A volatility basis set model for summertime secondary organic aerosols over the eastern United States in 2006

2012 ◽  
Vol 117 (D6) ◽  
pp. n/a-n/a ◽  
Author(s):  
R. Ahmadov ◽  
S. A. McKeen ◽  
A. L. Robinson ◽  
R. Bahreini ◽  
A. M. Middlebrook ◽  
...  
Keyword(s):  
United States ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Basis Set ◽  
Eastern United States

scholarly journals The effects of isoprene and NO<sub><i>x</i></sub> on secondary organic aerosols formed through reversible and irreversible uptake to aerosol water

2018 ◽  
Vol 18 (2) ◽  
pp. 1171-1184 ◽  
Author(s):  
Marwa M. H. El-Sayed ◽  
Diana L. Ortiz-Montalvo ◽  
Christopher J. Hennigan
Keyword(s):  
Secondary Organic Aerosols ◽  
Time Lag ◽  
Organic Aerosols ◽  
Water Soluble ◽  
Oxidation Products ◽  
Eastern United States ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon ◽  
Isoprene Oxidation ◽  
Organic Gases

Abstract. Isoprene oxidation produces water-soluble organic gases capable of partitioning to aerosol liquid water. The formation of secondary organic aerosols through such aqueous pathways (aqSOA) can take place either reversibly or irreversibly; however, the split between these fractions in the atmosphere is highly uncertain. The aim of this study was to characterize the reversibility of aqSOA formed from isoprene at a location in the eastern United States under substantial influence from both anthropogenic and biogenic emissions. The reversible and irreversible uptake of water-soluble organic gases to aerosol water was characterized in Baltimore, Maryland, USA, using measurements of particulate water-soluble organic carbon (WSOCp) in alternating dry and ambient configurations. WSOCp evaporation with drying was observed systematically throughout the late spring and summer, indicating reversible aqSOA formation during these times. We show through time lag analyses that WSOCp concentrations, including the WSOCp that evaporates with drying, peak 6 to 11 h after isoprene concentrations, with maxima at a time lag of 9 h. The absolute reversible aqSOA concentrations, as well as the relative amount of reversible aqSOA, increased with decreasing NOx ∕ isoprene ratios, suggesting that isoprene epoxydiol (IEPOX) or other low-NOx oxidation products may be responsible for these effects. The observed relationships with NOx and isoprene suggest that this process occurs widely in the atmosphere, and is likely more important in other locations characterized by higher isoprene and/or lower NOx levels. This work underscores the importance of accounting for both reversible and irreversible uptake of isoprene oxidation products to aqueous particles.

scholarly journals Estimates of non-traditional secondary organic aerosols from aircraft SVOC and IVOC emissions using CMAQ

2015 ◽  
Vol 15 (12) ◽  
pp. 6929-6942 ◽  
Author(s):  
M. C. Woody ◽  
J. J. West ◽  
S. H. Jathar ◽  
A. L. Robinson ◽  
S. Arunachalam
Keyword(s):  
Air Quality ◽  
Secondary Organic Aerosols ◽  
Fine Particulate Matter ◽  
Organic Aerosols ◽  
Oxidation Products ◽  
Basis Set ◽  
Chemical Mechanism ◽  
Smog Chamber ◽  
Aircraft Emissions ◽  
Inorganic Aerosols

Abstract. Utilizing an aircraft-specific parameterization based on smog chamber data in the Community Multiscale Air Quality (CMAQ) model with the volatility basis set (VBS), we estimated contributions of non-traditional secondary organic aerosols (NTSOA) for aircraft emissions during landing and takeoff (LTO) activities at the Hartsfield–Jackson Atlanta International Airport. NTSOA, formed from the oxidation of semi-volatile and intermediate volatility organic compounds (S/IVOCs), is a heretofore unaccounted component of fine particulate matter (PM2.5) in most air quality models. We expanded a prerelease version of CMAQ with VBS implemented for the Carbon Bond 2005 (CB05) chemical mechanism to use the Statewide Air Pollution Research Center 2007 (SAPRC-07) chemical mechanism and added species representing aircraft S/IVOCs and corresponding NTSOA oxidation products. Results indicated that the maximum monthly average NTSOA contributions occurred at the airport and ranged from 2.4 ng m−3 (34 % from idle and 66 % from non-idle aircraft activities) in January to 9.1 ng m−3 (33 and 67 %) in July. This represents 1.7 % (of 140 ng m−3) in January and 7.4 % in July (of 122 ng m−3) of aircraft-attributable PM2.5 compared to 41.0–42.0 % from elemental carbon and 42.8–58.0 % from inorganic aerosols. As a percentage of PM2.5, impacts were higher downwind of the airport, where NTSOA averaged 4.6–17.9 % of aircraft-attributable PM2.5 and, considering alternative aging schemes, was as high as 24.0 % – thus indicating the increased contribution of aircraft-attributable SOA as a component of PM2.5. However, NTSOA contributions were generally low compared to smog chamber results, particularly at idle, due to the considerably lower ambient organic aerosol concentrations in CMAQ compared to those in the smog chamber experiments.

scholarly journals Estimates of non-traditional secondary organic aerosols from aircraft SVOC and IVOC emissions using CMAQ

2014 ◽  
Vol 14 (22) ◽  
pp. 30667-30703
Author(s):  
M. C. Woody ◽  
J. J. West ◽  
S. H. Jathar ◽  
A. L. Robinson ◽  
S. Arunachalam
Keyword(s):  
Air Quality ◽  
Secondary Organic Aerosols ◽  
Fine Particulate Matter ◽  
Organic Aerosols ◽  
Oxidation Products ◽  
Basis Set ◽  
Chemical Mechanism ◽  
Smog Chamber ◽  
Aircraft Emissions ◽  
Inorganic Aerosols

Abstract. Utilizing an aircraft-specific parameterization based on smog chamber data in the Community Multiscale Air Quality (CMAQ) model with the Volatility Basis Set (VBS), we estimated contributions of non-traditional secondary organic aerosols (NTSOA) for aircraft emissions during landing and takeoff (LTO) activities at the Hartsfield-Jackson Atlanta International Airport. NTSOA, formed from the oxidation of semi-volatile and intermediate volatility organic compounds (S/IVOCs), is a heretofore unaccounted component of fine particulate matter (PM2.5) in most air quality models. We expanded a prerelease version of CMAQ with VBS implemented for the Carbon Bond 2005 (CB05) chemical mechanism to use the Statewide Air Pollution Research Center 2007 (SAPRC-07) chemical mechanism, and added species representing aircraft S/IVOCs and corresponding NTSOA oxidation products. Results indicated the maximum monthly average NTSOA contributions occurred at the airport, and ranged from 2.4 ng m−3 (34% from idle and 66% from non-idle aircraft activities) in January to 9.1 ng m−3 (33 and 67%) in July. This represents 1.7% (of 140 ng m−3) in January and 7.4% in July (of 122 ng m−3) of aircraft-attributable PM2.5, compared to 41.0–42.0% from elemental carbon and 42.8–58.0% from inorganic aerosols. As a percentage of PM2.5, impacts were higher downwind of the airport, where NTSOA averaged 4.6–17.9% of aircraft-attributable PM2.5 and, considering alternative aging schemes, was high as 24.0% – thus indicating the increased contribution of aircraft-attributable SOA, as a component of PM2.5. However, NTSOA contributions were generally low compared to smog chamber results, particularly at idle, due to the considerably lower ambient organic aerosol concentrations in CMAQ, vs. those in the smog chamber experiments.

scholarly journals The effects of isoprene and NO<sub><i>x</i></sub> on secondary organic aerosols formed through reversible and irreversible uptake to aerosol water

2017 ◽  
Author(s):  
Marwa M. H. El-Sayed ◽  
Diana L. Ortiz-Montalvo ◽  
Christopher J. Hennigan
Keyword(s):  
Secondary Organic Aerosols ◽  
Time Lag ◽  
Organic Aerosols ◽  
Water Soluble ◽  
Oxidation Products ◽  
Eastern United States ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon ◽  
Isoprene Oxidation ◽  
Organic Gases

Abstract. Isoprene oxidation produces water-soluble organic gases capable of partitioning to aerosol liquid water. The formation of secondary organic aerosols through such aqueous pathways (aqSOA) can take place either reversibly or irreversibly; however, the split between these fractions in the atmosphere is highly uncertain. The aim of this study was to characterize the reversibility of aqSOA formed from isoprene at a location in the eastern United States under substantial influence from both anthropogenic and biogenic emissions. The reversible and irreversible uptake of water-soluble organic gases to aerosol water was characterized in Baltimore, MD using measurements of particulate water-soluble organic carbon (WSOCp) in alternating dry and ambient configurations. WSOCp evaporation with drying was observed systematically throughout the late spring and summer, indicating reversible aqSOA formation during these times. We show through time lag analyses that WSOCp concentrations, including the WSOCp that evaporates with drying, peak ~ 6–11 h after isoprene concentrations, with maxima at a time lag of 9 h. The absolute reversible aqSOA concentrations, as well as the relative amount of reversible aqSOA, increased with decreasing NOx/isoprene ratios, suggesting that isoprene epoxydiol (IEPOX) or other low-NOx oxidation products were responsible for these effects. The observed relationships with NOx and isoprene suggest that this process occurs widely in the atmosphere, and is likely more important in other locations characterized by higher isoprene and/or lower NOx levels. It is also likely that this phenomenon will increase in importance in the future, given predictions of biogenic and anthropogenic emissions under future regulatory and climate scenarios.

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