Iron biogeochemistry in Antarctic pack ice during SIPEX-2

Our study quantified the spatial and temporal distribution of Fe and ancillary biogeochemical parameters at six stations visited during an interdisciplinary Australian Antarctic marine science voyage (SIPEX-2) within the East Antarctic first-year pack ice zone during September–October 2012. Unlike previous studies in the area, the sea ice Chlorophyll a, Particulate Organic Carbon and Nitrogen (POC and PON) maxima did not occur at the ice/water interface because of the snow loading and dynamic processes under which the sea ice formed. Iron in sea ice ranged from 0.9 to 17.4 nM for the dissolved (<0.2 µm) fraction and 0.04 to 990 nM for the particulate (>0.2 µm) fraction. Our results highlight that the concentration of particulate Fe in sea ice was highest when approaching the continent. The high POC concentration and high particulate iron to aluminium ratio in sea ice samples demonstrate that 71% of the particulate Fe was biogenic in composition. Our estimated Fe flux from melting pack ice to East Antarctic surface waters over a 30 day melting period was 0.2 µmol/m2/d of DFe, 2.7 µmol/m2/d of biogenic PFe and 1.3 µmol/m2/d of lithogenic PFe. These estimates suggest that the fertilization potential of the particulate fraction of Fe may have been previously underestimated due to the assumption that it is primarily lithogenic in composition. Our new measurements and calculated fluxes indicate that a large fraction of the total Fe pool within sea ice may be bioavailable and therefore, effective in promoting primary productivity in the marginal ice zone

Glacial influence on the geochemistry of riverine iron fluxes to the Gulf of Alaska and effects of deglaciation

This paper is not subject to U.S. copyright. The definitive version was published in Geophysical Research Letters 38 (2011): L16605, doi:10.1029/2011GL048367.Riverine iron (Fe) derived from glacial weathering is a critical micronutrient source to ecosystems of the Gulf of Alaska (GoA). Here we demonstrate that the source and chemical nature of riverine Fe input to the GoA could change dramatically due to the widespread watershed deglaciation that is underway. We examine Fe size partitioning, speciation, and isotopic composition in tributaries of the Copper River which exemplify a long-term GoA watershed evolution from one strongly influenced by glacial weathering to a boreal-forested watershed. Iron fluxes from glacierized tributaries bear high suspended sediment and colloidal Fe loads of mixed valence silicate species, with low concentrations of dissolved Fe and dissolved organic carbon (DOC). Iron isotopic composition is indicative of mechanical weathering as the Fe source. Conversely, Fe fluxes from boreal-forested systems have higher dissolved Fe concentrations corresponding to higher DOC concentrations. Iron colloids and suspended sediment consist of Fe (hydr)oxides and organic complexes. These watersheds have an iron isotopic composition indicative of an internal chemical processing source. We predict that as the GoA watershed evolves due to deglaciation, so will the source, flux, and chemical nature of riverine Fe loads, which could have significant ramifications for Alaskan marine and freshwater ecosystems.We appreciate support from the USGS CMGP, NCCWSC, and the Mendenhall Postdoctoral Program

The GEOTRACES Intermediate Data Product 2014

The GEOTRACES Intermediate Data Product 2014 (IDP2014) is the first publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2013. It consists of two parts: (1) a compilation of digital data for more than 200 trace elements and isotopes (TEIs) as well as classical hydrographic parameters, and (2) the eGEOTRACES Electronic Atlas providing a strongly inter-linked on-line atlas including more than 300 section plots and 90 animated 3D scenes. The IDP2014 covers the Atlantic, Arctic, and Indian oceans, exhibiting highest data density in the Atlantic. The TEI data in the IDP2014 are quality controlled by careful assessment of intercalibration results and multi-laboratory data comparisons at cross-over stations. The digital data are provided in several formats, including ASCII spreadsheet, Excel spreadsheet, netCDF, and Ocean Data View collection. In addition to the actual data values the IDP2014 also contains data quality flags and 1-? data error values where available. Quality flags and error values are useful for data filtering. Metadata about data originators, analytical methods and original publications related to the data are linked to the data in an easily accessible way. The eGEOTRACES Electronic Atlas is the visual representation of the IDP2014 data providing section plots and a new kind of animated 3D scenes. The basin-wide 3D scenes allow for viewing of data from many cruises at the same time, thereby providing quick overviews of large-scale tracer distributions. In addition, the 3D scenes provide geographical and bathymetric context that is crucial for the interpretation and assessment of observed tracer plumes, as well as for making inferences about controlling processes

Spéciation du fer en milieu océanique, interactions avec le phytoplancton

Toutes les fertilisations en fer (Fe) dans les zones HNLC (High Nutrient-Low Chlorophyll) ont montré le rôle crucial de cet élément dans la production primaire et la structure de la communauté planctonique. Cependant, l étude de son cycle biogéochimique est difficile en raison de ses faibles concentrations dans l océan ouvert et de sa spéciation complexe. De nombreuses inconnues persistent, notamment sur la prédominance relative de ses sources et sur la fraction bioassimilable. Les objectifs de cette thèse étaient d améliorer notre connaissance sur le cycle biogéochimique du Fe dans l océan, dans le but de répondre à deux questions: (1) Quelles sont les sources, la distribution et la spéciation physique du Fe en milieu océanique dans des zones ayant des apports contrastés en Fe ? et (2) Quelles sont les interactions entre sa spéciation et l activité biologique? Au cours de deux études en milieu naturel (KEOPS et BONUS-GoodHope), la spéciation physique du Fe a été mesurée. Le fer total dissolvable (échantillons non filtrés) s est révélé être un bon traceur des sources lithogéniques. Ces études ont montré que les distributions de Fe soluble et colloïdal étaient liées à l activité biologique et à la force des ligands organiques. Des expériences en laboratoire couplant ajouts d eau de pluie, mesures de la spéciation du Fe et activité biologique ont également été réalisées, en présence d une diatomée océanique, dans le cadre du projet BOA. Deux hypothèses quant à la biodisponibilité du Fe ont été formulées : une assimilation du Fe colloïdal ou du Fe soluble suivi d un transfert rapide entre fraction colloïdale et soluble.All iron (Fe) fertilizations in HNLC areas (High Nutrient-Low Chlorophyll) highlighted the crucial role of this element in primary production and planktonic community structure. However, the study of its biogeochemical cycle is difficult, due to the low Fe concentrations in the Open Ocean and to its complex speciation. Many unknowns persist, in particular on the relative predominance of its sources to the oceans and on the bioavailability of the different fractions. The objectives of this PhD were to improve our knowledge on the biogeochemical cycle of Fe in seawater, in order to answer to these questions: (1) What are the sources, distribution and physical speciation of Fe in seawater, in areas characterized by contrasted Fe supplies? And (2) What are the interactions between its speciation and the biological activity? A field approach was used in order to better determine and quantify Fe sources to the ocean. Fe physical speciation was measured during two cruises, KEOPS and BONUS-GoodHope. Total dissolvable Fe was shown to be a good proxy for lithogenic inputs. Those studies showed that the soluble and colloidal Fe distributions are linked to biological activity and to the strength of organic ligands. In order to better constrain the question of Fe bioavailabllity, laboratory experiments were conducted in the framework of the BOA project, coupling rainwater, Fe speciation and biological activity, in the presence of an oceanic diatom. Two hypothesis concerning Fe bioavailability were formulated: an assimilation of colloidal fraction or an assimilation of soluble fraction followed by a rapid exchange between the two fractions.BREST-BU Droit-Sciences-Sports (290192103) / SudocPLOUZANE-Bibl.La Pérouse (290195209) / SudocSudocFranceF

Les pratiques des professionnels du vrac : entre évolutions et renouveau

International audienc

Comprendre les spécificités de la distribution en vrac pour adapter le retailing mix : apport des théories des pratiques

International audienceObjectives/Research questions: Packaging-free shopping, i.e. selling products presented without any packaging, in quantities that the consumer chooses and in reusable containers, is a kind of distribution that currently experiences a renewed interest. Its development changes the retailers’ practices. Based on social practices theories, this article aims at understanding the specificities of packaging-free professionals’ practices in order to adapt the retailing mix to the case of packaging-free distribution.Methodology/Approach: This research uses a qualitative study, which includes interviews with retailers, visits of stores with observations and photographs, and a systematic review of a professional journal.Findings: Based on the three pillars of the retailing mix – product/service mix, physical distribution mix and communication mix – the results highlight the specificities of packaging-free distribution and, in particular, the permeability of the boundaries between the pillars of the mix and the importance of the meanings that create heterogeneity in the practices.Implications: Analyzing packaging-free distribution through the prism of practices theories reveals the need to adapt the retailing mix to this particular case. The contribution of this research is to propose an adapted retailing-mix integrating the material-skills-meaning dimensions to deploy it. Resulting managerial recommendations regarding the implementation of this adapted retailing-mix are therefore proposed. These propositions allow to remove some barriers that hinder the diffusion of packaging-free distribution. Originality: Contrary to previous studies that used social practices theories at the individuals’ level, this research uses them here in a new framework, the one of professionals of a specific sector. They prove to be relevant to understand the distribution of unpackaged products, a topic that remains unexplored in the marketing literature.Keywords: sustainable development; packaging; packaging-free products; retailing mix; theories of practices.Objectifs/questions de recherche : Le vrac, ou vente de produits présentés sans emballage, en quantité choisie par le consommateur, dans des contenants réemployables ou réutilisables, est un mode de distribution qui connaît un regain d'intérêt actuellement. Son développement bouleverse les pratiques des distributeurs. En s'appuyant sur les théories des pratiques sociales, cet article a pour objectif de comprendre les spécificités des pratiques des distributeurs de vrac afin de proposer une adaptation du retailing mix au cas du vrac. Méthodologie/approche : Pour donner à voir la pratique du vrac, cette recherche repose sur une étude qualitative comprenant des entretiens avec des distributeurs, des visites de points de vente avec observations et prises de photographies et une revue de presse systématique. Résultats : En s'appuyant sur les trois piliers du retailing mixmix produits/services, mix distribution physique et mix communicationles résultats mettent en évidence les spécificités des pratiques mises en place dans le vrac et, en particulier, la perméabilité des frontières entre les piliers du mix, d'une part, et l'importance des significations, qui créent de l'hétérogénéité dans les pratiques observées, d'autre part. Implications managériales/sociétales : Analyser la distribution en vrac au prisme des théories des pratiques révèle la nécessité d'adapter le retailing mix à ce cas particulier. L'apport de cette recherche réside dans la proposition d'un retailing-mix adapté intégrant les dimensions matériels-compétences-significations pour le déployer. Pour lever certains freins entravant la diffusion du vrac, des recommandations managériales permettant de mettre en oeuvre cette version du retailing-mix sont donc proposées. Originalité : Les théories des pratiques sociales, habituellement mobilisées au niveau des individus, le sont ici dans un cadre nouveau, celui des professionnels d'un secteur. Elles s'avèrent pertinentes pour éclairer la compréhension de la distribution en vrac, sujet encore peu étudié dans la littérature en marketing. Mots-clés : développement durable ; emballage ; vrac ; distribution ; théories des pratiques, retailing mix

Le vrac: un renouvellement des pratiques des consommateurs et des distributeurs ?

National audienc

Le passage à la vente en vrac oblige les distributeurs à revoir leurs pratiques

International audienceD'ici 2030, les magasins de plus de 400m2 devront consacrer « au moins 20 % de leur surface de vente de produits de grande consommation… à la vente de produits présentés sans emballage primaire » pour se mettre en conformité avec l'article 11 du projet de loi Climat et résilience. Cette loi vise à accélérer la vente en vrac, c'est-à-dire « la vente de produits présentés sans emballage, en quantité choisie par le consommateur, dans des contenants réemployables ou réutilisables », comme le définit le code de la consommation