A5036064307- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Air Quality Monitoring and Forecasting
- Air Quality and Health Impacts
- Catalytic Processes in Materials Science
- Spectroscopy and Laser Applications
- Polar Research and Ecology
- Advanced Chemical Sensor Technologies
- Ocean Acidification Effects and Responses
- Atmospheric aerosols and clouds
- Mass Spectrometry Techniques and Applications
- Isotope Analysis in Ecology
- Advanced Chemical Physics Studies
- Industrial Gas Emission Control
- Marine and coastal ecosystems
- Free Radicals and Antioxidants
- Cryospheric studies and observations
- Plant responses to elevated CO2
- Photochemistry and Electron Transfer Studies
- Astro and Planetary Science
- Catalysis and Oxidation Reactions
- Lichen and fungal ecology
- Surface and Thin Film Phenomena
- Neural Networks and Applications
Université d'Orléans
2013-2025
Centre National de la Recherche Scientifique
2012-2025
Laboratoire de Physique et Chimie de l’Environnement et de l’Espace
2013-2025
Laboratoire Chimie de l'Environnement
2013-2019
Sorbonne Université
2009-2017
Laboratoire atmosphères, milieux, observations spatiales
2009-2016
Université de Versailles Saint-Quentin-en-Yvelines
2009-2014
Institut de Combustion Aérothermique Réactivité et Environnement
2007-2012
Institut des Sciences Moléculaires
2009
Institut Pierre-Simon Laplace
2008-2009
Abstract. Nitrous acid measurements were carried out during the MEGAPOLI summer and winter field campaigns at SIRTA observatory in Paris surroundings. Highly variable HONO levels observed campaigns, ranging from 10 ppt to 500 1.7 ppb winter. Significant mixing ratios have also been measured daytime hours, comprised between some tenth of 200 for campaign few 1 campaign. Ancillary measurements, such as NOx, O3, photolysis frequencies, meteorological parameters (pressure, temperature, relative...
Abstract. Chemical Ionisation Mass Spectrometer measurements of hydroxyl radical (OH) and the sum hydroperoxy organic peroxy (HO2+RO2) radicals were conducted during MEGAPOLI summer field campaign at SIRTA observatory near Paris, France, in July 2009. OH showed a typical diurnal variation with averaged daytime maxima values around 5×106 1.2×108 molecule cm−3, respectively. Simultaneously, large number ancillary measurements, such as NOx, O3, HONO, HCHO other VOCs also conducted. These data...
Abstract. Concentrations of OH radicals and the sum peroxy radicals, RO2, were measured in boundary layer for first time on East Antarctic Plateau at Concordia Station (Dome C, 75.10° S, 123.31° E) during austral summer 2011/2012. The median concentrations RO2 3.1 × 106 molecule cm−3 9.9 cm−3, respectively. These values are comparable to those observed South Pole, confirming that elevated oxidative capacity atmospheric found Pole is not restricted but common over high plateau. At Concordia,...
A high-pressure turbulent flow reactor coupled with a chemical ionization mass-spectrometer was used to determine the branching ratio of HO2 + NO reaction: → OH NO2 (1a), HNO3 (1b). The ratio, β = k1b/k1a, derived from measurements “chemically amplified” concentrations and products in presence O2 CO. pressure temperature dependence determined range 72−600 Torr N2 carrier gas between 323 223 K. At each pressure, found increase decrease temperature, becoming less pronounced pressure. In...
The influence of water vapor on the production nitric acid in gas-phase HO(2) + NO reaction was determined at 298 K and 200 Torr using a high-pressure turbulent flow reactor coupled with chemical ionization mass spectrometer. yield HNO(3) found to increase linearly concentration reaching an enhancement factor about 8 [H(2)O] = 4 x 10(17) molecules cm(-3) ( approximately 50% relative humidity). A rate constant value k(1bw) 6 10(-13) cm(3) molecule(-1) s(-1) derived for involving HO(2)xH(2)O...
Abstract. During the austral summer 2011/2012 atmospheric nitrous acid (HONO) was investigated for second time at Concordia site (75°06' S, 123°33' E), located on East Antarctic Plateau, by deploying a long-path absorption photometer (LOPAP). Hourly mixing ratios of HONO measured in December 2011/January 2012 (35 ± 5.0 pptv) were similar to those 2010/January 2011 (30.4 3.5 pptv). The large value ratio remote suggests local source addition weak production from oxidation NO OH radical....
Abstract. Mixing ratios of the atmospheric nitrogen oxides NO and NO2 were measured as part OPALE (Oxidant Production in Antarctic Lands & Export) campaign at Dome C, East Antarctica (75.1° S, 123.3° E, 3233 m), during December 2011 to January 2012. Profiles NOx mixing lower 100 m atmosphere confirm that, contrast South Pole, air chemistry C is strongly influenced by large diurnal cycles solar irradiance a sudden collapse boundary layer early evening. Depth profiles firn suggest that...
Reactions of OH radicals with dimethyl sulfoxide (CH3)2SO (DMSO) (reaction 1) and methane sulfinic acid CH3S(O)OH (MSIA) 2) have been studied at 298 K 200 400 Torr N2 using a newly constructed high-pressure turbulent flow reactor coupled to an ion molecule reaction mass spectrometer. The experimental setup is discussed in detail. reactions DMSO MSIA were found proceed predominant formation SO2, respectively. yields 1 SO2 2 estimated be 0.9 ± 0.2. rate constants k1 = (9 × 10-11 cm3 molecule-1...
The mechanism of the gas-phase OH-initiated oxidation glycolaldehyde (HOCH2CHO) was studied in 233−296 K temperature range using a turbulent flow reactor coupled with chemical ionization mass spectrometer. In presence O2, formaldehyde, CO2, formic acid, and glyoxal were observed at room yields 80, 34, 18, 14%, respectively. Decrease to 233 led significant changes stable products: those formaldehyde decreased 50 4%, respectively, whereas that acid increased 52%. It also found OH + O2 reaction...
A high-pressure turbulent flow reactor coupled with a chemical ionization mass spectrometer was used to investigate the minor channel (1b) producing nitric acid, HNO3, in HO2 + NO reaction for which only one (1a) is known so far: --> OH NO2 (1a), HNO3 (1b). The has been investigated temperature range 223-298 K at pressure of 200 Torr N2 carrier gas. influence water vapor studied 298 K. branching ratio, k1b/k1a, found increase from (0.18(+0.04/-0.06))% (0.87(+0.05/-0.08))% 223 K,...
The mechanism of the gas-phase reaction OH radicals with hydroxyacetone (CH3C(O)CH2OH) was studied at 200 Torr over temperature range 236−298 K in a turbulent flow reactor coupled to chemical ionization mass-spectrometer. product yields and kinetics were measured presence O2 simulate atmospheric conditions. major stable all temperatures is methylglyoxal. However, its yield decreases from 82% 298 49% 236 K. Conversely, formic acetic acids increase about 8% 20%. Other observed products...
Abstract Earth, as a whole, can be considered living organism emitting gases and particles into its atmosphere, in order to regulate own temperature. In particular, oceans may respond climate change by that ultimately will influence cloud coverage. At the global scale, large fraction of aerosol number concentration is formed nucleation gas‐phase species, but this process has never been directly observed above oceans. Here we present, using semicontrolled seawater‐air enclosures, evidence...
Abstract. Through observations of NO, NO2, NOY and O3 in the Rambouillet forest near Paris, France, (as part ACROSS campaign, 2022) we have gained insight into nighttime processes controlling NOX an anthropogenically impacted environment. mixing ratios displayed a strong diel profile at site, which was driven by variable but generally rapid deposition to soil foliar surfaces. The strongly influenced relative humidity, surface resistance uptake, temperature inversion, rate entrainment from...
Abstract. The formation, abundance and distribution of organic nitrates are relevant for determining the production efficiency resident mixing ratios tropospheric ozone (O3) on both regional global scales. Here we investigate effect applying recently measured direct chemical methyl nitrate (CH3ONO2) during NOx recycling involving methyl-peroxy radical CH3ONO2 perturbations introduced towards O3 using TM5 chemistry transport model. By comparisons against numerous observations, show that...
Abstract. Variations in the stable oxygen isotope composition of atmospheric nitrate act as novel tools for studying oxidative processes taking place troposphere. They provide both qualitative and quantitative constraints on pathways determining fate nitrogen oxides (NO + NO2 = NOx). The unique distinctive 17O excess (Δ17O δ17O − 0.52 × δ18O) ozone, which is transferred to NOx via oxidation, a particularly useful isotopic fingerprint studies transformations. Constraining propagation within...
Abstract. Surface ozone has been measured since 2004 at the coastal East Antarctic site of Dumont d'Urville (DDU), and 2007 Concordia station located on high plateau. This paper discusses long-term changes, seasonal diurnal cycles, as well inter-annual summer variability observed these two sites. At Concordia, near-surface data were complemented by balloon soundings compared to similar measurements done South Pole. The DDU record is those obtained Syowa, also in Antarctica, sites Neumayer...
The source of nitrous acid (HONO) and its importance in island or marine environments are poorly understood. Herein, based on comprehensive field measurements at a hilltop Corsica Island, we find an inverse diel variation HONO with higher concentrations during daytime. Night-time budget analysis indicates significant formation air mass transport along the hillside. In daytime, although photosensitized NO2 uptake ground NO + OH make considerable contributions (26% 5%, respectively), large...
Abstract. The African Monsoon Multidisciplinary Analyses (AMMA) fourth airborne campaign was conducted in July–August 2006 to study the chemical composition of middle and upper troposphere West Africa with major objective better understand processing emissions by (WAM) its associated regional-scale vertical transports. In particular, french experiment organized around two goals. first characterize impact Mesoscale Convective Systems (MCSs) on ozone budget evolution these convective plumes as...
Measurements of OH and total peroxy RO 2 (HO plus organic peroxy) radicals were conducted in December 2010/January 2011 at the coastal East Antarctic site Dumont d'Urville (DDU, 66°40′S 140°01′E) as part Oxidant Production over Land its Export (OPALE) project. Compared to measurements carried out West coast, relatively high concentrations found with 24 h average values 2.1 × 10 6 3.3 8 molecule cm −3 for radicals, respectively. On basis steady state calculations, observed concentration is...
This paper summarizes the objectives and setting of OPALE (Oxidant Production over Antarctic Land its Export) project during summer 2010/2011 at Dumont d'Urville. The primary goal campaign is to characterize oxidizing environment atmospheric boundary layer along coast East Antarctica. A summary relevant field chemical measurements presented including carbon monoxide ammonia records that are used here identify local influences due station activities penguin emissions. An overview basic...
IO, BrO, and NO 2 were measured for the first time at Dumont d'Urville (East Antarctic coast) during summer 2011/2012 by using a near‐UV‐Visible laser spectrometer based on mode‐locked cavity‐enhanced absorption spectroscopy. IO mixing ratios ranged from 2σ detection limit (0.04 pptv) up to 0.15 pptv. BrO remained close or below (2 of instrument. Daily averaged values between (10 60 pptv being far higher than levels few commonly observed in remote marine boundary layer. Data are discussed...
The branching ratio β = k1b/k1a for the formation of methyl nitrate, CH3ONO2, in gas-phase CH3O2 + NO reaction, → CH3O NO2 (1a), CH3ONO2 (1b), has been determined over pressure and temperature ranges 50–500 Torr 223–300 K, respectively, using a turbulent flow reactor coupled with chemical ionization mass spectrometer. At 298 yield found to increase linearly from 0.33 ± 0.16% at 50 0.80 0.54% 500 (errors are 2σ). Decrease 300 220 K leads an by factor about 3 100–200 range. These data...
Abstract. We present direct measurements of biogenic volatile organic compound (BVOC)-induced nitrate radical (NO3) reactivity (kVOC) through the diel cycle in suburban, temperate forest Rambouillet near Paris (France). The data were obtained a 6-week summer period 2022 as part Atmospheric ChemistRy Of Suburban foreSt (ACROSS) campaign. kVOC was measured small (700 m2) clearing mainly at height 5.5 m above ground level but also 40 (for 5 d and nights). At nighttime, mean values (and...
The overall rate constant for the reaction OH + CH3COOH → products in temperature range of 229−300 K was determined using a chemical ionization mass spectrometer coupled to high-pressure turbulent flow reactor (∼200 Torr carrier gas N2). A strong negative dependence found this which can be expressed Arrhenius form as k1(T) = ((2.2 ± 0.2) × 10-14) exp((1012 80)/T) cm3 molecule-1 s-1 with k1 6.6 10-13 at 298 K. When these results are combined previous measurements 298−446 K,8 three-parameter...