scholarly journals Biomass burning contribution to Beijing aerosol

2013 ◽  
Vol 13 (3) ◽  
pp. 8387-8434 ◽  
Author(s):  
Y. Cheng ◽  
G. Engling ◽  
K. B. He ◽  
F. K. Duan ◽  
Y. L. Ma ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Elemental Carbon ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Winter Period ◽  
Summer Period ◽  
Pmf Model ◽  
Different Types ◽  
Biomass Burning Aerosol ◽  
Typical Summer

Abstract. Biomass burning, the largest global source of elemental carbon (EC) and primary organic carbon (OC), is strongly associated with many subjects of great scientific concern, such as secondary organic aerosol and brown carbon which exert important effects on the environment and on climate in particular. This study investigated the relationships between levoglucosan and other biomass burning tracers (i.e. water soluble potassium and mannosan) based on both ambient samples collected in Beijing and source samples. Compared with North America and Europe, Beijing was characterized by high ambient levoglucosan concentrations and low winter to summer ratios of levoglucosan, indicating significant impact of biomass burning activities throughout the year in Beijing. Comparison of levoglucosan and water soluble potassium (K+) levels suggested that it was acceptable to use K+ as a biomass burning tracer during summer in Beijing, while the contribution of fireworks to K+ could be significant during winter. Moreover, the levoglucosan to K+ ratio was found to be lower during the typical summer period (0.21±0.16) compared with the typical winter period (0.51±0.15). On the other hand, levoglucosan correlated strongly with mannosan (R2=0.97) throughout the winter and the levoglucosan to mannosan ratio averaged 9.49±1.63, whereas levoglucosan and mannosan exhibited relatively weak correlation (R2=0.73) during the typical summer period when the levoglucosan to mannosan ratio averaged 12.65±3.38. Results from PMF model analysis showed that about 50% of the OC and EC in Beijing were associated with biomass burning processes. In addition, a new source-identification method was developed based on the comparison of the levoglucosan to K+ ratio and the levoglucosan to mannosan ratio among different types of biomass. Using this method, the major source of biomass burning aerosol in Beijing was suggested to be the combustion of crop residuals, while the contribution from softwood burning was also non-negligible, especially in winter.

scholarly journals Biomass burning contribution to Beijing aerosol

2013 ◽  
Vol 13 (15) ◽  
pp. 7765-7781 ◽  
Author(s):  
Y. Cheng ◽  
G. Engling ◽  
K.-B. He ◽  
F.-K. Duan ◽  
Y.-L. Ma ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Winter Period ◽  
Summer Period ◽  
Positive Matrix ◽  
Pmf Model ◽  
Different Types ◽  
Biomass Burning Aerosol ◽  
Typical Summer

Abstract. Biomass burning, the largest global source of elemental carbon (EC) and primary organic carbon (OC), is strongly associated with many subjects of great scientific concern, such as secondary organic aerosol and brown carbon which exert important effects on the environment and on climate in particular. This study investigated the relationships between levoglucosan and other biomass burning tracers (i.e., water soluble potassium and mannosan) based on both ambient samples collected in Beijing and source samples. Compared with North America and Europe, Beijing was characterized by high ambient levoglucosan concentrations and low winter to summer ratios of levoglucosan, indicating significant impact of biomass burning activities throughout the year in Beijing. Comparison of levoglucosan and water soluble potassium (K+) levels suggested that it was acceptable to use K+ as a biomass burning tracer during summer in Beijing, while the contribution of fireworks to K+ could be significant during winter. Moreover, the levoglucosan to K+ ratio was found to be lower during the typical summer period (0.21 ± 0.16) compared with the typical winter period (0.51 ± 0.15). Levoglucosan correlated strongly with mannosan (R2 = 0.97) throughout the winter and the levoglucosan to mannosan ratio averaged 9.49 ± 1.63, whereas levoglucosan and mannosan exhibited relatively weak correlation (R2 = 0.73) during the typical summer period when the levoglucosan to mannosan ratio averaged 12.65 ± 3.38. Results from positive matrix factorization (PMF) model analysis showed that about 50% of the OC and EC in Beijing were associated with biomass burning processes. In addition, a new source identification method was developed based on the comparison of the levoglucosan to K+ ratio and the levoglucosan to mannosan ratio among different types of biomass. Using this method, the major source of biomass burning aerosol in Beijing was suggested to be the combustion of crop residuals, while the contribution from softwood burning was also non-negligible, especially in winter.

scholarly journals Mass absorption efficiency of elemental carbon and water-soluble organic carbon in Beijing, China

2011 ◽  
Vol 11 (22) ◽  
pp. 11497-11510 ◽  
Author(s):  
Y. Cheng ◽  
K.-B. He ◽  
M. Zheng ◽  
F.-K. Duan ◽  
Z.-Y. Du ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Light Absorption ◽  
Elemental Carbon ◽  
Organic Aerosol ◽  
Absorption Efficiency ◽  
Water Soluble ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon ◽  
Mass Absorption Efficiency

Abstract. The mass absorption efficiency (MAE) of elemental carbon (EC) in Beijing was quantified using a thermal-optical carbon analyzer. The MAE measured at 632 nm was 8.45±1.71 and 9.41±1.92 m2 g−1 during winter and summer respectively. The daily variation of MAE was found to coincide with the abundance of organic carbon (OC), especially the OC to EC ratio, perhaps due to the enhancement by coating with organic aerosol (especially secondary organic aerosol, SOA) or the artifacts resulting from the redistribution of liquid-like organic particles during the filter-based absorption measurements. Using a converting approach that accounts for the discrepancy caused by measurements methods of both light absorption and EC concentration, previously published MAE values were converted to the equivalent-MAE, which is the estimated value if using the same measurement methods as used in this study. The equivalent-MAE was found to be much lower in the regions heavily impacted by biomass burning (e.g., below 2.7 m2 g−1 for two Indian cities). Results from source samples (including diesel exhaust samples and biomass smoke samples) also demonstrated that emissions from biomass burning would decrease the MAE of EC. Moreover, optical properties of water-soluble organic carbon (WSOC) in Beijing were presented. Light absorption by WSOC exhibited strong wavelength (λ) dependence such that absorption varied approximately as λ−7, which was characteristic of the brown carbon spectra. The MAE of WSOC (measured at 365 nm) was 1.79±0.24 and 0.71±0.20 m2 g−1 during winter and summer respectively. The large discrepancy between the MAE of WSOC during winter and summer was attributed to the difference in the precursors of SOA such that anthropogenic volatile organic compounds (AVOCs) should be more important as the precursors of SOA in winter. The MAE of WSOC in Beijing was much higher than results from the southeastern United States which were obtained using the same method as used in this study, perhaps due to the stronger emissions of biomass burning in China.

scholarly journals Chemical oxidative potential of secondary organic aerosol (SOA) generated from the photooxidation of biogenic and anthropogenic volatile organic compounds

2016 ◽  
Author(s):  
Wing Y. Tuet ◽  
Yunle Chen ◽  
Lu Xu ◽  
Shierly Fok ◽  
Dong Gao ◽  
...  
Keyword(s):  
Health Effects ◽  
Biomass Burning ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Hydrocarbon Emissions ◽  
Reaction Conditions ◽  
Oxidative Potential ◽  
Incomplete Combustion ◽  
Volatile Organic ◽  
Biomass Burning Aerosol

Abstract. Particulate matter (PM), of which a significant fraction is comprised of secondary organic aerosols (SOA), has received considerable attention due to their health implications. In this study, the water-soluble oxidative potential (OPWS) of SOA generated from the photooxidation of biogenic and anthropogenic hydrocarbon precursors (isoprene, α-pinene, β-caryophyllene, pentadecane, m-xylene, and naphthalene) under different reaction conditions (RO2 + HO2/RO2 + NO dominant, dry/humid) was characterized using dithiothreitol (DTT) consumption. The measured intrinsic OPWS-DTT ranged from 9–205 pmol min−1 µg−1 and were highly dependent on the specific hydrocarbon precursor, with naphthalene and isoprene SOA generating the highest and lowest OPWS-DTT, respectively. Humidity and RO2 fate affected OPWS-DTT in a hydrocarbon-specific manner, with naphthalene SOA exhibiting the most pronounced effects, likely due to the formation of nitroaromatics. Together, these results suggest that precursor identity may be more influential than reaction condition in determining SOA health effects, demonstrating the importance of sources, such as incomplete combustion, to aerosol toxicity. In the context of other PM sources, all SOA systems with the exception of naphthalene SOA were less DTT active than ambient sources related to incomplete combustion, including diesel and gasoline combustion as well as biomass burning. Finally, naphthalene SOA was as DTT active as biomass burning aerosol, which was found to be the most DTT active OA source in a previous ambient study. These results highlight a need to consider SOA contributions (particularly from anthropogenic hydrocarbons) to health effects in the context of hydrocarbon emissions, SOA yields, and other PM sources.

scholarly journals Chemical oxidative potential of secondary organic aerosol (SOA) generated from the photooxidation of biogenic and anthropogenic volatile organic compounds

2017 ◽  
Vol 17 (2) ◽  
pp. 839-853 ◽  
Author(s):  
Wing Y. Tuet ◽  
Yunle Chen ◽  
Lu Xu ◽  
Shierly Fok ◽  
Dong Gao ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Hydrocarbon Emissions ◽  
Reaction Conditions ◽  
Oxidative Potential ◽  
Incomplete Combustion ◽  
Volatile Organic ◽  
Specific Manner ◽  
Biomass Burning Aerosol

Abstract. Particulate matter (PM), of which a significant fraction is comprised of secondary organic aerosols (SOA), has received considerable attention due to its health implications. In this study, the water-soluble oxidative potential (OPWS) of SOA generated from the photooxidation of biogenic and anthropogenic hydrocarbon precursors (isoprene, α-pinene, β-caryophyllene, pentadecane, m-xylene, and naphthalene) under different reaction conditions (RO2+ HO2 vs. RO2+ NO dominant, dry vs. humid) was characterized using dithiothreitol (DTT) consumption. The measured intrinsic OPWS-DTT values ranged from 9 to 205 pmol min−1 µg−1 and were highly dependent on the specific hydrocarbon precursor, with naphthalene and isoprene SOA generating the highest and lowest OPWS-DTT values, respectively. Humidity and RO2 fate affected OPWS-DTT in a hydrocarbon-specific manner, with naphthalene SOA exhibiting the most pronounced effects, likely due to the formation of nitroaromatics. Together, these results suggest that precursor identity may be more influential than reaction condition in determining SOA oxidative potential, demonstrating the importance of sources, such as incomplete combustion, to aerosol toxicity. In the context of other PM sources, all SOA systems, with the exception of naphthalene SOA, were less DTT active than ambient sources related to incomplete combustion, including diesel and gasoline combustion as well as biomass burning. Finally, naphthalene SOA was as DTT active as biomass burning aerosol, which was found to be the most DTT-active OA source in a previous ambient study. These results highlight a need to consider SOA contributions (particularly from anthropogenic hydrocarbons) to health effects in the context of hydrocarbon emissions, SOA yields, and other PM sources.

scholarly journals Chemical aging of single and multicomponent biomass burning aerosol surrogate-particles by OH: implications for cloud condensation nucleus activity

2015 ◽  
Vol 15 (5) ◽  
pp. 6771-6819
Author(s):  
J. H. Slade ◽  
R. Thalman ◽  
J. Wang ◽  
D. A. Knopf
Keyword(s):  
Biomass Burning ◽  
Wet Deposition ◽  
Water Solubility ◽  
Inorganic Compounds ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Oh Radicals ◽  
Chemical Aging ◽  
Biomass Burning Aerosol ◽  
Ccn Activity

Abstract. Multiphase OH and O3 oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low soluble single-component OA by OH and O3 can increase their water-solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water-solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate-particles exposed to OH and O3 is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH/O3 exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O3 exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ~0.1, indicating that chemically-aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally-mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH exposed MNC-coated KS particles is similar to the OH unexposed atomized 1 : 1 by mass MNC : KS binary-component particles. Our results strongly suggest that when OA is dominated by water-soluble organic carbon (WSOC) or inorganic ions, chemical aging has no significant impact on OA hygroscopicity. The organic compounds exhibiting low solubility behave as if they are infinitely soluble when mixed with a sufficient amount of water-soluble compounds. At and beyond this point, the particles' CCN activity is governed entirely by the water-soluble fraction and not influenced by the oxidized organic fraction. Our results have important implications for heterogeneous oxidation and its impact on cloud formation given that atmospheric aerosol is a complex mixture of organic and inorganic compounds exhibiting a wide-range of solubilities.

scholarly journals Chemical aging of single and multicomponent biomass burning aerosol surrogate particles by OH: implications for cloud condensation nucleus activity

2015 ◽  
Vol 15 (17) ◽  
pp. 10183-10201 ◽  
Author(s):  
J. H. Slade ◽  
R. Thalman ◽  
J. Wang ◽  
D. A. Knopf
Keyword(s):  
Biomass Burning ◽  
Wet Deposition ◽  
Water Solubility ◽  
Inorganic Compounds ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Oh Radicals ◽  
Chemical Aging ◽  
Biomass Burning Aerosol ◽  
Ccn Activity

Abstract. Multiphase OH and O3 oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low-soluble single-component OA by OH and O3 can increase their water solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate particles exposed to OH and O3 is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH and O3 exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O3 exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ~ 0.1, indicating that chemically aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH-exposed MNC-coated KS particles is similar to the OH unexposed atomized 1 : 1 by mass MNC : KS binary-component particles. Our results strongly suggest that when OA is dominated by water-soluble organic carbon (WSOC) or inorganic ions, chemical aging has no significant impact on OA hygroscopicity. The organic compounds exhibiting low solubility behave as if they are infinitely soluble when mixed with a sufficient number of water-soluble compounds. At and beyond this point, the particles' CCN activity is governed entirely by the water-soluble fraction and is not influenced by the oxidized organic fraction. Our results have important implications for heterogeneous oxidation and its impact on cloud formation given that atmospheric aerosol is a complex mixture of organic and inorganic compounds exhibiting a wide range of solubilities.

scholarly journals Mass absorption efficiency of elemental carbon and water-soluble organic carbon in Beijing, China

2011 ◽  
Vol 11 (9) ◽  
pp. 24727-24764 ◽  
Author(s):  
Y. Cheng ◽  
K.-B. He ◽  
M. Zheng ◽  
F.-K. Duan ◽  
Y.-L. Ma ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Light Absorption ◽  
Elemental Carbon ◽  
Organic Aerosol ◽  
Absorption Efficiency ◽  
Water Soluble ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon ◽  
Mass Absorption Efficiency

Abstract. The mass absorption efficiency (MAE) of elemental carbon (EC) in Beijing was quantified using a thermal-optical carbon analyzer. The MAE measured at 632 nm was 8.45 ± 1.71 and 9.41 ± 1.92 m2 g−1 during winter and summer, respectively. The daily variation of MAE was found to coincide with the OC (organic carbon) abundance, especially the OC to EC ratio, perhaps due to the enhancement by coating with organic aerosol (especially secondary organic aerosol, SOA) or the artifacts resulting from the redistribution of liquid-like organic particles during the filter-based absorption measurements. Using a converting approach that accounts for the discrepancy caused by measurements methods of both light absorption and EC concentration, previously published MAE values were converted to the equivalent MAE, which is the estimated value if using the same measurement methods as used in this study. The equivalent MAE was found to be much lower in the regions heavily impacted by biomass burning (e.g., India), probably due to the influence of brown carbon. Optical properties of water-soluble organic carbon (WSOC) in Beijing were also presented. Light absorption by WSOC exhibited strong wavelength (λ) dependence such that absorption varied approximately as λ−7, which was characteristic of the brown carbon spectra. The MAE of WSOC (measured at 365 nm) was 1.83 and 0.70 m2 g−1 during winter and summer, respectively. WSOC in Beijing has been demonstrated to be strongly linked to SOA; and the seasonal pattern of its MAE was attributed to the difference in the precursors of SOA such that anthropogenic volatile organic compounds (AVOCs) should be more important as the precursors of SOA in winter. Moreover, the MAE of WSOC in Beijing was much higher than results from the southeastern United States which were obtained using the same method as used in this study, perhaps due to the influence of biomass burning.

scholarly journals Long-range aerosol transport and impacts on size-resolved aerosol composition in Metro Manila, Philippines

2020 ◽  
Vol 20 (4) ◽  
pp. 2387-2405 ◽  
Author(s):  
Rachel A. Braun ◽  
Mojtaba Azadi Aghdam ◽  
Paola Angela Bañaga ◽  
Grace Betito ◽  
Maria Obiminda Cambaliza ◽  
...  
Keyword(s):  
Long Range ◽  
Biomass Burning ◽  
Dicarboxylic Acids ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Long Range Transport ◽  
Aerosol Transport ◽  
Range Transport ◽  
Metro Manila ◽  
Biomass Burning Aerosol

Abstract. This study analyzes long-range transport of aerosol and aerosol chemical characteristics based on instances of high- and low-aerosol-loading events determined via ground-based size-resolved aerosol measurements collected at the Manila Observatory in Metro Manila, Philippines, from July to October 2018. Multiple data sources, including models, remote sensing, and in situ measurements, are used to analyze the impacts of long-range aerosol transport on Metro Manila and the conditions at the local and synoptic scales facilitating this transport. Through the use of case studies, evidence of long-range transport of biomass burning aerosol and continental emissions is identified in Metro Manila. Long-range transport of biomass burning aerosol from the Maritime Continent, bolstered by southwesterly flow and permitted by low rainfall, was identified through model results and the presence of biomass burning tracers (e.g., K, Rb) in the ground-based measurements. The impacts of emissions transported from continental East Asia on the aerosol characteristics in Metro Manila are also identified; for one of the events analyzed, this transport was facilitated by the nearby passage of a typhoon. Changes in the aerosol size distributions, water-soluble chemical composition, and contributions of various organic aerosol species to the total water-soluble organic aerosol were examined for the different cases. The events impacted by biomass burning transport had the overall highest concentration of water-soluble organic acids, while the events impacted by long-range transport from continental East Asia showed high percent contributions from shorter-chain dicarboxylic acids (i.e., oxalate) that are often representative of photochemical and aqueous processing in the atmosphere. The low-aerosol-loading event was subject to a larger precipitation accumulation than the high-aerosol events, indicative of wet scavenging as an aerosol sink in the study region. This low-aerosol event was characterized by a larger relative contribution from supermicrometer aerosols and had a higher percent contribution from longer-chain dicarboxylic acids (i.e., maleate) to the water-soluble organic aerosol fraction, indicating the importance of both primary aerosol emissions and local emissions.

scholarly journals Characteristics and Seasonal Variations of Atmospheric Deposition of Selected Elements in the Urban and Industrial Environment of Košice (Slovakia)

2021 ◽  
Vol 906 (1) ◽  
pp. 012100
Author(s):  
Jozef Hančul’ák ◽  
Ol’ga Šestinová ◽  
Lenka Findoráková
Keyword(s):  
Atmospheric Deposition ◽  
Detailed Analysis ◽  
Pearson Correlation ◽  
Correlation Coefficients ◽  
Water Soluble ◽  
Dust Particles ◽  
Winter Period ◽  
Emission Sources ◽  
Summer Period ◽  
The Impact

Abstract This study aims to evaluate the impact of local emission sources on the environmental load through a detailed analysis of the atmospheric deposition (AD). The main sources of pollution are neighbouring iron and steelworks and typical urban sources, such as the heating plant, transport, construction, etc. Total atmospheric deposition, i.e. both wet and dry ones, were sampled from eleven sampling sites that have been placed on the roofs above the height of the surrounding buildings at a distance of 1 to 16 kilometers from the main source of pollution in the urban, suburban and rural areas. The atmospheric deposition fluxes of selected elements (Fe, Al, Mn, Zn, Pb, Cu, Cr, Cd, As) were determined separately for “water-soluble” and “insoluble phase” (particulate matter - PM) as well as in terms of the heating season for summer and winter half-year. The results from 2009–2020 are introduced. The average Fe deposition at urban stations in Košice was 2-3 times higher, compared with other urban areas. The very high values of iron deposition (9,181) and manganese (348 mg.m-2.yr-1) were measured mainly at sites near the ironworks. The highest values of correlation coefficients were calculated by Pearson correlation analysis for the elements Fe, Mn and Cr but also for Al and PM. Higher values of correlation coefficients were calculated for the winter period. The monitored elements are bound to the insoluble component AD in the order of Fe, Al, Cr, Pb, Mn and As. Cadmium and zinc are preferably bound to the soluble phase for sites north of the ironworks. Significant differences for fluxes of AD of the most observed parameters were found between the summer and winter periods. In winter, higher values of AD were found for the elements Fe, Pb, Mn, Cr, and Cd. In the case of zinc and arsenic higher values were recorded in the summer period. The share of emission sources of iron and steelworks on the fluxes of iron at the urban sites in winter was more than doubled compared to the summer period. The smallest seasonal differences for all observed components were found at localities near the ironworks. Detailed analysis of AD showed that in addition to Fe, Mn, and Cr, the ironworks complex is also a source of dust particles, aluminum and other observed elements in descending order of lead, zinc, copper, arsenic and cadmium.

scholarly journals Long-Range Transport Mechanisms in East and Southeast Asia and Impacts on Size-Resolved Aerosol Composition: Contrasting High and Low Aerosol Loading Events

2019 ◽  
Author(s):  
Rachel A. Braun ◽  
Mojtaba Azadi Aghdam ◽  
Paola Angela Bañaga ◽  
Grace Betito ◽  
Maria Obiminda Cambaliza ◽  
...  
Keyword(s):  
Long Range ◽  
Biomass Burning ◽  
Dicarboxylic Acids ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Long Range Transport ◽  
Aerosol Loading ◽  
Range Transport ◽  
Metro Manila ◽  
East And Southeast Asia

Abstract. This study analyzes mechanisms of long-range transport of aerosol and aerosol chemical characteristics in and around East and Southeast Asia. Ground-based size-resolved aerosol measurements collected at the Manila Observatory in Metro Manila, Philippines from July–October 2018 were used to identify and contrast high and low aerosol loading events. Multiple data sources, including models, remote-sensing, and in situ measurements, are used to analyze the impacts of long-range aerosol transport on Metro Manila and the conditions at the local and synoptic scales facilitating this transport. Evidence of long-range transport of biomass burning aerosol from the Maritime Continent was identified through model results and the presence of biomass burning tracers (e.g. K, Rb) in the ground-based measurements. The impacts of emissions transported from continental East Asia are also identified; for one of the events analyzed, this transport was facilitated by the nearby passage of a typhoon. Changes in the aerosol size distributions, water-soluble chemical composition, and contributions of various organic aerosol species to the total water-soluble organic aerosol were examined for the different cases. The events impacted by biomass burning transport had the overall highest concentration of water-soluble organic acids, while the events impacted by long-range transport from continental East Asia, showed high percent contributions from shorter chain dicarboxylic acids (i.e. oxalate) that are often representative of photochemical and aqueous processing in the atmosphere. The low aerosol loading event was subject to a larger precipitation accumulation than the high aerosol events, indicative of wet scavenging as an aerosol sink in the study region. This low aerosol event was characterized by a larger relative contribution from supermicrometer aerosols and had a higher percent contribution from longer-chain dicarboxylic acids (i.e. maleate) to the water-soluble organic aerosol fraction. Results of this study have implications for better understanding of the transport and chemical characteristics of aerosol in a highly-populated region that has thus far been difficult to measure through remote-sensing methods. Furthermore, findings associated with the effects of air mass mixing on aerosol physiochemical properties are applicable to other global regions impacted by both natural and anthropogenic sources.

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