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Review on the removal and degradation methods of chloridazon and its metabolites
No full textInternational audienceDue to their excessive use, pesticides are considered emerging micropollutants in water. The risk induced comes not only from their presence in surface and groundwater and the inability of conventional water treatments to fully eliminate them, but also from their transformation products in the environment. The latter are reported to be more persistent and more difficult to treat than their parent compounds. In addition to this, potentially more toxic degradation products can be formed following treatments. Given the pollution of drinking water, as recently highlighted in the Hauts-de-France region by the metabolites of the herbicide chloridazon, and the risk they induce on human health and the environment, this review was written in order to summarize all the methods of remediation with regard to chloridazon and its metabolites, whether they are removal or degradation methods, and to compare the effectiveness of the treatments. In addition, the degradation products known in the literature are reported and a brief overlook on their toxicological properties is discussed, shedding light on the lack of data for these compounds
chapitre III : situations complexes et incertitude. Les régimes de précaution dans les relations internationales
No full textNational audienc
Estimating Rhizosphere Priming in European Agricultural Soils
No full textInternational audienceThe rhizosphere priming effect (RPE) is a key process where the mineralization of soil organic carbon (SOC) by microorganisms is modified by the presence and activity of plant roots compared to SOC mineralization on bare soil, increasing carbon fluxes from soils to the atmosphere. However, its magnitude in agricultural systems remains uncertain. Moreover, since the RPE is not specifically accounted for in earth system models it is a source of uncertainty in global carbon loss estimates relevant to achieve climate change targets. The PrimeSCale model offers a simple framework to quantify RPE-induced SOC respiration at large spatial scales. Here we aim to estimate the RPE in specific European croplands.The PrimeSCale model estimates the RPE using root carbon input to the soil derived from the combination of MODIS gross primary production (GPP) and net primary production (NPP) data, root depth distribution, heterotrophic respiration, soil bulk density and soil organic carbon content. A central component of PrimeSCale is the RPE ratio, the relative increase in heterotrophic respiration induced by priming based on literature using living plants. Our analysis of the time period 2010-2020 covers six types of croplands (maize, wheat, oat, barley, legumes, and soy) across Europe at a 5 km resolution, down to a depth of 200 cm. The model outputs include the magnitude of the RPE ratio and RPE-induced SOC loss in these croplands and how they vary within Europe according to climate and crops. Our findings will enhance understanding of the processes behind carbon cycling in managed environments and provide insights for carbon-farming policies to better suit mitigation strategies
Biomonitoring of elements airborne pollution in European Mediterranean region by two Tillandsia species
No full textInternational audienceTillandsia genus belongs to the Bromeliaceae family plants and some species display active or passive biomonitoring capacities in their natural habitat as it has been described mostly in the American continent. However, Tillandsia aeranthos (Loisiel.) Desf. and Tillandsia bergeri Mez have never been studied for their metal air pollution biomonitor potential. A recent study conducted in our laboratory brought to light the maximum capacity of elements bioconcentration into these two species leaves. The aim of the present study is to determine if T. aeranthos and T. bergeri acclimated to Southern/European region are good biomonitors for airborne elements pollution. Twelve elements were chosen to evaluate the biomonitoring potential (As, Ba, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Ti and Zn). After sampling, the content of the twelve elements in leaves was measured by Inductively Coupled Plasma-Optical Emission Spectrometry and Inductively Coupled Plasma-Mass Spectrometry. Data sets were treated according to sampling sites by box plots over time and Principal Component Analysis. The results showed differences between the two species, with T. bergeri possessing a higher capacity in accumulating elements than T. aeranthos. Fe, Zn and Co showed a higher contribution in the accumulation process in the two Tillandsia species leading to the hypothesis of a good affinity of the two species with these elements. Values obtained for five elements (As, Cr, Ni, Pb and Zn) were compared with values recorded by a monitoring station close to sampling sites showing the efficiency of these two Tillandsia species as biomonitors. High Co accumulation rates obtained in both Tillandsia species were particularly intriguing but could not be rationalized as this metal is not currently monitored by air pollution station in this region. T. aeranthos and T. bergeri proved their efficiency for the biomonitoring of elements air pollution, especially for Co, Fe and Zn
Ability and adsorption processes of anionic dye by polymer and surfactant-based organoclays
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β-Cyclodextrin-derived alternating poly(glyco-triazole)s behave as amylose mimics
No full textInternational audienceCarbohydrate-derived polymers combine attractive features like abundant renewable resources, large stereochemical diversity and defined functionalization of the carbohydrates. Starting from β-cyclodextrin, a diazido heptasaccharide was regioselectively obtained in a few steps. It was used as a prepolymer for the A2B2 synthesis of alternating poly(glyco-triazole)s by copper assisted azido alkyne cycloaddition (CuAAC) with two dialkynes of different length and polarity, namely, 1,7-octadiyne and bispropargyl-polyetileneglycol-5. The resulting polymers were completely characterized by FTIR, NMR, MALDI-TOF-MS, SEC MALS, thermal analysis (TG and DSC), and SEM. The alternating insertion of the heptasaccharide and dialkyne in linear polymeric structures was confirmed by NMR and MALDI-TOF experiments. The water-soluble poly(glyco-triazole) containing PEG units had Mn 20,640 and Mw 39,650. The thermal properties (Tg = 27–42 °C) were close to those of amylose but were influenced by the linker. Therefore, these new poly(glyco-triazole)s could be considered as polysaccharide mimics and alternatives to modified native polysaccharides or brush polymers
Enhancing 5-hydroxymethylfurfural oxidation to 2,5-furan-dicarboxylic acid with Au-supported catalysts: Optimizing reaction parameters and unraveling degradation mechanism through DFT calculations
No full textInternational audienceLignocellulosic biomass holds promise for producing valuable chemicals. Among possible key reactions, the 5hydroxymethylfurfural (HMF) oxidation to 2,5-furandicarboxylic acid (FDCA) using O 2 as a final oxidant and supported Au catalysts is a promising route but that suffers from carbon balance issues. This study explores the mechanism of HMF oxidation to FDCA on a Au(111) model catalyst using computational modeling. Our results identify the main intermediate (HMFCA) and the major degradation pathways from HMF and HMFCA. Since we predict a higher degradation rate for HMF, we designed an experimental two-step approach, using a low temperature to convert fully HMF and improve the carbon balance and then raising the temperature to convert the HMFCA intermediate into FDCA. This approach was successful, reaching a high yield in FDCA (>90 %) in 8 hours while keeping the carbon balance above 97 %.</div
High-temperature resistant boron nitride-based coatings for specialty silica optical fibers
No full textInternational audienceh-BN is well known for its thermal stability. h-BN coated silica optical fibers were manufactured. The coating solution is compatible with optical fiber drawing process, which allows the preparation of tens of meter of h-BN coated fibers. In addition, it is possible to use this coating material for the preparation of short length fiber samples in a post-production approach. Bentonite acts as a binder and allows the adhesion of h-BN to the silica optical fiber. The thermal stability of this protected optical fiber has been demonstrated over a short period of time (several hours) up to 900°C and over a long period of time (1500 h) up to 800°C in air. Moreover, the coated optical fiber can resist up to 1000°C in neutral atmosphere (tested over 6 h)
