What we (possibly) know about the 3-D structure of crust and mantle beneath the Alpine chain

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Point de vue des acteurs sur l'accès à la connaissance sur les sols en France. Quelles améliorations possibles ?

International audienceLife on earth depends on soil health. However, soils are threatened across the world. To respond to the challenges posed byclimate change and soil degradation, there is a need to better integrate scientific soil knowledge into the practice. The aim of thispaper is to better understand the access to soil knowledge in France and identify opportunities for further improvement, with aparticular focus on the difference of point of view between six categories of stakeholders. This study is based on 1,951 responsesfrom a participatory stakeholders’ consultation we conducted in France. Our results showed that most stakeholders considered theknowledge they have access to as not adapted to their needs. They also expressed that knowledge sharing between stakeholderswas not sufficient. To improve access to soil knowledge, stakeholders suggested adapting at the territorial level the content of soilknowledge shared and transferred, as well as improving ways of sharing and transfer soil knowledge. Additionally, stakeholdersvalued different exchange networks based on their type of knowledge. Stakeholders with more theoretical soil knowledge (publicauthorities, NGOs, researchers) stated being more interested in networks between policy, science and society. However, networkswith farmers and advisors were more favored by stakeholders with empirical soil knowledge. Considering our findings, in order tostrengthen knowledge transfer and sharing, we encourage the promotion of the profession of scientific mediator, as well as theimplementation of Living Labs and Lighthouse farms to bring together various stakeholders at a local level towards innovation,training and education. This will ensure a transition towards a more sustainable soil management in Europe.La vida en la Tierra depende de la salud del suelo. Sin embargo, los suelos están amenazados a escala mundial. Para hacerfrente a los desafíos del cambio climático y a la degradación de las tierras, es necesario integrar mejor los conocimientoscientíficos sobre los suelos en las prácticas agrícolas. El objetivo de este artículo es comprender mejor el acceso al conocimientode los actores sobre los suelos en Francia e identificar las posibilidades de mejoramiento, considerando el punto de vista de seiscategorías de actores. Este estudio se basa en 1.951 respuestas de una consulta que realizamos en la Francia metropolitana.Nuestros resultados han demostrado que la mayoría de los actores consideran que los conocimientos a los que tienen acceso nose adaptan a sus necesidades. También señalaron que el intercambio de conocimientos entre los interesados no era suficiente.A fin de mejorar el acceso a los conocimientos sobre el suelo, los interesados sugirieron que el contenido de los conocimientossobre el suelo se adaptara al nivel local y que se mejoraran los métodos de intercambio y transferencia de conocimientos.Las diferentes categorías de actores valoran diferentes redes de intercambio según su tipo de conocimiento. Los actores conconocimientos más teóricos sobre los suelos (autoridades públicas, ONG, investigación y enseñanza superior) declararon estarmás interesados en las redes de intercambio entre política, investigación y sociedad. En cambio, las redes de intercambiosque incluyen a los agricultores y a los asesores agrícolas son más favorecidas por los actores que tienen un conocimientoempírico sobre los suelos. Teniendo en cuenta nuestros resultados, con el fin de reforzar la transferencia y el intercambio deconocimientos, fomentamos la promoción de la profesión de mediador científico, así como la creación de laboratorios vivos(laboratorios de vida) y granjas piloto (Lighthouse Farms) para reunir a nivel local a las distintas categorías de actores. Estogarantizará una transición hacia una gestión más sostenible del suelo en Europa.La vie sur terre dépend de la santé des sols. Cependant, les sols sont menacés à l’échelle mondiale. Pour répondre aux défis liés au changement climatique et à la dégradation des sols, il est nécessaire de mieux intégrer les connaissances scientifiques sur les sols dans les pratiques agricoles. L'objectif de cet article est de mieux comprendre l'accès à la connaissance des acteurs sur les sols en France et d'identifier les possibilités d'amélioration, en considérant le point de vue de six catégories d'acteurs. Cette étude est basée sur 1 951 réponses issues d'une consultation que nous avons menée en France métropolitaine. Nos résultats ont montré que la majorité des acteurs considèrent que les connaissances auxquelles ils ont accès ne sont pas adaptées à leurs besoins. Ils ont également indiqué que le partage de connaissances entre les acteurs n'était pas suffisant. Pour améliorer l'accès aux connaissances sur les sols, les acteurs ont suggéré d'adapter au niveau local le contenu des connaissances sur les sols, ainsi que d'améliorer les méthodes de partage et de transfert des connaissances. Les différentes catégories d’acteurs valorisent différents réseaux d'échanges selon leur type de connaissance. Les acteurs ayant des connaissances plus théoriques sur les sols (autorités publiques, ONG, recherche et enseignement supérieur) ont déclaré être plus intéressés par les réseaux d’échanges entre politique, recherche et société. En revanche, les réseaux d’échanges incluant les agriculteurs et les conseillers agricoles sont davantage privilégiés par les acteurs ayant une connaissance empirique sur les sols. Compte tenu de nos résultats, afin de renforcer le transfert et le partage des connaissances, nous encourageons la promotion de la profession de médiateur scientifique, ainsi que la mise en place de laboratoires vivants (living labs) et de fermes pilotes (lighthouse farms) pour rassembler au niveau local les diverses catégories d’acteurs. Cela permettra d'assurer une transition vers une gestion plus durable des sols en Europe

The Greenhouse Gas Budget of Terrestrial Ecosystems in East Asia Since 2000

International audienceEast Asia (China, Japan, Koreas, and Mongolia) has been the world's economic engine over a

Quantifying the direct and indirect relationships linking the environment, seagrass, and their associated fauna

International audienceFoundation species such as seagrasses modulate critical ecosystem processes, promote biodiversity, and structure community spatial and temporal dynamics. Hence, they play a key role in mediating the response of biodiversity to environmental changes. The breadth of their contribution to biodiversity maintenance and the potential cascading effects of their alteration remain unclear as we lack a comprehensive understanding of the intricate mechanisms governing their response to environmental changes and that of their associated fauna. Indeed, the mechanisms involved are often studied in isolation or at scales that only provide incomplete representations of the complex functioning of these ecosystems. This study aimed to clarify the direct and indirect relationships linking the environment, seagrass, and their associated faunal assemblages, using structural equation modeling (SEM). To this end, we review the literature to derive theoretical models of the functioning of seagrass ecosystems and test them using long‐term monitoring data covering 14 years of nine different Zostera marina seagrass beds across 500 km of coastline. We show that contradictory relationships and ambiguities regarding seagrass–biodiversity relationships emerge from the currently available literature (covering experimental, observational, and modeling studies). The SEM approach allowed us to clarify these direct and indirect relationships and resolve most ambiguities. In particular, we show that seagrass mediates the effect of the environment on its associated communities. However, this mediating effect is different, both qualitatively and quantitatively, for epifauna and infauna. Unexpectedly, the diversity of benthic macrofauna appeared to be controlled and promoted by the biomass rather than by the shoot density of the seagrass beds. We also provide quantitative estimates for the direct and cascading pathways linking seagrass biodiversity to environmental changes. Overall, by synthesizing, clarifying, and quantifying the multiple relationships linking a foundation species such as seagrass to its environment and associated biodiversity, we contribute to a better understanding of seagrass meadows functioning and help predict the potential consequences of foundation species alteration on their associated fauna

Nickel-Copper Deposits on Mars? Discovery of Ore-Grade Abundances, and Implications on Formation and Alteration

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A comparative economic analysis of industrial fisheries targeting small pelagic fish in Mauritanian waters: Free license versus charter regime

International audienceAbstract Industrial fisheries targeting small pelagic fish have significant socio‐economic implications for North West African countries. This study examines the economic performance of fleets operating in Mauritania's exclusive economic zone under the free license and chartering systems. Using national production data from 1989 to 2010 and economic indicator ratios from European pelagic fishing vessels, we assess the economic performance of pelagic fisheries over one decade. Our findings show that vessel characteristics have rapidly evolved, with free‐licenced vessels having a higher average fishing capacity than chartered vessels. The nominal number of free licenses increased from under 8% in 1995; the year of free licencing began in Mauritania, to over 80% in 2010. The estimated average economic output for 2000–2010 was US$231 million, with free licenses contributing over 80$ 187 million). Vessels operating under free licenses made a greater contribution to wealth creation than the chartering regime. Foreign ship owners generated US$40.7 million (22$ 3.6 million (8%). However, the chartering regime was more fiscally advantageous, contributing over 68% of pelagic fisheries tax revenues (estimated at over US$ 29 million). The small pelagic fishery has been subject to a system of total allowable catches and fishing quotas since 2015. This study provides insights into the economic dynamics of the small pelagic fishery, informing decision‐making and potential strategies to enhance the sector's performance and overall economic impact

Could old tide gauges help estimate past atmospheric variability?

The storm surge is the non-tidal component of coastal sea-level. It responds to the atmosphere both through the direct effect of atmospheric pressure on the sea-surface, and through Ekman transport induced by wind-stress. Tide gauges have been used to measure the sea-level in coastal cities for centuries, with many records dating back to the 19th-century or even further, at times when direct pressure observations were scarce. Therefore, these old tide gauge records may be used as indirect observations of sub-seasonal atmospheric variability, complementary to other sensors such as barometers. To investigate this claim, the present work relies on tide gauge records of Brest and Saint-Nazaire, two portal cities in western France, and on the members of NOAA's 20th-century reanalysis (20CRv3) which only assimilates surface pressure observations and uses numerical weather prediction model. Using simple statistical relationships between storm surges and pressure maps, we show that the tide gauge records reveal part of the 19th-century atmospheric variability that was uncaught by the pressure-observations-based reanalysis. In particular, weighing the 80 reanalysis members based on tide gauge observations indicates that a large number of members are very unlikely, which induces corrections of several tens of Hectopascals in the Bay of Biscay. These findings support the use of early tide gauge records in sensor-scarce areas, both to validate old atmospheric reanalyses and to better probe old atmospheric sub-seasonal variability

Muddy sediments are an important potential source of silicon in coastal and continental margin zones

International audienceThe dissolution of silicate minerals on the seafloor releases an important amount of dissolved silicon (dSi), which is necessary for maintaining high diatom production in Coastal and Continental Margin Zones (CCMZs). However, the dissolution of silicate minerals along the continental shelves is variable, which hinders our understanding of the marine Si cycle on both a regional and global scale. To understand the discrepancy of silicon (Si) released in different sediment matrices and its potential controlling factors, we investigated surface sediments of typical CCMZs of the Chinese marginal Seas using a continuous alkaline extraction technique, grain size and chemical (carbon and total nitrogen) analysis as well as a qualitative measurement of clay mineral composition by X-ray diffraction. The results showed that the amount of Si and aluminum (Al) leached from muddy sediments were 2 times greater than those released from sandy sediments. High dissolution rates (> 0.20 mg-SiO2 g−1 min−1) of silicate minerals are caused by a large sediment-specific surface area. Further, our data showed that biogenic silica (bSi) with high Al content (Si:Al < 40) has low reactivity and that the source of Al incorporated in bSi is silicate minerals undergoing dissolution. We show that although the dissolution of silicate minerals is less active than that of bSi, it still potentially releases more bio-available Si and Al to seawater due to its dominant presence on the seafloor (70.3% − 99.0%wt). This study highlights silicate minerals as an important potential marine Si source and emphasizes the need for a better understanding of the roles of silicate minerals in the Si cycle of marginal seas in future studies

Evaluation of two methods allowing the full preparation in a single day of silicate rocks in view of radiogenic isotope (Nd, Sr, and Pb) analyses

International audienceIn this paper, two approaches are described aiming to circumvent the bottle-neck associated with sample decomposition of silicate samples and subsequent isolation of three elements (Nd, Sr, and Pb) of major interest for their radiogenic isotope compositions. These new methods alleviate the need for any evaporation and repeated dissolution steps and make it possible to achieve in a single day the complete preparation of a batch of 10 samples. Specifically, samples are decomposed either by alkaline fusion with a LiBO2 flux followed by quenching in nitric acid, or by quick dissolution in an HF–HNO3 mixture immediately followed by reaction with an aqueous solution of boric acid to neutralize excess HF and dissolve sparingly soluble fluorides. In both cases, the resulting sample solutions are directly loaded onto small chromatographic columns filled with RE and Sr resins, respectively, used in tandem, in order to achieve the concomitant separation of the LREE, Sr, and Pb from matrix elements. While Sr and Pb fractions suitable for isotopic analyses are directly stripped from the Sr resin, an additional column of DGA resin is used, in tandem with the RE resin column, to obtain a Nd fraction isolated from the other LREE. The potential of these most straightforward approaches is demonstrated by repeated analyses of eleven geological reference materials (RMs) spanning a wide range of major element concentrations

Sea-level trends and variability along the coast of Vietnam over 2002–2018: Insights from the X-TRACK/ALES altimetry dataset and coastal tide gauges

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