A5013997551- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Air Quality and Health Impacts
- Atmospheric aerosols and clouds
- Air Quality Monitoring and Forecasting
- Atmospheric and Environmental Gas Dynamics
- Spectroscopy and Laser Applications
- Catalytic Processes in Materials Science
- Vehicle emissions and performance
- Catalysis and Oxidation Reactions
- Analytical Chemistry and Chromatography
- Marine and coastal ecosystems
- Water Quality Monitoring and Analysis
- Fire effects on ecosystems
- Advanced Chemical Sensor Technologies
- Spectroscopy and Quantum Chemical Studies
- Odor and Emission Control Technologies
- Data Analysis with R
- Molecular Spectroscopy and Structure
- Plant responses to elevated CO2
- Industrial Gas Emission Control
- Analytical Chemistry and Sensors
- Graphite, nuclear technology, radiation studies
- Gene expression and cancer classification
- Gas Sensing Nanomaterials and Sensors
Wageningen University & Research
2022-2025
Reed College
2014-2023
University of California, Berkeley
2007-2012
California Institute of Technology
2004-2008
Forschungszentrum Jülich
2008
University of California, San Diego
2006
University of Otago
2006
Centre d’Immunologie de Marseille-Luminy
1990
Oxidation of biogenic volatile organic compounds (BVOC) by the nitrate radical (NO3) represents one important interactions between anthropogenic emissions related to combustion and natural from biosphere. This interaction has been recognized for more than 3 decades, during which time a large body research emerged laboratory, field, modeling studies. NO3-BVOC reactions influence air quality, climate visibility through regional global budgets reactive nitrogen (particularly nitrates), ozone,...
Abstract. The yields of organic nitrates and secondary aerosol (SOA) particle formation were measured for the reaction NO3+β-pinene under dry humid conditions in atmosphere simulation chamber SAPHIR at Research Center Jülich. These experiments conducted low concentrations NO3 (NO3+N2O5<10 ppb) β-pinene (peak~15 ppb), with no seed aerosol. SOA was observed to be prompt substantial (~50% mass yield both 60% RH), highly correlated nitrate formation. gas/aerosol partitioning can simulated...
Abstract Brown carbon aerosol consists of light‐absorbing organic particulate matter with wavelength‐dependent absorption. Aerosol optical extinction, absorption, size distributions, and chemical composition were measured in rural Alabama during summer 2013. The field site was well located to examine sources brown aerosol, influence by high biogenic concentrations, pollution from two nearby cities, biomass burning aerosol. We report the closure between dry extinction at 365 nm calculated...
The secondary organic aerosol (SOA) mass yields from NO3 oxidation of a series biogenic volatile compounds (BVOCs), consisting five monoterpenes and one sesquiterpene (α-pinene, β-pinene, Δ-3-carene, limonene, sabinene, β-caryophyllene), were investigated in continuous flow experiments 10 m3 indoor Teflon chamber. By making situ measurements the nitrate radical employing kinetics box model, we generate time-dependent yield curves as function reacted BVOC. SOA varied dramatically among...
Organic nitrates are an important aerosol constituent in locations where biogenic hydrocarbon emissions mix with anthropogenic NOx sources. While regional and global chemical transport models may include a representation of organic from monoterpene reactions nitrate radicals (the primary source particle-phase the Southeast United States), secondary (SOA) can underestimate yields. Furthermore, SOA parametrizations do not explicitly take into account compounds produced gas phase. In this work,...
Stay-at-home policies invoked in response to COVID-19 have led well-publicized drops some air pollutants. The extent which such reductions translate improved quality is dictated by not only emissions and meteorology, but also chemical transformations the atmosphere.
Abstract. At the Rocky Mountain Biogenic Aerosol Study (BEACHON-RoMBAS) field campaign in Colorado front range, July–August 2011, measurements of gas- and aerosol-phase organic nitrates enabled a study role NOx (NOx = NO + NO2) oxidation forest-emitted volatile compounds (VOCs) subsequent aerosol formation. Substantial formation peroxy- alkyl-nitrates is observed every morning, with an apparent 2.9% yield alkyl from daytime RO2 reactions. Aerosol-phase nitrates, however, peak concentration...
Abstract. Alkyl nitrates and secondary organic aerosol (SOA) produced during the oxidation of isoprene by nitrate radicals has been observed in SAPHIR (Simulation Atmospheric PHotochemistry In a large Reaction Chamber) chamber. A 16 h dark experiment was conducted with temperatures at 289–301 K, maximum concentrations 11 ppb isoprene, 62.4 O3 31.1 NOx. We find yield is 70±8% from + NO3 reaction, for dinitrates reaction primary 40±20%. an effective rate constant group first generation...
<p><strong>Abstract.</strong> Gas- and aerosol-phase measurements of oxidants, biogenic volatile organic compounds (BVOCs) nitrates made during the Southern Oxidant Aerosol Study (SOAS campaign, Summer 2013) in central Alabama show that a nitrate radical (NO<sub>3</sub>) reaction with monoterpenes leads to significant secondary aerosol formation. Cumulative losses NO<sub>3</sub> terpenes are correlated increase gas- aerosol-organic concentrations...
Abstract. The formation of organic nitrates and secondary aerosol (SOA) were monitored during the NO3 + limonene reaction in atmosphere simulation chamber SAPHIR at Research Center Jülich. 24-h run began a purged, dry, particle-free comprised two injections oxidants, such that first experiment measured SOA yield absence seed aerosol, second yields presence 10 μg m−3 aerosol. After each injection, separate increases mass observed, corresponding to sequential oxidation double bonds. Analysis...
Abstract. Peroxyacetyl nitrate (PAN) and its chemical analogues are increasingly being quantified in the ambient atmosphere by thermal dissociation (TD) followed detection of either peroxyacyl radical or NO2 product. Here we present details technique developed at University California, Berkeley which detects sum all peroxynitrates (ΣPNs) via laser-induced fluorescence (LIF) We review various deployments compare ΣPNs measurements with sums PAN homologue species detected individually other...
Abstract. Several models were used to describe the partitioning of ammonia, water, and organic compounds between gas particle phases for conditions in southeastern US during summer 2013. Existing equilibrium frameworks found be sufficient, although additional improvements terms estimating pure-species vapor pressures are needed. Thermodynamic model predictions consistent, first order, with a molar ratio ammonium sulfate approximately 1.6 1.8 (ratio 2 × sulfate, RN∕2S ≈ 0.8 0.9) 70 % total...
Oxidation of monoterpenes (C10H16) by nitrate radicals (NO3) constitutes an important source atmospheric secondary organic aerosol (SOA) and organonitrates. However, knowledge the mechanisms their formation is incomplete differences in yields between similar are poorly understood. In particular, SOA organonitrates from α-pinene + NO3 low, while those Δ3-carene high. Using computational methods, we suggest that bond scission nitrooxy alkoxy lead to reactive keto-nitrooxy-alkyl radicals, which...
Abstract. Nighttime reaction of nitrate radicals (NO3) with biogenic volatile organic compounds (BVOC) has been proposed as a potentially important but also highly uncertain source secondary aerosol (SOA). The southeastern United States both high BVOC and nitrogen oxide (NOx) emissions, resulting in large model-predicted NO3-BVOC SOA. Coal-fired power plants this region constitute substantial NOx emissions point sources into nighttime atmosphere characterized by regionally widespread...
Abstract. The lifetime of nitrogen oxides (NOx) affects the concentration and distribution NOx spatial patterns deposition. Despite its importance, is poorly constrained in rural remote continental regions. We use measurements from a site central Alabama during Southern Oxidant Aerosol Study (SOAS) summer 2013 to provide new insights into chemistry reservoirs. find that daytime controlled primarily by production loss alkyl multifunctional nitrates (ΣANs). During SOAS, ΣAN was rapid,...
Abstract. Isoprene oxidation by nitrate radical (NO3) is a potentially important source of secondary organic aerosol (SOA). It suggested that the second or later-generation products are more substantial contributors to SOA. However, there few studies investigating multi-generation chemistry isoprene-NO3 reaction, and information about volatility different isoprene nitrates, which essential evaluate their potential form SOA determine atmospheric fate, rare. In this work, we studied reaction...
Dark chamber experiments were conducted to study the SOA formed from oxidation of α-pinene and Δ-carene under different peroxy radical (RO2) fate regimes: RO2 + NO3, RO2, HO2. mass yields <1 ∼25% strongly dependent on available OA up ∼100 μg m-3. The strong yield dependence is driven by absorptive partitioning not surface area for condensation. Yields NO3 consistently higher, ranging ∼10-50% with some <25 Explicit kinetic modeling including vapor wall losses was enable comparisons across VOC...
Abstract. NO2 concentrations were measured by various instruments during the NO3Comp campaign at atmosphere simulation chamber SAPHIR Forschungszentrum Jülich, Germany, in June 2007. Analytical methods included photolytic conversion with chemiluminescence (PC-CLD), broadband cavity ring-down spectroscopy (BBCRDS), pulsed (CRDS), incoherent cavity-enhanced absorption (IBB\\-CEAS), and laser-induced fluorescence (LIF). All spectrometers optimized for detection of main target species campaign,...
Abstract The chemical species emitted by forests create complex atmospheric oxidation chemistry and influence global capacity climate. Southern Oxidant Aerosol Study (SOAS) provided an opportunity to test the in a forest where isoprene is dominant biogenic volatile organic compound. Hydroxyl (OH) hydroperoxyl (HO2) radicals were two of hundreds measured, as was OH reactivity (the inverse lifetime). measured laser-induced fluorescence (LIF) taking difference signals without with scavenger...
Abstract. Ambient pine forest air was oxidized by OH, O3, or NO3 radicals using an oxidation flow reactor (OFR) during the BEACHON-RoMBAS (Bio–hydro–atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen – Rocky Mountain Biogenic Aerosol Study) campaign to study biogenic secondary organic aerosol (SOA) formation (OA) aging. A wide range equivalent atmospheric photochemical ages sampled, from hours up days (for O3 NO3) weeks OH). processed OFR typically sampled every...
Abstract. The effect of NO2 on secondary organic aerosol (SOA) formation from ozonolysis α-pinene, β-pinene, Δ3-carene, and limonene was investigated using a dark flow-through reaction chamber. SOA mass yields were calculated for each monoterpene with varying concentrations. Kinetics modeling the first-generation gas-phase chemistry suggests that differences in observed different concentrations are consistent NO3 subsequent competition between O3 to oxidize monoterpene. α-Pinene only studied...
Abstract. Inorganic aerosol composition was measured in the southeastern United States, a region that exhibits high mass loading during summer, as part of 2013 Southern Oxidant and Aerosol Study (SOAS) campaign. Measurements using Monitor for AeRosols GAses (MARGA) revealed two periods nitrate (NO3−) concentrations These were correlated with increased supermicron crustal sea spray species, particularly Na+ Ca2+, shift towards larger (1 to 2.5 μm) diameters. We suggest this forms by...