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Development of an inorganic and organic aerosol model (Chimere2017β v1.0) : seasonal and spatial evaluation over Europe
No full textInternational audienceA new aerosol module was developed and integrated in the air quality model CHIMERE. Developments include an update of biogenic emissions and of the inorganic thermodynamic model ISORROPIA, revision of wet deposition processes and of the algorithms of condensation/evaporation and coagulation and the implementation of the SOA mechanism H2O and the thermodynamic model SOAP. Concentrations of particles over Europe were simulated by the model for the year 2013. Model concentrations were compared to the EMEP program observations and other observations available in the EBAS database to evaluate the performances of the model. Performances were determined for several components of particles (sea salts, sulfate, ammonium, nitrate, organic aerosol) with a seasonal and regional analysis of results. The model gives good performances in general. For sea salts, the model succeeds in reproducing the seasonal evolution of concentrations for Western and Central Europe. For sulfate, except for an overestimation of sulfate in Northern Europe, modeled concentrations are close to observations with a good seasonal evolution of concentrations. For organic aerosol, the model performs well for stations with strong modeled biogenic SOA concentrations. However, the model strongly overestimates ammonium nitrate concentrations during late autumn (possibly due to problems in the temporal evolution of emissions) and strongly underestimates SOA concentrations over most of stations (especially in the Northern half of Europe). This underestimation could be due to a lack of anthropogenic SOA in the model. A list of recommended tests and developments to improve the model is also given
How solid phase extraction conditions affect suspect and non-target screening for the evaluation of surface water contamination
No full textInternational audienceIdentifying organic contaminants present in aquatic environments is of major concern for water qualitymonitoring. New analytical and data treatment tools have been developed to meet this challenge. Thesample preparation before analyses is the first crucial step to be optimized before using suspect and nontarget-screening approaches for qualitative evaluations of water pollution by contaminants from variouschemical and usage families.As part of the action of Aquaref (www.aquaref.fr, French reference laboratory for environmentalmonitoring in the Water Framework Directive), different solid phase extraction conditions (SPE, n=3 percondition) were tested towards ultrahigh pressure liquid chromatography hyphenated to high resolutionmass spectrometry (UHPLC-HRMS) analysis. The SPE protocols varied according to the extraction phase(Oasis HLB or multilayer cartridge), the elution solvent (methanol or methanol and dichloromethane)and sample pH (pH 3 or 7). To ensure data quality, blank solvents, extracted blanks and quality control(QC) were also injected. The QC sample corresponds to a pool of 5 μL of each sample extract and isinjected repeatedly throughout the injection sequence to monitor the analytical repeatability.By suspect screening strategy, most of the investigated compounds were found in all SPE extracts. Theresults revealed the presence of contaminants such as pesticides, pharmaceuticals, sweeteners, or anticorrosiveagents. For pesticides, approved (e.g. diuron) and not approved (e.g. terbutryn) compoundswere both detected. Concerning the pharmaceuticals, drugs acting on the nervous system were mostcommon (e.g. oxazepam), as well as betablockers (e.g. metoprolol). The without any a priori non-targetapproach highlighted that the SPE conditions affect the quality and the interpretation of the data. Foreach sample preparation method tested the number of signals (features) detected varies, as does thenumber of signals associated with background noise
Passive sampling in effect-based monitoring of two European rivers - explicability of in vitro toxic potentials by detected chemicals
No full textInternational audienceEU commission Water Framework Directive considers employment of passive sampling and use of effect-based tools in the monitoring of aquatic pollution. A combination of both approaches was used for monitoring of two rivers differing significantly in pollution levels. The Bosna, moderate-sized river in Bosnia-Herzegovina, which is burdened by untreated wastewaters, was sampled by semipermeable passive sampling devices (SPMD) and POCIS samplers. The Danube, the largest river in the EU with relatively low pollution level, was sampled using a mobile dynamic passive sampling device with silicone rubber (SR) and SDB-RPS Empore™ (ED) disc samplers. Both sampler sets consisted of partitioning sampler for non-polar chemicals (SPMD, SR) and adsorption sampler for the polar-ones (POCIS, ED). For the partitioning samplers, concentrations of collected chemicals in river water were derived using dissipation of performance reference compounds. For the adsorption samplers, the sampling rates were either taken from literature (POCIS) or calculated from correlated levels of chemicals that were detected both in adsorption (ED) and partitioning samplers (SR). The samples were analyzed for aryl hydrocarbon-, estrogen- and androgen receptor-mediated effects using in vitro bioassays. The effects were expressed as bioanalytical equivalents (BEQbio) of respective model compounds in water. The BEQbio levels were significantly higher in extracts from POCIS and ED samplers showing that the polar chemicals were responsible for most of the detected effects. Chemical analyses detected 103 and 209 chemicals in the Bosna and the Danube samples, respectively. The passive sampling allowed detection of chemicals at pg/L concentrations. The levels of chemicals with known biological potency for the studied endpoints were used for modeling of bioanalytical equivalents (BEQchem). The comparison of bioassay- and chemical analysis-derived equivalents showed that the detected chemicals explained mostly a low fraction of the BEQbio. Only in the case of estrogenicity in extracts of the samplers collecting polar chemicals, the BEQchem was comparable with the BEQbio levels. Both sampler combinations proved to be suitable for the detection of a large set of chemicals even at trace levels and for the complementary assessment of the biological potentials of the environmental mixtures. The SOLUTIONS Project was supported by the 7th Framework Programme EU (FP7-ENV-2013) with grant agreement no. 603437
A polynomial approximation of the traffic contributions for kriging-based interpolation of urban air quality model
No full textInternational audienceThe European directives for ambient air quality require to assess areas where air pollutant concentrations exceed a regulatory threshold. As the spatial distribution of the pollutant is not exactly known, deterministic atmospheric dispersion models are commonly used to supplement the observational network. To reduce the computational time, the simulations are made on irregular grids, especially in urban areas where the grid is refined close to the roads. An interpolation method is then necessary to map the dispersion model at any location. We propose a new geostatistical approach based on kriging with external drift to distinguish the information along and across the roads. An exponential function is introduced to describe the decrease of the concentrations across the roads. Its series expansion is used to build a set of polynomial auxiliary predictors with unknown coefficients. This framework leads to a drift that is more generic and flexible in the kriging system
Speciation of organic fractions does matter for aerosol source apportionment. Part 2 : Intensive short-term campaign in the Paris area (France)
No full textInternational audienceThe present study aimed at performing PM10 source apportionment, using positive matrix factorization (PMF), based on filter samples collected every 4 h at a sub-urban station in the Paris region (France) during a PM pollution event in March 2015 (PM10 > 50 μg m−3 for several consecutive days). The PMF model allowed to deconvolve 11 source factors. The use of specific primary and secondary organic molecular markers favoured the determination of common sources such as biomass burning and primary traffic emissions, as well as 2 specific biogenic SOA (marine + isoprene) and 3 anthropogenic SOA (nitro-PAHs + oxy-PAHs + phenolic compounds oxidation) factors. This study is probably the first one to report the use of methylnitrocatechol isomers as well as 1-nitropyrene to apportion secondary OA linked to biomass burning emissions and primary traffic emissions, respectively. Secondary organic carbon (SOC) fractions were found to account for 47% of the total OC. The use of organic molecular markers allowed the identification of 41% of the total SOC composed of anthropogenic SOA (namely, oxy-PAHs, nitro-PAHs and phenolic compounds oxidation, representing 15%, 9%, 11% of the total OC, respectively) and biogenic SOA (marine + isoprene) (6% in total). Results obtained also showed that 35% of the total SOC originated from anthropogenic sources and especially PAH SOA (oxy-PAHs + nitro-PAHs), accounting for 24% of the total SOC, highlighting its significant contribution in urban influenced environments. Anthropogenic SOA related to nitro-PAHs and phenolic compounds exhibited a clear diurnal pattern with high concentrations during the night indicating the prominent role of night-time chemistry but with different chemical processes involved
A time dependency prediction of the number of mining subsidence events over a large mining field with uncertainties considerations
No full textInternational audienceOre and mineral extraction via underground mining may induce ground subsidence. Depending on the technique used for excavation, subsidence may be intentional and occur during the extraction or accidental and occur long after the end of mining. This latter case holds for room and pillar mines that were assumed stable at the end of mining but then develop instabilities over the long term. Many regions exists where a large number of mines were excavated and are now abandoned. This is the case in France with the iron-ore field that displays more than 500 abandoned mines over a surface of 140 km2. Mining subsidence can be considered a hazard that leads to ground movement and may damage buildings and the time prediction of subsidence is a key point for risk analysis studies. Prediction may concern a specific mine: What is the probability of collapse of a given mine in the next decade?, or a whole region: What is the probability of observing a given number of subsidences in the next decade ? This second question is investigated in this study..
Investigating the impact of sugar-based surfactants structure on surface tension at critical micelle concentration with structure-property relationships
No full textInternational audienceHypothesis : Surface tension of aqueous solutions of surfactants at their critical micelle concentrations (γCMC), may be quantitatively linked to the surfactant structure using Quantitative Structure Property Relationships (QSPR), all other factors held equal (temperature, presence of additive or salts). Thus, QSPR models can allow improved understanding and quantification of structure-γCMC trends, direct γCMC predictions, and finally help to design renewable substitutes for petroleum-based surfactants. Experiments and methods : A dataset of 70 γCMC of single surfactants at ambient temperature has been gathered from several research papers. Then, descriptors of the whole structure, of polar heads and of alkyl chains of the 70 surfactants were calculated and introduced in multilinear regressions to evidence the most predictive and physically meaningful structure property relationships. Findings : The best model, based on quantum chemical descriptors, achieved a standard error of 2.4 mN/m on an external validation. Simpler models were also achieved based solely on the count of H atoms of the polar head but with prediction error of 2.9 mN/m. Among all identified factors affecting γCMC of sugar-based surfactants (polar head size, alkyl chain length and branching), polar head size was found to exhibit the only effect clearly taken into account by all the models
Non-equilibrium micelles formed by sugar-based surfactants under their Krafft temperature
No full textInternational audienceSugar-based surfactants are renewable substitutes to petroleum-based ones as wetting, dispersing and emulsifying agents in the formulation industry. In a substitution approach, knowledge of physico-chemical properties (e. g. critical micelle concentration – CMC – or minimum surface tension) of the sugar-based surfactant candidates is crucial. However, conflicting physico-chemical properties, such as widely different CMC and surface tensions at CMC (γCMC) can be published about of a given surfactant. Such conflict is illustrated and investigated for two surfactants as case studies, octyl-α-D-glucoside and dodecyl-β-d-glucoside surfactants, which have typical behavior and a Krafft temperature (Tk, which characterizes the solubility of solid surfactant) above room temperature. Tensiometry curves have been measured and discussed for a range of surfactant solutions prepared using different temperature conditions. Complementary methods such as colorimetry, spectrophotometry and dynamic light scattering were used in combination with tensiometry curves. Overall, this study evidences the persistence of out of equilibrium micelles below Tk for a noticeable time on realistic experimental conditions, for both octyl-α-d-glucoside and dodecyl-β-d-glucoside surfactants, as a potential explanation for the conflicting CMC and surface tensions at CMC published in literature. This study evidences that investigating the solubility of the surfactant in water as represented by Tk to complement tensiometric curves analysis is important to confirm the derived CMC and γCMC values
Exploiting ToxCast data to develop Structure-Activity Relationships (QSAR) for molecular initiating events of adverse outcome pathways leading to hepatic steatosis
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Improving the accuracy of personal radiofrequency measurements using a novel body-worn measurement device and comparison with measurements using exposimeters
No full textInternational audienceThe aim of this study is to compare measurement results of a newly developed prototype of a multiband body-worn distributed-exposimeter (BWDM) with two commercially available personal exposimeters (EXPOM and EME SPY 200).We are currently conducting field measurements in various indoor and outdoor microenvironments in Belgium, Spain, France, Netherlands and Switzerland.Our data will allow the comparison of the measurements of the three different exposimeters and will be informativebetter understanding and interpretation of existing epidemiological research results