A5003102262- Atmospheric chemistry and aerosols
- Atmospheric aerosols and clouds
- Atmospheric Ozone and Climate
- Air Quality and Health Impacts
- Aeolian processes and effects
- Air Quality Monitoring and Forecasting
- Atmospheric and Environmental Gas Dynamics
- Vehicle emissions and performance
- Catalytic Processes in Materials Science
- Ionosphere and magnetosphere dynamics
- Heavy metals in environment
- Maritime Transport Emissions and Efficiency
- Geochemistry and Elemental Analysis
- Geology and Paleoclimatology Research
- Spectroscopy and Laser Applications
- Microbial Community Ecology and Physiology
- Indoor Air Quality and Microbial Exposure
- Marine and coastal ecosystems
- Fire effects on ecosystems
- Meteorological Phenomena and Simulations
- Aquatic Ecosystems and Phytoplankton Dynamics
- Odor and Emission Control Technologies
- Mercury impact and mitigation studies
- Oceanographic and Atmospheric Processes
- Plant responses to elevated CO2
University of Miami
2016-2025
University of California, Santa Cruz
2023
Finnish Meteorological Institute
2023
University of Washington
2012-2020
Seattle University
2018-2020
Scripps Institution of Oceanography
2010-2018
University of California, San Diego
2010-2018
The reactive uptake of isoprene-derived epoxydiols (IEPOX) is thought to be a significant source atmospheric secondary organic aerosol (SOA). However, the IEPOX reaction probability (γIEPOX) and its dependence upon particle composition remain poorly constrained. We report measurements γIEPOX for trans-β-IEPOX, predominant isomer, on submicron particles as function composition, acidity, relative humidity (RH). Particle acidity had strongest effect. more than 500 times greater ammonium...
We present measurements as part of the Southern Oxidant and Aerosol Study (SOAS) during which atmospheric aerosol particles were comprehensively characterized. results utilizing a Filter Inlet for Gases AEROsol coupled to chemical ionization mass spectrometer (CIMS). focus on volatility composition isoprene derived organic tracers bulk aerosol. By online molecular information provided by FIGAERO–CIMS, we show that vast majority commonly reported epoxydiol (IEPOX) secondary (SOA) is from...
Acid-catalyzed reactions between gas- and particle-phase constituents are critical to atmospheric secondary organic aerosol (SOA) formation. The aerosol-phase state is thought influence the reactive uptake of gas-phase precursors particles by altering diffusion rates within particles. However, few experimental studies have explored precise role on processes. This laboratory study systematically examines coefficient (γ) trans-β-isoprene epoxydiol (trans-β-IEPOX), predominant IEPOX isomer,...
Significance Phosphorus (P) deposition from aerosols can stimulate primary productivity in P-depleted marine and terrestrial ecosystems. We tested the hypothesis that African dust fertilizes Amazon Basin Tropical Atlantic Ocean (TAO) by measuring windborne dust, P, soluble P samples collected at a coastal site on northeastern edge of Amazon. Using satellite data models, we identified previously underestimated source P: biomass burning aerosol transported southern Africa supply to Amazon,...
Abstract Risks associated with dust hazards are often underappreciated, a gap between the knowledge pool and public awareness that can be costly for impacted communities. This study reviews emission sources chemical, physical, biological characteristics of airborne soil particles (dust) their effects on human environmental health safety in Pan‐American region. American originates from both local (western United States, northern Mexico, Peru, Bolivia, Chile, Argentina) long‐range transport...
Ship emissions contribute significantly to gaseous and particulate pollution worldwide. To better understand the impact of ship on air quality, measurements size-resolved chemistry individual particles in were made at Port Los Angeles using real-time, single-particle mass spectrometry. plumes identified through a combination position information gases aerosol site 500 m from center main shipping channel Angeles. Single containing mixtures organic carbon, vanadium, sulfate (OC-V-sulfate)...
Intense wildfires burning >360000 acres in San Diego during October, 2007 provided a unique opportunity to study the impact of on local air quality and biomass aerosol (BBA) aging. The size-resolved mixing state individual particles was measured real-time with an time-of-flight mass spectrometer (ATOFMS) for 10 days after fires commenced. Particle concentrations were high county-wide due wildfires; 84% 120-400 nm by number identified as BBA, <400 contributing dangerous public health, up 148...
[1] Aerosols impact the microphysical properties of clouds by serving as cloud condensation nuclei (CCN) and ice (IN). By modifying properties, aerosols have potential to alter location intensity precipitation, but determining magnitude reproducibility aerosol-induced changes precipitation remains a significant challenge experimentalists modelers. During CalWater Early Start campaign (22 February 11 March 2009), uniquely comprehensive set atmospheric chemistry, meteorological measurements...
Low bulk diffusivity inside viscous semisolid atmospheric secondary organic aerosol (SOA) can prolong equilibration time scale, but its broader impacts on growth and size distribution dynamics are poorly understood. Here, we present quantitative insights into the effects of evaporation kinetics SOA formed under dry conditions from photooxidation isoprene in presence a bimodal consisting Aitken (ammonium sulfate) accumulation (isoprene or α-pinene SOA) mode particles. Aerosol composition...
A combination of flow reactor studies and chamber modeling is used to constrain two uncertain parameters central the formation secondary organic aerosol (SOA) from isoprene-derived epoxides: (1) rate heterogeneous uptake epoxide particle phase (2) molar fraction reactively taken up that contributes SOA, SOA yield (ϕSOA). Flow measurements trans-β-isoprene epoxydiol (trans-β-IEPOX) methacrylic acid (MAE) reaction probability (γ) were performed on atomized aerosols with compositions similar...
Abstract Soils in the Amazon Basin are deficient phosphorus, essential to soil fertility. Previous studies suggested that African mineral dust deposited Amazonian soils served as an important source of phosphorus enhances These lacked quantitative measurements validate estimates. Here we present daily and PM 10 carried trade winds at Cayenne, French Guiana, during 2002–2017. MERRA‐2 model concentrations showed excellent agreement with over this period. Consequently, used estimate temporal...
Abstract. We measured N2O5 reactive uptake onto mixed organic/inorganic submicron particles using organic compounds with a variety of oxidation states (using mainly atomic O : C ratios as proxy) and molecular weights. The mass fraction, composition, relative humidity (RH) were varied to assess their effects separately on the coefficient, γ(N2O5). At constant RH, mixtures components having an < 0.5 ammonium bisulfate significantly suppressed N2O5(g) compared pure bisulfate, even at small...
During the Ice in Clouds Experiment‐Layer (ICE‐L), dry lakebed, or playa, salts from Great Basin region of United States were observed as cloud nuclei orographic wave clouds over Wyoming. Using a counterflow virtual impactor series with single‐particle mass spectrometer, sodium‐potassium‐magnesium‐calcium‐chloride identified residues droplets. Importantly, these produced similar spectral signatures to playa elevated condensation (CCN) efficiencies close sea salt. suite chemical...
Dimethyl sulfide (DMS), produced by oceanic phytoplankton, is oxidized to form methanesulfonic acid (MSA) and sulfate, which influence particle chemistry hygroscopicity. Unlike MSA has no known anthropogenic source making it a useful tracer for ocean-derived biogenic sulfur. Despite numerous observations of MSA, predominately in marine environments, the production pathways have remained elusive highlighting need additional measurements, particularly at inland locations. During Study Organic...
Abstract. We present measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation in an environmental simulation chamber at a variety oxidant conditions and using dry neutral seed particles to suppress acid-catalyzed multiphase chemistry. A high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) utilizing iodide-adduct coupled the Filter Inlet for Gases Aerosols (FIGAERO) allowed simultaneous online sampling gas particle...
[1] Oceans represent a significant natural source of gases and particles to the atmosphere. Relative gas phase compounds, less is known regarding influence changes in biological activity ocean on chemistry sea spray aerosols produced marine environments. To gain insight into biology atmospheric aerosol chemistry, simultaneous real-time measurements were made size chemical mixing-state, dimethyl sulfide (DMS), as well seawater DMS chlorophyll a. In three different environments with elevated...
The rates of heterogeneous reactions trace gases with aerosol particles are complex functions particle chemical composition, morphology, and phase state. Currently, the majority model parametrizations reaction kinetics focus on population average mass, assuming that individual have same composition as Here we assess impact mixing state using N2O5 reactive uptake coefficient, γ(N2O5), dependence particulate chloride-to-nitrate ratio (nCl(-)/nNO3(-)). We describe first simultaneous ambient...
Abstract. We present measurements utilizing the Filter Inlet for Gases and Aerosols (FIGAERO) applied to chamber of isoprene-derived epoxydiol (IEPOX) reactive uptake aqueous acidic particles associated secondary organic aerosol (SOA) formation. Similar recent field observations with same instrument, we detect two molecular components desorbing from IEPOX SOA in high abundance: C5H12O4 C5H10O3. The thermal desorption signal former, presumably 2-methyltetrols, exhibits distinct maxima,...
Abstract. The Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign (ATOMIC) took place from 7 January to 11 July 2020 in the tropical North between eastern edge of Barbados and 51∘ W, longitude Northwest Tropical Station (NTAS) mooring. Measurements were made gather information on shallow atmospheric convection, effects aerosols clouds ocean surface energy budget, mesoscale oceanic processes. Multiple platforms deployed during ATOMIC including NOAA RV Ronald H. Brown (RHB) (7...
The climate effects of atmospheric aerosol particles serving as cloud condensation nuclei (CCN) depend on chemical composition and hygroscopicity, which are highly variable spatial temporal scales. Here we present global CCN measurements, covering diverse environments from pristine to polluted conditions. We show that the effective κ, can be derived accurately fine mass fractions organic particulate matter (ϵorg) inorganic ions (ϵinorg) through a linear combination, κ = ϵorg ⋅ κorg + ϵinorg...
Abstract. The number concentration and properties of aerosol particles serving as cloud condensation nuclei (CCN) are important for understanding properties, including in the tropical Atlantic marine boundary layer (MBL), where cumulus clouds reflect incoming solar radiation obscure low-albedo ocean surface. Studies linking source, composition, water uptake this region have been conducted primarily during summertime dust transport season, despite receiving a variety particle types throughout...
Abstract. Direct measurements of N2O5 reactivity on ambient aerosol particles were made during September 2009 at the Scripps Institution Oceanography (SIO) Pier facility located in La Jolla, CA. using a custom flow reactor and particle modulation technique alongside size distributions non-refractory composition. The pseudo-first order rate coefficients derived from surface area concentrations used to determine population average reaction probability, γ(N2O5), approximately every 50 min....
Abstract. Bioaerosols are emerging as important yet poorly understood players in atmospheric processes. Microorganisms can impact chemistry through metabolic reactions and potentially influence physical processes by participating ice nucleation cloud droplet formation. Microbial roles thought to be species-specific dependent on cell viability. Using a coastal pier monitoring site sampling platform, culture-dependent (i.e. agar plates) culture-independent DNA clone libraries from filters)...
Heterogeneous reactions of dinitrogen pentoxide (N2O5) on aerosol particles impact air quality and climate, yet aspects the relevant physical chemistry remain unresolved. One important consideration is competing effects diffusion rate chemical reaction within particle, which determines length that N2O5 travels a particle before reacting, referred to as reacto-diffusive (l). Large values l imply dependence reactive uptake efficiency N2O5, i.e., γ(N2O5), size. We present measurements size...