Analysis of reduced and oxidized nitrogen-containing organic compounds at a coastal site in summer and winter

Abstract

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 uncertain effects on climate and human health. Using gas and liquid chromatography with soft ionization and high-resolution mass spectrometry, we performed a molecular-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 the emissions of reactive anthropogenic, biogenic, and marine-derived compounds and their chemical transformation products. We observed a range of functionalized compounds containing oxygen, nitrogen, and/or sulfur atoms resulting 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 of functionalized particle-phase species ionized by our analytical techniques, with 85 % and 68 % of total measured ion abundance containing a nitrogen atom, 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-phase measurements, collected on adsorptive samplers and analyzed with a novel liquid chromatography-based method, suggest that gas-phase reduced nitrogen compounds are possible contributing precursors to the observed nitrogen-containing particles. Altogether, this work highlights the prevalence of reduced nitrogen-containing compounds in the less-studied northeastern US and potentially in other regions with similar anthropogenic, biogenic, and marine source signatures.

Production of Volatile Organic Compounds by Ozone Oxidation Chemistry at the South China Sea Surface Microlayer

“…A suite of compounds were identified, including acetaldehyde ( m / z 45, [C 2 H 4 O]­H + ), acetone and/or propanal ( m / z 59, [C 3 H 6 O]­H + ), m / z 69 and 83, cyclohexanone ( m / z 99, [C 6 H 10 O]­H + ), hexanal ( m / z 101, [C 6 H 12 O]­H + ), heptanal ( m / z 115, [C 7 H 14 O]­H + ), 2,4-dimethyl-1-heptene ( m / z 127, [C 9 H 18 ]­H + ), octanal ( m / z 129, [C 8 H 16 O]­H + ), 2-ethylhexanol ( m / z 131, [C 8 H 18 O]­H + ), nonanal ( m / z 143, [C 9 H 18 O]­H + ), and decanal ( m / z 157, [C 10 H 20 O]­H + ). Two compounds with m / z 84 and 98 could possibly be attributed to the nitrogen-containing compounds [C 4 H 5 ON]­H + and [C 5 H 7 ON]­H + , which are most likely azole-like compounds that have been observed at coastal sites. , All of the detected masses by PTR–TOF–MS and estimated production rates are shown in Table S5 of the Supporting Information. Figure shows the formation profiles of m / z 59, 69, 83, and 101, which were detected as common product compounds upon ozone oxidation of all 10 SML samples.…”

Development and Performance Evaluation of a Low-Cost Portable PM2.5 Monitor for Mobile Deployment

“…Collocation refers to operating sensors and a reference instrument at the same time and the same place under real world conditions [ 10 ]. To evaluate the Smart-P performance, we collocated four monitors (IDs: 501, 502, 503, and 504) at the Yale Costal Field Station (YCFS) in Guildford, Connecticut, U.S. (41.2583° N, 72.7312° W), shown in Figure 4 with site description and characterization in prior work [ 21 , 55 ]. The YCFS ( Figure 4 a) is equipped with a Met One BAM-1020 monitor to measure ambient PM 2.5 with hourly resolution.…”

Opinion: Atmospheric Multiphase Chemistry: Past, Present, and Future

“…For multiphase chemistry, advances in analytical mass spectrometry have been transformative. Within the last twenty years, online characterization of aerosol composition has become commonplace (Canagaratna et al, 2007), studies of single particle composition allow us to observe the variability in mixing state and chemical diversity (Murphy et al, 2006;Prather et al, 2008), and offline filter sampling has progressed from the characterization of a few targeted species to non-targeted analyses using a range of mass spectral ionization methods (Papazian et al, 2022;Ditto et al, 2022). Identifying specific molecular "markers" for organics and functional groups is still somewhat uncertain; developing such identification would be very helpful.…”