The importance of crop growth modeling to interpret the Δ14CO2 signature of annual plants

[1] The 14C/C abundance in CO2(¿14CO2) promises to provide useful constraints on regional fossil fuel emissions and atmospheric transport through the large gradients introduced by anthropogenic activity. The currently sparse atmospheric ¿14CO2 monitoring network can potentially be augmented by using plant biomass as an integrated sample of the atmospheric ¿14CO2. But the interpretation of such an integrated sample requires knowledge about the day¿to¿day CO2 uptake of the sampled plants. We investigate here the required detail in daily plant growth variations needed to accurately interpret regional fossil fuel emissions from annual plant samples. We use a crop growth model driven by daily meteorology to reproduce daily fixation of ¿14CO2 in maize and wheat plants in the Netherlands in 2008. When comparing the integrated ¿14CO2 simulated with this detailed model to the values obtained when using simpler proxies for daily plant growth (such as radiation and temperature), we find differences that can exceed the reported measurement precision of ¿14CO2(~2‰). Furthermore, we show that even in the absence of any spatial differences in fossil fuel emissions, differences in regional weather can induce plant growth variations that result in spatial gradients of up to 3.5‰ in plant samples. These gradients are even larger when interpreting separate plant organs (leaves, stems, roots, or fruits), as they each develop during different time periods. Not accounting for these growth¿induced differences in ¿14CO2 in plant samples would introduce a substantial bias (1.5–2¿ppm) when estimating the fraction of atmospheric CO2 variations resulting from nearby fossil fuel emission

La déstabilisation colloïdale des boissons limpides : recherche sur les mécanismes impliqués et développement d'itinéraires technologiques de prévention

Ce projet concerne les boissons limpides produites à partir de pommes à cidre (cidre, pommeau, jus de pomme), les vins (rouges et blancs) et les bières, produits qui présentent assez fréquemment une perte de limpidité néfaste pour l'appréciation du produit par le consommateur. Les résultats de recherche acquis au cours du projet ont permis d'identifier les acteurs de la déstabilisation colloïdale des différents produits mais aussi de lever, au moins partiellement, les verrous de connaissance sur les mécanismes impliqués. Ces nouvelles connaissances ont été mises à profit à la fois pour améliorer la fiabilité des outils de diagnostic prédictifs pour les praticiens, mais aussi pour proposer et optimiser les traitements curatifs ou préventifs de l'instabilité colloïdale. Abstract: Colloidal destabilization of clear beverages: research on the mechanisms involved and development of technological prevention routes This project concerns clear drinks produced from cider apples (cider, pommeau, apple juice), wines (red and white) and beers, products that quite often exhibit a loss of clarity that is detrimental to the consumer appreciation of the final product. The research results acquired during the project made it possible to identify the sources involved in the colloidal destabilization of the various products but also to remove, at least partially, the knowledge barriers on the mechanisms involved. This new knowledge has been used both to improve the reliability of predictive diagnostic tools for producers and to propose and optimize curative or preventive treatments for colloidal instability

Climate Sensitivity in the Anthropocene

Various radiative forcing definitions have been adopted in the scientific literature. The simplest of these is the instantaneous forcing, which is defined as the radiative flux change at the tropopause after the forcing agent has been introduced with the climate held fixed. Another forcing definition, and the one adopted by the Intergovernmental Panel on Climate Change (IPCC), is the adjusted forcing, which is the flux change at the top-ofatmosphere (TOA) and throughout the stratosphere after stratospheric temperatures have been allowed to adjust radiatively to the presence of the forcing agent. Alternative methods of calculating the forcing further allow for adjustment of tropospheric and land surface temperatures, and for various carbon dioxide (CO2) and aerosol effects on clouds. See Liepert (2010) for a recent review of this topic. The traditional paradigm for climate sensitivity tends to focus exclusively on radiative forcings, without consideration of how anthropogenic (or natural) perturbations may affect the non-radiative energy fluxes in the surface energy budget that also determine th