Ozone chemistry in western U.S. wildfire plumes

Xu, Lu; Crounse, J. D.; Vasquez, Krystal; Allen, Hannah M.; Wennberg, P. O.; Bourgeois, Ilann; Brown, Steven S.; Campuzano‐Jost, Pedro; Coggon, Matthew M.; DiGangi, J. P.; Diskin, G. S.; Fried, Alan; Gargulinski, Emily; Gilman, J. B.; Gkatzelis, Georgios I.; Guo, Hongyu; Hair, Johnathan W.; Hall, Samuel R.; Halliday, Hannah A; Hanisco, T. F.; Hannun, Reem A.; Holmes, Christopher D.; Huey, L. G.; Jimenez, José L.; Lamplugh, Aaron; Lee, Young Ro; Liao, J.; Lindaas, Jakob; Neuman, J. A.; Nowak, John B.; Peischl, J.; Peterson, David A.; Piel, Felix; Richter, Dirk; Rickly, Pamela S.; Robinson, Michael; Rollins, A. W.; Ryerson, Thomas B.; Sekimoto, Kanako; Selimovic, Vanessa; Shingler, Taylor; Soja, A. J.; Clair, J. M. St; Tanner, David J.; Ullmann, Kirk; Veres, P. R.; Walega, J.; Warneke, C.; Washenfelder, R. A.; Weibring, Petter; Wisthaler, Armin; Wolfe, G. M.; Womack, Caroline C.; Yokelson, R. J.

doi:10.1126/sciadv.abl3648

Cited by 72 publications

(62 citation statements)

References 100 publications

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“…Lower O3 in the plume centers was likely due to O3 titration by NOx with NO2 photolysis too low to regenerate O3, consistent with the anticorrelation between O3 and NOx clearly seen in this transect (Figure 12a). Higher O3 production in the diluted edges of the plume is discussed in detail by Xu et al (2021), Decker et al (2021). NEMRPASBrC also tended to be higher in the edge regions between the plumes where O3 was higher leading to a positive correlation between NEMRPASBrC and O3 (Figure 12c).…”

Section: Possible Role Of O3mentioning

confidence: 76%

Characteristics and Evolution of Brown Carbon in Western United States Wildfires

Zeng

Dibb

Scheuer

et al. 2022

Preprint

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Abstract. Brown carbon (BrC) associated with aerosol particles in western United States wildfires was measured between Jul. and Aug. 2019 onboard the NASA DC-8 research aircraft during the Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) study. Two BrC measurement methods are investigated; highly spectrally-resolved light absorption in solvent (water and methanol) extracts of particles collected on filters and in-situ bulk aerosol particle light absorption measured at three wavelengths (405, 532, 664 nm) with a photo acoustic spectrometer (PAS). A light absorption closure analysis for wavelengths between 300 and 700 nm was performed. The combined light absorption of particle pure black carbon material, including enhancements due to internally mixed materials, plus soluble BrC and a Mie-predicted factor for conversion of soluble BrC to aerosol particle BrC, was compared to absorption spectra from a power law fit to the three PAS wavelengths. For the various parameters used, at a wavelength of roughly 400 nm they agreed, at lower wavelengths the individual component-predicted particle light absorption significantly exceeded the PAS and at higher wavelengths the PAS absorption was consistently higher, but more variable. Limitations with extrapolation of PAS data to wavelengths below 405 nm and missing BrC species of low solubility that more strongly absorb at higher wavelengths may account for the differences. Based on measurements closest to fires, the emission ratio of PAS measured BrC at 405 nm relative to carbon monoxide (CO) was on average 0.13 Mm−1 ppbv−1, emission ratios for soluble BrC are also provided. As the smoke moved away from the burning regions the evolution over time of BrC was observed to be highly complex; BrC enhancement, depletion, or constant levels with age were all observed in the first 8 hours after emission in different plumes. Within 8 hours following emissions, 4-nitrocatechol, a well characterized BrC chromophore commonly found in smoke particles, was largely depleted relative to the bulk BrC. In a descending plume where temperature increased by 15 K, 4-nitrocatechol dropped possibly due to temperature-driven evaporation, but bulk BrC remained largely unchanged. Evidence was found for reactions with ozone, or related species, as a pathway for secondary formation of BrC under both low and high oxides of nitrogen (NOx) conditions, while BrC was also observed to be bleached in regions of higher ozone and low NOx, consistent with complex behaviors of BrC observed in laboratory studies. Although the evolution of smoke in the first hours following emission is highly variable, a limited number of measurements of more aged smoke (15 to 30 hours) indicate a net loss of BrC. It is yet to be determined how the near-field BrC evolution in smoke affects the characteristics of smoke over longer time and spatial scales, where its environmental impacts are likely to be greater.

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Section: Possible Role Of O3mentioning

confidence: 76%

Characteristics and Evolution of Brown Carbon in Western United States Wildfires

Zeng

Dibb

Scheuer

et al. 2022

Preprint

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“…12a). Higher O 3 production in the diluted edges of the plume is discussed in detail by Xu et al (2021), and Decker et al (2021). NEMR PASBrC also tended to be higher in the edge regions between the plumes where O 3 was higher, leading to a positive correlation between NEMR PASBrC and O 3 (Fig.…”

Section: Possible Role Of Omentioning

confidence: 78%

Characteristics and evolution of brown carbon in western United States wildfires

et al. 2022

Self Cite

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Abstract. Brown carbon (BrC) associated with aerosol particles in western United States wildfires was measured between July and August 2019 aboard the NASA DC-8 research aircraft during the Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) study. Two BrC measurement methods are investigated, highly spectrally resolved light absorption in solvent (water and methanol) extracts of particles collected on filters and in situ bulk aerosol particle light absorption measured at three wavelengths (405, 532 and 664 nm) with a photoacoustic spectrometer (PAS). A light-absorption closure analysis for wavelengths between 300 and 700 nm was performed. The combined light absorption of particle pure black carbon material, including enhancements due to internally mixed materials, plus soluble BrC and a Mie-predicted factor for conversion of soluble BrC to aerosol particle BrC, was compared to absorption spectra from a power law fit to the three PAS wavelengths. For the various parameters used, at a wavelength of roughly 400 nm they agreed, at lower wavelengths the individual component-predicted particle light absorption significantly exceeded the PAS and at higher wavelengths the PAS absorption was consistently higher but more variable. Limitations with extrapolation of PAS data to wavelengths below 405 nm and missing BrC species of low solubility that more strongly absorb at higher wavelengths may account for the differences. Based on measurements closest to fires, the emission ratio of PAS-measured BrC at 405 nm relative to carbon monoxide (CO) was on average 0.13 Mm−1 ppbv−1; emission ratios for soluble BrC are also provided. As the smoke moved away from the burning regions, the evolution over time of BrC was observed to be highly complex; BrC enhancement, depletion or constant levels with age were all observed in the first 8 h after emission in different plumes. Within 8 h following emissions, 4-nitrocatechol, a well-characterized BrC chromophore commonly found in smoke particles, was largely depleted relative to the bulk BrC. In a descending plume where temperature increased by 15 K, 4-nitrocatechol dropped, possibly due to temperature-driven evaporation, but bulk BrC remained largely unchanged. Evidence was found for reactions with ozone, or related species, as a pathway for secondary formation of BrC under both low and high oxides of nitrogen (NOx) conditions, while BrC was also observed to be bleached in regions of higher ozone and low NOx, consistent with complex behaviors of BrC observed in laboratory studies. Although the evolution of smoke in the first hours following emission is highly variable, a limited number of measurements of more aged smoke (15 to 30 h) indicate a net loss of BrC. It is yet to be determined how the near-field BrC evolution in smoke affects the characteristics of smoke over longer timescales and spatial scales, where its environmental impacts are likely to be greater.

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“…Second, increases in DOC were greatest at sites proximate to the largest fire systems (Figure b, Table S1). Third, significant Spearman’s rank correlations were observed between prefire-normalized changes in DOC concentrations and equivalent changes in atmospheric PM 2.5 and ozone, both byproducts of wildfires used as indices of burn intensity over time (Figure , Table S2). Site-specific correlation factors ( r s ) ranged from 0.81 to 0.95, and across-site correlations were also significant: PM 2.5 r (22) = 0.70, p < 0.001, ozone r (22) = 0.68, p < 0.001.…”

Section: Resultsmentioning

confidence: 99%

Of Sea and Smoke: Evidence of Marine Dissolved Organic Matter Deposition from 2020 Western United States Wildfires

Coward¹,

Seech²,

Carter³

et al. 2022

Environ. Sci. Technol. Lett.

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The record-setting wildfires that ravaged the western United States throughout 2020 released high concentrations of organic carbon (C) into the environment, including the adjacent Pacific Ocean. Yet little is known about the fate of marine wildfire-derived C, solubilized as dissolved organic matter (DOM), despite growing observations of ash deposition in such systems. We sought to quantify and characterize DOM inputs to Pacific surface waters spanning the California coastline from August 1 to October 31, 2020. Across over 290 field samples, dissolved organic C concentrations peaked 2- to 4-fold higher after the eruption of fire systems than immediate pre-wildfire levels. C concentrations were well correlated with atmospheric pyrogenic proxies PM2.5 and ozone, supporting pyrogenic sourcing. Molecular characterization of DOM by ultrahigh-resolution FTICR-MS revealed both a diversity of formulas, supporting a growing consensus of pyrogenic heterogeneity, and temporal shifts conserved across sites. An initial increase in highly aromatic, oxygen-containing compounds aligned with PM2.5 concentrations, burn extent, and C deposition. Over time, transformation to increasingly aliphatic DOM occurred. The latter is hypothesized to be a result of complex interplay between biotic and abiotic processes, warranting further study. Our observations suggest that wildfires are a substantial yet dynamic source of marine surface organic C.

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Ozone chemistry in western U.S. wildfire plumes

Abstract: While ozone increases rapidly in wildfire plumes, downwind its production rate slows dramatically as nitrogen oxide levels decline.

Cited by 72 publications

References 100 publications

Characteristics and Evolution of Brown Carbon in Western United States Wildfires

Characteristics and Evolution of Brown Carbon in Western United States Wildfires

Characteristics and evolution of brown carbon in western United States wildfires

Of Sea and Smoke: Evidence of Marine Dissolved Organic Matter Deposition from 2020 Western United States Wildfires

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