Diel cycle impacts on the chemical and light absorption properties of organic carbon aerosol from wildfires in the western United States

Abstract. Organic aerosol (OA) emissions from biomass burning have been the subject of intense research in recent years, involving a combination of field campaigns and laboratory studies. These efforts have aimed at improving our limited understanding of the diverse processes and pathways involved in the atmospheric processing and evolution of OA properties, culminating in their accurate parameterizations in climate and chemical transport models. To bring closure between laboratory and field studies, wildfire plumes in the western United States were sampled and characterized for their chemical and optical properties during the ground-based segment of the 2019 Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) field campaign. Using a custom-developed multiwavelength integrated photoacoustic-nephelometer spectrometer in conjunction with a suite of instruments, including an oxidation flow reactor equipped to generate hydroxyl (OH⚫) or nitrate (NO3⚫) radicals to mimic daytime or nighttime oxidative aging processes, we investigated the effects of multiple equivalent hours of OH⚫ or NO3⚫ exposure on the chemical composition and mass absorption cross-sections (MAC(λ)) at 488 and 561 nm of OA emitted from wildfires in Arizona and Oregon. We found that OH⚫ exposure induced a slight initial increase in absorption corresponding to short timescales; however, at longer timescales, the wavelength-dependent MAC(λ) decreased by a factor of 0.72 ± 0.08, consistent with previous laboratory studies and reports of photobleaching. On the other hand, NO3⚫ exposure increased MAC(λ) by a factor of up to 1.69 ± 0.38. We also noted some sensitivity of aerosol aging to different fire conditions between Arizona and Oregon. The MAC(λ) enhancement following NO3⚫ exposure was found to correlate with an enhancement in CHO1N and CHOgt1N ion families measured by an Aerodyne aerosol mass spectrometer.

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Diel Cycle Impacts on the Chemical and Light Absorption Properties of Organic Carbon Aerosol from Wildfires in the Western United States

10.5194/acp-2021-247 ◽

2021 ◽

Author(s):

Benjamin Sumlin ◽

Edward Fortner ◽

Andrew Lambe ◽

Nishit Shetty ◽

Conner Daube ◽

...

Keyword(s):

United States ◽

Cross Sections ◽

Flow Reactor ◽

Field Studies ◽

Western United States ◽

Laboratory Studies ◽

Aerosol Mass Spectrometer ◽

Oxidative Aging ◽

Aerosol Mass ◽

Atmospheric Processing

Abstract. Organic aerosol (OA) emissions from biomass burning have been the subject of intense research in recent years, involving a combination of field campaigns and laboratory studies. These efforts have aimed at improving our limited understanding of the diverse processes and pathways involved in the atmospheric processing and evolution of OA properties, culminating in their accurate parameterizations in climate and chemical transport models. To bring closure between laboratory and field studies, wildfire plumes in the western United States were sampled and characterized for their chemical and optical properties during the ground-based segment of the 2019 Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) field campaign. Using a custom-developed multiwavelength integrated photoacoustic-nephelometer (MIPN) spectrometer in conjunction with a suite of instruments, including an oxidation flow reactor equipped to generate hydroxyl (OH∙) or nitrate (NO3∙) radicals to mimic daytime or nighttime oxidative aging processes, we investigated the effects of multiple equivalent days or nights of OH∙/NO3∙ exposure on the chemical composition and mass absorption cross-sections (MAC(λ)) at 488 and 561 nm of OA emitted from wildfires in Arizona and Oregon. We found that OH∙ exposure reduced the wavelength-dependent MAC(λ) by a factor of 0.72 ± 0.08, consistent with previous laboratory studies. On the other hand, NO3∙ exposure increased it by a factor of up to 1.69 ± 0.38. The MAC enhancement following NO3∙ exposure was correlated with an enhancement in CHO1N and CHOgt1N ion families measured with an aerosol mass spectrometer.

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Susceptibility of Walnut and Hickory Species to Geosmithia morbida

Plant Disease ◽

10.1094/pdis-07-12-0636-re ◽

2013 ◽

Vol 97 (5) ◽

pp. 601-607 ◽

Cited By ~ 45

Author(s):

Curtis Utley ◽

Tivonne Nguyen ◽

Tatiana Roubtsova ◽

Mark Coggeshall ◽

Tim M. Ford ◽

...

Keyword(s):

United States ◽

Field Studies ◽

Western United States ◽

Eastern United States ◽

Geosmithia Morbida ◽

Pityophthorus Juglandis ◽

Production Areas ◽

Walnut Twig Beetle ◽

Native Host ◽

Half Sibling

Thousand cankers disease (TCD) of walnut is a result of feeding in the phloem by the walnut twig beetle (WTB), Pityophthorus juglandis, and subsequent canker formation caused by Geosmithia morbida around galleries. TCD has caused extensive morbidity and mortality to Juglans nigra in the western United States and, in 2010, was discovered in the eastern United States, where the tree is a highly valuable timber resource. WTB and G. morbida also have been found in J. regia orchards throughout major production areas in California, and the numbers of damaged trees are increasing. We tested the susceptibility of walnut and hickory species to G. morbida in greenhouse and field studies. Carya illinoinensis, C. aquatica, and C. ovata were immune. All walnut species tested, including J. ailantifolia, J. californica, J. cinerea, J. hindsii, J. major, J. mandshurica, J. microcarpa, J. nigra, and J. regia, developed cankers following inoculation with G. morbida. J. nigra was the most susceptible, whereas J. major, a native host of the WTB and, presumably, G. morbida, had smaller and more superficial cankers. Canker formation differed among maternal half-sibling families of J. nigra and J. cinerea, indicating genetic variability in resistance to G. morbida. Our inoculation studies with G. morbida have corroborated many of the field observations on susceptibility of walnut and hickory species to TCD, although the ability of the WTB to successfully attack and breed in walnut is also an important component in TCD resistance.

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Origins of fine aerosol mass in the western United States using positive matrix factorization

Journal of Geophysical Research Atmospheres ◽

10.1029/2003jd003678 ◽

2003 ◽

Vol 108 (D23) ◽

Cited By ~ 22

Author(s):

Wei Liu

Keyword(s):

United States ◽

Matrix Factorization ◽

Positive Matrix Factorization ◽

Western United States ◽

Positive Matrix ◽

Aerosol Mass ◽

Fine Aerosol

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Writing Time in Metaphors

10.3366/edinburgh/9781474423939.003.0004 ◽

2018 ◽

Author(s):

Jennifer J. Smith

Keyword(s):

United States ◽

The United States ◽

Western United States ◽

Entire System ◽

Language And Culture ◽

Space Race ◽

Do So

Coherence of place often exists alongside irregularities in time in cycles, and chapter three turns to cycles linked by temporal markers. Ray Bradbury’s The Martian Chronicles (1950) follows a linear chronology and describes the exploration, conquest, and repopulation of Mars by humans. Conversely, Louise Erdrich’s Love Medicine (1984) jumps back and forth across time to narrate the lives of interconnected families in the western United States. Bradbury’s cycle invokes a confluence of historical forces—time as value-laden, work as a calling, and travel as necessitating standardized time—and contextualizes them in relation to anxieties about the space race. Erdrich’s cycle invokes broader, oppositional conceptions of time—as recursive and arbitrary and as causal and meaningful—to depict time as implicated in an entire system of measurement that made possible the destruction and exploitation of the Chippewa people. Both volumes understand the United States to be preoccupied with imperialist impulses. Even as they critique such projects, they also point to the tenacity with which individuals encounter these systems, and they do so by creating “interstitial temporalities,” which allow them to navigate time at the crossroads of language and culture.

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