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 (12) ◽  
pp. 17189-17227 ◽  
Author(s):  
T. Fang ◽  
H. Guo ◽  
V. Verma ◽  
R. E. Peltier ◽  
R. J. Weber
Keyword(s):  
Biomass Burning ◽  
Method Development ◽  
Mineral Dust ◽  
Water Soluble ◽  
Formation Factor ◽  
Mobile Source ◽  
Southeastern Us ◽  
Redox Active ◽  
Secondary Formation

Abstract. Water-soluble redox-active metals are potentially toxic due to the 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, and a road-side site) in the southeastern US, 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 %). These two factors were higher in warm (dryer) periods that favored particle re-suspension. 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 was apportioned to the secondary formation factor, likely through increased solubility by sulfur-driven aerosol 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.

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.

scholarly journals Brown carbon and water-soluble organic aerosols over the southeastern United States

2010 ◽  
Vol 10 (3) ◽  
pp. 7601-7639 ◽  
Author(s):  
A. Hecobian ◽  
X. Zhang ◽  
M. Zheng ◽  
N. Frank ◽  
E. S. Edgerton ◽  
...  
Keyword(s):  
Factor Analysis ◽  
Biomass Burning ◽  
Fine Particle ◽  
Reference Method ◽  
Water Soluble ◽  
Secondary Source ◽  
Mobile Source ◽  
Brown Carbon ◽  
Southeastern Us ◽  
Yearly Average

Abstract. Fine particle (PM2.5) light absorption characteristics of aqueous extracts over wavelengths of 250 to 700 nm were investigated based on two data sets; 24-h Federal Reference Method (FRM) filter extracts from 15 southeastern US monitoring sites over the year of 2007 (900 filters), and online measurements from a Particle-Into-Liquid Sampler deployed from July to mid-August 2009 in Atlanta, Georgia. Three main sources of soluble chromophores were identified, biomass burning, mobile source emissions, and compounds linked to Secondary Organic Aerosol (SOA) formation. Absorption spectra of aerosol solutions from different sources were similar. Angstrom exponents were ~7±1 for biomass burning and non-biomass burning-impacted samples (delineated by a levoglucosan concentration of 50 ng m−3) at both rural and urban sites. The absorption coefficient from measurements averaged between wavelength 360 and 370 nm (Abs365, in units m−1) was used as a measure of overall brown carbon absorptivity. Biomass-burning-impacted samples were highest during colder months and Abs365 was correlated with levoglucosan at all sites. During periods of little biomass burning in summer, light absorbing compounds were still ubiquitous and correlated with fine particle Water-Soluble Organic Carbon (WSOC), but comprised a much smaller fraction of the WSOC, where Abs365/WSOC (i.e., mass absorption efficiency) was typically ~3 times higher in biomass burning-impacted samples. Factor analysis attributed 50% of the yearly average Abs365 to biomass burning sources. Brown carbon from primary urban emissions (mobile sources) was also observed and accounted for ~10% of the regional yearly average Abs365. Summertime diurnal profiles of Abs365 and WSOC showed that morning to midday increases in WSOC from photochemical production were associated with a decrease in Abs365/WSOC. After noon this ratio substantially increased, indicating that either some fraction of the non-light absorbing fresh SOA was rapidly (within hours) converted to chromophores heterogeneously, or that SOA from gas-particle partitioning later in the day was more light-absorbing. Factor analysis associated ~20 to 30% of Abs365 over 2007 with a secondary source that was highest in summer and also the main source for oxalic acid, suggesting that aqueous phase reactions may account for the light-absorbing fraction of WSOC observed throughout the southeastern US in summer.

Contrasting signatures of the sources and types of aerosols in the western and eastern Himalayas: Radiative implications

2021 ◽  
Author(s):  
Arun Bs ◽  
Mukunda Gogoi ◽  
Prashant Hegde ◽  
Suresh Babu
Keyword(s):  
Mineral Dust ◽  
Water Soluble ◽  
The Other ◽  
Anthropogenic Source ◽  
Chemical Compositions ◽  
Eastern Himalayas ◽  
Chemical Aging ◽  
Other Hand ◽  
Secondary Formation ◽  
The Impact

&lt;p&gt;The rapid changes in the pattern of atmospheric warming over the Himalayas, along with severe degradation of Himalayan glaciers in recent years suggest the inevitability of accurate source characterization and quantification of the impact of aerosols on the Himalayan atmosphere and snow. In this regard, extensive study of the chemical compositions of aerosols at two distinct regions, Himansh (32.4&lt;sup&gt;&amp;#7484;&lt;/sup&gt;N, 77.6&lt;sup&gt;&amp;#7484;&lt;/sup&gt;E, ~ 4080 m a.s.l) and Lachung (27.4&lt;sup&gt;&amp;#7484;&lt;/sup&gt;N, 88.4&lt;sup&gt;&amp;#7484;&lt;/sup&gt;E, ~ 2700 m a.s.l), elucidates distinct signatures of the sources and types of aerosols prevailing over the western and eastern parts of Himalayas. The mass-mixing ratios of water-soluble (Na&lt;sup&gt;+&lt;/sup&gt;, NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;, K&lt;sup&gt;+&lt;/sup&gt;, Ca&lt;sup&gt;2+&lt;/sup&gt;, Mg&lt;sup&gt;2+&lt;/sup&gt;, Cl-, SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;, NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;, MSA&lt;sup&gt;-&lt;/sup&gt;, C&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;), carbonaceous (EC, OC, WSOC) and selected elemental (Al, Fe, Cu, Cr, Ti) species depicted significant abundance of mineral dust aerosols (~ 67%), along with a significant contribution of carbonaceous aerosols (~ 9%) during summer to autumn (August-October) over the western Himalayan site. On the other hand, the eastern Himalayan site is found to be dominant of OC (~ 53% in winter) followed by SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt; (as high as 37% in spring) and EC (8-12%) during August to February. However, OC/EC and WSOC/OC ratios showed significantly higher values over both the sites (~ 12.5, and 0.56 at Himansh; ~ 5.7 and ~ 0.74 at Lachung) indicating the secondary formation of organic aerosols via chemical aging over both the sites. The enrichment factors estimated from the concentrations of trace elements over the western Himalayan site revealed the influence of anthropogenic source contribution from the regional hot-spots of Indo-Gangetic Plains, in addition to that of west Asia and the Middle East countries. On the other hand, the source apportionment of aerosols (based on positive matrix factorization - PMF model) over the eastern Himalayas demonstrated the biomass-burning aerosols (25.94%), secondary formation of aerosols via chemical aging (15.94%), vehicular and industrial emissions (20.54%), primary emission sources associated with mineral dust sources (22.28%) and aged secondary aerosols (15.31%) as the major sources of aerosols. Due to abundant anthropogenic source impacts at the eastern Himalayan site, the atmospheric forcing is most elevated in winter (13.4 &amp;#177; 4.4 Wm&lt;sup&gt;-2&lt;/sup&gt;), which is more than two times the average values seen at the western Himalayan region during the study period. The heavily polluted eastern part of the IGP is a potential anthropogenic source region contributing to the aerosol loading at the eastern Himalayas. These observations have far-reaching implications in view of the role of aerosols on regional radiative balance and their impact on snow/glacier coverage.&lt;/p&gt;

scholarly journals Optical, physical and chemical characteristics of Australian continental aerosols: results from a field experiment

2010 ◽  
Vol 10 (13) ◽  
pp. 5925-5942 ◽  
Author(s):  
M. Radhi ◽  
M. A. Box ◽  
G. P. Box ◽  
R. M. Mitchell ◽  
D. D. Cohen ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Ion Chromatography ◽  
Biomass Burning ◽  
Mineral Dust ◽  
Ion Beam ◽  
Water Soluble ◽  
Size Distributions ◽  
Ion Beam Analysis ◽  
Beam Analysis ◽  
Scatter Plots

Abstract. Mineral dust is one of the major components of the world's aerosol mix, having a number of impacts within the Earth system. However, the climate forcing impact of mineral dust is currently poorly constrained, with even its sign uncertain. As Australian deserts are more reddish than those in the Northern Hemisphere, it is important to better understand the physical, chemical and optical properties of this important aerosol. We have investigated the properties of Australian desert dust at a site in SW Queensland, which is strongly influenced by both dust and biomass burning aerosol. Three years of ground-based monitoring of spectral optical thickness has provided a statistical picture of gross aerosol properties. The aerosol optical depth data showed a clear though moderate seasonal cycle with an annual mean of 0.06 ± 0.03. The Angstrom coefficient showed a stronger cycle, indicating the influence of the winter-spring burning season in Australia's north. AERONET size distributions showed a generally bimodal character, with the coarse mode assumed to be mineral dust, and the fine mode a mixture of fine dust, biomass burning and marine biogenic material. In November 2006 we undertook a field campaign which collected 4 sets of size-resolved aerosol samples for laboratory analysis – ion beam analysis and ion chromatography. Ion beam analysis was used to determine the elemental composition of all filter samples, although elemental ratios were considered the most reliable output. Scatter plots showed that Fe, Al and Ti were well correlated with Si, and Co reasonably well correlated with Si, with the Fe/Al ratio somewhat higher than values reported from Northern Hemisphere sites (as expected). Scatter plots for Ca, Mn and K against Si showed clear evidence of a second population, which in some cases could be identified with a particular sample day or size fraction. These data may be used to attempt to build a signature of soil in this region of the Australian interior. Ion chromatography was used to quantify water soluble ions for 2 of our sample sets, complementing the picture provided by ion beam analysis. The strong similarities between the MSA and SO42− size distributions argue strongly for a marine origin of much of the SO42−. The similarity of the Na+, Cl− and Mg2+ size distributions also argue for a marine contribution. Further, we believe that both NO3− and NH4+ are the result of surface reactions with appropriate gases.

scholarly journals Chemical composition and source apportionment of atmospheric aerosols on the Namibian coast

2020 ◽  
Vol 20 (24) ◽  
pp. 15811-15833
Author(s):  
Danitza Klopper ◽  
Paola Formenti ◽  
Andreas Namwoonde ◽  
Mathieu Cazaunau ◽  
Servanne Chevaillier ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Biomass Burning ◽  
Mineral Dust ◽  
Open Ocean ◽  
Sea Salt ◽  
Water Soluble ◽  
Marine Phytoplankton ◽  
Fugitive Dust ◽  
The South ◽  
North West

Abstract. The chemical composition of aerosols is of particular importance to assess their interactions with radiation, clouds and trace gases in the atmosphere and consequently their effects on air quality and the regional climate. In this study, we present the results of the first long-term dataset of the aerosol chemical composition at an observatory on the coast of Namibia, facing the south-eastern Atlantic Ocean. Aerosol samples in the mass fraction of particles smaller than 10 µm in aerodynamic diameter (PM10) were collected during 26 weeks between 2016 and 2017 at the ground-based Henties Bay Aerosol Observatory (HBAO; 22∘6′ S, 14∘30′ E; 30 m above mean sea level). The resulting 385 filter samples were analysed by X-ray fluorescence and ion chromatography for 24 inorganic elements and 15 water-soluble ions. Statistical analysis by positive matrix factorisation (PMF) identified five major components, sea salt (mass concentration: 74.7±1.9 %), mineral dust (15.7±1.4 %,), ammonium neutralised (6.1±0.7 %), fugitive dust (2.6±0.2 %) and industry (0.9±0.7 %). While the contribution of sea salt aerosol was persistent, as the dominant wind direction was south-westerly and westerly from the open ocean, the occurrence of mineral dust was episodic and coincided with high wind speeds from the south-south-east and the north-north-west, along the coastline. Concentrations of heavy metals measured at HBAO were higher than reported in the literature from measurements over the open ocean. V, Cd, Pb and Nd were attributed to fugitive dust emitted from bare surfaces or mining activities. As, Zn, Cu, Ni and Sr were attributed to the combustion of heavy oils in commercial ship traffic across the Cape of Good Hope sea route, power generation, smelting and other industrial activities in the greater region. Fluoride concentrations up to 25 µg m−3 were measured, as in heavily polluted areas in China. This is surprising and a worrisome result that has profound health implications and deserves further investigation. Although no clear signature for biomass burning could be determined, the PMF ammonium-neutralised component was described by a mixture of aerosols typically emitted by biomass burning, but also by other biogenic activities. Episodic contributions with moderate correlations between NO3-, nss-SO42- (higher than 2 µg m−3) and nss-K+ were observed, further indicative of the potential for an episodic source of biomass burning. Sea salt accounted for up to 57 % of the measured mass concentrations of SO42-, and the non-sea salt fraction was contributed mainly by the ammonium-neutralised component and small contributions from the mineral dust component. The marine biogenic contribution to the ammonium-neutralised component is attributed to efficient oxidation in the moist marine atmosphere of sulfur-containing gas phase emitted by marine phytoplankton in the fertile waters offshore in the Benguela Upwelling System. The data presented in this paper provide the first ever information on the temporal variability of aerosol concentrations in the Namibian marine boundary layer. This data also provide context for intensive observations in the area.

scholarly journals Biomass burning impact on PM<sub> 2.5</sub> over the southeastern US during 2007: integrating chemically speciated FRM filter measurements, MODIS fire counts and PMF analysis

2010 ◽  
Vol 10 (14) ◽  
pp. 6839-6853 ◽  
Author(s):  
X. Zhang ◽  
A. Hecobian ◽  
M. Zheng ◽  
N. H. Frank ◽  
R. J. Weber
Keyword(s):  
Biomass Burning ◽  
Reference Method ◽  
Water Soluble ◽  
Poor Correlation ◽  
Aerosol Mass ◽  
Southeastern Us ◽  
Soluble Ions ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon ◽  
Rural Sites

Abstract. Archived Federal Reference Method (FRM) Teflon filters used by state regulatory agencies for measuring PM2.5 mass were acquired from 15 sites throughout the southeastern US and analyzed for water-soluble organic carbon (WSOC), water-soluble ions and carbohydrates to investigate biomass burning contributions to fine aerosol mass. Based on over 900 filters that spanned all of 2007, levoglucosan and K+ were studied in conjunction with MODIS Aqua fire count data to compare their performances as biomass burning tracers. Levoglucosan concentrations exhibited a distinct seasonal variation with large enhancement in winter and spring and a minimum in summer, and were well correlated with fire counts, except in winter when residential wood burning contributions were significant. In contrast, K+ concentrations had no apparent seasonal trend and poor correlation with fire counts. Levoglucosan and K+ only correlated well in winter (r2=0.59) when biomass burning emissions were highest, whereas in other seasons they were not correlated due to the presence of other K+ sources. Levoglucosan also exhibited larger spatial variability than K+. Both species were higher in urban than rural sites (mean 44% higher for levoglucosan and 86% for K+). Positive Matrix Factorization (PMF) was applied to analyze PM2.5 sources and four factors were resolved: biomass burning, refractory material, secondary light absorbing WSOC and secondary sulfate/WSOC. The biomass burning source contributed 13% to PM2.5 mass annually, 27% in winter, and less than 2% in summer, consistent with other souce apportionment studies based on levoglucosan, but lower in summer compared to studies based on K+.

scholarly journals A semi-automated system for quantifying the oxidative potential of ambient particles in aqueous extracts using the dithiothreitol (DTT) assay: results from the Southeastern Center for Air Pollution and Epidemiology (SCAPE)

2014 ◽  
Vol 7 (7) ◽  
pp. 7245-7279 ◽  
Author(s):  
T. Fang ◽  
V. Verma ◽  
H. Guo ◽  
L. E. King ◽  
E. S. Edgerton ◽  
...  
Keyword(s):  
Air Pollution ◽  
Large Scale ◽  
Limit Of Detection ◽  
Water Soluble ◽  
Automated System ◽  
Oxidative Potential ◽  
Data Set ◽  
Ambient Particles ◽  
Southeastern Us

Abstract. A variety of methods are used to measure the capability of particulate matter (PM) to catalytically generate reactive oxygen species (ROS) in vivo, also defined as the aerosol oxidative potential. A widely used measure of aerosol oxidative potential is the dithiothreitol (DTT) assay, which monitors the depletion of DTT (a surrogate for cellular antioxidants) as catalyzed by the redox-active species in PM. However, a major constraint in the routine use of the DTT assay for integrating it with the large-scale health studies is its labor-intensive and time-consuming protocol. To specifically address this concern, we have developed a semi-automated system for quantifying the oxidative potential of aerosol liquid extracts using the DTT assay. The system, capable of unattended analysis at one sample per hour, has a high analytical precision (Coefficient of Variation of 12% for standards, 4% for ambient samples), and reasonably low limit of detection (0.31 nmol min−1). Comparison of the automated approach with the manual method conducted on ambient samples yielded good agreement (slope = 1.08 ± 0.12, r2 = 0.92, N = 9). The system was utilized for the Southeastern Center for Air Pollution and Epidemiology (SCAPE) to generate an extensive data set on DTT activity of ambient particles collected from contrasting environments (urban, road-side, and rural) in the southeastern US. We find that water-soluble PM2.5 DTT activity on a per air volume basis was spatially uniform and often well correlated with PM2.5 mass (r = 0.49 to 0.88), suggesting regional sources contributing to the PM oxidative potential in southeast US. However, the greater heterogeneity in the intrinsic DTT activity (per PM mass basis) across seasons indicates variability in the DTT activity associated with aerosols from sources that vary with season. Although developed for the DTT assay, the instrument can also be used to determine oxidative potential with other acellular assays.

scholarly journals Characteristics of Locally Occurring High PM2.5 Concentration Episodes in a Small City in South Korea

Atmosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 86
Author(s):  
Su-Yeon Choi ◽  
Sung-Won Park ◽  
Jin-Yeo Byun ◽  
Young-Ji Han
Keyword(s):  
Biomass Burning ◽  
Principal Component ◽  
Sampling Period ◽  
Ambient Air ◽  
Quality Standard ◽  
Water Soluble ◽  
Strongly Correlated ◽  
Secondary Formation ◽  
Ambient Air Quality Standard ◽  
Pm2.5 Concentration

In this study, the ionic and carbonaceous compounds in PM2.5 were analysed in the small residential city of Chuncheon, Korea. To identify the local sources that substantially influence PM2.5 concentrations, the samples were divided into two groups: samples with PM2.5 concentrations higher than those in the upwind metropolitan area (Seoul) and samples with lower PM2.5 concentrations. During the sampling period (December 2016–August 2018), the average PM2.5 was 23.2 μg m−3, which exceeds the annual national ambient air quality standard (15 μg m−3). When the PM2.5 concentrations were higher in Chuncheon than in Seoul, the organic carbon (OC) and elemental carbon (EC) concentrations increased the most among all the PM2.5 components measured in this study. This is attributable to secondary formation and biomass burning, because secondary OC was enhanced and water soluble OC was strongly correlated with K+, EC, and OC. A principal component analysis identified four factors contributing to PM2.5: fossil-fuel combustion, secondary inorganic and organic reactions in biomass burning plumes, crustal dust, and secondary NH4+ formation.

scholarly journals Measurement report: Long emission-wavelength chromophores dominate the light absorption of brown carbon in Aerosols over Bangkok: impact from biomass burning

2021 ◽  
Author(s):  
Jiao Tang ◽  
Jiaqi Wang ◽  
Guangcai Zhong ◽  
Hongxing Jiang ◽  
Yangzhi Mo ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Light Absorption ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Water Soluble ◽  
Emission Wavelength ◽  
Brown Carbon ◽  
Molecular Weights ◽  
Secondary Formation ◽  
Combustion Emission

Abstract. Chromophores represent an important portion of light-absorbing species, i.e. brown carbon. Yet knowledge on what and how chromophores contribute to aerosol light absorption is still sparse. To address this problem, we examined soluble independent chromophores in a set of year-round aerosol samples from Bangkok. The water-soluble chromophores identified via excitation-emission matrix (EEM) spectroscopy and follow-up parallel factor analysis could be mainly assigned as humic-like substances and protein-like substances, which differed in their EEM pattern from that of the methanol-soluble fraction. The emission wavelength of chromophores in environmental samples tended to increase compared with that of the primary combustion emission, which could be attributed to secondary formation or the aging process. Fluorescent indices inferred that these light-absorbing chromophores were not significantly humified and comprised a mixture of organic matter of terrestrial and microbial origin, while these inferences exhibited a refutation with primary biomass burning and coal combustion results. A multiple linear regression analysis revealed that larger chromophores that were oxygen-rich and highly aromatic with high molecular weights, were the key contributors of light absorption, preferably at longer emission wavelength (λmax > 500 nm). Positive matrix factorization analysis further suggested that up to 60 % of these responsible chromophores originated from biomass burning emissions.

scholarly journals Optical, physical and chemical characteristics of Australian Desert dust aerosols: results from a field experiment

2009 ◽  
Vol 9 (6) ◽  
pp. 25085-25125 ◽  
Author(s):  
M. Radhi ◽  
M. A. Box ◽  
G. P. Box ◽  
R. M. Mitchell ◽  
D. D. Cohen ◽  
...  
Keyword(s):  
Ion Chromatography ◽  
Biomass Burning ◽  
Mineral Dust ◽  
Ion Beam ◽  
Size Fraction ◽  
Water Soluble ◽  
Ion Beam Analysis ◽  
Desert Dust ◽  
Beam Analysis ◽  
Scatter Plots

Abstract. Mineral dust is one of the major components of the world's aerosol mix, having a number of impacts within the Earth system. However, the climate forcing impact of mineral dust is currently poorly constrained, with even its sign uncertain. As Australian deserts are more reddish than those in the northern hemisphere, it is important to better understand the physical, chemical and optical properties of this important aerosol. We have investigated the properties of Australian desert dust at a site in SW Queensland, which is strongly influenced by both dust and biomass burning aerosol. Three years of ground-based monitoring of spectral optical thickness has provided a statistical picture of gross aerosol properties. In November 2006 we undertook a field campaign which collected 4 sets of size-resolved aerosol samples for laboratory analysis – both ion beam analysis and ion chromatography. The aerosol optical depth data showed a weak seasonal cycle with an annual mean of 0.06±0.03. The Angstrom coefficient showed a stronger cycle, indicating the influence of the winter-spring burning season in Australia's north. Size distribution inversions showed a bimodal character, with the coarse mode assumed to be mineral dust, and the fine mode a mixture of biomass burning and marine biogenic material. Ion Beam Analysis was used to determine the elemental composition of all filter samples, although elemental ratios were considered the most reliable output. Scatter plots showed that Fe, Al and Ti were well correlated with Si, and Co reasonably well correlated, with the Fe/Si ratio higher than the crustal average, as expected. Scatter plots for Ca, Mn and K against Si showed clear evidence of a second population, which in some cases could be identified with a particular sample day or size fraction. Ion Chromatography was used to quantify water soluble ions for 2 of our sample sets, showing the importance of marine influences on both fine (biogenic) and coarse (sea salt) modes.

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