scholarly journals Biomass burning dominates brown carbon absorption in the rural southeastern United States

2015 ◽  
Vol 42 (2) ◽  
pp. 653-664 ◽  
Author(s):  
R. A. Washenfelder ◽  
A. R. Attwood ◽  
C. A. Brock ◽  
H. Guo ◽  
L. Xu ◽  
...  
Keyword(s):  
United States ◽  
Biomass Burning ◽  
Southeastern United States ◽  
Brown Carbon ◽  
Carbon Absorption

scholarly journals Reactive oxygen species associated with water-soluble PM<sub>2.5</sub> in the southeastern United States: spatiotemporal trends and source apportionment

2014 ◽  
Vol 14 (23) ◽  
pp. 12915-12930 ◽  
Author(s):  
V. Verma ◽  
T. Fang ◽  
H. Guo ◽  
L. King ◽  
J. T. Bates ◽  
...  
Keyword(s):  
United States ◽  
Reactive Oxygen Species ◽  
Source Apportionment ◽  
Biomass Burning ◽  
Southeastern United States ◽  
Reactive Oxygen ◽  
Water Soluble ◽  
Ros Generation ◽  
Vehicular Emissions ◽  
Oxygen Species

Abstract. We assess the potential of the water-soluble fraction of atmospheric fine aerosols in the southeastern United States to generate reactive oxygen species (ROS) and identify major ROS-associated emission sources. ROS-generation potential of particles was quantified by the dithiothreitol (DTT) assay and involved analysis of fine particulate matter (PM) extracted from high-volume quartz filters (23 h integrated samples) collected at various sites in different environmental settings in the southeast, including three urban-Atlanta sites, in addition to a rural site. Paired sampling was conducted with one fixed site in Atlanta (Jefferson Street), representative of the urban environment, with the others rotating among different sites, for ~250 days between June 2012 and September 2013 (N=483). A simple linear regression between the DTT activity and aerosol chemical components revealed strong associations between PM ROS-generation potential and secondary organic aerosol (WSOC – water-soluble organic carbon) in summer, and biomass burning markers in winter. Redox-active metals were also somewhat correlated with the DTT activity, but mostly at urban and roadside sites. Positive matrix factorization (PMF) was applied to apportion the relative contribution of various sources to the ROS-generation potential of water-soluble PM2.5 in urban Atlanta. PMF showed that vehicular emissions contribute uniformly throughout the year (12–25%), while secondary oxidation processes dominated the DTT activity in summer (46%) and biomass burning in winter (47%). Road dust was significant only during drier periods (~12% in summer and fall). Source apportionment by chemical mass balance (CMB) was reasonably consistent with PMF, but with higher contribution from vehicular emissions (32%). Given the spatially large data set of PM sampled over an extended period, the study reconciles the results from previous work that showed only region- or season-specific aerosol components or sources contributing to PM ROS activity, possibly due to smaller sample sizes. The ubiquitous nature of the major sources of PM-associated ROS suggests widespread population exposures to aerosol components that have the ability to catalyze the production of oxidants in vivo.

scholarly journals Brown carbon absorption linked to organic mass tracers in biomass burning particles

2013 ◽  
Vol 13 (5) ◽  
pp. 2415-2422 ◽  
Author(s):  
D. A. Lack ◽  
R. Bahreini ◽  
J. M. Langridge ◽  
J. B. Gilman ◽  
A. M. Middlebrook
Keyword(s):  
Organic Matter ◽  
Black Carbon ◽  
Biomass Burning ◽  
Absorption Efficiency ◽  
Brown Carbon ◽  
Internal Mixing ◽  
Carbon Absorption ◽  
Mass Fractions ◽  
Biomass Burning Particles ◽  
532 Nm

Abstract. Traditional gas and particle phase chemical markers used to identify the presence of biomass burning (BB) emissions were measured for a large forest fire near Boulder, Colorado. Correlation of the organic matter mass spectroscopic m/z 60 with measured particle light absorption properties found no link at 532 nm, and a strong correlation at 404 nm. Non-black carbon absorption at 404 nm was well correlated to the ratio of the mass fractions of particulate organic matter (POM) that was m/z 60 (f60) to m/z 44 (f44). The f60 to f44 ratio did not fully explain the variability in non-BC absorption, due to contributions of brown carbon (BrC) absorption and absorption due to internal mixing of POM with black carbon (BC). The absorption Ångstrom exponent (ÅAbs) showed a good correlation to f60/f44; however the best correlation resulted from the mass absorption efficiency (MAE) of BrC at 404 nm (MAEPOM-404 nm) and f60/f44. This result indicates that the absorption of POM at low visible and UV wavelengths is linked to emissions of organic matter that contribute to the m/z 60 mass fragment, although they do not contribute to 532 nm absorption. m/z 60 is often attributed to levoglucosan and related compounds. The linear relationship between MAEPOM-404 nm and f60/f44 suggests that the strength of BrC absorption for this fire can be predicted by emissions of f60-related organic matter.

scholarly journals On the link between hygroscopicity, volatility, and oxidation state of ambient and water-soluble aerosols in the southeastern United States

2015 ◽  
Vol 15 (15) ◽  
pp. 8679-8694 ◽  
Author(s):  
K. M. Cerully ◽  
A. Bougiatioti ◽  
J. R. Hite ◽  
H. Guo ◽  
L. Xu ◽  
...  
Keyword(s):  
United States ◽  
Oxidation State ◽  
Biomass Burning ◽  
Cloud Condensation Nuclei ◽  
Southeastern United States ◽  
Organic Aerosols ◽  
Sampling Period ◽  
Water Soluble ◽  
Rural Site ◽  
Ccn Activity

Abstract. The formation of secondary organic aerosols (SOAs) combined with the partitioning of semivolatile organic components can impact numerous aerosol properties including cloud condensation nuclei (CCN) activity, hygroscopicity, and volatility. During the summer 2013 Southern Oxidant and Aerosol Study (SOAS) field campaign in a rural site in the southeastern United States, a suite of instruments including a CCN counter, a thermodenuder (TD), and a high-resolution time-of-flight aerosol mass spectrometer (AMS) were used to measure CCN activity, aerosol volatility, composition, and oxidation state. Particles were either sampled directly from ambient or through a particle-into-liquid sampler (PILS), allowing the investigation of the water-soluble aerosol component. Ambient aerosols exhibited size-dependent composition with larger particles being more hygroscopic. The hygroscopicity of thermally denuded aerosols was similar between ambient and PILS-generated aerosols and showed limited dependence on volatilization. Results of AMS three-factor positive matrix factorization (PMF) analysis for the PILS-generated aerosols showed that the most hygroscopic components are most likely the most and the least volatile features of the aerosols. No clear relationship was found between organic hygroscopicity and the oxygen-to-carbon ratio; in fact, isoprene-derived organic aerosols (isoprene-OAs) were found to be the most hygroscopic factor, while at the same time being the least oxidized and likely most volatile of all PMF factors. Considering the diurnal variation of each PMF factor and its associated hygroscopicity, isoprene-OA and more-oxidized oxygenated organic aerosols are the prime contributors to hygroscopicity and co-vary with less-oxidized oxygenated organic aerosols in a way that induces the observed diurnal invariance in total organic hygroscopicity. Biomass burning organic aerosols contributed little to aerosol hygroscopicity, which is expected since there was little biomass burning activity during the sampling period examined.

scholarly journals On the link between hygroscopicity, volatility, and oxidation state of ambient and water-soluble aerosol in the Southeastern United States

2014 ◽  
Vol 14 (22) ◽  
pp. 30835-30877 ◽  
Author(s):  
K. M. Cerully ◽  
A. Bougiatioti ◽  
J. R. Hite Jr. ◽  
H. Guo ◽  
L. Xu ◽  
...  
Keyword(s):  
United States ◽  
Oxidation State ◽  
Biomass Burning ◽  
Cloud Condensation Nuclei ◽  
Southeastern United States ◽  
Sampling Period ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Rural Site ◽  
Ccn Activity

Abstract. The formation of secondary organic aerosol (SOA) combined with the partitioning of semi-volatile organic components can impact numerous aerosol properties including cloud condensation nuclei (CCN) activity, hygroscopicity and volatility. During the summer 2013 Southern Oxidant and Aerosol Study (SOAS) field campaign in a rural site in the Southeastern United States, a suite of instruments including a CCN counter, a thermodenuder (TD) and a high resolution time-of-flight aerosol mass spectrometer (AMS) were used to measure CCN activity, aerosol volatility, composition and oxidation state. Particles were either sampled directly from ambient or through a Particle Into Liquid Sampler (PILS), allowing the investigation of the water-soluble aerosol component. Ambient aerosol exhibited size-dependent composition with larger particles being more hygroscopic. The hygroscopicity of thermally-denuded aerosol was similar between ambient and PILS-generated aerosol and showed limited dependence on volatilization. Results of AMS 3-factor Positive Matrix Factorization (PMF) analysis for the PILS-generated aerosol showed that the most hygroscopic components are most likely the most and the least volatile features of the aerosol. No clear relationship was found between organic hygroscopicity and oxygen-to-carbon ratio; in fact, Isoprene organic aerosol (Isoprene-OA) was found to be the most hygroscopic factor, while at the same time being the least oxidized and likely most volatile of all PMF factors. Considering the diurnal variation of each PMF factor and its associated hygroscopicity, Isoprene-OA and More Oxidized – Oxidized Oxygenated Organic Aerosol (MO-OOA) are the prime contributors to hygroscopicity and covary with Less Oxidized – Oxidized Oxygenated Organic Aerosol (LO-OOA) in a way that induces the observed diurnal invariance in total organic hygroscopicity. Biomass Burning Organic Aerosol (BBOA) contributed little to aerosol hygroscopicity, which is expected since there was little biomass burning activity during the sampling period examined.

Molecular-Size-Separated Brown Carbon Absorption for Biomass-Burning Aerosol at Multiple Field Sites

2017 ◽  
Vol 51 (6) ◽  
pp. 3128-3137 ◽  
Author(s):  
Robert A. Di Lorenzo ◽  
Rebecca A. Washenfelder ◽  
Alexis R. Attwood ◽  
Hongyu Guo ◽  
Lu Xu ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Molecular Size ◽  
Brown Carbon ◽  
Carbon Absorption ◽  
Biomass Burning Aerosol ◽  
Multiple Field

scholarly journals Global analysis of the relation between aerosols and short-lived trace gases

2010 ◽  
Vol 10 (8) ◽  
pp. 18919-18951
Author(s):  
J. P. Veefkind ◽  
K. F. Boersma ◽  
J. Wang ◽  
T. Kurosu ◽  
N. Krotkov ◽  
...  
Keyword(s):  
United States ◽  
Biomass Burning ◽  
Western Europe ◽  
Southeastern United States ◽  
Satellite Observations ◽  
Trace Gas ◽  
Eastern United States ◽  
Aerosol Formation ◽  
The Tropics ◽  
Combustion Processes

Abstract. The spatial and temporal correlations between concurrent satellite observations of aerosol optical thickness (AOT) from the Moderate Resolution Imaging Spectroradiometer (MODIS) and tropospheric columns of nitrogen dioxide, sulfur dioxide, and formaldehyde from the Ozone Monitoring Instrument (OMI) are used to infer information on the global composition of aerosol particles. When averaging the satellite data over large regions and longer time periods, we find significant correlation between MODIS AOT and OMI trace gas columns for various regions in the world. This suggests that enhanced aerosol and trace gas concentrations originate from common sources, such as fossil fuel combustion, biomass burning, and organic compounds released from the biosphere. This leads us to propose that satellite-inferred AOT to NO2 ratios for regions with comparable photochemical regimes can be used as indicators for the relative (local) efficiency of combustion processes. Indeed, satellites observe low AOT to NO2 ratios over the eastern United States and western Europe, and high AOT to NO2 ratios over comparably industrialized regions in eastern Europe and China. Emission databases and OMI SO2 observations over these regions suggest a much stronger sulfur contribution to aerosol formation than over the well-regulated areas of the eastern United States and western Europe. Furthermore, satellite observations show AOT to NO2 ratios are a factor 100 higher over biomass burning regions than over industrialized areas, reflecting the unregulated burning practices with strong primary particle emissions in the tropics compared to the heavily controlled combustion processes in the industrialized Northern Hemisphere. Simulations with a global chemistry transport model (GEOS-Chem) capture most of these differences, providing some confidence in our understanding of aerosol sources, formation mechanisms, and sinks. Wintertime aerosol concentrations show strongest correlations with NO2 throughout most of the Northern Hemisphere. During summertime, AOT is often (also) correlated with enhanced HCHO concentrations, reflecting the importance of secondary organic aerosol formation in that season. We also find significant correlations between AOT and HCHO over biomass burning regions, the tropics in general, and over industrialized regions in southeastern Asia. The distinct summertime maximum in AOT (0.4 at 550 nm) and HCHO over the southeastern United States strengthens existing hypotheses that local emissions of volatile organic compounds lead to the formation of secondary organic aerosols there. GEOS-Chem underestimates the AOT over the southeastern United States by a factor of 2, most likely due to too strong precipitation and too low SOA yield in the model.

scholarly journals Global satellite analysis of the relation between aerosols and short-lived trace gases

2011 ◽  
Vol 11 (3) ◽  
pp. 1255-1267 ◽  
Author(s):  
J. P. Veefkind ◽  
K. F. Boersma ◽  
J. Wang ◽  
T. P. Kurosu ◽  
N. Krotkov ◽  
...  
Keyword(s):  
United States ◽  
Biomass Burning ◽  
Western Europe ◽  
Southeastern United States ◽  
Satellite Observations ◽  
Trace Gas ◽  
Eastern United States ◽  
Aerosol Formation ◽  
The Tropics ◽  
Combustion Processes

Abstract. The spatial and temporal correlations between concurrent satellite observations of aerosol optical thickness (AOT) from the Moderate Resolution Imaging Spectroradiometer (MODIS) and tropospheric columns of nitrogen dioxide (NO2), sulfur dioxide (SO2), and formaldehyde (HCHO) from the Ozone Monitoring Instrument (OMI) are used to infer information on the global composition of aerosol particles. When averaging the satellite data over large regions and longer time periods, we find significant correlation between MODIS AOT and OMI trace gas columns for various regions in the world. This shows that these enhanced aerosol and trace gas concentrations originate from common sources, such as fossil fuel combustion, biomass burning, and organic compounds released from the biosphere. This leads us to propose that satellite-inferred AOT to NO2 ratios for regions with comparable photochemical regimes can be used as indicators for the relative regional pollution control of combustion processes. Indeed, satellites observe low AOT to NO2 ratios over the eastern United States and western Europe, and high AOT to NO2 ratios over comparably industrialized regions in eastern Europe and China. Emission databases and OMI SO2 observations over these regions suggest a much stronger sulfur contribution to aerosol formation than over the well-regulated areas of the eastern United States and western Europe. Furthermore, satellite observations show AOT to NO2 ratios are a factor 100 higher over biomass burning regions than over industrialized areas, reflecting the unregulated burning practices with strong primary particle emissions in the tropics compared to the heavily controlled combustion processes in the industrialized Northern Hemisphere. Simulations with a global chemistry transport model (GEOS-Chem) capture most of these variations, although on regional scales significant differences are found. Wintertime aerosol concentrations show strongest correlations with NO2 throughout most of the Northern Hemisphere. During summertime, AOT is often (also) correlated with enhanced HCHO concentrations, reflecting the importance of secondary organic aerosol formation in that season. We also find significant correlations between AOT and HCHO over biomass burning regions, the tropics in general, and over industrialized regions in southeastern Asia. The distinct summertime maximum in AOT (0.4 at 550 nm) and HCHO over the southeastern United States strengthens existing hypotheses that local emissions of volatile organic compounds lead to the formation of secondary organic aerosols there. GEOS-Chem underestimates the AOT over the southeastern United States by a factor of 2, most likely due to too strong precipitation and too low SOA yield in the model.

scholarly journals PM<sub>2.5</sub> water-soluble elements in the southeastern United States: automated analytical method development, spatiotemporal distributions, source apportionment, and implications for heath studies

2015 ◽  
Vol 15 (20) ◽  
pp. 11667-11682 ◽  
Author(s):  
T. Fang ◽  
H. Guo ◽  
V. Verma ◽  
R. E. Peltier ◽  
R. J. Weber
Keyword(s):  
United States ◽  
Biomass Burning ◽  
Method Development ◽  
Mineral Dust ◽  
Southeastern United States ◽  
Water Soluble ◽  
Formation Factor ◽  
Mobile Source ◽  
Redox Active ◽  
Secondary Formation

Abstract. Water-soluble redox-active metals are potentially toxic due to its ability to catalytically generate reactive oxygen species (ROS) in vivo, leading to oxidative stress. As part of the Southeastern Center for Air Pollution and Epidemiology (SCAPE), we developed a method to quantify water-soluble elements, including redox-active metals, from a large number of filter samples (N = 530) in support of the center's health studies. PM2.5 samples were collected during 2012–2013 at various sites (three urban, two rural, a near-road site, and a road-side site) in the southeastern United States, using high-volume samplers. Water-soluble elements (S, K, Ca, Ti, Mn, Fe, Cu, Zn, As, Se, Br, Sr, Ba, and Pb) were determined by extracting filters in deionized water and re-aerosolized for analyses by X-ray fluorescence (XRF) using an online aerosol element analyzer (Xact, Cooper Environmental). Concentrations ranged from detection limits (nominally 0.1 to 30 ng m−3) to 1.2 μg m−3, with S as the most abundant element, followed by Ca, K, Fe, Cu, Zn, and Ba. Positive matrix factorization (PMF) identified four factors that were associated with specific sources based on relative loadings of various tracers. These include brake/tire wear (with tracers Ba and Cu), biomass burning (K), secondary formation (S, Se, and WSOC), and mineral dust (Ca). Of the four potentially toxic and relatively abundant metals (redox-active Cu, Mn, Fe, and redox-inactive Zn), 51 % of Cu, 32 % of Fe, 17 % of Mn, and 45 % of Zn were associated with the brake/tire factor. Mn was mostly associated with the mineral dust factor (45 %). Zn was found in a mixture of factors, with 26 % associated with mineral dust, 14 % biomass burning, and 13 % secondary formation. Roughly 50 % of Fe and 40 % of Cu were apportioned to the secondary formation factor, likely through increases in the soluble fraction of these elements by sulfur-driven aerosol water and acidity. Linkages between sulfate and water-soluble Fe and Cu may account for some of the past observed associations between sulfate/sulfur oxide and health outcomes. For Cu, Mn, Fe, and Zn, only Fe was correlated with PM2.5 mass (r = 0.73–0.80). Overall, mobile source emissions generated through mechanical processes (re-entrained road dust, tire and break wear) and processing by secondary sulfate were major contributors to water-soluble metals known to be capable of generating ROS.

Light Absorption by Brown Carbon in the Southeastern United States is pH-dependent

2017 ◽  
Vol 51 (12) ◽  
pp. 6782-6790 ◽  
Author(s):  
Sabrina M. Phillips ◽  
Aleia D. Bellcross ◽  
Geoffrey D. Smith
Keyword(s):  
United States ◽  
Light Absorption ◽  
Southeastern United States ◽  
Brown Carbon ◽  
Ph Dependent
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