Study of the trace metal ion influence on the turnover of soil organic matter in cultivated contaminated soils

The role of metals in the behaviour of soil organic matter (SOM) is not well documented. Therefore, we investigated the influence of metals (Pb, Zn, Cu and Cd) on the dynamic of SOM in contaminated soils where maize (C4 plant) replaced C3 cultures. Three pseudogley brown leached soil profiles under maize with a decreasing gradient in metals concentrations were sampled. On size fractions, stable carbon isotopic ratio (d13C), metals, organic carbon and nitrogen concentrations were measured in function of depth. The determined sequence for the amount of C4 organic matter in the bulk fractions: M3 (0.9) > M2 (0.4) > M1 (0.3) is in agreement with a significant influence of metals on the SOM turnover. New C4 SOM, mainly present in the labile coarser fractions and less contaminated by metals than the stabilised C3 SOM of the clay fraction, is more easily degraded by microorganism

Sources of dissolved organic carbon in small volcanic mountainous tropical rivers, examples from Guadeloupe (French West Indies)

International audienceIn the tropical zone, small watersheds are affected by intense meteorological events. These events play an important role in the erosion of soils and therefore on the sources of organic carbon in small tropical rivers. We studied the geochemistry of two soils on Basse-Terre Island (French West Indies, FWI): ferralitic soil and Andosol. The two studied soils are very similar in terms of soil organic matter (SOM) and soil solution parameters. The total organic carbon (TOC) and total nitrogen (TN) contents vary between 1.7 and 92 g kg‐1 and between 0.1 and 5.5 g kg‐1, respectively, with the highest concentrations observed in the topsoil. The C/N ratios are relatively constant throughout the soil profiles (ca. 12). The carbon isotopic composition of SOM varies between ‐27.3‰ and ‐22.7‰ and presents an enrichment with increasing depth of soil profiles. Dissolved organic carbon (DOC) concentrations in soil solutions, varying from 3.2 to 91.3 mg L‐1, are similar for the both extraction used in lab (with milliQ water and Ca(NO3)2) but are higher than those measured in soil solutions sampled from lysimeters (0.65–1.46 mg L‐1). The isotopic compositions of DOC obtained by extractions and SOM are comparable, with δ13C values ranging from ‐28.6‰ to ‐25.8‰. The DOC sampled from lysimeters is systematically depleted in 13C compared to DOC obtained by extractions, with δ13C values of ‐33.8‰ to ‐30.6‰. The enrichment of δ13C of SOM through the soil profiles is either consistent with the carbon isotopic fractionation of SOM by decomposing organisms, or the differential mineralization of both labile and stable carbon stocks in soils. DOC concentrations in stream waters vary between 0.46 and 5.75 mg L‐1, and are generally lower during low water level than floods. The isotopic compositions of DOC in the rivers range from ‐38.9‰ to ‐27.2‰, with δ13C values, which are more depleted in 13C during low water level than flood events. The δ13CDOC of water river samples and soil solutions obtained by extraction and collected with lysimeters demonstrates that the DOC in rivers derives essentially from both the lixiviation of the soil surface layers during floods and groundwater flow during low water levels. Lixiviation of soil surface layers can be boosted by significant increases of intensity and duration of meteorological events and can strongly favor the release of surface soil organic matter in rivers and the impoverishment in nutrients of soil surface layers

LES NANOPARTICULES: QUELS RISQUES EN SEINE ?

32 pInternational audienceL'obtention de nanoparticules (NPs) manufacturées et les propriétés physico-chimiques spécifiques qu'elles présentent autorisent aujourd'hui des applications de plus en plus nombreuses et innovantes. La quantité de nanoparticules manufacturées mises sur le marché est en constante augmentation et elles sont aujourd'hui présentes dans de nombreux produits de consommation courante. Cela alimente un débat croissant sur les coûts environnementaux et sociétaux qui pourraient dépasser les bénéfices escomptés par l'utilisation des nanotechnologies en général et des nanomatériaux ou nanoparticules (i.e. taille < 100 nm) en particulier. Elles sont devenues un enjeu majeur de santé publique du point de vue de la toxicité potentielle qu'elles pourraient engendrer dans les écosystèmes. Les nanoparticules peuvent en effet présenter un risque écotoxicologique (dispersion et dégradation dans l'environnement) et un risque en termes de santé humaine (exposition au poste de travail par exemple). Il est donc nécessaire d'évaluer la persistance, le devenir et l'impact de ces nouveaux polluants sur les écosystèmes et sur la qualité des ressources naturelles (eaux, cultures, etc...). Dans ce contexte, l'objectif de cette étude était de mieux cerner l'état physique et chimique des NPs dans des concentrations représentatives des niveaux de toxicité observés et dans des conditions proches de celles des milieux naturels. Elle s'est focalisée sur l'eau de Seine, représentative des eaux naturelles de surface qui sont un des vecteurs principaux de la dispersion de ces NPs manufacturées. Les NPs étudiées ici sont produites en grande quantité et largement utilisées dans différents domaines industriels : il s'agit de NPs d'oxydes de zinc (ZnO) et de dioxyde de titane (TiO2). L'analyse des NPs de ZnO par XPS a mis en évidence l'existence d'un cœur de ZnO et d'un coquille de Zn(OH)2 en surface. Parallèlement, des NPs enrobées ont été étudiées et caractérisées, afin de mettre en évidence le rôle de l'enrobage organique sur la solubilité des NPs. Les expériences de mesures de solubilité des nanoparticules manufacturées en milieu naturel ont été réalisées par utilisation combinée des techniques de DMT et d'UF, associée à des calculs thermodynamiques. Il s'avère que la forme nanoparticulaire du TiO2 n'est pas davantage soluble que ses homologues microparticulaire ou macroparticulaire. A l'inverse, une fraction non négligeable des nanoparticules d'oxydes de zinc est rapidement dissoute dans l'eau de Seine. Puis les NPs sont "piégées" dans des phases secondaires carbonatées, ce qui peut signifier leur isolement par rapport au milieu et donc l'arrêt des réactions impliquant les NPs, soit une forme de passivation des nanoparticules. Le comportement des NPs dans le milieu est donc en grande partie contrôlé par la couche directement à leur surface (Gélabert et al., 2014; Sivry et al., 2014) : la couche d'hydroxydes de zinc contrôle le Ks apparent, l'enrobage organique augmente la vitesse et le taux de dissolution des NPs et, enfin, la formation d'une gangue carbonatée emprisonne les NPs et provoque potentiellement leur passivation

Statistical Physics of Structural Glasses

This paper gives an introduction and brief overview of some of our recent work on the equilibrium thermodynamics of glasses. We have focused onto first principle computations in simple fragile glasses, starting from the two body interatomic potential. A replica formulation translates this problem into that of a gas of interacting molecules, each molecule being built of $m$ atoms, and having a gyration radius (related to the cage size) which vanishes at zero temperature. We use a small cage expansion, valid at low temperatures, which allows to compute the cage size, the specific heat (which follows the Dulong and Petit law), and the configurational entropy. The no-replica interpretation of the computations is also briefly described. The results, particularly those concerning the Kauzmann tempaerature and the configurational entropy, are compared to recent numerical simulations.Comment: 21 pages, 6 figures, to appear in the proceedings of the Trieste workshop on "Unifying Concepts in Glass Physics

Notes on a paper of Mess

These notes are a companion to the article "Lorentz spacetimes of constant curvature" by Geoffrey Mess, which was first written in 1990 but never published. Mess' paper will appear together with these notes in a forthcoming issue of Geometriae Dedicata.Comment: 26 page

BioTIME: A database of biodiversity time series for the Anthropocene.

MotivationThe BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene.Main types of variables includedThe database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record.Spatial location and grainBioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2).Time period and grainBioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year.Major taxa and level of measurementBioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates.Software format.csv and .SQL

Constraints on the structure and seasonal variations of Triton's atmosphere from the 5 October 2017 stellar occultation and previous observations

Context. A stellar occultation by Neptune's main satellite, Triton, was observed on 5 October 2017 from Europe, North Africa, and the USA. We derived 90 light curves from this event, 42 of which yielded a central flash detection. Aims. We aimed at constraining Triton's atmospheric structure and the seasonal variations of its atmospheric pressure since the Voyager 2 epoch (1989). We also derived the shape of the lower atmosphere from central flash analysis. Methods. We used Abel inversions and direct ray-tracing code to provide the density, pressure, and temperature profiles in the altitude range similar to 8 km to similar to 190 km, corresponding to pressure levels from 9 mu bar down to a few nanobars. Results. (i) A pressure of 1.18 +/- 0.03 mu bar is found at a reference radius of 1400 km (47 km altitude). (ii) A new analysis of the Voyager 2 radio science occultation shows that this is consistent with an extrapolation of pressure down to the surface pressure obtained in 1989. (iii) A survey of occultations obtained between 1989 and 2017 suggests that an enhancement in surface pressure as reported during the 1990s might be real, but debatable, due to very few high S/N light curves and data accessible for reanalysis. The volatile transport model analysed supports a moderate increase in surface pressure, with a maximum value around 2005-2015 no higher than 23 mu bar. The pressures observed in 1995-1997 and 2017 appear mutually inconsistent with the volatile transport model presented here. (iv) The central flash structure does not show evidence of an atmospheric distortion. We find an upper limit of 0.0011 for the apparent oblateness of the atmosphere near the 8 km altitude.J.M.O. acknowledges financial support from the Portuguese Foundation for Science and Technology (FCT) and the European Social Fund (ESF) through the PhD grant SFRH/BD/131700/2017. The work leading to these results has received funding from the European Research Council under the European Community's H2020 2014-2021 ERC grant Agreement nffi 669416 "Lucky Star". We thank S. Para who supported some travels to observe the 5 October 2017 occultation. T.B. was supported for this research by an appointment to the National Aeronautics and Space Administration (NASA) Post-Doctoral Program at the Ames Research Center administered by Universities Space Research Association (USRA) through a contract with NASA. We acknowledge useful exchanges with Mark Gurwell on the ALMA CO observations. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium).Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. J.L.O., P.S.-S., N.M. and R.D. acknowledge financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709), they also acknowledge the financial support by the Spanish grant AYA-2017-84637-R and the Proyecto de Excelencia de la Junta de Andalucia J.A. 2012-FQM1776. The research leading to these results has received funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement no. 687378, as part of the project "Small Bodies Near and Far" (SBNAF). P.S.-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 "LEO-SBNAF". The work was partially based on observations made at the Laboratorio Nacional de Astrofisica (LNA), Itajuba-MG, Brazil. The following authors acknowledge the respective CNPq grants: F.B.-R. 309578/2017-5; R.V.-M. 304544/2017-5, 401903/2016-8; J.I.B.C. 308150/2016-3 and 305917/2019-6; M.A. 427700/20183, 310683/2017-3, 473002/2013-2. This study was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior -Brasil (CAPES) -Finance Code 001 and the National Institute of Science and Technology of the e-Universe project (INCT do e-Universo, CNPq grant 465376/2014-2). G.B.R. acknowledges CAPES-FAPERJ/PAPDRJ grant E26/203.173/2016 and CAPES-PRINT/UNESP grant 88887.571156/2020-00, M.A. FAPERJ grant E26/111.488/2013 and A.R.G.Jr. FAPESP grant 2018/11239-8. B.E.M. thanks CNPq 150612/2020-6 and CAPES/Cofecub-394/2016-05 grants. Part of the photometric data used in this study were collected in the frame of the photometric observations with the robotic and remotely controlled telescope at the University of Athens Observatory (UOAO; Gazeas 2016). The 2.3 m Aristarchos telescope is operated on Helmos Observatory by the Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing of the National Observatory of Athens. Observations with the 2.3 m Aristarchos telescope were carried out under OPTICON programme. This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 730890. This material reflects only the authors views and the Commission is not liable for any use that may be made of the information contained therein. The 1. 2m Kryoneri telescope is operated by the Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing of the National Observatory of Athens. The Astronomical Observatory of the Autonomous Region of the Aosta Valley (OAVdA) is managed by the Fondazione Clement Fillietroz-ONLUS, which is supported by the Regional Government of the Aosta Valley, the Town Municipality of Nus and the "Unite des Communes valdotaines Mont-Emilius". The 0.81 m Main Telescope at the OAVdA was upgraded thanks to a Shoemaker NEO Grant 2013 from The Planetary Society. D.C. and J.M.C. acknowledge funds from a 2017 'Research and Education' grant from Fondazione CRT-Cassa di Risparmio di Torino. P.M. acknowledges support from the Portuguese Fundacao para a Ciencia e a Tecnologia ref. PTDC/FISAST/29942/2017 through national funds and by FEDER through COMPETE 2020 (ref. POCI010145 FEDER007672). F.J. acknowledges Jean Luc Plouvier for his help. S.J.F. and C.A. would like to thank the UCL student support observers: Helen Dai, Elise Darragh-Ford, Ross Dobson, Max Hipperson, Edward Kerr-Dineen, Isaac Langley, Emese Meder, Roman Gerasimov, Javier Sanjuan, and Manasvee Saraf. We are grateful to the CAHA, OSN and La Hita Observatory staffs. This research is partially based on observations collected at Centro Astronomico HispanoAleman (CAHA) at Calar Alto, operated jointly by Junta de Andalucia and Consejo Superior de Investigaciones Cientificas (IAA-CSIC). This research was also partially based on observation carried out at the Observatorio de Sierra Nevada (OSN) operated by Instituto de Astrofisica de Andalucia (CSIC). This article is also based on observations made with the Liverpool Telescope operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. Partially based on observations made with the Tx40 and Excalibur telescopes at the Observatorio Astrofisico de Javalambre in Teruel, a Spanish Infraestructura Cientifico-Tecnica Singular (ICTS) owned, managed and operated by the Centro de Estudios de Fisica del Cosmos de Aragon (CEFCA). Tx40 and Excalibur are funded with the Fondos de Inversiones de Teruel (FITE). A.R.R. would like to thank Gustavo Roman for the mechanical adaptation of the camera to the telescope to allow for the observation to be recorded. R.H., J.F.R., S.P.H. and A.S.L. have been supported by the Spanish projects AYA2015-65041P and PID2019-109467GB-100 (MINECO/FEDER, UE) and Grupos Gobierno Vasco IT1366-19. Our great thanks to Omar Hila and their collaborators in Atlas Golf Marrakech Observatory for providing access to the T60cm telescope. TRAPPIST is a project funded by the Belgian Fonds (National) de la Recherche Scientifique (F.R.S.-FNRS) under grant PDR T.0120.21. TRAPPIST-North is a project funded by the University of Liege, and performed in collaboration with Cadi Ayyad University of Marrakesh. E.J. is a FNRS Senior Research Associate

A MSFD complementary approach for the assessment of pressures, knowledge and data gaps in Southern European Seas : the PERSEUS experience

PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES. 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license.peer-reviewe

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio