scholarly journals Laboratory investigation of photochemical oxidation of organic aerosol from wood fires – Part 2: Analysis of aerosol mass spectrometer data

2008 ◽  
Vol 8 (5) ◽  
pp. 17095-17130 ◽  
Author(s):  
A. P. Grieshop ◽  
N. M. Donahue ◽  
A. L. Robinson
Keyword(s):  
Mass Spectrometer ◽  
Biomass Burning ◽  
Explicit Knowledge ◽  
Uv Light ◽  
Organic Aerosol ◽  
Photochemical Oxidation ◽  
Wood Smoke ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Spectrometer Data

Abstract. Experiments were conducted to investigate the effects of photo-oxidation on organic aerosol (OA) in dilute wood smoke by exposing emissions from soft- and hard-wood fires to UV light in a smog chamber. This paper focuses on changes in OA composition measured using a unit mass resolution quadrupole Aerosol Mass Spectrometer (AMS). The results highlight how photochemical processing can lead to considerable evolution of the mass, the volatility and the level of oxygenation of biomass-burning OA. Photochemical oxidation produced substantial new OA, more than doubling the primary contribution after a few hours of aging under typical summertime conditions. Aging decreased the OA volatility of the total OA as measured with a thermodenuder; it also made the OA progressively more oxygenated in every experiment. With explicit knowledge of the condensed-phase mass spectrum (MS) of the primary emissions from each fire, each MS can be decomposed into primary and residual spectra throughout the experiment. The residual spectra provide an estimate of the composition of the photochemically produced OA. These spectra are also very similar to those of the oxygenated OA that dominates ambient AMS datasets. In addition, aged wood smoke spectra are shown to be similar to those from OA created by photo-oxidized dilute diesel exhaust and aged biomass-burning OA measured in urban and remote locations. This demonstrates that the oxygenated OA observed in the atmosphere can be produced by photochemical aging of dilute emissions from combustion of fuels containing both modern and fossil carbon.

scholarly journals Laboratory investigation of photochemical oxidation of organic aerosol from wood fires 2: analysis of aerosol mass spectrometer data

2009 ◽  
Vol 9 (6) ◽  
pp. 2227-2240 ◽  
Author(s):  
A. P. Grieshop ◽  
N. M. Donahue ◽  
A. L. Robinson
Keyword(s):  
Source Apportionment ◽  
Mass Spectrometer ◽  
Mass Spectra ◽  
Motor Vehicle ◽  
Organic Aerosol ◽  
Photochemical Oxidation ◽  
Wood Smoke ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Spectrometer Data

Abstract. Experiments were conducted to investigate the effects of photo-oxidation on organic aerosol (OA) in dilute wood smoke by exposing emissions from soft- and hard-wood fires to UV light in a smog chamber. This paper focuses on changes in OA composition measured using a unit-mass-resolution quadrupole Aerosol Mass Spectrometer (AMS). The results highlight how photochemical processing can lead to considerable evolution of the mass, volatility and level of oxygenation of biomass-burning OA. Photochemical oxidation produced substantial new OA, more than doubling the OA mass after a few hours of aging under typical summertime conditions. Aging also decreased the volatility of the OA and made it progressively more oxygenated. The results also illustrate strengths of, and challenges with, using AMS data for source apportionment analysis. For example, the mass spectra of fresh and aged BBOA are distinct from fresh motor-vehicle emissions. The mass spectra of the secondary OA produced from aging wood smoke are very similar to those of the oxygenated OA (OOA) that dominates ambient AMS datasets, further reinforcing the connection between OOA and OA formed from photo-chemistry. In addition, aged wood smoke spectra are similar to those from OA created by photo-oxidizing dilute diesel exhaust. This demonstrates that the OOA observed in the atmosphere can be produced by photochemical aging of dilute emissions from different types of combustion systems operating on fuels with modern or fossil carbon. Since OOA is frequently the dominant component of ambient OA, the similarity of spectra of aged emissions from different sources represents an important challenge for AMS-based source apportionment studies.

scholarly journals Laboratory investigation of photochemical oxidation of organic aerosol from wood fires – Part 1: Measurement and simulation of organic aerosol evolution

2008 ◽  
Vol 8 (4) ◽  
pp. 15699-15737 ◽  
Author(s):  
A. P. Grieshop ◽  
J. M. Logue ◽  
N. M. Donahue ◽  
A. L. Robinson
Keyword(s):  
Mass Spectrometer ◽  
Uv Light ◽  
Organic Aerosol ◽  
Proton Transfer Reaction ◽  
Current Approach ◽  
Photochemical Oxidation ◽  
Basis Set ◽  
Organic Vapors ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass

Abstract. Experiments were conducted to investigate the effects of photo-oxidation on organic aerosol (OA) in wood smoke by exposing diluted emissions from soft- and hard-wood fires to UV light in a smog chamber. Particle- and gas-phase concentrations were monitored with a suite of instruments including a Proton Transfer Reaction Mass Spectrometer (PTR-MS), an Aerosol Mass Spectrometer (AMS) and a thermodenuder to measure aerosol volatility. The measurements highlight how in-plume processing can lead to considerable evolution of the mass and volatility of biomass burning OA. Photochemical oxidation produced substantial new OA, increasing concentrations by a factor of 1.5 to 2.8 after several hours of exposure to typical summertime hydroxyl radical (OH) concentrations. Less than 20% of this new OA could be explained using the measured decay of traditional secondary organic aerosol (SOA) precursors and a state-of-the-art SOA model. Aging also created less volatile OA; at 50°C between 50 and 80% of the fresh primary OA evaporated but only 20 to 40% of aged OA. Therefore, the data provide additional evidence that primary OA is semivolatile. They also raise questions about the current approach used to simulate OA in chemical transport models, which assume that primary OA are non-volatile but that SOA is semivolatile. Predictions of a volatility basis-set model that explicitly tracks the partitioning and aging of low-volatile organics are compared to the chamber data. This model demonstrates that the OA production observed in these experiments can be explained by oxidation of low volatility organic vapors. The basis-set model can also simulate observed changes in OA volatility and composition, predicting the OA production and the increased oxygenation and decreased volatility of the OA.

scholarly journals Elemental analysis of chamber organic aerosol using an aerodyne high-resolution aerosol mass spectrometer

2010 ◽  
Vol 10 (9) ◽  
pp. 4111-4131 ◽  
Author(s):  
P. S. Chhabra ◽  
R. C. Flagan ◽  
J. H. Seinfeld
Keyword(s):  
High Resolution ◽  
Elemental Composition ◽  
Mass Spectrometer ◽  
Organic Aerosol ◽  
Uptake System ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Single Ring ◽  
Spectrometer Data ◽  
Ambient Measurements

Abstract. The elemental composition of laboratory chamber secondary organic aerosol (SOA) from glyoxal uptake, α-pinene ozonolysis, isoprene photooxidation, single-ring aromatic photooxidation, and naphthalene photooxidation is evaluated using Aerodyne high-resolution time-of-flight mass spectrometer data. SOA O/C ratios range from 1.13 for glyoxal uptake experiments to 0.30–0.43 for α-pinene ozonolysis. The elemental composition of α-pinene and naphthalene SOA is also confirmed by offline mass spectrometry. The fraction of organic signal at m/z 44 is generally a good measure of SOA oxygenation for α-pinene/O3, isoprene/high-NOx, and naphthalene SOA systems. The agreement between measured and estimated O/C ratios tends to get closer as the fraction of organic signal at m/z 44 increases. This is in contrast to the glyoxal uptake system, in which m/z 44 substantially underpredicts O/C. Although chamber SOA has generally been considered less oxygenated than ambient SOA, single-ring aromatic- and naphthalene-derived SOA can reach O/C ratios upward of 0.7, well within the range of ambient PMF component OOA, though still not as high as some ambient measurements. The spectra of aromatic and isoprene-high-NOx SOA resemble that of OOA, but the spectrum of glyoxal uptake does not resemble that of any ambient organic aerosol PMF component.

scholarly journals Receptor modeling of near-roadway aerosol mass spectrometer data in Las Vegas, Nevada, with EPA PMF

2011 ◽  
Vol 11 (8) ◽  
pp. 22909-22950 ◽  
Author(s):  
S. G. Brown ◽  
T. Lee ◽  
G. A. Norris ◽  
P. T. Roberts ◽  
J. L. Collett ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Las Vegas ◽  
Organic Aerosol ◽  
Receptor Modeling ◽  
Factor Solution ◽  
Aerosol Mass Spectrometer ◽  
Source Profiles ◽  
Aerosol Mass ◽  
The Us ◽  
Spectrometer Data

Abstract. Ambient non-refractory PM1 aerosol particles were measured with an Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-AMS) at an elementary school 20 m from the US 95 freeway in Las Vegas, Nevada, during January 2008. Additional collocated continuous measurements of black carbon (BC), carbon monoxide (CO), nitrogen oxides (NOx), and meteorological data were collected. The US Environmental Protection Agency's (EPA) positive matrix factorization (PMF) data analysis tool was used to apportion organic matter (OM) as measured by HR-AMS, and rotational tools in EPA PMF were used to better characterize the solution space and pull resolved factors toward known source profiles. Three- to six-factor solutions were resolved. The four-factor solution was the most interpretable, with the typical AMS PMF factors of hydrocarbon-like organic aerosol (HOA), low-volatility oxygenated organic aerosol (LV-OOA), biomass burning organic aerosol (BBOA), and semi-volatile oxygenated organic aerosol (SV-OOA). When the measurement site was downwind of the freeway, HOA composed about half the OM, with SV-OOA and LV-OOA accounting for the rest. Attempts to pull the PMF factor profiles toward source profiles were successful but did not qualitatively change the results, indicating that these factors are very stable. Oblique edges were present in G-space plots, suggesting that the obtained rotation may not be the most plausible one. Since solutions found by pulling the profiles or using Fpeak retained these oblique edges, there appears to be little rotational freedom in the base solution. On average, HOA made up 26 % of the OM, and it made up nearly half of the OM when the monitoring site was downwind of US 95 during morning rush hour. LV-OOA was highest in the afternoon and accounted for 26 % of the OM. BBOA occurred in the evening hours, was predominantly from the residential area to the north, and on average constituted 12 % of the OM; SV-OOA accounted for the remaining third of the OM. Use of the pulling techniques available in EPA PMF and ME-2 suggested that the four-factor solution was very stable.

scholarly journals Identification and quantification of organic aerosol from cooking and other sources in Barcelona using aerosol mass spectrometer data

2011 ◽  
Vol 11 (10) ◽  
pp. 27383-27420 ◽  
Author(s):  
C. Mohr ◽  
P. F. DeCarlo ◽  
M. F. Heringa ◽  
R. Chirico ◽  
J. G. Slowik ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Biomass Burning ◽  
Ambient Air ◽  
Organic Aerosol ◽  
Data Matrix ◽  
High Mass ◽  
Organic Mass ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Data Points

Abstract. PM1 (particulate matter with an aerodynamic diameter <1 μm) non-refractory components and black carbon were measured continuously together with additional parameters at an urban background site in Barcelona, Spain, during March 2009 (campaign DAURE, Determination of the sources of atmospheric Aerosols in Urban and Rural Environments in the western Mediterranean). Positive matrix factorization (PMF) was conducted on the organic aerosol (OA) data matrix measured by an aerosol mass spectrometer, on both unit mass (UMR) and high resolution (HR) data. Five factors or sources could be identified: LV-OOA (low-volatility oxygenated OA), related to regional, aged secondary OA; SV-OOA (semi-volatile oxygenated OA), a fresher oxygenated OA; HOA (hydrocarbon-like OA, related to traffic emissions); BBOA (biomass burning OA) from domestic heating or agricultural biomass burning activities; and COA (cooking OA). LV-OOA contributed 28% to OA, SV-OOA 27%, COA 17%, HOA 16%, and BBOA 11%. The COA HR spectrum contained substantial signal from oxygenated ions (O/C: 0.21) whereas the HR HOA spectrum had almost exclusively contributions from chemically reduced ions (O/C: 0.03). If we assume that the carbon in HOA is fossil while that in COA and BBOA is modern, primary OA in Barcelona contains a surprisingly high fraction (59%) of non-fossil carbon. This paper presents a method for estimating cooking organic aerosol in ambient datasets based on the fractions of organic mass fragments at m/z 55 and 57: their data points fall into a V-shape in a scatter plot, with strongly influenced HOA data aligned to the right arm and strongly influenced COA data points aligned to the left arm. HR data show that this differentiation is mainly driven by the oxygen-containing ions C3H3O+ and C3H5O+, even though their contributions to m/z 55 and 57 are low compared to the reduced ions C4H7+ and C4H9+. A simple estimation method based on the organic mass fragments at m/z 55, 57, and 44 is developed here and allows for a first-order-estimation of COA in urban air. This study emphasizes the importance of cooking activities for ambient air quality and confirms the importance of chemical composition measurements with a high mass and time resolution.

scholarly journals Evolving mass spectra of the oxidized component of organic aerosol: results from aerosol mass spectrometer analyses of aged diesel emissions

2008 ◽  
Vol 8 (5) ◽  
pp. 1139-1152 ◽  
Author(s):  
A. M. Sage ◽  
E. A. Weitkamp ◽  
A. L. Robinson ◽  
N. M. Donahue
Keyword(s):  
Mass Spectrometer ◽  
Mass Spectra ◽  
Explicit Knowledge ◽  
Organic Aerosol ◽  
Diesel Emissions ◽  
Vapor Pressures ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Primary Emissions ◽  
Organic Particles

Abstract. The species and chemistry responsible for secondary organic aerosol (SOA) formation remain highly uncertain. Laboratory studies of the oxidation of individual, high-flux SOA precursors do not lead to particles with mass spectra (MS) matching those of ambient aged organic material. Additionally, the complexity of real organic particles challenges efforts to identify their chemical origins. We have previously hypothesized that SOA can form from the atmospheric oxidation of a large suite of precursors with varying vapor pressures. Here, we support this hypothesis by using an aerosol mass spectrometer to track the chemical evolution of diesel exhaust as it is photochemically oxidized in an environmental chamber. With explicit knowledge of the condensed-phase MS of the primary emissions from our engine, we are able to decompose each recorded MS into contributing primary and secondary spectra throughout the experiment. We find that the SOA becomes increasingly oxidized as a function of time, quickly approaching a final MS that closely resembles that of ambient aged organic particulate matter. This observation is consistent with our hypothesis of an evolving suite of SOA precursors. Low vapor pressure, semi-volatile organic emissions can form condensable products with even a single generation of oxidation, resulting in an early-arising, relatively less-oxidized SOA. Continued gas-phase oxidation can form highly oxidized SOA in surprisingly young air masses via reaction mechanisms that can add multiple oxygen atoms per generation and result in products with sustained or increased reactivity toward OH.

scholarly journals Receptor modeling of near-roadway aerosol mass spectrometer data in Las Vegas, Nevada, with EPA PMF

2012 ◽  
Vol 12 (1) ◽  
pp. 309-325 ◽  
Author(s):  
S. G. Brown ◽  
T. Lee ◽  
G. A. Norris ◽  
P. T. Roberts ◽  
J. L. Collett ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Las Vegas ◽  
Organic Aerosol ◽  
Receptor Modeling ◽  
Factor Solution ◽  
Aerosol Mass Spectrometer ◽  
Source Profiles ◽  
Aerosol Mass ◽  
The Us ◽  
Spectrometer Data

Abstract. Ambient non-refractory PM1 aerosol particles were measured with an Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-AMS) at an elementary school 18 m from the US 95 freeway soundwall in Las Vegas, Nevada, during January 2008. Additional collocated continuous measurements of black carbon (BC), carbon monoxide (CO), nitrogen oxides (NOx), and meteorological data were collected. The US~Environmental Protection Agency's (EPA) positive matrix factorization (PMF) data analysis tool was used to apportion organic matter (OM) as measured by HR-AMS, and rotational tools in EPA PMF were used to better characterize the solution space and pull resolved factors toward known source profiles. Three- to six-factor solutions were resolved. The four-factor solution was the most interpretable, with the typical AMS PMF factors of hydrocarbon-like organic aerosol (HOA), low-volatility oxygenated organic aerosol (LV-OOA), biomass burning organic aerosol (BBOA), and semi-volatile oxygenated organic aerosol (SV-OOA). When the measurement site was downwind of the freeway, HOA composed about half the OM, with SV-OOA and LV-OOA accounting for the rest. Attempts to pull the PMF factor profiles toward source profiles were successful but did not qualitatively change the results, indicating that these factors are very stable. Oblique edges were present in G-space plots, suggesting that the obtained rotation may not be the most plausible one. Since solutions found by pulling the profiles or using Fpeak retained these oblique edges, there appears to be little rotational freedom in the base solution. On average, HOA made up 26% of the OM, while LV-OOA was highest in the afternoon and accounted for 26% of the OM. BBOA occurred in the evening hours, was predominantly from the residential area to the north, and on average constituted 12% of the OM; SV-OOA accounted for the remaining third of the OM. Use of the pulling techniques available in EPA PMF and ME-2 suggested that the four-factor solution was very stable.

scholarly journals Identification and quantification of organic aerosol from cooking and other sources in Barcelona using aerosol mass spectrometer data

2012 ◽  
Vol 12 (4) ◽  
pp. 1649-1665 ◽  
Author(s):  
C. Mohr ◽  
P. F. DeCarlo ◽  
M. F. Heringa ◽  
R. Chirico ◽  
J. G. Slowik ◽  
...  
Keyword(s):  
Air Quality ◽  
Mass Spectrometer ◽  
Biomass Burning ◽  
Ambient Air ◽  
Organic Aerosol ◽  
Data Matrix ◽  
High Mass ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Data Points

Abstract. PM1 (particulate matter with an aerodynamic diameter <1 μm) non-refractory components and black carbon were measured continuously together with additional air quality and atmospheric parameters at an urban background site in Barcelona, Spain, during March 2009 (campaign DAURE, Determination of the sources of atmospheric Aerosols in Urban and Rural Environments in the western Mediterranean). Positive matrix factorization (PMF) was conducted on the organic aerosol (OA) data matrix measured by an aerosol mass spectrometer, on both unit mass (UMR) and high resolution (HR) data. Five factors or sources could be identified: LV-OOA (low-volatility oxygenated OA), related to regional, aged secondary OA; SV-OOA (semi-volatile oxygenated OA), a fresher oxygenated OA; HOA (hydrocarbon-like OA, related to traffic emissions); BBOA (biomass burning OA) from domestic heating or agricultural biomass burning activities; and COA (cooking OA). LV-OOA contributed 28% to OA, SV-OOA 27%, COA 17%, HOA 16%, and BBOA 11%. The COA HR spectrum contained substantial signal from oxygenated ions (O:C: 0.21) whereas the HR HOA spectrum had almost exclusively contributions from chemically reduced ions (O:C: 0.03). If we assume that the carbon in HOA is fossil while that in COA and BBOA is modern, primary OA in Barcelona contains a surprisingly high fraction (59%) of non-fossil carbon. This paper presents a method for estimating cooking organic aerosol in ambient datasets based on the fractions of organic mass fragments at m/z 55 and 57: their data points fall into a V-shape in a scatter plot, with strongly influenced HOA data aligned to the right arm and strongly influenced COA data points aligned to the left arm. HR data show that this differentiation is mainly driven by the oxygen-containing ions C3H3O+ and C3H5O+, even though their contributions to m/z 55 and 57 are low compared to the reduced ions C4H7+ and C4H9+. A simple estimation method based on the markers m/z 55, 57, and 44 is developed here and allows for a first-order-estimation of COA in urban air. This study emphasizes the importance of cooking activities for ambient air quality and confirms the importance of chemical composition measurements with a high mass and time resolution.

scholarly journals Evolving mass spectra of the oxidized component of organic aerosol: results from aerosol mass spectrometer analyses of aged diesel emissions

2007 ◽  
Vol 7 (4) ◽  
pp. 10065-10096 ◽  
Author(s):  
A. M. Sage ◽  
E. A. Weitkamp ◽  
A. L. Robinson ◽  
N. M. Donahue
Keyword(s):  
Mass Spectrometer ◽  
Mass Spectra ◽  
Explicit Knowledge ◽  
Organic Aerosol ◽  
Diesel Emissions ◽  
Vapor Pressures ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Lower Vapor Pressure ◽  
Organic Particles

Abstract. The species and chemistry responsible for secondary organic aerosol (SOA) formation remain highly uncertain. Laboratory studies of the oxidation of individual, high-flux SOA precursors do not lead to particles with mass spectra (MS) matching those of ambient aged organic material. And, the complexity of real organic particles challenges efforts to identify their chemical origins. We have previously hypothesized that SOA can form from the atmospheric oxidation of a large suite of precursors with varying vapor pressures. Here, we support this hypothesis by using an aerosol mass spectrometer to track the chemical evolution of diesel exhaust as it is photochemically oxidized in an environmental chamber. With explicit knowledge of the condensed-phase MS of the primary emissions from our engine, we are able to decompose each recorded MS into contributing primary and secondary spectra throughout the experiment. We find that the SOA MS becomes increasingly oxidized as a function of time, eventually reaching a final MS that closely resembles that of ambient aged organic particulate matter. This observation is consistent with the idea that lower vapor pressure, semi-volatile organic emissions can form condensable products with fewer generations of oxidation, and therefore, they form relatively less oxidized SOA very quickly.

scholarly journals Elemental analysis of chamber organic aerosol using an aerodyne high-resolution aerosol mass spectrometer

2009 ◽  
Vol 9 (6) ◽  
pp. 27485-27542 ◽  
Author(s):  
P. S. Chhabra ◽  
R. C. Flagan ◽  
J. H. Seinfeld
Keyword(s):  
High Resolution ◽  
Elemental Composition ◽  
Mass Spectrometer ◽  
Organic Aerosol ◽  
Resolution Time ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Single Ring ◽  
Spectrometer Data ◽  
Ambient Measurements

Abstract. The elemental composition of laboratory chamber secondary organic aerosol (SOA) from glyoxal uptake, α-pinene ozonolysis, isoprene photooxidation, single-ring aromatic photooxidation, and naphthalene photooxidation is evaluated using Aerodyne high-resolution time-of-flight mass spectrometer data. SOA O/C ratios ranged from 1.13 for glyoxal to 0.30–0.43 for α-pinene ozonolysis. The elemental composition of α-pinene and naphthalene SOA was also confirmed by offline mass spectrometry. The fraction of organic signal at m/z 44 is generally a good measure of SOA oxygenation for all systems except for glyoxal uptake, in which m/z 44 substantially underpredicts O/C. Although chamber SOA has generally been considered less oxygenated than ambient SOA, single-ring aromatic- and naphthalene-derived SOA can reach O/C ratios upward of 0.7, well within the range of OOA, though still not as high as some ambient measurements. The spectra of aromatic- and isoprene-high-NOx SOA resemble that of OOA, but the spectrum of glyoxal uptake does not resemble that of any PMF component.

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