International audience | he aim of this study is to bring to light the influence on firewood emissions and performance of several parameters like the moisture content of the fuel, the presence of bark, the caliber of the fuel but also the ignition mode. Many results emerge from this study. First of all, all these parameters significantly impact the emissions of the firewood at the nominal thermal heat output, especially the particles emissions. The presence of bark modifies the particles composition in total carbon. Moreover, the presence of bark induces the emissions of a new family of particles: the nanocrystal. A high moisture of the fuel led to a lower temperature in the combustion chamber. Then, the emissions of unburned gases, like the Volatile Organic Compounds, will considerably increase. The particles emissions and the composition of those particles were also significantly impacted by the moisture of the fuel. Two ignition modes were also studied. It appears that the top-down ignition against the traditional ignition allowed a significant decrease of all the emissions. Nevertheless, the elemental carbon emissions were more important with a top-down ignition. | L’objectif de cette étude est de mettre en évidence l’influence sur les émissions et les performances d’un appareil de différents paramètres, comme l’humidité du bois, la présence d’écorce ou non, le calibre utilisé ainsi que le mode d’allumage. De nombreux résultats ressortent de cette étude. Tout d’abord, tous ces paramètres influent de manière considérable sur les émissions des appareils, notamment les émissions de particules, et ce, même à régime nominal. La présence d’écorce modifie la composition en carbone total des particules totales et implique l’émission d’un nouveau type de particule : les nano-cristaux. Une humidité élevée induit des niveaux de températures plus faibles. Ainsi, les émissions d’imbrûlés gazeux tels que les Composés Organiques Volatils vont augmenter de manière importante. Les émissions de particules, en quantité et en composition chimique, sont aussi significativement impactées par l’humidité du combustible. Deux modes d’allumage ont aussi été étudiés. Il s’avère qu’un allumage inversé permet de réduire de manière significative la globalité des émissions par rapport à un allumage classique. En effet, seules les émissions de Carbone Elémentaire sont plus importantes avec un allumage inversé.

International audience | Polycyclic aromatic hydrocarbon (PAH) concentrations and N, C stable isotope signatures were determined in mosses Hypnum cupressiforme Hedw. from 61 sites of 3 European regions: Île-de-France (France); Navarra (Spain); the Swiss Plateau and Basel area (Switzerland). Total PAH concentrations of 100-700 ng g-1, as well as δ13C values of -32 to -29‰ and δ15N values of -11 to -3‰ were measured. Pearson correlation tests revealed opposite trends between high molecular weight PAH (4-6 aromatic rings) content and δ13C values. Partial Least Square regressions explained the very significant correlations (r > 0.91, p < 0.001) between high molecular weight PAH concentrations by local urban land use (<10 km) and environmental factors such as elevation and pluviometry. Finally, specific correlations between heavy metal and PAH concentrations were attributed to industrial emissions in Switzerland and road traffic emissions in Spain.

no sp Assessment of Nitrogen Fluxes to Air and Water from Site Scale to Continental Scale | absent

International audience | Endocrine disrupting compounds (EDCs) have been found in surface waters worldwide. They are known for exerting adverse effects on animals of many species, including humans. EDCs comprise compounds of anthropogenic origin. They can enter waterways via either discharges from wastewater treatment plant (WWTPs), combined sewer overflows (CSO) or atmospheric deposition. In this work, the fate and removal of four phthalates and two alkylphenols: Diethyl phthalate (DEP), Di-n-Butyl phthalate (DnBP), Butyl Benzyl phthalate (BBP), Di-(2-ethylhexyl) phthalate (DEHP), nonylphenol (NP) and octylphenol (OP) were investigated within a wastewater treatment plant (WWTP) using lamellar clarification and biofiltration. This plant receives about 240,000 m 3 d -1 of wastewater. The whole treatment process comprises: screening, grit removal, primary sedimentation using coagulant and flocculant, followed by biofiltration units. Phthalates and alkylphenols were monitored at three locations, including raw sewage, before primary treatment, decanted effluents, before biological treatment, and final effluents, just before discharge to receiving waters. Nine campaigns were performed in 2011 during different seasons. In raw wastewater, DEHP was the major compound (32.42 to 71.88, median 42.95 μg.l -1), followed by DEP (7.00 to 36.03, median 21.00 μg.l -1) and NP (4.08 to 10.63, median 5.95 μg.l -1). Other compounds averaged few μg.l -1. During the WWTP treatment, DEP becomes major contaminant (0.46 to 6.77, median 2.95 μg.l -1), followed by DEHP (0.95 to 6.43, median 2.30 μg.l -1) and NP (0.31 to 1.36, median 0.63 μg.l -1). Contaminant removal depends on the physicochemical characteristics of the compounds. For example, for lamellar clarification, removal efficiency was found to be strongly dependent to log Kow and, hence, to be highly correlated with their sorption coefficient (Kd). As a consequence, compounds with high log Kow (>3) were removed to a significant extent. DEHP was highly removed by lamellar clarification (68.8%), followed by BBP (61.5%) and NP (51.0%). Besides, DEP (log Kow < 3) was slightly removed (13.8%). During biofiltration, both hydrophilic and hydrophobic compounds were equally eliminated. Therefore, DEP (87.3%), OP (88.0%) and DEHP (81.9%) were mostly removed during biological treatment. © 201 WIT Press.

International audience | The reuse of treated wastewater (TWW) for irrigation is widely applied to alleviate pressure on freshwater resources. However, TWW contains antibiotics that once in soils, can exert selective pressure, promoting the emergence and spread of antimicrobial resistance (AMR) in the environment. Current environmental risk assessments for antibiotic residues rely on indicators such as Predicted No Effect Concentrations (PNECs), usually determined in liquid media. These PNECs aim to predict antibiotic concentrations that may promote resistance in the environment. Given the complexity of soil matrices, few studies have established PNEC values for soil, which likely differ significantly from aquatic environments.To address this gap, we developed a simplified experimental model using soil microcosms irrigated with TWW and the antibiotic sulfamethoxazole (SMX) to estimate threshold concentrations favouring resistance transfer or/and emergence within the soil microbiome. We identified SMX concentrations between 0.01 and 0.1 mg/kgdry soil that likely increased the abundance of sulfonamide resistance genes in soil. A time window of 1 to 7 days post-exposure showed a temporary rise in sul1 and intl1 gene abundance (over 1 log/soil 16S rDNA), the appearance of SMX transformation products, and an increase in some Rhodocyclaceae. After 1.5 months of incubation and complete SMX transformation, the relative abundance of sul1 and intl1 remained about 0.5 log higher than in SMX-free controls and soils with SMX levels below 0.1 mg/kg dry soil. A persistent transformation product, 4-N-glucuronide-SMX, was also observed.Here, the estimated PNEC for SMX in soil, between 0.01 and 0.1 mg/kg, exceeds typical SMX concentrations found in soils exposed to TWW. This may suggest low impact on resistance selection for this compound in the context of TWW exposure. However further studies on other soils, water, and antibiotics need to be conducted to expand our knowledge on soil PNECs.

International audience | Anthropogenic fibers, gathering synthetic fibers, artificial fibers and natural fibers are ubiquitous in the natural environment. Tremendous concentrations of anthropogenic fibers were previously measured in the tropical Saigon River (Vietnam), i.e. a river impacted by textile and apparel industries. In the present study, we want to examine the role of contrasted seasonal variation (e.g., dry and rainy seasons), via the rainfall and monthly water discharges, and of water's physico-chemical conditions on the concentrations of anthropogenic fibers in the surface water. The one year and half monthly survey evidenced that concentrations of anthropogenic fibers varied from 22 to 251 items L-1 and their variations were not related to rainfall, water discharge or abiotic factors. However, their color and length distribution varied monthly suggesting variations in sources and sinks. Based on the 2017 survey, we estimated an annual emission of anthropogenic fibers from the river to the downstream coastal zone of 115e164 × 10 12 items yr-1.

International audience | Sources, pathways and reservoirs of microplastics, plastic particles smaller than 5 mm, remain poorly documented in an urban context. While some studies pointed out wastewater treatment plants as a potential pathway of microplastics, none have focused on the atmospheric compartment. In this work, the atmospheric fallout of microplastics was investigated in two different urban and sub-urban sites. Microplastics were collected continuously with a stainless steel funnel. Samples were then filtered and observed with a stereomicroscope. Fibers accounted for almost all the microplastics collected. An atmospheric fallout between 2 and 355 particles/m2/day was highlighted. Registered fluxes were systematically higher at the urban than at the sub-urban site. Chemical characterization allowed to estimate at 29% the proportion of these fibers being all synthetic (made with petrochemicals), or a mixture of natural and synthetic material. Extrapolation using weight and volume estimates of the collected fibers, allowed a rough estimation showing that between 3 and 10 tons of fibers are deposited by atmospheric fallout at the scale of the Parisian agglomeration every year (2500 km²). These results could serve the scientific community working on the different sources of microplastic in both continental and marine environments.

International audience | The cocktail of pesticides sprayed to protect crops generates a miscellaneous and generalized contamination of water bodies. Sorption, especially on soils, regulates the spreading and persistence of these contaminants. Fine resolution sorption data and knowledge of its drivers are needed to manage this contamination. The aim of this study is to investigate the potential of Mid-Infrared spectroscopy (MIR) to predict and specify the adsorption and desorption of a diversity of pesticides. We constituted a set of 37 soils from French mainland and West Indies covering large ranges of texture, organic carbon, minerals and pH. We measured the adsorption and desorption coefficients of glyphosate, 2,4-dichlorophenoxyacetic acid (2,4-D) and difenoconazole and acquired MIR Lab spectra for these soils. We developed Partial Least Square Regression (PLSR) models for the prediction of the sorption coefficients from the MIR spectra. We further identified the most influencing spectral bands and related these to putative organic and mineral functional groups. The prediction performance of the PLSR models was generally high for the adsorption coefficients Kdads (0.4 < R 2 < 0.9 & RPIQ > 1.8). It was contrasted for the desorption coefficients and related to the magnitude of the desorption hysteresis. The most significant spectral bands in the PLSR differ according to the pesticides indicating contrasted interactions with mineral and organic functional groups. Glyphosate interacts primarily with polar mineral groups (OH) and difenoconazole with hydrophobic organic groups (CH2, C=C, COO-, CO , CO -C). 2,4-D has both positive and negative interactions with these groups. Finally, this work suggests that MIR combined with PLSR is a promising and cost-effective tool. It allows both the prediction of adsorption and desorption parameters and the specification of these mechanisms for a diversity of pesticides including polar active ingredients.

International audience | Mercury pollution is currently a major public health concern, given the adverse effects of mercury on wildlife and humans. Soil plays an essential role in speciation of mercury and its global cycling, while being a habitat for a wide range of terrestrial fauna. Soil fauna, primarily soil-feeding taxa that are in intimate contact with soil pollutants are key contributors in the cycling of soil mercury and might provide relevant indications about soil pollution. We studied the enrichment of various mercury species in the nests and bodies of soil-feeding termites Silvestritermes spp. in French Guiana. Soil-feeding termites are the only social insects using soil as both shelter and food and are major decomposers of organic matter in neotropical forests. Nests of S. minutus were depleted in total and mobile mercury compared to nearby soil. In contrast, they were enriched 17 times in methylmercury. The highest concentrations of methylmercury were found in body of both studied termite species, with mean bioconcentration factors of 58 for S. minutus and 179 for S. holmgreni relative to the soil. The assessment of the body distribution of methylmercury in S. minutus showed concentrations of 221 ng g−1 for the guts and even higher for the gut-free carcasses (683 ng g−1), suggesting that methylmercury is not confined to the gut where it was likely produced, but rather stored in various tissues. This enrichment in the most toxic form of Hg in termites may be of concern on termite predators and the higher levels in the food chain that may be endangered through prey-to-predator transfers and bioaccumulation. Soil-feeding termites appear to be promising candidates as bio-indicators of mercury pollution in soils of neotropical rainforest ecosystems.

International audience | Both macroplastic and microplastic contamination levels were assessed for the first time in a tropical river estuary system, i.e. the Saigon River, that traverses a developing South East Asian megacity, i.e. Ho Chi Minh City, Vietnam. The analysis of floating debris collected daily on the Nhieu Loc - Thi Nghe canal by the municipal waste management service shows that the plastic mass percentage represents 11-43%, and the land-based plastic debris entering the river was estimated from 0.96 to 19.91 g inhabitant-1d-1, namely 350 to 7270 g inhabitant-1yr-1. Microplastics were assessed in the Saigon River and in four urban canals by sampling bulk water for anthropogenic fiber analysis and 300 μm mesh size plankton net exposition for fragment analysis. Fibers and fragments are highly concentrated in this system, respectively 172,000 to 519,000 items m-3and 10 to 223 items m-3. They were found in various colors and shapes with smallest size and surface classes being predominant. The macroplastics and fragments were mainly made of polyethylene and polypropylene while the anthropogenic fibers were mainly made of polyester. The relation between macroplastic and microplastic concentrations, waste management, population density and water treatment are further discussed.