A5001923827- Atmospheric chemistry and aerosols
- Air Quality and Health Impacts
- Air Quality Monitoring and Forecasting
- Atmospheric aerosols and clouds
- Vehicle emissions and performance
- Coagulation and Flocculation Studies
- Aerosol Filtration and Electrostatic Precipitation
- Advanced oxidation water treatment
- Radioactivity and Radon Measurements
- Mass Spectrometry Techniques and Applications
- Water Treatment and Disinfection
- Advanced Proteomics Techniques and Applications
- Atmospheric and Environmental Gas Dynamics
- Analytical Chemistry and Chromatography
- Atmospheric Ozone and Climate
- Water Quality Monitoring and Analysis
Bay Area Air Quality Management District
2021-2024
California Institute of Technology
2012-2017
University of Florida
2010
City University of Hong Kong
2000
The production, size, and chemical composition of sea spray aerosol (SSA) particles strongly depend on seawater chemistry, which is controlled by physical, chemical, biological processes. Despite decades studies in marine environments, a direct relationship has yet to be established between ocean biology the physicochemical properties SSA. ability establish such relationships hindered fact that SSA measurements are typically dominated overwhelming background concentrations even remote...
We use historical and new atmospheric trace gas observations to refine the estimated source of methane (CH4) emitted into California's South Coast Air Basin (the larger Los Angeles metropolitan region). Referenced California Resources Board (CARB) CO emissions inventory, total CH4 are 0.44 ± 0.15 Tg each year. To investigate possible contribution fossil fuel emissions, we ambient air (CH4), ethane (C2H6), carbon monoxide (CO), together with measured C2H6 enhancement ratios in natural supply....
Abstract. Recent work has demonstrated that organic and mixed organic–inorganic particles can exhibit multiple phase states depending on their chemical composition ambient conditions such as relative humidity (RH). To explore the extent to which water uptake varies with particle-phase behavior, hygroscopic growth factors (HGFs) of nine laboratory-generated, aerosol systems physical ranging from well-mixed liquids phase-separated viscous or semi-solids were measured Differential Aerosol...
Air sensors can provide valuable non-regulatory and supplemental data as they be affordably deployed in large numbers stationed remote areas far away from regulatory air monitoring stations. have inherent limitations that are critical to understand before collecting interpreting the data. Many of these mechanistic nature, which will require technological advances. However, there documented quality assurance (QA) methods promote quality. These include laboratory field evaluation...
Performance evaluation studies of low-cost sensors (LCS) measuring air pollutants have been conducted by academic and governmental groups for stationary applications. In contrast, protocols are nonexistent LCS used in mobile deployments, though this manner research may be employed to complement regulatory directives community monitoring. Mobile measurements with a nascent but growing use-case, questions data quality will become increasingly important. The South Coast Air Quality Management...
The first application of a novel differential mobility analyzer, the radial opposed migration ion and aerosol classifier (ROMIAC), is demonstrated. ROMIAC uses antiparallel forces from an electric field cross-flow gas to both scan mobilities continuously transmit target ions with 100% duty cycle. In ROMIAC, diffusive losses are minimized, resolution ions, collisional cross-sections 200-2000 Å(2), achieved near nondispersive ~20. Higher theoretically possible greater rates. was coupled linear...
We present the design, simulation, and characterization of radial opposed migration ion aerosol classifier (ROMIAC), a compact differential electrical mobility classifier. evaluate performance ROMIAC using combination finite element modeling experimental validation two nearly identical instruments tetra-alkyl ammonium halide mass standards sodium chloride particles. Mobility efficiency calibrations were performed over wide range particle diameters flow rates to characterize under anticipated...
The inference of particle size distributions from differential mobility analyzer (DMA) data requires knowledge the charge distribution on particles being measured. produced by a bipolar aerosol charger depends properties ions in charger, and kinetics transfer molecular or ion clusters to particles. A single parameterization theoretically predicted is employed most DMA analyses regardless atmospheric conditions probed. Deviations actual that assumed analysis will bias estimated distribution....
The application of oxidative reactions Oxone® [2KHSO5 KHSO4 K2SO4] as an active decontaminant has been mainly utilized through the aqueous solution. However, little is known about reactivity aerosolized Oxone particles although use appropriate oxidants would have significant value in remediating contaminated surfaces. In this study, feasibility producing chlorine species from saline-Oxone aerosols was studied using a 2-m3 Teflon film chamber. To evaluate capability aerosol, aerosol collected...
Abstract. Recent work has demonstrated that organic and mixed organic–inorganic particles can exhibit multiple phase states depending on their chemical composition ambient conditions such as relative humidity (RH). To explore the extent to which water uptake varies with particle behavior, hygroscopic growth factors (HGFs) of nine laboratory-generated, aerosol systems physical ranging from well-mixed liquids, phase-separated particles, viscous liquids or semi-solids were measured Differential...
Sensors and sensor systems for monitoring fine particles with aerodynamic diameters smaller than 2.5 µm can provide real-time feedback on indoor air quality thus help guide actions to manage pollutant concentrations. Standardized verification of the performance accuracy sensors is crucial predicting efficacy such monitoring. A new ASTM International standard test method (ASTM D8405) was created this need most exacting laboratory protocol published date evaluating measuring in diameter. D8405...