Nighttime and daytime dark oxidation chemistry in wildfire plumes: an observation and model analysis of FIREX-AQ aircraft data

Abstract. Wildfires are increasing in size across the western US, leading to increases in human smoke exposure and associated negative health impacts. The impact of biomass burning (BB) smoke, including wildfires, on regional air quality depends on emissions, transport, and chemistry, including oxidation of emitted BB volatile organic compounds (BBVOCs) by the hydroxyl radical (OH), nitrate radical (NO3), and ozone (O3). During the daytime, when light penetrates the plumes, BBVOCs are oxidized mainly by O3 and OH. In contrast, at night or in optically dense plumes, BBVOCs are oxidized mainly by O3 and NO3. This work focuses on the transition between daytime and nighttime oxidation, which has significant implications for the formation of secondary pollutants and loss of nitrogen oxides (NOx=NO+NO2) and has been understudied. We present wildfire plume observations made during FIREX-AQ (Fire Influence on Regional to Global Environments and Air Quality), a field campaign involving multiple aircraft, ground, satellite, and mobile platforms that took place in the United States in the summer of 2019 to study both wildfire and agricultural burning emissions and atmospheric chemistry. We use observations from two research aircraft, the NASA DC-8 and the NOAA Twin Otter, with a detailed chemical box model, including updated phenolic mechanisms, to analyze smoke sampled during midday, sunset, and nighttime. Aircraft observations suggest a range of NO3 production rates (0.1–1.5 ppbv h−1) in plumes transported during both midday and after dark. Modeled initial instantaneous reactivity toward BBVOCs for NO3, OH, and O3 is 80.1 %, 87.7 %, and 99.6 %, respectively. Initial NO3 reactivity is 10–104 times greater than typical values in forested or urban environments, and reactions with BBVOCs account for >97 % of NO3 loss in sunlit plumes (jNO2 up to 4×10-3s-1), while conventional photochemical NO3 loss through reaction with NO and photolysis are minor pathways. Alkenes and furans are mostly oxidized by OH and O3 (11 %–43 %, 54 %–88 % for alkenes; 18 %–55 %, 39 %–76 %, for furans, respectively), but phenolic oxidation is split between NO3, O3, and OH (26 %–52 %, 22 %–43 %, 16 %–33 %, respectively). Nitrate radical oxidation accounts for 26 %–52 % of phenolic chemical loss in sunset plumes and in an optically thick plume. Nitrocatechol yields varied between 33 % and 45 %, and NO3 chemistry in BB plumes emitted late in the day is responsible for 72 %–92 % (84 % in an optically thick midday plume) of nitrocatechol formation and controls nitrophenolic formation overall. As a result, overnight nitrophenolic formation pathways account for 56 %±2 % of NOx loss by sunrise the following day. In all but one overnight plume we modeled, there was remaining NOx (13 %–57 %) and BBVOCs (8 %–72 %) at sunrise.

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Nighttime and Daytime Dark Oxidation Chemistry in Wildfire Plumes: An Observation and Model Analysis of FIREX-AQ Aircraft Data

10.5194/acp-2021-267 ◽

2021 ◽

Author(s):

Zachary C. J. Decker ◽

Michael A. Robinson ◽

Kelley C. Barsanti ◽

Ilann Bourgeois ◽

Matthew M. Coggon ◽

...

Keyword(s):

Air Quality ◽

Atmospheric Chemistry ◽

The United States ◽

Urban Environments ◽

Nitrate Radical ◽

Mobile Platforms ◽

Radical Oxidation ◽

Research Aircraft ◽

Oxidation Chemistry ◽

The Impact

Abstract. Wildfires are increasing in size across the western U.S., leading to increases in human smoke exposure and associated negative health impacts. The impact of biomass burning (BB) smoke, including wildfires, on regional air quality depends on emissions, transport, and chemistry, including oxidation of emitted BB volatile organic compounds (BBVOCs) by the hydroxyl radical (OH), nitrate radical (NO3), and ozone (O3). During the daytime, when light penetrates the plumes, BBVOCs are oxidized mainly by O3 and OH. In contrast, at night, or in optically dense plumes, BBVOCs are oxidized mainly by O3 and NO3. This work focuses on the transition between daytime and nighttime oxidation, which has significant implications for the formation of secondary pollutants and loss of nitrogen oxides (NOx = NO + NO2), and has been understudied. We present wildfire plume observations made during FIREX-AQ (Fire Influence on Regional to Global Environments and Air Quality), a field campaign involving multiple aircraft, ground, satellite, and mobile platforms that took place in the United States in the summer of 2019 to study both wildfire and agricultural burning emissions and atmospheric chemistry. We use observations from two research aircraft, the NASA DC-8 and the NOAA Twin Otter, with a detailed chemical box model, including updated phenolic mechanisms, to analyze smoke sampled during mid-day, sunset, and nighttime. Aircraft observations suggest a range of NO3 production rates (0.1–1.5 ppbv h−1) in plumes transported both mid-day and after dark. Modeled initial instantaneous reactivity toward BBVOCs for NO3, OH, and O3 is 80.1 %, 87.7 %, 99.6 %, respectively. Initial NO3 reactivity is 10–104 times greater than typical values in forested or urban environments and reactions with BBVOCs account for ≥ 98 % of NO3 loss in sunlit plumes (jNO2 up to 4 x 10–3 s–1), while conventional photochemical NO3 loss through reaction with NO and photolysis are minor pathways. Alkenes and furans are mostly oxidized by OH and O3 (11–43 %, 54–88 % for alkenes; 18–55 %, 39–76 %, for furans, respectively), but phenolic oxidation is split between NO3, O3, and OH (26–52 %, 22–43 %, 16–33 %, respectively). Nitrate radical oxidation accounts for 26–52 % of phenolic chemical loss in sunset plumes and in an optically thick plume. Nitrocatechol yields varied between 33 % and 45 %, and NO3 chemistry in BB plumes emitted late in the day is responsible for 72–92 % (84 % in an optically thick mid-day plume) of nitrocatechol formation and controls nitrophenolic formation overall. As a result, overnight nitrophenolic formation pathways account for 56 ± 2 % of NOx loss by sunrise the following day. In all but one overnight plume we model, there is remaining NOx (13 %–57 %) and BBVOCs (8 %–72 %) at sunrise.

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Examining the impact of heterogeneous nitryl chloride production on air quality across the United States

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-6145-2012 ◽

2012 ◽

Vol 12 (2) ◽

pp. 6145-6183 ◽

Cited By ~ 1

Author(s):

G. Sarwar ◽

H. Simon ◽

P. Bhave ◽

G. Yarwood

Keyword(s):

United States ◽

Air Quality ◽

Atmospheric Chemistry ◽

Forest Fires ◽

The United States ◽

Anthropogenic Sources ◽

Reactive Nitrogen ◽

Nitryl Chloride ◽

The Impact ◽

Hydrolysis Of

Abstract. The heterogeneous hydrolysis of dinitrogen pentoxide (N2O5) has typically been modeled as only producing nitric acid. However, recent field studies have confirmed that the presence of particulate chloride alters the reaction product to produce nitryl chloride (ClNO2) which undergoes photolysis to generate chlorine atoms and nitrogen dioxide (NO2). Both chlorine and NO2 affect atmospheric chemistry and air quality. We present an updated gas-phase chlorine mechanism that can be combined with the Carbon Bond 05 mechanism and incorporate the combined mechanism into the Community Multiscale Air Quality modeling system. We then update the current model treatment of heterogeneous hydrolysis of N2O5 to include ClNO2 as a product. The model, in combination with a comprehensive inventory of chlorine compounds, reactive nitrogen, particulate matter, and organic compounds, is used to evaluate the impact of the heterogeneous ClNO2 production on air quality across the United States for the months of February and September in 2006. The heterogeneous production increases ClNO2 in coastal as well as many in-land areas in the United States. Particulate chloride derived from sea-salts, anthropogenic sources, and forest fires activates the heterogeneous production of ClNO2. With current estimates of tropospheric emissions burden, it modestly enhances monthly mean 8-h ozone (up to 1–2 ppbv or 3–4%) but causes large increases (up to 13 ppbv) in isolated episodes. It also substantially reduce the mean total nitrate by up to 0.8–2.0 μg m−3 or 11–21%. Modeled ClNO2 accounts for up to 3–4% of the monthly mean total reactive nitrogen. Sensitivity results of the model suggest that ClNO2 formation is limited more by the presence of particulate chloride than by the abundance of N2O5.

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The impact of marine organics on the air quality of the western United States

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-6257-2010 ◽

2010 ◽

Vol 10 (3) ◽

pp. 6257-6278 ◽

Cited By ~ 1

Author(s):

B. Gantt ◽

N. Meskhidze ◽

A. G. Carlton

Keyword(s):

United States ◽

Air Quality ◽

Atmospheric Chemistry ◽

Environmental Protection Agency ◽

Regional Scale ◽

The United States ◽

Coastal Areas ◽

Western United States ◽

The Us ◽

The Impact

Abstract. The impact of marine organic emissions to the air quality in coastal areas of the western United States is studied using the latest version of the US Environmental Protection Agency (EPA) regional-scale Community Multiscale Air Quality (CMAQv4.7) modeling system. Emissions of marine isoprene, monoterpenes, and primary organic matter (POM) from the ocean are implemented into the model to provide a comprehensive view of the connection between ocean biology and atmospheric chemistry and air pollution. Model simulations show that marine organics can increase the concentration of PM2.5 by 0.1–0.3 μg m−3 (up to 5%) in coastal cities. This increase in the PM2.5 concentration is primarily attributed to the POM emissions, with small contributions from the marine isoprene and monoterpenes. When marine organic emissions are included, organic carbon (OC) concentrations over the remote ocean are increased by up to 50% (25% in coastal areas), values consistent with recent observational findings. This study is the first to quantify the air quality impacts from marine POM and monoterpenes for the United States, and highlights the need for inclusion of marine organic emissions in air quality models.

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Examining the impact of heterogeneous nitryl chloride production on air quality across the United States

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-6455-2012 ◽

2012 ◽

Vol 12 (14) ◽

pp. 6455-6473 ◽

Cited By ~ 86

Author(s):

G. Sarwar ◽

H. Simon ◽

P. Bhave ◽

G. Yarwood

Keyword(s):

United States ◽

Air Quality ◽

Atmospheric Chemistry ◽

Forest Fires ◽

The United States ◽

Anthropogenic Sources ◽

Reactive Nitrogen ◽

Nitryl Chloride ◽

The Impact ◽

Hydrolysis Of

Abstract. The heterogeneous hydrolysis of dinitrogen pentoxide (N2O5) has typically been modeled as only producing nitric acid. However, recent field studies have confirmed that the presence of particulate chloride alters the reaction product to produce nitryl chloride (ClNO2) which undergoes photolysis to generate chlorine atoms and nitrogen dioxide (NO2). Both chlorine and NO2 affect atmospheric chemistry and air quality. We present an updated gas-phase chlorine mechanism that can be combined with the Carbon Bond 05 mechanism and incorporate the combined mechanism into the Community Multiscale Air Quality (CMAQ) modeling system. We then update the current model treatment of heterogeneous hydrolysis of N2O5 to include ClNO2 as a product. The model, in combination with a comprehensive inventory of chlorine compounds, reactive nitrogen, particulate matter, and organic compounds, is used to evaluate the impact of the heterogeneous ClNO2 production on air quality across the United States for the months of February and September in 2006. The heterogeneous production increases ClNO2 in coastal as well as many in-land areas in the United States. Particulate chloride derived from sea-salts, anthropogenic sources, and forest fires activates the heterogeneous production of ClNO2. With current estimates of tropospheric emissions, it modestly enhances monthly mean 8-h ozone (up to 1–2 ppbv or 3–4%) but causes large increases (up to 13 ppbv) in isolated episodes. This chemistry also substantially reduces the mean total nitrate by up to 0.8–2.0 μg m−3 or 11–21%. Modeled ClNO2 accounts for up to 6% of the monthly mean total reactive nitrogen. Sensitivity results of the model suggest that heterogeneous production of ClNO2 can further increase O3 and reduce TNO3 if elevated particulate-chloride levels are present in the atmosphere.

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First year of real-time VOC measurements at the SIRTA facility (Paris region, France): diurnal and seasonal variabilities, impact of lockdowns on air quality

10.5194/egusphere-egu21-8643 ◽

2021 ◽

Author(s):

Leïla Simon ◽

Valérie Gros ◽

Jean-Eudes Petit ◽

François Truong ◽

Roland Sarda-Esteve ◽

...

Keyword(s):

Air Quality ◽

Atmospheric Chemistry ◽

Seasonal Variability ◽

Anthropogenic Sources ◽

First Year ◽

Good Representation ◽

Atmospheric Measurements ◽

Paris Region ◽

The Impact

Volatile Organic Compounds (VOCs) have direct influences on air quality and climate. They also play a key role in atmospheric chemistry, as they are precursors of secondary pollutants, such as ozone (O3) and secondary organic aerosols (SOA).Long-term datasets of in-situ atmospheric measurements are crucial to characterize the variability of atmospheric chemical composition. Online and continuous measurements of O3, NOx and aerosols have been achieved at the SIRTA-ACTRIS facility (Paris region, France), since 2012. Regarding VOCs, they have been measured there for several years thanks to bi-weekly samplings followed by offline Gas Chromatography analysis. However, this method doesn&#8217;t provide a good representation of the temporal variability of VOC concentrations. To tackle this issue, online VOC measurements using a Proton-Transfer-Reaction Quadrupole Mass-Spectrometer (PTR-Q-MS) have been started in January 2020.The dataset acquired during the first year of online VOC measurements is analyzed, which gives insights on VOC seasonal variability. The additional long-term datasets obtained from co-located measurements (O3, NOx, aerosol physical and chemical properties, meteorological parameters) are also used for the sake of this study.Due to Covid-19 pandemic, the year 2020 notably comprised a total lockdown in France in Spring, and a lighter one in Autumn. Therefore, a focus can be made on the impact of these lockdowns on the VOC variability and sources. To this end, the diurnal cycles of VOCs considered markers for anthropogenic sources are carefully investigated. Results notably indicate that markers for traffic and wood burning sources behave quite differently during the Spring lockdown in comparison to the other periods. A source apportionment analysis using positive matrix factorization allows to further document the seasonal variability of VOC sources and the impacts on air quality associated with the lockdown measures.

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The Effect of the Covid-19 Lockdown on Air Quality in Three Italian Medium-Sized Cities

Atmosphere ◽

10.3390/atmos11101118 ◽

2020 ◽

Vol 11 (10) ◽

pp. 1118 ◽

Cited By ~ 2

Author(s):

Gabriele Donzelli ◽

Lorenzo Cioni ◽

Mariagrazia Cancellieri ◽

Agustin Llopis Morales ◽

Maria Morales Suárez-Varela

Keyword(s):

Air Quality ◽

Heavy Traffic ◽

Urban Environments ◽

Meteorological Conditions ◽

Control Measures ◽

Source Control ◽

Vehicular Traffic ◽

Urban Centers ◽

Italian Government ◽

The Impact

Despite the societal and economic impacts of the COVID-19 pandemic, the lockdown measures put in place by the Italian government provided an unprecedented opportunity to increase our knowledge of the effect transportation and industry-related emissions have on the air quality in our cities. This study assessed the effect of reduced emissions during the lockdown period, due to COVID-19, on air quality in three Italian cities, Florence, Pisa, and Lucca. For this study, we compared the concentration of particulate matter PM10, PM2.5, NO2, and O3 measured during the lockdown period, with values obtained in the same period of 2019. Our results show no evidence of a direct relationship between the lockdown measures implemented and PM reduction in urban centers, except in areas with heavy traffic. Consistent with recently published studies, we did, however, observe a significant decrease in NO2 concentrations among all the air-monitoring stations for each city in this study. Finally, O3 levels remained unchanged during the lockdown period. Of note, there were slight variations in the meteorological conditions for the same periods of different years. Our results suggest a need for further studies on the impact of vehicular traffic and industrial activities on PM air pollution, including adopting holistic source-control measures for improved air quality in urban environments.

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The contribution of marine organics to the air quality of the western United States

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-7415-2010 ◽

2010 ◽

Vol 10 (15) ◽

pp. 7415-7423 ◽

Cited By ~ 17

Author(s):

B. Gantt ◽

N. Meskhidze ◽

A. G. Carlton

Keyword(s):

United States ◽

Air Quality ◽

San Francisco ◽

Atmospheric Chemistry ◽

Environmental Protection Agency ◽

Regional Scale ◽

The United States ◽

Coastal Areas ◽

Western United States ◽

The Us

Abstract. The contribution of marine organic emissions to the air quality in coastal areas of the western United States is studied using the latest version of the US Environmental Protection Agency (EPA) regional-scale Community Multiscale Air Quality (CMAQv4.7) modeling system. Emissions of marine isoprene, monoterpenes, and primary organic matter (POM) from the ocean are implemented into the model to provide a comprehensive view of the connection between ocean biology and atmospheric chemistry and air pollution. Model simulations show that marine organics can increase the concentration of PM2.5 by 0.1–0.3 μg m−3 (up to 5%) in some coastal cities such as San Francisco, CA. This increase in the PM2.5 concentration is primarily attributed to the POM emissions, with small contributions from the marine isoprene and monoterpenes. When marine organic emissions are included, organic carbon (OC) concentrations over the remote ocean are increased by up to 50% (25% in coastal areas), values consistent with recent observational findings. This study is the first to quantify the air quality impacts from marine POM and monoterpenes for the United States, and it highlights the need for inclusion of marine organic emissions in air quality models.

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A CHANGE POINT ANALYSIS OF THE IMPACT OF “ENVIRONMENTAL FEDERALISM” ON AGGREGATE AIR QUALITY IN THE UNITED STATES: 1940-98

Economic Inquiry ◽

10.1093/ei/cbj006 ◽

2006 ◽

Vol 44 (1) ◽

pp. 109-120 ◽

Cited By ~ 14

Author(s):

THOMAS B. FOMBY ◽

LIMIN LIN

Keyword(s):

United States ◽

Air Quality ◽

Change Point ◽

The United States ◽

Change Point Analysis ◽

Environmental Federalism ◽

Point Analysis ◽

The Impact

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The relationship between indoor environment, outdoor environment, and behavior on indoor air quality and health

10.31219/osf.io/y7z4x ◽

2021 ◽

Author(s):

SDAG Lab

Keyword(s):

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

The United States ◽

Outdoor Environment ◽

Equation Modeling ◽

Health Symptoms ◽

Surface Dust ◽

Air Purifier ◽

The Impact

We should be concerned about the impact of indoor air quality on health because in the United States, people spend most of their time indoors. While earlier studies have characterized the odds of developing illness based on the home environment, they have not investigated the behaviors that can ameliorate the negative effect of indoor, outdoor, and behavioral sources. The purpose of this study was to 1) investigate the contributions of indoor, outdoor, and behavioral sources of pollutants on health symptoms, and 2) to identify the behaviors that can worsen or mitigate the number of health symptoms. Data came from two surveys (n=83,284) and include questions on home conditions, outdoor conditions, occupants’ behaviors, and health symptoms. I used negative binomial regression and identified that demographics and outdoor characteristics explain 2% of the variability in health symptoms, and maintenance behaviors explain 8% of the variability in health symptoms. Next, structural equation modeling (SEM) was used to examine the behaviors that can mitigate or worsen the number of health symptoms. The results show that maintenance issue such as mold result in significantly more health symptoms (β = .12, p <.001). and factors such as leaks, and frequent long shower may result in an increase in mold. Leaks may cause water stains (β = .39, p <.001) which could lead to molds (β = .47, p <.001). While frequent long shower can result in an increase in mold (β = .05, p <.001), the use of a bathroom exhaust during shower may help to reduce molds (β = -.04, p <.001). In terms of personal behaviors, the presence of carpet (β = .08, p <.001), and smoking also result in an increase in surface dust (β = .17`, p <.001) but frequent vacuuming could mitigate the impact of surface dust on health symptoms (β = -.12, p <.001). Home occupants who live near environmental hazards are also likely to use air purifier (β = .03, p <.001); however, air purifier is associated with more health symptoms (β = .05, p <.001). Based on the findings, it is recommended that home occupants engage in periodic maintenance to prevent issues such as leaks from escalating to molds, regular vacuuming to reduce the accumulation of surface dust. Regarding air purifier, it could be that participants who experienced more health symptoms were more likely to use an air purifier. However, some air purifiers are sources of ozone, therefore home occupants should err on the side of caution when it comes to air purifier (Britigan et al., 2006; Cestonaro et al., 2017).

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