Preliminary results of the ACTRIS ACSM intercomparison study at the SIRTA French Atmospheric Supersite in the region of Paris

As part of the EU-FP7 ACTRIS program (Aerosols, Clouds, and Trace gases Research InfraStructure Network; http://www.actris.net), 14 of 19 ACSMs (Aerosol Chemical Scpeciation Monitor; Aerodyne Research Inc., MA, USA) have been deployed for long-term observations within background monitoring stations, among which the French SIRTA atmospheric supersite (Site Instrumental de Recherche par Télédétection Atmosphérique; http://sirta.ipsl.fr) located 20km southwest of Paris. In order to have homogenous quality-controlled ACSM datasets at an European scale, an intercomparison study was conducted from 15 Nov. to 2 Dec. 2013 at the SIRTA station. The real-time mass concentrations and chemical composition (Organic, nitrate, sulfate, ammonium) of nonrefractory submicronic aerosols (NR-PM1) measured by the ACSMs were compared providing new insights on the precision of this instrument. Accuracy of these measurements was then evaluated with various co-located instruments (TEOM-FDMS, SMPS, OPC, OC-EC Sunset Field analyzer, PILS-IC, HR-ToF-AMS, aethalometers, nephelometers, filter sampling). Preliminary results of this significant intercomparison stduy are presented which compare ACSM measurement precision, accuracy and validity of source apportionment data

Sharp Images Detection for Microscope Pollen Slides Observation

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Temporal Variability and Geographical Origins of Airborne Pollen Grains Concentrations from 2015 to 2018 at Saclay, France

International audienceThe study of the origin and dispersion processes associated with airborne pollen grains are important to understand due to their impacts on health. In this context, a Hirst-type spore trap was utilized over the period 2015-2018 to monitor ambient pollen grains at Saclay, France, a receptor site influenced by both clean air masses originating from the Atlantic Ocean and polluted air masses under anticyclonic conditions. The objective of this work was to use ZeFir (a user-friendly, software tool recently-developed to investigate the geographical origin and point sources of atmospheric pollution) as a method to analyse total and allergenic airborne pollen grain concentrations. Strong interannual variability was exhibited for the total pollen grains concentrations and it was determined that this was mainly driven by Betulaceae pollen, with a general increasing trend displayed. The start of the pollen season was seen to be triggered by particular synoptic conditions after a period of dormancy and two maximums were displayed, one in April and a second in June. Results from the ZeFir tool, fed with on-site hourly meteorological and pollen measurements, demonstrate that the dominant pollen grains inputs to Saclay are favoured by non-prevailing winds originating from East and North in association with dry air, moderate winds, mild temperature and enhanced insolation

Comparison of 14 ACSMs and co-located real-time aerosol instruments at the SIRTA French Atmospheric Supersite in the region of Paris (France)

International audienceAs part of the EU-FP7 ACTRIS program (Aerosols, Clouds, and Trace gases Research InfraStructure Network), European monitoring stations have been equipped with innovative real-time measuring techniques. Among those, the ACSM (Aerosol Chemical Speciation Monitor; Aerodyne Res. Inc., Ng et al., 2011) is a powerful technique for the determination of the chemical mass composition of non-refractory submicron particles (NR-PM1) and the identification of PM emission sources. Given its relatively recent development, the firstever ACSM intercomparison exercise was conducted, consisting of 14 ACSMs (including 1 ToF-ACSM) conducted sampling together from 15 Nov. to 2 Dec. 2013 at the French SIRTA atmospheric supersite located in the region of Paris. This exercise allowed assessment of ACSM performance and comparability in ambient conditions characterized by variable contributions of different emission sources such as road traffic and biomass burning

Automatic Pollen Grains Counter

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Characterization of particulate and gaseous pollutants from a French dairy and sheep farm

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Étude des composés organiques volatils biogéniques émis par une forêt méditerranéenne

International audienceVolatile organic compounds (VOCs) are key components in atmospheric chemistry. On a global scale, biogenic VOCs (BVOCs) constitute approximately 90 % of global VOC emissions. They participate in photochemical reactions and thus play a major role in the formation of tropospheric ozone and secondary organic aerosols. However, the impact of BVOCs on air quality is still characterized by large uncertainties, partly because emissions are not well quantified. As part of the Canopee project, a field campaign took place at the Oak Observatory of the Observatoire de Haute-Provence (O3HP), with the aim of quantifying BVOC emissions from a forest representative of the Mediterranean region.Measurements of concentrations and emission fluxes were carried out from the branch to the canopy level. Branch-level measurements enabled a better understanding of the environmental and physiological parameters of the plant that govern emissions. Fluxmeasurements above the top of the canopy enabled us to quantify the outgoing flow of BVOCs from the forest entering the troposphere. The results showed that white oak is a strong emitter of isoprene but a weak emitter ofmethanol andmonoterpenes. Isoprene emission fluxes were estimated at 7.2 mg m-2 h-1 (under standard conditions of temperature and solar radiation), thusmaking theO3HP forest one of the strongest isoprene emitting ecosystems worldwideLes composés organiques volatils (COV) sont des composants clés en chimie atmosphérique. À l'échelle globale, on estime que 10 % ont une origine anthropique et 90 % une origine biogénique. L'impact des COV biogéniques (COVB), notamment sur la formation d'ozone (polluant et gaz à effet de serre) et d'aérosols organiques secondaires (à impact sanitaire et radiatif) en font un objet d'étude d'actualité. Toutefois, l'importance de l'impact des COVB sur la qualité de l'air est encore marquée par de larges incertitudes, en partie parce que les émissions demeurent mal quantifiées. Dans le cadre du projet Canopee, une campagne de mesure a eu lieu à l'O3HP, Observatoire du chêne pubescent à l'OHP (Observatoire de Haute-Provence), avec pour objectif de quantifier les émissions de COVB issues d'une forêt représentative de la région méditerranéenne. Des mesures de concentrations et de flux d'émission ont été réalisées à plusieurs échelles : de la branche à la canopée. L'étude des émissions à l'échelle du de la plante a permis une meilleure compréhension des paramètres environnementaux et physiologiques qui régissent les émissions. Les flux de COVB sortant de la canopée et exportés vers la troposphère ont pu être quantifiés. Les résultats montrent que le chêne blanc est un fort émetteur d'isoprène, mais un faible émetteur de méthanol et de monoterpènes. À l'échelle de la forêt, les flux d'émissions d'isoprène ont été estimés à 7,2 mg m-2 h-1 en conditions standard, ce qui fait de l'O3HP un des écosystèmes les plus fortement émetteurs d'isoprène à travers le monde

First year of real-time VOC measurements at the SIRTA facility (Paris region, France): diurnal and seasonal variabilities, impact of lockdowns on air quality

International audienceVolatile Organic Compounds (VOCs) have direct influences on air quality and climate. They also play a key role in atmospheric chemistry, as they are precursors of secondary pollutants, such as ozone (O<sub>3</sub>) and secondary organic aerosols (SOA).Long-term datasets of in-situ atmospheric measurements are crucial to characterize the variability of atmospheric chemical composition. Online and continuous measurements of O<sub>3</sub>, NO<sub>x</sub> and aerosols have been achieved at the SIRTA-ACTRIS facility (Paris region, France), since 2012. Regarding VOCs, they have been measured there for several years thanks to bi-weekly samplings followed by offline Gas Chromatography analysis. However, this method doesn’t provide a good representation of the temporal variability of VOC concentrations. To tackle this issue, online VOC measurements using a Proton-Transfer-Reaction Quadrupole Mass-Spectrometer (PTR-Q-MS) have been started in January 2020.The dataset acquired during the first year of online VOC measurements is analyzed, which gives insights on VOC seasonal variability. The additional long-term datasets obtained from co-located measurements (O<sub>3</sub>, NO<sub>x</sub>, aerosol physical and chemical properties, meteorological parameters) are also used for the sake of this study.Due to Covid-19 pandemic, the year 2020 notably comprised a total lockdown in France in Spring, and a lighter one in Autumn. Therefore, a focus can be made on the impact of these lockdowns on the VOC variability and sources. To this end, the diurnal cycles of VOCs considered markers for anthropogenic sources are carefully investigated. Results notably indicate that markers for traffic and wood burning sources behave quite differently during the Spring lockdown in comparison to the other periods. A source apportionment analysis using positive matrix factorization allows to further document the seasonal variability of VOC sources and the impacts on air quality associated with the lockdown measures

Variability and Geographical Origin of Five Years Airborne Fungal Spore Concentrations Measured at Saclay, France from 2014 to 2018

International audienceAirborne fungal spores (AFS) represent the major fraction of primary biological aerosol particles (PBAPs), and they are studied worldwide largely due to their important role within the Earth system. They have an impact on climate and human health, and they contribute to the propagation of diseases. As their presence in the air depends largely on studied ecosystems, a spore trap was used to monitor their atmospheric concentrations from 2014 to December 2018 in Saclay, a suburban area in the megacity of Paris. The main objective of this work was: (1) to understand the atmospheric variability of AFS in relation to different variables such as meteorological factors, agricultural practice, and (2) to identify their geographical origin by using a source receptor model. During our period of observation, 30 taxa have been identified under a light microscope. In order of importance, Ascospores, Cladosporium, Basidiospores, Tilletiopsis, Alternaria were found to be the most abundant types respectively (50.8%, 33.6%, 7.6%, 1.8%, and 1.3%) accounting for 95% of the atmospheric concentrations. We observed a general decrease associated with a strong interannual variability. A bimodal seasonal cycle was identified with a first maximum in July and a second in October. The main parameters driving the atmospheric concentration are temperature and precipitation. The daily variability is strongly activated by successive periods of hot weather and rainfall, multiplying the concentration by a factor of 1000 in less than 12 hours. Results from the source receptor model ZeFir point out unambiguous different origins of AFS due to specific sources impacting the observation site. Our study also indicated that a hydrological stress has a direct effect on the daily concentrations. This last point should be taken into account for every stressed ecosystem studied in a global warming context. This is particularly important for Mediterranean areas where water is a key control of the growth and dispersion of fungal spores