Sainte-Foy-lès-Lyon, France
Sainte-Foy-lès-Lyon, France
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Baudic A.,French Climate and Environment Sciences Laboratory | Gros V.,French Climate and Environment Sciences Laboratory | Sauvage S.,Sage | Locoge N.,Sage | And 13 more authors.
Atmospheric Chemistry and Physics | Year: 2016

Within the framework of air quality studies at the megacity scale, highly time-resolved volatile organic compound (C2-C8) measurements were performed in downtown Paris (urban background sites) from January to November 2010. This unique dataset included non-methane hydrocarbons (NMHCs) and aromatic/oxygenated species (OVOCs) measured by a GC-FID (gas chromatograph with a flame ionization detector) and a PTR-MS (proton transfer reaction - mass spectrometer), respectively. This study presents the seasonal variability of atmospheric VOCs being monitored in the French megacity and their various associated emission sources. Clear seasonal and diurnal patterns differed from one VOC to another as the result of their different origins and the influence of environmental parameters (solar radiation, temperature). Source apportionment (SA) was comprehensively conducted using a multivariate mathematical receptor modeling. The United States Environmental Protection Agency's positive matrix factorization tool (US EPA, PMF) was used to apportion and quantify ambient VOC concentrations into six different sources. The modeled source profiles were identified from near-field observations (measurements from three distinct emission sources: inside a highway tunnel, at a fireplace and from a domestic gas flue, hence with a specific focus on road traffic, wood-burning activities and natural gas emissions) and hydrocarbon profiles reported in the literature. The reconstructed VOC sources were cross validated using independent tracers such as inorganic gases (NO, NO2, CO), black carbon (BC) and meteorological data (temperature). The largest contributors to the predicted VOC concentrations were traffic-related activities (including motor vehicle exhaust, 15g% of the total mass on the annual average, and evaporative sources, 10g%), with the remaining emissions from natural gas and background (23g%), solvent use (20g%), wood-burning (18g%) and a biogenic source (15g%). An important finding of this work is the significant contribution from wood-burning, especially in winter, where it could represent up to ∼50% of the total mass of VOCs. Biogenic emissions also surprisingly contributed up to ∼30% in summer (due to the dominating weight of OVOCs in this source). Finally, the mixed natural gas and background source exhibited a high contribution in spring (35g%, when continental air influences were observed) and in autumn (23g%, for home heating consumption). © Author(s) 2016.

Zhang Q.J.,University Paris Est Creteil | Beekmann M.,University Paris Est Creteil | Drewnick F.,Max Planck Institute for Chemistry | Freutel F.,Max Planck Institute for Chemistry | And 25 more authors.
Atmospheric Chemistry and Physics | Year: 2013

Simulations with the chemistry transport model CHIMERE are compared to measurements performed during the MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation) summer campaign in the Greater Paris region in July 2009. The volatility-basis-set approach (VBS) is implemented into this model, taking into account the volatility of primary organic aerosol (POA) and the chemical aging of semi-volatile organic species. Organic aerosol is the main focus and is simulated with three different configurations with a modified treatment of POA volatility and modified secondary organic aerosol (SOA) formation schemes. In addition, two types of emission inventories are used as model input in order to test the uncertainty related to the emissions. Predictions of basic meteorological parameters and primary and secondary pollutant concentrations are evaluated, and four pollution regimes are defined according to the air mass origin. Primary pollutants are generally overestimated, while ozone is consistent with observations. Sulfate is generally overestimated, while ammonium and nitrate levels are well simulated with the refined emission data set. As expected, the simulation with non-volatile POA and a single-step SOA formation mechanism largely overestimates POA and underestimates SOA. Simulation of organic aerosol with the VBS approach taking into account the aging of semi-volatile organic compounds (SVOC) shows the best correlation with measurements. High-concentration events observed mostly after long-range transport are well reproduced by the model. Depending on the emission inventory used, simulated POA levels are either reasonable or underestimated, while SOA levels tend to be overestimated. Several uncertainties related to the VBS scheme (POA volatility, SOA yields, the aging parameterization), to emission input data, and to simulated OH levels can be responsible for this behavior. Despite these uncertainties, the implementation of the VBS scheme into the CHIMERE model allowed for much more realistic organic aerosol simulations for Paris during summertime. The advection of SOA from outside Paris is mostly responsible for the highest OA concentration levels. During advection of polluted air masses from northeast (Benelux and Central Europe), simulations indicate high levels of both anthropogenic and biogenic SOA fractions, while biogenic SOA dominates during periods with advection from Southern France and Spain. © Author(s) 2013.

Bressi M.,French Climate and Environment Sciences Laboratory | Bressi M.,French Environment and Energy Management Agency | Sciare J.,French Climate and Environment Sciences Laboratory | Ghersi V.,AIRPARIF | And 8 more authors.
Atmospheric Chemistry and Physics | Year: 2013

Studies describing the chemical composition of fine aerosol (PM2.5) in urban areas are often conducted for a few weeks only and at one sole site, giving thus a narrow view of their temporal and spatial characteristics. This paper presents a one-year (11 September 2009-10 September 2010) survey of the daily chemical composition of PM2.5 in the region of Paris, which is the second most populated "Larger Urban Zone" in Europe. Five sampling sites representative of suburban (SUB), urban (URB), northeast (NER), northwest (NWR) and south (SOR) rural backgrounds were implemented. The major chemical components of PM2.5 were determined including elemental carbon (EC), organic carbon (OC), and the major ions. OC was converted to organic matter (OM) using the chemical mass closure methodology, which leads to conversion factors of 1.95 for the SUB and URB sites, and 2.05 for the three rural ones. On average, gravimetrically determined PM2.5 annual mass concentrations are 15.2, 14.8, 12.6, 11.7 and 10.8 μg m-3 for SUB, URB, NER, NWR and SOR sites, respectively. The chemical composition of fine aerosol is very homogeneous at the five sites and is composed of OM (38-47%), nitrate (17-22%), non-sea-salt sulfate (13-16%), ammonium (10-12%), EC (4-10%), mineral dust (2-5%) and sea salt (3-4%). This chemical composition is in agreement with those reported in the literature for most European environments. On an annual scale, Paris (URB and SUB sites) exhibits its highest PM2.5 concentrations during late autumn, winter and early spring (higher than 15 μg m-3 on average, from December to April), intermediates during late spring and early autumn (between 10 and 15 μg m-3 during May, June, September, October, and November) and the lowest during summer (below 10 μg m-3 during July and August). PM levels are mostly homogeneous on a regional scale, during the whole project (e.g. for URB plotted against NER sites: slope 1.06, r 2=0.84, n=330), suggesting the importance of mid-or long-range transport, and regional instead of local scale phenomena. During this one-year project, two thirds of the days exceeding the PM2.5 2015 EU annual limit value of 25 μg m-3 were due to continental import from countries located northeast, east of France. This result questions the efficiency of local, regional and even national abatement strategies during pollution episodes, pointing to the need for a wider collaborative work with the neighbouring countries on these topics. Nevertheless, emissions of local anthropogenic sources lead to higher levels at the URB and SUB sites compared to the others (e.g. 26% higher on average at the URB than at the NWR site for PM2.5, during the whole campaign), which can even be emphasised by specific meteorological conditions such as low boundary layer heights. OM and secondary inorganic species (nitrate, non-sea-salt sulfate and ammonium, noted SIA) are mainly imported by mid-or long-range transport (e.g. for NWR plotted against URB sites: slope 0.79,r2=0.72, n=335 for OM, and slope 0.91,r2=0.89, n=335 for SIA) whereas EC is primarily locally emitted (e.g. for SOR plotted against URB sites: slope 0.27;r2=0.03; n=335). This database will serve as a basis for investigating carbonaceous aerosols, metals as well as the main sources and geographical origins of PM in the region of Paris. © 2013 Author(s).

Lopez M.,French Climate and Environment Sciences Laboratory | Schmidt M.,French Climate and Environment Sciences Laboratory | Delmotte M.,French Climate and Environment Sciences Laboratory | Colomb A.,French National Center for Scientific Research | And 9 more authors.
Atmospheric Chemistry and Physics | Year: 2013

Measurements of the mole fraction of the CO2 and its isotopes were performed in Paris during the MEGAPOLI winter campaign (January-February 2010). Radiocarbon (14CO2) measurements were used to identify the relative contributions of 77% CO2 from fossil fuel consumption (CO2ff from liquid and gas combustion) and 23% from biospheric CO2 (CO2 from the use of biofuels and from human and plant respiration: CO2bio). These percentages correspond to average mole fractions of 26.4 ppm and 8.2 ppm for CO2ff and CO2bio, respectively. The 13CO2 analysis indicated that gas and liquid fuel contributed 70% and 30%, respectively, of the CO2 emission from fossil fuel use. Continuous measurements of CO and NOx and the ratios CO/CO2ff and NOx/CO2ff derived from radiocarbon measurements during four days make it possible to estimate the fossil fuel CO2 contribution over the entire campaign. The ratios CO/CO2ff and NOx/CO2ff are functions of air mass origin and exhibited daily ranges of 7.9 to 14.5 ppb ppm-1 and 1.1 to 4.3 ppb ppm-1, respectively. These ratios are consistent with different emission inventories given the uncertainties of the different approaches. By using both tracers to derive the fossil fuel CO2, we observed similar diurnal cycles with two maxima during rush hour traffic. © 2013 Author(s).

Ammoura L.,CEA Saclay Nuclear Research Center | Xueref-Remy I.,CEA Saclay Nuclear Research Center | Gros V.,CEA Saclay Nuclear Research Center | Baudic A.,CEA Saclay Nuclear Research Center | And 7 more authors.
Atmospheric Chemistry and Physics | Year: 2014

Measurements of CO2, CO, NOx and selected Volatile Organic Compounds (VOCs) mole fractions were performed continuously during a 10-day period in the Guy Môquet tunnel in Thiais, a peri-urban area about 15 km south of the centre of Paris, between 28 September and 8 October 2012. This data set is used here to identify the characteristics of traffic-emitted CO2 by evaluating its ratios to co-emitted species for the first time in the Paris region. High coefficients of determination (r2> 0.7) are observed between CO2 and certain compounds that are characteristic of the traffic source (CO, NOx, benzene, xylenes and acetylene). Weak correlations (2 0.2) are found with species such as propane, n-butane and i-butane that are associated with fuel evaporation, an insignificant source for CO2. To better characterise the traffic signal we focus only on species that are well-correlated with CO2 and on rush-hour periods characterised by the highest traffic-related mole fractions. From those mole fractions we remove the nighttime-average weekday mole fraction obtained for each species that we infer to be the most appropriate background signal for our study. Then we calculate observed δspecies δCO2 ratios, which we compare with the ones provided by the 2010 bottom-up high-resolved regional emission inventory from Airparif (the association in charge of monitoring the air quality in Île-de-France), focusing on local emission data for the specific road of the tunnel. We find an excellent agreement (2%) between the local inventory emission CO2 ratio and our observed CO2 ratio. Former tunnel experiments carried out elsewhere in the world provided observed CO2 ratios that differ from 49 to 592% to ours. This variability can be related to technological improvement of vehicles, differences in driving conditions, and fleet composition. We also find a satisfactory agreement with the Airparif inventory for n-propylbenzene, n-pentane and xylenes to CO2 ratios. For most of the other species, the ratios obtained from the local emission inventory overestimate the observed ratios to CO2 by 34 to more than 300%. However, the emission ratios of NOx, o-xylene and i-pentane are underestimated by 30 to 79%. One main cause of such high differences between the inventory and our observations is likely the obsolete feature of the VOCs speciation matrix of the inventory that has not been updated since 1998, although law regulations on some VOCs have occurred since that time. Our study bears important consequences, discussed in the conclusion, for the characterisation of the urban CO2 plume and for atmospheric inverse modelling of urban CO2 emissions. © Author(s) 2014.

Bressi M.,CEA Saclay Nuclear Research Center | Bressi M.,French Environment and Energy Management Agency | Sciare J.,CEA Saclay Nuclear Research Center | Ghersi V.,AIRPARIF | And 11 more authors.
Atmospheric Chemistry and Physics | Year: 2014

The present study aims at identifying and apportioning fine aerosols to their major sources in Paris (France) - the second most populated "larger urban zone" in Europe - and determining their geographical origins. It is based on the daily chemical composition of PM2.5 examined over 1 year at an urban background site of Paris (Bressi et al., 2013). Positive matrix factorization (EPA PMF3.0) was used to identify and apportion fine aerosols to their sources; bootstrapping was performed to determine the adequate number of PMF factors, and statistics (root mean square error, coefficient of determination, etc.) were examined to better model PM2.5 mass and chemical components. Potential source contribution function (PSCF) and conditional probability function (CPF) allowed the geographical origins of the sources to be assessed; special attention was paid to implement suitable weighting functions. Seven factors, namely ammonium sulfate (A.S.)-rich factor, ammonium nitrate (A.N.)-rich factor, heavy oil combustion, road traffic, biomass burning, marine aerosols and metal industry, were identified; a detailed discussion of their chemical characteristics is reported. They contribute 27, 24, 17, 14, 12, 6 and 1% of PM2.5 mass (14.7 μ1/4g mg -3) respectively on the annual average; their seasonal variability is discussed. The A.S.- and A.N.-rich factors have undergone mid- or long-range transport from continental Europe; heavy oil combustion mainly stems from northern France and the English Channel, whereas road traffic and biomass burning are primarily locally emitted. Therefore, on average more than half of PM2.5 mass measured in the city of Paris is due to mid- or long-range transport of secondary aerosols stemming from continental Europe, whereas local sources only contribute a quarter of the annual averaged mass. These results imply that fine-aerosol abatement policies conducted at the local scale may not be sufficient to notably reduce PM2.5 levels at urban background sites in Paris, suggesting instead more coordinated strategies amongst neighbouring countries. Similar conclusions might be drawn in other continental urban background sites given the transboundary nature of PM2.5 pollution. © Author(s) 2014.

Sciare J.,French Climate and Environment Sciences Laboratory | D'Argouges O.,French Climate and Environment Sciences Laboratory | Zhang Q.J.,University Paris Diderot | Sarda-Esteve R.,French Climate and Environment Sciences Laboratory | And 4 more authors.
Atmospheric Chemistry and Physics | Year: 2010

Hourly concentrations of inorganic salts (ions) and carbonaceous material in fine aerosols (aerodynamic diameter, A.D. <2.5 μm) have been determined experimentally from fast measurements performed for a 3-week period in spring 2007 in Paris (France). The sum of these two chemical components (ions and carbonaceous aerosols) has shown to account for most of the fine aerosol mass (PM2.5). This time-resolved dataset allowed investigating the factors controlling the levels of PM2.5 in Paris and showed that polluted periods with PM2.5 > 15 μg mg-3 were characterized by air masses of continental (North-Western Europe) origin and chemical composition made by 75% of ions. By contrast, periods with clean marine air masses have shown the lowest PM2.5 concentrations (typically of about 10 μg mg-3); carbonaceous aerosols contributing for most of this mass (typically 75%). In order to better discriminate between local and continental contributions to the observed chemical composition and concentrations of PM2.5 over Paris, a comparative study was performed between this time-resolved dataset and the outputs of a chemistry transport model (CHIMERE), showing a relatively good capability of the model to reproduce the time-limited intense maxima observed in the field for PM2.5 and ion species. Different model scenarios were then investigated switching off local and European (North-Western and Central) emissions. Results of these scenarios have clearly shown that most of the ions observed over Paris during polluted periods, were either transported or formed in-situ from gas precursors transported from Northern Europe. On the opposite, long-range transport from Europe appeared to weakly contribute to the levels of carbonaceous aerosols observed over Paris. The model failed to properly account for the concentration levels and variability of secondary organic aerosols (SOA) determined experimentally by the EC-tracer method. The abundance of SOA (relatively to organic aerosol, OA) was as much as 75%, showing a weak dependence on air masses origin. Elevated SOA/OA ratios were also observed for air masses having residence time above ground of less than 10 h, suggesting intense emissions and/or photochemical processes leading to rapid formation of secondary organic aerosols. © 2010 Author(s).

Petetin H.,University Paris Est Creteil | Beekmann M.,University Paris Est Creteil | Sciare J.,French Climate and Environment Sciences Laboratory | Bressi M.,French Climate and Environment Sciences Laboratory | And 3 more authors.
Geoscientific Model Development | Year: 2014

Aerosol simulations in chemistry transport models (CTMs) still suffer from numerous uncertainties, and diagnostic evaluations are required to point out major error sources. This paper presents an original approach to evaluate CTMs based on local and imported contributions in a large megacity rather than urban background concentrations. The study is applied to the CHIMERE model in the Paris region (France) and considers the fine particulate matter (PM 2.5) and its main chemical constituents (elemental and organic carbon, nitrate, sulfate and ammonium), for which daily measurements are available during a whole year at various stations (PARTICULES project). Back-trajectory data are used to locate the upwind station, from which the concentration is identified as the import, the local production being deduced from the urban concentration by subtraction. Uncertainties on these contributions are quantified. Small biases in urban background PM2.5 simulations (bias of +16%) hide significant error compensations between local and advected contributions, as well as in PM2.5 chemical compounds. In particular, winter time organic matter (OM) imports appear strongly underestimated while local OM and elemental carbon (EC) production is overestimated all along the year. Erroneous continental wood burning emissions and missing secondary organic aerosol (SOA) pathways may explain errors on advected OM, while the carbonaceous compounds is likely to be related to errors in emissions and dynamics. A statistically significant local formation of nitrate is also highlighted from observations, but missed by the model. Together with the overestimation of nitrate imports, it leads to a bias of +51% on the local PM2.5 contribution. Such an evaluation finally gives more detailed insights on major gaps in current CTMs on which future efforts are needed. © Author(s) 2014.

Poulakis E.,University of Crete | Theodosi C.,University of Crete | Bressi M.,CEA Saclay Nuclear Research Center | Sciare J.,CEA Saclay Nuclear Research Center | And 3 more authors.
Environmental Science and Pollution Research | Year: 2015

A variety of mineral components (Al, Fe) and trace metals (V, Cr, Mn, Ni, Cu, Zn, Cd, Pb) were simultaneously measured in PM2.5 and PM10 fractions at three different locations (traffic, urban, and suburban) in the Greater Paris Area (GPA) on a daily basis throughout a year. Mineral species and trace metal levels measured in both fractions are in agreement with those reported in the literature and below the thresholds defined by the European guidelines for toxic metals (Cd, Ni, Pb). Size distribution between PM2.5 and PM10 fractions revealed that mineral components prevail in the coarse mode, while trace metals are mainly confined in the fine one. Enrichment factor analysis, statistical analysis, and seasonal variability suggest that elements such as Mn, Cr, Zn, Fe, and Cu are attributed to traffic, V and Ni to oil combustion while Cd and Pb to industrial activities with regional origin. Meteorological parameters such as rain, boundary layer height (BLH), and air mass origin were found to significantly influence element concentrations. Periods with high frequency of northern and eastern air masses (from high populated and industrialized areas) are characterized by high metal concentrations. Finally, inner city and traffic emissions were also evaluated in PM2.5 fraction. Significant contributions (>50 %) were measured in the traffic site for Mn, Fe, Cr, Zn, and Cu, confirming that vehicle emissions contribute significantly to their levels, while in the urban site, the lower contributions (18 to 33 %) for all measured metals highlight the influence of regional sources on their levels. © 2015, Springer-Verlag Berlin Heidelberg.

Sanchez O.,AIRPARIF | Dugay F.,AIRPARIF | Pernot P.,AIRPARIF
HARMO 2010 - Proceedings of the 13th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes | Year: 2010

In the Ile de France region, road traffic is of major concern with regard to air pollution: EU air quality limit values are exceeded for several pollutants like NO2, PM10 and even benzene at roadside along busy streets. In the frame of the Duplex A86 tunnel project which will allow completing the A86 beltway around Paris AIRPARIF has been assigned by the French state to assess air quality outside the tunnel. The first section of the tunnel (5 km long) between Rueil-Malmaison and Vaucresson was put into service the 26th of June 2009, the second one between Vaucresson and Versailles, 6 km long will be opened to traffic in almost 2 years. In order to fulfil this objective, an air quality survey system has been set-up using 2 types of tools. First, intensive measurement campaigns have been set up around the tunnel for background impact assessment with special focus around ventilation stacks and ends of the tunnel. Secondly, a modelling system integrating background concentrations from a regional air quality system based on the CHIMERE model (IPSL/LISA/INERIS) coupled with the shortrange dispersion model CALPUFF (ASG from TRC) has been set up in order to provide near real-time air quality information for the main road traffic pollutants on a 200 km2 area in the western part of the agglomeration of Paris. During the set-up phase, the Ggaussian air dispersion model ADMS-urban (CERC) has also been tested. The concentration maps for NO2, PM10, PM2.5, benzene and CO are accessible via the following web site The complete report concerning the evaluation of the modelling system is available in French on the AIRPARIF website.

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