A5019206517- Atmospheric chemistry and aerosols
- Air Quality and Health Impacts
- Air Quality Monitoring and Forecasting
- Atmospheric Ozone and Climate
- Vehicle emissions and performance
- Indoor Air Quality and Microbial Exposure
- Atmospheric aerosols and clouds
- Catalytic Processes in Materials Science
- Atmospheric and Environmental Gas Dynamics
- Toxic Organic Pollutants Impact
- Industrial Gas Emission Control
- Marine and coastal ecosystems
- Catalysis and Oxidation Reactions
- Plant responses to elevated CO2
- Zeolite Catalysis and Synthesis
- Water Quality Monitoring and Analysis
- Aquatic Ecosystems and Phytoplankton Dynamics
- Methane Hydrates and Related Phenomena
- Marine Toxins and Detection Methods
- Clinical Nutrition and Gastroenterology
- Carbon Dioxide Capture Technologies
- Hydrocarbon exploration and reservoir analysis
- Gas Sensing Nanomaterials and Sensors
- Odor and Emission Control Technologies
- Membrane Separation and Gas Transport
University of Florida
2015-2024
University of Florida Health
2018
Gainesville Obstetrics & Gynecology
2016
National Institute for Occupational Safety and Health
2009
University of North Carolina at Chapel Hill
1997-2007
Environmental Protection Agency
2006
Research Triangle Park Foundation
2006
University of Delaware
2004
Korea Gas Corporation (South Korea)
1993
Abstract. Secondary organic aerosol (SOA) accounts for a significant fraction of ambient tropospheric and detailed knowledge the formation, properties transformation SOA is therefore required to evaluate its impact on atmospheric processes, climate human health. The chemical physical processes associated with formation are complex varied, and, despite considerable progress in recent years, quantitative predictive understanding does not exist represents major research challenge science. This...
According to evidence from our laboratory, acidic surfaces on atmospheric aerosols lead potentially multifold increases in secondary organic aerosol (SOA) mass. Experimental observations using a multichannel flow reactor, Teflon (polytetrafluoroethylene) film bag batch reactors, and outdoor Teflon-film smog chambers strongly confirm that inorganic acids, such as sulfuric acid, catalyze particle-phase heterogeneous reactions of carbonyl species. The net result is large increase SOA mass...
The formation of oligomeric molecules, an important step in secondary organic aerosol production, is reported. Aerosols were produced by the reaction α-pinene and ozone presence acid seed characterized exact mass measurements tandem spectrometry. Oligomeric products between 200 900 u detected with both electrospray ionization matrix-assisted laser desorption ionization. masses dissociation these ions consistent various combinations known primary this ("monomers") and/or without expected...
Abstract Fine particulate matters less than 2.5 µm (PM ) in the ambient atmosphere are strongly associated with adverse health effects. However, it is unlikely that all fine particles equally toxic view of their different sizes and chemical components. Toxicity produced from various combustion sources (diesel engine, gasoline biomass burning (rice straw pine stem burning), coal combustion) non-combustion (road dust including sea spray aerosols, ammonium sulfate, nitrate, secondary organic...
Abstract. Wood-burning aerosol produced under smoldering conditions was photochemically aged with different relative humidity (RH) and NOx using a 104 m3 dual outdoor chamber natural sunlight. Light absorption of organic carbon (OC) measured over the course photooxidation UV–visible spectrometer connected to an integrating sphere. At high RH, color decayed rapidly. slightly prolonged wood smoke, suggesting that promotes formation chromophores via secondary processes. Overall, mass cross...
Secondary organic aerosol (SOA) from the photooxidation of toluene in a hydrocarbon-NOx mixture was generated 190 m3 outdoor Teflon chamber. The reaction gas phase leads to substituted aromatics (TOL-AR), nonaromatic ring retaining (TOL-R), and opening products (TOL-RO). In this work, following oxycarboxylic acids were newly identified: glyoxylic acid, methylglyoxylic 4-oxo-2-butenoic oxo-C5-alkenoic acids, dioxopentenoic oxo-C7-alkadienoic dioxo-C6-alkenoic hydroxydioxo-C7-alkenoic...
Particle growth by the heterogeneous reaction of aldehydes was evaluated in 0.5 m3 Teflon film bags under darkness presence background seed aerosols. The used were as follows: glyoxal, butanal, hexanal, octanal, and decanal. To study acid catalyst effects on aldehyde reactions, one initially filled with aerosols composed ammonium sulfate-aerosol acidified sulfuric acid. These results compared to particle reactions that contained only sulfate a aerosol. gas-phase then added bags. In selected...
As a result of new aerosol compositional information, we have implemented an exploratory model for predicting yields from the reaction α-pinene with ozone in atmosphere. This approach has ability to embrace range different atmospheric chemical conditions, which bring about biogenic formation. A kinetic mechanism was used describe gas-phase reactions ozone. scheme produces low vapor pressure products that distribute between gas and particle phases. Some subcooled liquid pressures are enough...
Abstract. The daytime oxidation of biogenic hydrocarbons is attributed to both OH radicals and O3, while nighttime chemistry dominated by the reaction with O3 NO3 radicals. Here, patterns secondary organic aerosol (SOA) originating from were predicted under varying environmental conditions (temperature, humidity, sunlight intensity, NOx levels, seed conditions) using UNIfied Partitioning Aerosol phase Reaction (UNIPAR) model, which comprises multiphase gas–particle partitioning in-particle...
Aerosol growth by the heterogeneous reactions of different aliphatic and α,β-unsaturated carbonyls in presence/absence acidified seed aerosols was studied a 2 m long flow reactor (2.5 cm i.d.) 0.5-m3 Teflon film bag under darkness. For experiments, 2,4-hexadienal, 5-methyl-3-hexen-2-one, 2-cyclohexenone, 3-methyl-2-cyclopentenone, 3-methyl-2-cyclohexenone, octanal were studied. The selected based on their reactivity for acid-catalyzed reactions, proton affinity, similarity to ring-opening...
Abstract. The secondary organic aerosol (SOA) produced by the photooxidation of isoprene with and without inorganic seed is simulated using Unified Partitioning Aerosol Phase Reaction (UNIPAR) model. Recent work has found SOA formation to be sensitive both acidity ([H+], mol L−1) liquid water content (LWC) presence either leading significant phase mass generation large growth in yields (YSOA). Classical partitioning models alone are insufficient predict due high volatility products...
Abstract. The Unified Partitioning-Aerosol phase Reaction (UNIPAR) model has been developed to predict the secondary organic aerosol (SOA) formation through multiphase reactions. was evaluated with aromatic SOA data produced from photooxidation of toluene and 1,3,5-trimethylbenzene (135-TMB) under various concentrations NOx SO2 using an outdoor reactor (University Florida Atmospheric PHotochemical Outdoor Reactor (UF-APHOR) chamber). When inorganic species (sulfate, ammonium water) are...
The impact of authentic mineral dust particles sourced from the Gobi Desert (GDD) on kinetic uptake coefficient SO2 was studied under varying environments (humidity, O3, and NOx) using both an indoor chamber outdoor chamber. There a significant increase in (γSO42-,light) for GDD UV light compared to value (γSO42-,dark) dark conditions at various relative humidities (RH) ranging 20% 80%. In presence absence O3 NOx, γSO42-,light γSO42-,dark greatly increased with increasing RH. resulting also...
The atmospheric process dynamically changes the chemical compositions of organic aerosol (OA), thereby complicating interpretation its health effects. In this study, dynamic evolution oxidative potential various OA was studied, including wood combustion particles and secondary aerosols (SOA) generated from different hydrocarbons (i.e., gasoline, toluene, isoprene, α-pinene). at aging stages subsequently measured by dithiothreitol consumption (DTTm, mass normalized). We hypothesized that DTT...
The formation of terpene secondary organic aerosol (SOA) was simulated using the unified partitioning phase reaction model that predicted multiphase reactions hydrocarbons in presence electrolytic inorganic aerosols. To predict oxygenated products from atmospheric oxidation terpenes, master chemistry mechanism, an explicit gas kinetic implemented. resulting were then classified into 51 lumping groups mass-based stoichiometric coefficients according to their volatility and reactivity. In wet...
Humidity effects on the gas/particle partitioning of different types semivolatile organic compounds (SOCs) in layer wood soot, diesel and secondary aerosols were studied outdoor environmental chambers. Experimental coefficients, Kp, SOCs measured using Teflon film chambers compared to theoretical Kp values calculated with aid activity coefficients vapor pressures. A thermodynamic model based group contribution methods was used estimate SOC liquid atmospheric particles. The equilibrated water...
Little is known about atmospheric reaction mechanisms or products of polycyclic aromatic hydrocarbons associated with aerosol particles. Products benz[a]anthracene photodegradation were determined after irradiation in the presence three common constituents aerosols previously found to accelerate photodegradation; 9,10-anthraquinone, 9-xanthone, and vanillin. Irradiation was carried out toluene, benzene, benzene-d6, analyzed by GCMS, FTIR, NMR. Among major tentatively identified...
Atmospheric particulate matter is a complex mixture consisting of organic and inorganic chemicals. Their sources include various combustion processes, aerosolized dusts soils, chemical reactions which produce secondary aerosols. The partitioning semivolatile toxic compounds (SOCs) between the gas phase strongly influenced by temperature, water concentration, composition matter, fraction matter. Many investigations have recently suggested that considerable portion gas−particle (G/P) in...
A predictive model for secondary organic aerosol (SOA) formation including both partitioning and heterogeneous reactions is explored the SOA produced from oxidation of toluene in presence inorganic seed aerosols. The comprises explicit gas-phase chemistry toluene, gas−particle partitioning, chemistry. resulting products gas phase are lumped into several classes chemical species based on their vapor pressure reactivity reactions. Both coefficient reaction rate constant each product...
Abstract. Heterogeneous chemistry of oxidized carbons in aerosol phase is known to significantly contribute secondary organic (SOA) burdens. The UNIfied Partitioning Aerosol Reaction (UNIPAR) model was developed process the multiphase various oxygenated organics into SOA mass predictions presence salted aqueous phase. In this study, UNIPAR simulated formation from gasoline fuel, which a major contributor observed concentration urban areas. products, predicted by explicit mechanism, were...
Abstract. The UNIfied Partitioning-Aerosol phase Reaction (UNIPAR) model was integrated into the Comprehensive Air quality Model with extensions (CAMx) to process secondary organic aerosol (SOA) formation by capturing multiphase reactions of hydrocarbons (HCs) in regional scales. SOA growth simulated using a wide range anthropogenic HCs, including 10 aromatics and linear alkanes different carbon lengths. atmospheric processes biogenic HCs (isoprene, terpenes, sesquiterpene) were for major...