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International audience; Phytoattenuation combines phytoextraction or phytostabilization with the economic valorization of the biomass produced on the contaminated soil. Sorghum bicolor is a suitable crop for this strategy, as it is known to be metal-tolerant and can be used for biogas or bioethanol production or in strategies toward biofortification. In the current investigation, two cultivars, Biomass 133 and Trudan Headless (HL), were studied in a metal-contaminated (Cd, Pb, Zn) field site located in northern France to assess their potential use in a phytoattenuation strategy. The biomass yield and the metal transfer in the produced biomass were monitored in three plots with different pollution levels. Both cultivars were tolerant to high levels of metal pollution in field conditions, with yields similar to that obtained on uncontaminated sites. Neither of the cultivars changed the metal mobility of the soil and both exhibited a metal-excluder behavior. Nevertheless, Cd concentration in the aboveground part of Trudan HL, and of Biomass 133 to a lesser extent, could restrict their use in some valorization options. However, biogas production was possible with the produced biomass, indicating anaerobic digestion to be a possible valorization route for sorghum grown on contaminated sites.

International audience; Biomethane is a renewable energy gas with great potential to contribute to the diversification and greening of the natural gas supply. Ideally, biomethane can directly be injected into the natural gas grid system. For grid injection, specifications such as those in EN 16723-1 shall be met. One of the impurities to be monitored is hydrogen chloride (HCl). To assess conformity with the specification for HCl, accurate and reliable test methods are required. Here, we report the development of three novel test methods, based on a variety of laser absorption spectroscopy techniques (Direct absorption spectroscopy-DAS and wavelength modulation spectroscopy-WMS) and ion-exchange chromatography, for the measurement of HCl in biomethane. Gas mixtures of HCl in biomethane were used to demonstrate the performance of the spectroscopic systems in the nmol mol−1 to low μmol mol−1 ranges, achieving uncertainties in the 4% range, k = 2. For ion-exchange chromatography analysis, HCl was first collected on an alkali-impregnated quartz fiber filter. The analysis was performed according to ISO 21438-2 and validated using synthetic biomethane spiked with HCl. The relative expanded uncertainties for the ion exchange chromatography HCl measurements are in the 10–37% range, k = 2. The results presented for the 3 test methods demonstrate that the respective methods can be used for HCl conformity assessment in biomethane.

Phytotechnologies for the management of lands contaminated with potentially toxic elements (PTEs) are considered as gentle alternatives to conventional remediation techniques. During the last few years, phytotechnologies have progressively shifted to phytomanagement, a concept that includes the valorization of the plant biomass produced on the contaminated site. This study aimed at evaluating the mid-term effect of ecto- and endomycorrhizal inoculation on the reduction of PTE mobility in soils and foliar accumulation by two poplar clones, Skado ( Populus trichocarpa x P. maximowiczii ) and I-214 ( P. deltoides x P. nigra ), dedicated to bioenergy purposes. The effects of inoculation were investigated in two large scale trials of 1 ha each. Poplars grown on highly contaminated soils accumulated excessive Cd and Zn in leaves compared with those planted on less contaminated soils, and the I-214 clone generally accumulated less PTEs than the Skado clone. Interestingly, the filtering capacity of mycorrhizal fungi was significant for Zn, Cu, Pb and Cr in Skado leaves only at the most contaminated areas after two growing seasons. These foliar concentrations were not correlated with Ca(NO 3 ) 2 -extractable concentrations in soils, suggesting that mycorrhizal fungi limited PTE translocation from roots to leaves without impacting PTE mobility in soils. Therefore, the reduction of PTE accumulation in poplar leaves may be optimized by selecting appropriate combinations of cultivars and inocula at specific PTE levels and soil conditions. Because Cd and Zn may pose a risk after leaf abscission and wood harvest, further research is needed to efficiently reduce Cd and Zn concentrations in poplar tissues. Otherwise, the phytomanagement of metal contaminated sites with poplars should include options to safely manage both leaves and wood.

Afforestation of trace element (TE)-contaminated soil, notably with fast growing trees producing large biomass has been demonstrated to be an attractive option for their bioremediation. Mycorrhizal fungi can form symbiotic associations with plants, contributing to TE tolerance and participating actively in bioremediation processes. We studied the effects of mycorrhizal inoculation on the growth of two poplar clones (Skado and I214), to large-scale. Two TE-contaminated sites of ca . 1 ha (Pierrelaye and Fresnes-sur-Escaut, France) were planted with 2200 trees, and were either inoculated with a mixed commercial inoculum or not-inoculated and allometric parameters were determined after 2 and 4 years of growth. The height diameter relationships remained linear overtime, although the second period of the experiment has been more favorable to growth of the Skado clone and its survival rates were higher compared than those of the I214 clone, at both sites. The inoculation with mycorrhizal significantly impacted the biomass production of the Skado clone at both sites, despite striking differences in soil structure and contamination. In overall, this bioaugmentation option with mycorrhizal fungi influenced more poplar growth than soil contamination and highly improved its biomass production.

Torrefaction (290 °C) and pyrolysis (450 and 800 °C) trials were performed at pilot scale with a patented reactor on metal-enriched poplars from a contaminated soil managed by phytotechnologies and poplars cultivated on uncontaminated soil, for comparison. This study emphasized the influence of temperature on end-product yield, metal distribution in end-products and metal behavior. Results showed that the evolution of the end-product yield, i.e. biochar, bio-oil and gas fractions, was depending on temperature rather than other parameters such as the origin or metal content of the tested poplars. Torrefaction decreased the processed poplars weight, leading to metal-enriched torrefied biomass as a major end-product. At 450 and 800 °C, metal behavior was governed by temperature. Nevertheless, the different chlorine content of initial biomass was hypothesized to be an important factor that could modify the metal behavior by increasing metal volatilization at process temperatures. Amongst the studied metals, Zn and Pb were hypothesized to form volatile metal chlorides, therefore increased metal volatilization from Control poplar biomass could be explained by increased chlorine content of such biomass. At 450 °C, metals were recovered in biochar, then in bio-oil and finally in gases. At 800 °C, similar results were obtained for Cu, confirming that Cu was not easily volatilized. On the contrary, Zn, Pb and Cd were mostly recovered in gases, which became the second metal recovery compartment. According to metal concentrations, valorization options were discussed for end-products.

5 p.; International audience; The eruption of the Eyjafjallajökull in April 2010 led to the injection in the troposphere of an important quantity of volcanic ash whose advection towards densely populated areas raised serious concerns regarding potential impacts on air quality. Here we investigate to what extent air quality in France was altered using exclusively quantitative data that was available in near real-time. We rely on a combination of atmospheric dispersion modelling, ground-based remote sensing, and chemical characterization of airborne particles. One week after the onset of the eruption we were able to conclude that the Eyjafjallajökull ash plume was locally responsible for an increase of up to 30 +/- 10 µgm-3 of total PM10 (particulate matter finer than 10 µm) that reached 65 mg m-3 on 18 and 19 April 2010. The methodology presented in this letter offers promising perspectives in terms of emergency response strategy when facing such unforeseen atmospheric dispersion events.

A series of amphiboles along the magnesioriebeckite - square Na2Mg3Fe3+ 2Si8O22(OH)(2)- ferri-clinoholmquistite - circle Li2Mg3Fe3+ 2Si8O22(OH)2 - join, defined by the Li-B(B) Na-1 exchange vector, were hydrothermally synthesized at 700 degrees C, 0.4 GPa, NNO + 1 redox conditions. Powder XRD and SEM-EDAX showed a very high (> 90%) amphibole yield for all samples. X-ray patterns were indexed in the C2/m space group; refined cell-parameters show a linear decrease of alpha and beta as a function of chemistry. IR spectra in the OH-stretching region show four main and rather sharp bands; these are assigned to Mg and Fe2+ at M(1,3), and indicate that the obtained amphiboles depart from the nominal octahedral composition (Mg-M1,3(3)). The IR spectra also show that there is an increasing filling-up of the A-site for increasing Na in the system (increasing solid-solution toward, arfvedsonite). Mossbauer spectra show four well-defined quadrupole doublets which are assigned to Fe3+ at M2 and to Fe2+ at M1, M3 and M4, respectively. The Fe3+/Fe2+ content derived from fitted peak areas show variable Fe3+ concentration along the series. Mossbauer spectra also show a distinct alteration of Fe-57 hyperfine parameters with changing Na-Li at M4. The most evident variation is observed for the quadrupole splitting of Fe3+ at M2, which increases by approximate to 50% from ferri-clinoholmquistite to magnesio-riebeckite; this suggest that the M2 octahedron in ferri-clinoholmquistite is much closer to the ideal geometry than the M2 octahedron in magnesio-riebeckite. Mossbauer spectra show also a well-defined increase in the Fe2+ quadrupole splitting of the M1 and M3 octahedra, which is attributed to the Na-Li distribution at the B-sites.