Douglas A. Day
A5022238184- Atmospheric chemistry and aerosols
- Air Quality and Health Impacts
- Atmospheric Ozone and Climate
- Air Quality Monitoring and Forecasting
- Atmospheric aerosols and clouds
- Atmospheric and Environmental Gas Dynamics
- Vehicle emissions and performance
- Indoor Air Quality and Microbial Exposure
- Advanced Chemical Sensor Technologies
- Odor and Emission Control Technologies
- Water Quality Monitoring and Analysis
- Catalytic Processes in Materials Science
- Toxic Organic Pollutants Impact
- Fire effects on ecosystems
- Cyclone Separators and Fluid Dynamics
- Spectroscopy and Laser Applications
- Advanced Aircraft Design and Technologies
- Analytical Chemistry and Chromatography
- Conservation Techniques and Studies
- Groundwater and Isotope Geochemistry
- Mass Spectrometry Techniques and Applications
- Industrial Gas Emission Control
- Aerosol Filtration and Electrostatic Precipitation
- Methane Hydrates and Related Phenomena
- Isotope Analysis in Ecology
University of Colorado Boulder
2016-2025
Cooperative Institute for Research in Environmental Sciences
2016-2025
University of Colorado System
2011-2025
Ceres
2023
Mississippi State University
2023
NSF National Center for Atmospheric Research
2020
Scripps Institution of Oceanography
2009-2013
University of California, San Diego
2009-2013
University of California, Davis
2006-2009
University of California, Berkeley
2002-2009
Abstract. Biomass burning (BB) is a large source of primary and secondary organic aerosols (POA SOA). This study addresses the physical chemical evolution BB aerosols. Firstly, lifetime POA SOA signatures observed with Aerodyne Aerosol Mass Spectrometer are investigated, focusing on measurements at high-latitudes acquired during 2008 NASA ARCTAS mission, in comparison to data from other field studies laboratory aging experiments. The parameter f60, ratio integrated signal m/z 60 total...
Emissions from gasoline and diesel vehicles are predominant anthropogenic sources of reactive gas-phase organic carbon key precursors to secondary aerosol (SOA) in urban areas. Their relative importance for formation is a controversial issue with implications air quality control policy public health. We characterize the chemical composition, mass distribution, potential emissions vehicles, find exhaust seven times more efficient at forming than exhaust. However, both important quality;...
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. Bioaerosols are relevant for public health and may play an important role in the climate system, but their atmospheric abundance, properties, sources not well understood. Here we show that concentration of airborne biological particles a North American forest ecosystem increases significantly during rain bioparticles closely correlated with ice nuclei (IN). The greatest increase IN occurred size range 2–6 μm, which is characteristic bacterial aggregates fungal spores. By DNA...
Abstract Particulate brown carbon (BrC) in the atmosphere absorbs light at subvisible wavelengths and has poorly constrained but potentially large climate forcing impacts. BrC from biomass burning virtually unknown lifecycle atmospheric stability. Here, emitted intense wildfires was measured plumes transported over 2 days two main fires, during 2013 NASA SEAC4RS mission. Concurrent measurements of organic aerosol (OA) black (BC) mass concentration, BC coating thickness, absorption Ångström...
Abstract. Organic aerosols (OA) represent one of the major constituents submicron particulate matter (PM1) and comprise a huge variety compounds emitted by different sources. Three intensive measurement field campaigns to investigate aerosol chemical composition all over Europe were carried out within framework European Integrated Project on Aerosol Cloud Climate Air Quality Interactions (EUCAARI) Monitoring Evaluation Programme (EMEP) during 2008 (May–June September–October) 2009...
Speciated particle-phase organic nitrates (pONs) were quantified using online chemical ionization MS during June and July of 2013 in rural Alabama as part the Southern Oxidant Aerosol Study. A large fraction pONs is highly functionalized, possessing between six eight oxygen atoms within each carbon number group, not common first generation alkyl previously reported. Using calibrations for isoprene hydroxynitrates measured molecular compositions, we estimate that account 3% 8% total...
Significance Atmospheric fine organic aerosol impacts air quality, climate, and human health. Speciating quantifying the sources of on molecular level improves understanding their formation chemistry hence resulting impacts. Such study, however, has not been possible due to chemical complexity atmospheric aerosol. Here, we provide comprehensive characterization samples from southeastern United States by combining state-of-the-art high-resolution mass spectrometry techniques. We find that...
Laboratory studies have established a number of chemical pathways by which nitrogen oxides (NO(x)) affect atmospheric organic aerosol (OA) production. However, these effects not been directly observed in ambient OA. We report measurements particulate nitrates Bakersfield, California, the nighttime formation increases with NO(x) and is suppressed high concentrations molecules that rapidly react nitrate radical (NO(3))--evidence multigenerational chemistry responsible for This class represents...
Abstract. Isoprene emitted by vegetation is an important precursor of secondary organic aerosol (SOA), but the mechanism and yields are uncertain. Aerosol prevailingly aqueous under humid conditions typical isoprene-emitting regions. Here we develop aqueous-phase for isoprene SOA formation coupled to a detailed gas-phase oxidation scheme. The based on reactive uptake coefficients (γ) water-soluble products, including sensitivity acidity nucleophile concentrations. We apply this simulation...
Abstract In the atmosphere nighttime removal of volatile organic compounds is initiated to a large extent by reaction with nitrate radical (NO 3 ) forming nitrates which partition between gas and particulate phase. Here we show based on particle phase measurements performed at suburban site in Netherlands that contribute substantially mass. Comparisons chemistry transport model indicate most measured are formed NO oxidation. Using aerosol composition data from three intensive observation...
Dimethyl sulfide (DMS), emitted from the oceans, is most abundant biological source of sulfur to marine atmosphere. Atmospheric DMS oxidized condensable products that form secondary aerosols affect Earth's radiative balance by scattering solar radiation and serving as cloud condensation nuclei. We report atmospheric discovery a previously unquantified oxidation product, hydroperoxymethyl thioformate (HPMTF, HOOCH2SCHO), identified through global-scale airborne observations demonstrate it be...
Abstract Wildfires emit significant amounts of pollutants that degrade air quality. Plumes from three wildfires in the western U.S. were measured aircraft during Studies Emissions and Atmospheric Composition, Clouds Climate Coupling by Regional Surveys (SEAC 4 RS) Biomass Burning Observation Project (BBOP), both summer 2013. This study reports an extensive set emission factors (EFs) for over 80 gases 5 components submicron particulate matter (PM 1 ) these temperate wildfires. These include...
Abstract. We report the physical and chemical effects of photochemically aging dilute biomass-burning smoke. A "potential aerosol mass" (PAM) flow reactor was used with analysis by a high-resolution mass spectrometer proton-transfer-reaction ion-trap during FLAME-3 campaign. Hydroxyl (OH) radical concentrations in reached up to ~1000 times average tropospheric levels, producing effective OH exposures equivalent 5 days atmosphere, allowing for us extend investigation smoke beyond oxidation...
Gas-phase low volatility organic compounds (LVOC), produced from oxidation of isoprene 4-hydroxy-3-hydroperoxide (4,3-ISOPOOH) under low-NO conditions, were observed during the FIXCIT chamber study. Decreases in LVOC directly correspond to appearance and growth secondary aerosol (SOA) consistent elemental composition, indicating that condense (at OA below 1 μg m–3). This represents first simultaneous measurement condensing species both gas particle phases. The SOA formation this study is...
Abstract. Formation of organic nitrates (RONO2) during oxidation biogenic volatile compounds (BVOCs: isoprene, monoterpenes) is a significant loss pathway for atmospheric nitrogen oxide radicals (NOx), but the chemistry RONO2 formation and degradation remains uncertain. Here we implement new BVOC mechanism (including updated isoprene chemistry, monoterpene particle uptake RONO2) in GEOS-Chem global chemical transport model with ∼ 25 × km2 resolution over North America. We evaluate using...
Abstract The Deep Convective Clouds and Chemistry (DC3) field experiment produced an exceptional dataset on thunderstorms, including their dynamical, physical, electrical structures impact the chemical composition of troposphere. gathered detailed information inflow outflow regions midlatitude thunderstorms in northeast Colorado, west Texas to central Oklahoma, northern Alabama. A unique aspect DC3 strategy was locate sample convective a day after active convection order measure...
Abstract. Substantial amounts of secondary organic aerosol (SOA) can be formed from isoprene epoxydiols (IEPOX), which are oxidation products mainly under low-NO conditions. Total IEPOX-SOA, may include SOA other parallel pathways, was quantified by applying positive matrix factorization (PMF) to mass spectrometer (AMS) measurements. The IEPOX-SOA fractions (OA) in multiple field studies across several continents summarized here and show consistent patterns with the concentration gas-phase...
We present results from a high-resolution chemical ionization time-of-flight mass spectrometer (HRToF-CIMS), operated with two different thermal desorption inlets, designed to characterize the gas and aerosol composition. Data field campaigns at forested sites are shown. Particle volatility distributions estimated using three methods: thermograms, elemental formulas, measured partitioning. Thermogram-based consistent those an (AMS) denuder, implying that is reproducible across very...
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 The Observations and Modeling of the Green Ocean Amazon 2014–2015 (GoAmazon2014/5) experiment took place around urban region Manaus in central Amazonia across 2 years. pollution plume was used to study susceptibility gases, aerosols, clouds, rainfall human activities a tropical environment. Many aspects air quality, weather, terrestrial ecosystems, climate work differently tropics than more thoroughly studied temperate regions Earth. GoAmazon2014/5, cooperative project Brazil,...
Oxidation flow reactors (OFRs) containing low-pressure mercury (Hg) lamps that emit UV light at both 185 and 254 nm ("OFR185") to generate OH radicals O3 are used in many areas of atmospheric science pollution control devices. The widely potential aerosol mass (PAM) OFR was designed for studies on the formation oxidation secondary organic aerosols (SOA), allowing a wide range oxidant exposures short experiment duration with reduced wall loss effects. Although fundamental photochemical...
<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. An oxidation flow reactor (OFR) is a vessel inside which the concentration of chosen oxidant can be increased for purpose studying SOA formation and aging by that oxidant. During BEACHON-RoMBAS (Bio-hydro-atmosphere interactions Energy, Aerosols, Carbon, H2O, Organics &amp; Nitrogen–Rocky Mountain Biogenic Aerosol Study) field campaign, ambient pine forest air was oxidized OH radicals in an OFR to measure amount could formed from real mix precursor gases, how changed with time...