations tended to present with milder symptoms than those with TPM3 mutations, DA being present only in the TPM2 group. Previous studies have shown that five of the mutations in TPM2 and one in TPM3 cause increased Ca2+ sensitivity resulting in a hypercontractile molecular phenotype. Patients with hypercontractile phenotype more often had contractures of the limb joints (18/19) and jaw (6/19) than those with nonhypercontractile ones (2/22 and 1/22), whereas patients with the non-hypercontractile molecular phenotype more often (19/22) had axial contractures than the hypercontractile group (7/19). Our in silico predictions show that most mutations affect tropomyosin–actin association or tropomyosin head-to-tail binding

Bioturbation effects on bioaccumulation of cadmium in the wetland plant Typha latifolia: A nature-based experiment

The development of efficient bioremediation techniques to reduce aquatic pollutant load in natural sediment is one of the current challenges in ecological engineering. A nature-based solution for metal bioremediation is proposed through a combination of bioturbation and phytoremediation processes in experimental indoor microcosms. The invertebrates Tubifex tubifex (Oligochaeta Tubificidae) was used as an active ecological engineer for bioturbation enhancement. The riparian plant species Typha latifolia was selected for its efficiency in phytoaccumulating pollutants from sediment. Phytoremediation efficiency was estimated by using cadmium as a conservative pollutant known to bioaccumulate in plants, and in itially introduced in the overlying water (20 μg Cd/L of cadmium nitrate – Cd(NO3)2· 4H2O). Biological sedim ent reworking by invertebrates' activity was quantified using luminophores(inert particulates). Our results showed that bioturbation caused by tubificid worms' activity followed the bio-conveying transport model with a downward vertical velocity (V) of luminophores ranging from 16.7 ± 4.5 to 18.5 ± 3.9 cm· year− 1. The biotransport changed the granulometric properties of the surface sediments, and this natural process was still efficient under cadmium contamination. The highest value of Cd enrichment coefficient for plant roots was observed in subsurface sediment layer (below 1 cm to 5 cm depth) with tubificids addition. We demonstrated that biotransport changed the distribution of cadmium across the sediment column as well as it enhanced the pumping of this metal from the surface to the anoxic sediment layers, thereby increasing the bioaccumulation of cadmium in the root system of Typha latifolia. This therefore highlights the potential of bioturbation as a tool to be considered in future as integrated bioremediation strategies of metallic polluted sediment in aquatic ecosystems