skip to main content

This content will become publicly available on January 30, 2025

Title: Real-world observations of reduced nitrogen and ultrafine particles in commercial cooking organic aerosol emissions

Abstract. Cooking is an important but understudied source of urban anthropogenic fine particulate matter (PM2.5). Using a mobile laboratory, we measured PM size and composition in urban restaurant plumes. Size distribution measurements indicate that restaurants are a source of urban ultrafine particles (UFPs, particles <100 nm mobility diameter), with a mode diameter <50 nm across sampled restaurants and particle number concentrations (PNCs, a proxy for UFPs) that were substantially elevated relative to the urban background. In our observations, PM mass emitted from restaurants was almost entirely organic aerosol (OA). Aerosol mass spectra show that while emissions from most restaurants were similar, there were key mass spectral differences. All restaurants emit OA at m/z 41, 43, and 55, though the composition (e.g., the ratio of oxygenated to reduced ions at specific m/z) varied across locations. All restaurant emissions included reduced-nitrogen species detected as CxHyN+ fragments, making up ∼15 % of OA mass measured in plumes, with reduced molecular functionalities (e.g., amines, imides) that were often accompanied by oxygen-containing functional groups. The largest reduced-nitrogen emissions were observed from a commercial bread bakery (i.e., 30 %–50 % of OA mass), highlighting the marked differences between restaurants and their importance for emissions of both urban UFPs and reduced nitrogen.

more » « less
Award ID(s):
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
Date Published:
Journal Name:
Atmospheric Chemistry and Physics
Page Range / eLocation ID:
1281 to 1298
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. The evolution of organic aerosol (OA) and brown carbon (BrC) in wildfire plumes, including the relative contributions of primary versus secondary sources, has been uncertain in part because of limited knowledge of the precursor emissions and the chemical environment of smoke plumes. We made airborne measurements of a suite of reactive trace gases, particle composition, and optical properties in fresh western US wildfire smoke in July through August 2018. We use these observations to quantify primary versus secondary sources of biomass-burning OA (BBPOA versus BBSOA) and BrC in wildfire plumes. When a daytime wildfire plume dilutes by a factor of 5 to 10, we estimate that up to one-third of the primary OA has evaporated and subsequently reacted to form BBSOA with near unit yield. The reactions of measured BBSOA precursors contribute only 13 ± 3% of the total BBSOA source, with evaporated BBPOA comprising the rest. We find that oxidation of phenolic compounds contributes the majority of BBSOA from emitted vapors. The corresponding particulate nitrophenolic compounds are estimated to explain 29 ± 15% of average BrC light absorption at 405 nm (BrC Abs405) measured in the first few hours of plume evolution, despite accounting for just 4 ± 2% of average OA mass. These measurements provide quantitative constraints on the role of dilution-driven evaporation of OA and subsequent radical-driven oxidation on the fate of biomass-burning OA and BrC in daytime wildfire plumes and point to the need to understand how processing of nighttime emissions differs.

    more » « less
  2. Abstract. The evolution of organic aerosol (OA) and aerosol sizedistributions within smoke plumes is uncertain due to the variability inrates of coagulation and OA condensation/evaporation between different smokeplumes and at different locations within a single plume. We use aircraftdata from the FIREX-AQ campaign to evaluate differences in evolving aerosolsize distributions, OA, and oxygen to carbon ratios (O:C) between and withinsmoke plumes during the first several hours of aging as a function of smokeconcentration. The observations show that the median particle diameterincreases faster in smoke of a higher initial OA concentration (>1000 µg m−3), with diameter growth of over 100 nm in 8 h – despite generally having a net decrease in OA enhancementratios – than smoke of a lower initial OA concentration (<100 µg m−3), which had net increases in OA. Observations of OA and O:Csuggest that evaporation and/or secondary OA formation was greater in lessconcentrated smoke prior to the first measurement (5–57 min afteremission). We simulate the size changes due to coagulation and dilution andadjust for OA condensation/evaporation based on the observed changes in OA.We found that coagulation explains the majority of the diameter growth, withOA evaporation/condensation having a relatively minor impact. We found thatmixing between the core and edges of the plume generally occurred ontimescales of hours, slow enough to maintain differences in aging betweencore and edge but too fast to ignore the role of mixing for most of our cases. 
    more » « less
  3. The reactive partitioning of cis and trans β-IEPOX was investigated on hydrated inorganic seed particles, without the addition of acids. No organic aerosol (OA) formation was observed on dry ammonium sulfate (AS); however, prompt and efficient OA growth was observed for the cis and trans β-IEPOX on AS seeds at liquid water contents of 40–75% of the total particle mass. OA formation from IEPOX is a kinetically limited process, thus the OA growth continues if there is a reservoir of gas-phase IEPOX. There appears to be no differences, within error, in the OA growth or composition attributable to the cis / trans isomeric structures. Reactive uptake of IEPOX onto hydrated AS seeds with added base (NaOH) also produced high OA loadings, suggesting the pH dependence for OA formation from IEPOX is weak for AS particles. No OA formation, after particle drying, was observed on seed particles where Na+ was substituted for NH4+. The Henry's Law partitioning of IEPOX was measured on NaCl particles (ionic strength ~9 M) to be 3 × 107 M atm−1 (−50 / +100%). A small quantity of OA was produced when NH4+ was present in the particles, but the chloride (Cl-) anion was substituted for sulfate (SO42-), possibly suggesting differences in nucleophilic strength of the anions. Online time-of-flight aerosol mass spectrometry and offline filter analysis provide evidence of oxygenated hydrocarbons, organosulfates, and amines in the particle organic composition. The results are consistent with weak correlations between IEPOX-derived OA and particle acidity or liquid water observed in field studies, as the chemical system is nucleophile-limited and not limited in water or catalyst activity.

    more » « less
  4. Abstract. Emission of organic aerosol (OA) from wood combustion is not well constrained;understanding the governing factors of OA emissions would aid in explainingthe reported variability. Pyrolysis of the wood during combustion is theprocess that produces and releases OA precursors. We performed controlledpyrolysis experiments at representative combustion conditions. The conditionschanged were the temperature, wood length, wood moisture content, and woodtype. The mass loss of the wood, the particle concentrations, and light-gasconcentrations were measured continuously. The experiments were repeatable asshown by a single experiment, performed nine times, in which the real-timeparticle concentration varied by a maximum of 20 %. Highertemperatures increased the mass loss rate and the released concentration ofgases and particles. Large wood size had a lower yield of particles than thesmall size because of higher mass transfer resistance. Reactions outside thewood became important between 500 and 600 ∘C. Elevatedmoisture content reduced product formation because heat received was sharedbetween pyrolysis reactions and moisture evaporation. The thermophysicalproperties, especially the thermal diffusivity, of wood controlled thedifference in the mass loss rate and emission among seven wood types. Thiswork demonstrates that OA emission from wood pyrolysis is a deterministicprocess that depends on transport phenomena. 
    more » « less
  5. Abstract

    As part of the WINTER (Wintertime Investigation of Transport, Emissions, and Reactivity) campaign, a Particle‐into‐Liquid Sampler with a fraction collector was flown aboard the National Center for Atmospheric Research C‐130 aircraft. Two‐minute integrated liquid samples containing dissolved fine particulate matter (PM1) species were collected and analyzed off‐line for the smoke marker levoglucosan using high‐performance anion‐exchange chromatography‐pulsed amperometric detection to compare levoglucosan with aerosol mass spectrometer (AMS) biomass burning markers and investigate the contribution from residential burning during the study. Levoglucosan was correlated with AMS organic aerosol (R2 = 0.49) and with carbon monoxide (CO;R2 = 0.51) for all flights. Levoglucosan was not correlated with the inorganic smoke marker water‐soluble potassium but was correlated with the AMS markers ∆C2H4O2+(high resolution,R2 = 0.60) and ∆m/z60 (unit mass resolution,R2 = 0.61). However, at low levoglucosan, AMS markers deviated potentially due to interferences from other sources or differences with the species captured by the AMS markers. Analysis of levoglucosan changes relative to carbon monoxide as plumes advected from source regions showed no systematic levoglucosan loss for plumes up to 20 hr old. Based on literature residential burning source ratios and measured levoglucosan, contributions of organic carbon (OC) due to residential burning were estimated. The contribution ranged from ~30 to 100% of the OC, with significant variability depending on the source ratio used; however, the results show that biomass burning was a significant PM1OC source across the entire sampling region. A GEOS‐Chem model simulation predicted significantly less smoke contribution.

    more » « less