Abstract. Nitrogen-containing organic compounds, which may be directly emitted into the atmosphere or which may form via reactions with prevalent reactive nitrogen species (e.g., NH3, NOx, NO3), have important but uncertaineffects on climate and human health. Using gas and liquid chromatographywith soft ionization and high-resolution mass spectrometry, we performed amolecular-level speciation of functionalized organic compounds at a coastal site on the Long Island Sound in summer (during the 2018 Long Island Sound Tropospheric Ozone Study – LISTOS – campaign) and winter. This region often experiences poor air quality due to theemissions of reactive anthropogenic, biogenic, and marine-derived compoundsand their chemical transformation products. We observed a range offunctionalized compounds containing oxygen, nitrogen, and/or sulfur atomsresulting from these direct emissions and chemical transformations,including photochemical and aqueous-phase processing that was more pronounced in summer and winter, respectively. In both summer and winter, nitrogen-containing organic aerosols dominated the observed distribution offunctionalized particle-phase species ionized by our analytical techniques,with 85 % and 68 % of total measured ion abundance containing a nitrogenatom, respectively. Nitrogen-containing particles included reduced nitrogen functional groups (e.g., amines, imines, azoles) and common NOz contributors (e.g., organonitrates). Reduced nitrogen functional groups observed in the particle phase were frequently paired with oxygen-containing groups elsewhere on the molecule, and their prevalence often rivaled that of oxidized nitrogen groups detected by our methods. Supplemental gas-phasemeasurements, collected on adsorptive samplers and analyzed with a novelliquid chromatography-based method, suggest that gas-phase reduced nitrogen compounds are possible contributing precursors to the observed nitrogen-containing particles. Altogether, this work highlights theprevalence of reduced nitrogen-containing compounds in the less-studied northeastern US and potentially in other regions with similar anthropogenic, biogenic, and marine source signatures.
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Atmospheric evolution of emissions from a boreal forest fire: the formation of highly functionalized oxygen-, nitrogen-, and sulfur-containing organic compounds
Abstract. Forest fires are major contributors of reactive gas- and particle-phaseorganic compounds to the atmosphere. We used offline high-resolution tandemmass spectrometry to perform a molecular-level speciation of gas- andparticle-phase compounds sampled via aircraft from an evolving boreal forestfire smoke plume in Saskatchewan, Canada. We observed diversemultifunctional compounds containing oxygen, nitrogen, and sulfur (CHONS),whose structures, formation, and impacts are understudied. Thedilution-corrected absolute ion abundance of particle-phase CHONS compoundsincreased with plume age by a factor of 6.4 over the first 4 h ofdownwind transport, and their relative contribution to the observedfunctionalized organic aerosol (OA) mixture increased from 19 % to 40 %.The dilution-corrected absolute ion abundance of particle-phase compoundswith sulfide functional groups increased by a factor of 13 with plume age,and their relative contribution to observed OA increased from 4 % to40 %. Sulfides were present in up to 75 % of CHONS compounds and theincreases in sulfides were accompanied by increases in ring-bound nitrogen;both increased together with CHONS prevalence. A complex mixture ofintermediate- and semi-volatile gas-phase organic sulfur species wasobserved in emissions from the fire and depleted downwind, representingpotential precursors to particle-phase CHONS compounds. These resultsdemonstrate CHONS formation from nitrogen- and oxygen-containing biomass burningemissions in the presence of reduced sulfur species. In addition, theyhighlight chemical pathways that may also be relevant in situations withelevated emissions of nitrogen- and sulfur-containing organic compounds fromresidential biomass burning and fossil fuel use (e.g., coal), respectively.
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- Award ID(s):
- 1764126
- NSF-PAR ID:
- 10255419
- Date Published:
- Journal Name:
- Atmospheric Chemistry and Physics
- Volume:
- 21
- Issue:
- 1
- ISSN:
- 1680-7324
- Page Range / eLocation ID:
- 255 to 267
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5194/acp-21-255-2021
