scholarly journals Total organic carbon and contribution from speciated organics in cloud water: Airborne data analysis from the CAMP<sup>2</sup>Ex field campaign

2021 ◽  
Author(s):  
Connor Stahl ◽  
Ewan Crosbie ◽  
Paola Angela Bañaga ◽  
Grace Betito ◽  
Rachel A. Braun ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Biomass Burning ◽  
Dicarboxylic Acids ◽  
Cloud Water ◽  
Water Soluble ◽  
Monocarboxylic Acids ◽  
Study Region ◽  
Carbon Mass ◽  
Measured Mass

Abstract. This work focuses on total organic carbon (TOC) and contributing species in cloud water over Southeast Asia using a rare airborne dataset collected during NASA’s Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP2Ex), in which a wide variety of maritime clouds were studied, including cumulus congestus, altocumulus, altostratus, and cumulus. Knowledge of TOC levels and their contributing species is needed for improved modeling of cloud processing of organics and to understand how aerosols and gases impact and are impacted by clouds. This work relies on 159 samples collected with an Axial Cyclone Cloud water Collector at altitudes of 0.2–6.8 km that had sufficient volume for both TOC and speciated organic composition analysis. Species included monocarboxylic acids (glycolate, acetate, formate, and pyruvate), dicarboxylic acids (glutarate, adipate, succinate, maleate, and oxalate), methanesulfonate (MSA), and dimethylamine (DMA). TOC values range between 0.018–13.660 ppm C with a mean of 0.902 ppm C. The highest TOC values are observed below 2 km with a general reduction aloft. An exception is samples impacted by biomass burning for which TOC remains enhanced as high as 6.5 km (7.048 ppm C). Estimated total organic matter derived from TOC contributes a mean of 30.7 % to total measured mass (inorganics + organics). Speciated organics contribute (on carbon mass basis) an average of 30.0 % to TOC in the study region, and account for an average of 10.3 % to total measured mass. The order of the average contribution of species to TOC, in decreasing contribution of carbon mass, is as follows: acetate (14.7 ± 20.5 %), formate (5.4 ± 9.3 %), oxalate (2.8 ± 4.3 %), DMA (1.7 ± 6.3 %), succinate (1.6 ± 2.4 %), pyruvate (1.3 ± 4.5 %), glycolate (1.3 ± 3.7 %), adipate (1.0 ± 3.6 %), MSA (0.1 ± 0.1 %), glutarate (0.1 ± 0.2 %), maleate (< 0.1 ± 0.1 %). Approximately 70 % of TOC remains unaccounted for, thus highlighting the complex nature of organics in the study region; samples collected in biomass burning plumes have up to 95.6 % of unaccounted TOC mass based on the species detected. Consistent with other regions, monocarboxylic acids dominate the speciated organic mass (~75 %) and are about four times in greater abundance than dicarboxylic acids. Samples are categorized into four cases based on back-trajectory history revealing source-independent similarity between the bulk contributions of monocarboxylic and dicarboxylic acids to TOC (16.03 %–23.66 % and 3.70 %–8.75 %, respectively). Furthermore, acetate, formate, succinate, glutarate, pyruvate, oxalate, and MSA are especially enhanced during biomass burning periods, attributed to peat emissions transported from Sumatra and Borneo. Lastly, dust (Ca2+) and sea salt (Na+/Cl−) tracers exhibit strong correlations with speciated organics, thus supporting how coarse aerosol surfaces interact with these water-soluble organics.

scholarly journals Total organic carbon and the contribution from speciated organics in cloud water: airborne data analysis from the CAMP<sup>2</sup>Ex field campaign

2021 ◽  
Vol 21 (18) ◽  
pp. 14109-14129
Author(s):  
Connor Stahl ◽  
Ewan Crosbie ◽  
Paola Angela Bañaga ◽  
Grace Betito ◽  
Rachel A. Braun ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Biomass Burning ◽  
Dicarboxylic Acids ◽  
Cloud Water ◽  
Water Soluble ◽  
Monocarboxylic Acids ◽  
Study Region ◽  
Carbon Mass ◽  
Measured Mass

Abstract. This work focuses on total organic carbon (TOC) and contributing species in cloud water over Southeast Asia using a rare airborne dataset collected during NASA's Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP2Ex), in which a wide variety of maritime clouds were studied, including cumulus congestus, altocumulus, altostratus, and cumulus. Knowledge of TOC masses and their contributing species is needed for improved modeling of cloud processing of organics and to understand how aerosols and gases impact and are impacted by clouds. This work relies on 159 samples collected with an axial cyclone cloud-water collector at altitudes of 0.2–6.8 km that had sufficient volume for both TOC and speciated organic composition analysis. Species included monocarboxylic acids (glycolate, acetate, formate, and pyruvate), dicarboxylic acids (glutarate, adipate, succinate, maleate, and oxalate), methanesulfonic acid (MSA), and dimethylamine (DMA). TOC values range between 0.018 and 13.66 ppm C with a mean of 0.902 ppm C. The highest TOC values are observed below 2 km with a general reduction aloft. An exception is samples impacted by biomass burning for which TOC remains enhanced at altitudes as high as 6.5 km (7.048 ppm C). Estimated total organic matter derived from TOC contributes a mean of 30.7 % to total measured mass (inorganics + organics). Speciated organics contribute (on a carbon mass basis) an average of 30.0 % to TOC in the study region and account for an average of 10.3 % to total measured mass. The order of the average contribution of species to TOC, in decreasing contribution of carbon mass, is as follows (±1 standard deviation): acetate (14.7 ± 20.5 %), formate (5.4 ± 9.3 %), oxalate (2.8 ± 4.3 %), DMA (1.7 ± 6.3 %), succinate (1.6 ± 2.4 %), pyruvate (1.3 ± 4.5 %), glycolate (1.3 ± 3.7 %), adipate (1.0 ± 3.6 %), MSA (0.1 ± 0.1 %), glutarate (0.1 ± 0.2 %), and maleate (< 0.1 ± 0.1 %). Approximately 70 % of TOC remains unaccounted for, highlighting the complex nature of organics in the study region; in samples collected in biomass burning plumes, up to 95.6 % of TOC mass is unaccounted for based on the species detected. Consistent with other regions, monocarboxylic acids dominate the speciated organic mass (∼ 75 %) and are about 4 times more abundant than dicarboxylic acids. Samples are categorized into four cases based on back-trajectory history, revealing source-independent similarity between the bulk contributions of monocarboxylic and dicarboxylic acids to TOC (16.03 %–23.66 % and 3.70 %–8.75 %, respectively). Furthermore, acetate, formate, succinate, glutarate, pyruvate, oxalate, and MSA are especially enhanced during biomass burning periods, which is attributed to peat emissions transported from Sumatra and Borneo. Lastly, dust (Ca2+) and sea salt (Na+/Cl-) tracers exhibit strong correlations with speciated organics, supporting how coarse aerosol surfaces interact with these water-soluble organics.

scholarly journals Size distributions of dicarboxylic acids, ketoacids, α-dicarbonyls, sugars, WSOC, OC, EC and inorganic ions in atmospheric particles over Northern Japan: implication for long-range transport of Siberian biomass burning and East Asian polluted aerosols

2010 ◽  
Vol 10 (3) ◽  
pp. 6713-6754 ◽  
Author(s):  
S. Agarwal ◽  
S. G. Aggarwal ◽  
K. Okuzawa ◽  
K. Kawamura
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Fine Particles ◽  
Source Region ◽  
Inorganic Ions ◽  
Dicarboxylic Acids ◽  
Water Soluble ◽  
Anthropogenic Source ◽  
Night Time ◽  
Chemical Tracers

Abstract. To better understand the size-segregated chemical composition of aged organic aerosols in the western Pacific rim, day- and night-time aerosol samples were collected in Sapporo, Japan during summer 2005 using Andersen impactor sampler with 5 size bins: <1.1, 1.1–2.0, 2.0–3.3, 3.3–7.0, >7.0 μm. Samples were analyzed for the molecular compositions of dicarboxylic acids, ketoacids, α-dicarbonyls, and sugars, together with water-soluble organic carbon (WSOC), organic carbon (OC), elemental carbon (EC) and inorganic ions. Based on the analyses of backward trajectory and chemical tracers, we found that during campaign, the air masses were arrived from Siberia (biomass burning source region) on 8–9 August, China (anthropogenic source region) on 9–10 August and from the East China Sea/Sea of Japan (a mixed source receptor region) on 10–11 August. Most of the diacids, ketoacids, dicarbonyls, levoglucosan, WSOC, and inorganic ions, i.e., SO42−, NH42+ and K+ were enriched in fine particles (PM1.1) whereas Ca2+, Mg2+ and Cl− peaked in coarse sizes (>1.1 μm). Interestingly, OC, most sugar compounds and NO4

scholarly journals Quantifying primary and secondary humic-like substances in urban aerosol based on emission source characterization and a source-oriented air quality model

2018 ◽  
Author(s):  
Xinghua Li ◽  
Junzan Han ◽  
Philip K. Hopke ◽  
Jingnan Hu ◽  
Qi Shu ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Coal Combustion ◽  
Power Plants ◽  
Water Soluble ◽  
Aerosol Formation ◽  
Source Characterization ◽  
Air Quality Model ◽  
Coal Burning ◽  
Residential Coal

Abstract. Humic-like substances (HULIS) are a mixture of high molecular weight, water-soluble organic compounds that are widely distributed in atmospheric aerosol. Their sources are rarely studied quantitatively. Biomass burning is generally accepted as a major primary source of ambient humic-like substances (HULIS) with additional secondary material formed in the atmosphere. However, the present study provides direct evidence that residential coal burning is also a significant source of ambient HULIS, especially in the heating season in northern China based on source measurements, ambient sampling and analysis, and apportionment with source-oriented CMAQ modeling. Emissions tests show that residential coal combustion produces 5 to 24 % of the emitted organic carbon (OC) as HULIS carbon (HULISc). Estimation of primary emissions of HULIS in Beijing indicated that residential biofuel and coal burning contribute about 70 % and 25 % of annual primary HULIS, respectively. Vehicle exhaust, industry, and power plants contributions are negligible. Average concentration of ambient HULIS was 7.5 μg/m3 in atmospheric PM2.5 in urban Beijing and HULIS exhibited obvious seasonal variations with the highest concentrations in winter. HULISc account for 7.2 % of PM2.5 mass, 24.5 % of OC, and 59.5 % of water-soluble organic carbon, respectively. HULIS are found to correlate well with K+, Cl−, sulfate, and secondary organic aerosol suggesting its sources include biomass burning, coal combustion and secondary aerosol formation. Source apportionment based on CMAQ modeling shows residential biofuel and coal burning, secondary formation are important annual sources of ambient HULIS, contributing 57.5 %, 12.3 %, and 25.8 %, respectively.

Investigation of atmospheric aerosols over semi-urban and urban areas in Eastern Indo-Gangetic Plain: seasonal variability and source apportionment using PMF

2021 ◽  
Author(s):  
Kanishtha Dubey ◽  
Shubha Verma
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Atmospheric Aerosols ◽  
Urban Areas ◽  
Relative Concentration ◽  
Road Dust ◽  
Water Soluble ◽  
Carbonaceous Aerosols ◽  
Gangetic Plain ◽  
Brick Kilns

&lt;p&gt;The study investigates the chemical composition and source of aerosol origin at a semi-urban (Kharagpur&amp;#8211;Kgp) and urban (Kolkata&amp;#8211;Kol) region during the period February 2015 to January 2016 and September 2010 to August 2011 respectively. Major water-soluble inorganic aerosols (WSII) were determined using Ion chromatography and carbonaceous aerosols (CA) using OC&amp;#8211;EC analyser. A multivariate factor analysis Positive Matrix Factorization (PMF) was used in resolving source of aerosols at the study locations. Seasonal analysis of WSII at Kgp and Kol indicated relative dominance of calcium at both the places followed by sodium, chloride, and magnesium ions. Non-sea salt potassium (nss&amp;#8211;K&lt;sup&gt;+&lt;/sup&gt;), a biomass burning tracer was found higher at Kol than at Kgp. Sum of secondary aerosols sulphate (SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;), nitrate (NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;) and ammonium (NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;) was higher at Kol than Kgp with relative concentration of SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt; being higher than NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; at Kgp which was vice-versa at Kol. Examination of carbonaceous aerosols showed three times higher concentration of organic carbon (OC) than elemental carbon (EC) with monthly mean of OC/EC ratio &gt; 2, indicating likely formation of secondary organic carbon formation. Seasonal influence of biomass burning inferred from nss&amp;#8211;K&lt;sup&gt;+&lt;/sup&gt; (OC/EC) ratio relationship indicated dissimilarity in seasonality of biomass burning at Kgp (Kol). PMF resolved sources for Kgp constituted of secondary aerosol emissions, biomass burning, fugitive dust, marine aerosols, crustal dust and emissions from brick kilns while for Kol factors constituted of burning of waste, resuspended paved road dust, coal combustion, sea spray aerosols, vehicular emissions and biomass burning.&lt;/p&gt;

scholarly journals Fossil vs. non-fossil sources of fine carbonaceous aerosols in four Chinese cities during the extreme winter haze episode of 2013

2015 ◽  
Vol 15 (3) ◽  
pp. 1299-1312 ◽  
Author(s):  
Y.-L. Zhang ◽  
R.-J. Huang ◽  
I. El Haddad ◽  
K.-F. Ho ◽  
J.-J. Cao ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Organic Carbon ◽  
Biomass Burning ◽  
Water Soluble ◽  
Total Carbon ◽  
World Health ◽  
Biomass Combustion ◽  
Carbonaceous Aerosols ◽  
Haze Episode ◽  
Mass Concentrations

Abstract. During winter 2013, extremely high concentrations (i.e., 4–20 times higher than the World Health Organization guideline) of PM2.5 (particulate matter with an aerodynamic diameter < 2.5 μm) mass concentrations (24 h samples) were found in four major cities in China including Xi'an, Beijing, Shanghai and Guangzhou. Statistical analysis of a combined data set from elemental carbon (EC), organic carbon (OC), 14C and biomass-burning marker measurements using Latin hypercube sampling allowed a quantitative source apportionment of carbonaceous aerosols. Based on 14C measurements of EC fractions (six samples each city), we found that fossil emissions from coal combustion and vehicle exhaust dominated EC with a mean contribution of 75 ± 8% across all sites. The remaining 25 ± 8% was exclusively attributed to biomass combustion, consistent with the measurements of biomass-burning markers such as anhydrosugars (levoglucosan and mannosan) and water-soluble potassium (K+). With a combination of the levoglucosan-to-mannosan and levoglucosan-to-K+ ratios, the major source of biomass burning in winter in China is suggested to be combustion of crop residues. The contribution of fossil sources to OC was highest in Beijing (58 ± 5%) and decreased from Shanghai (49 ± 2%) to Xi'an (38 ± 3%) and Guangzhou (35 ± 7%). Generally, a larger fraction of fossil OC was from secondary origins than primary sources for all sites. Non-fossil sources accounted on average for 55 ± 10 and 48 ± 9% of OC and total carbon (TC), respectively, which suggests that non-fossil emissions were very important contributors of urban carbonaceous aerosols in China. The primary biomass-burning emissions accounted for 40 ± 8, 48 ± 18, 53 ± 4 and 65 ± 26% of non-fossil OC for Xi'an, Beijing, Shanghai and Guangzhou, respectively. Other non-fossil sources excluding primary biomass burning were mainly attributed to formation of secondary organic carbon (SOC) from non-fossil precursors such as biomass-burning emissions. For each site, we also compared samples from moderately to heavily polluted days according to particulate matter mass. Despite a significant increase of the absolute mass concentrations of primary emissions from both fossil and non-fossil sources during the heavily polluted events, their relative contribution to TC was even decreased, whereas the portion of SOC was consistently increased at all sites. This observation indicates that SOC was an important fraction in the increment of carbonaceous aerosols during the haze episode in China.

scholarly journals Molecular Composition and Photochemical Evolution of Water Soluble Organic Carbon (WSOC) Extracted from Field Biomass Burning Aerosols using High Resolution Mass Spectrometry

2019 ◽  
Author(s):  
Jing Cai ◽  
Xiangying Zeng ◽  
Guorui Zhi ◽  
Sasho Gligorovski ◽  
Guoying Sheng ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Organic Carbon ◽  
Biomass Burning ◽  
High Resolution Mass Spectrometry ◽  
Water Soluble ◽  
Oxygenated Compounds ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon ◽  
Resolution Mass

Abstract. Photochemistry plays an important role in the evolution of atmospheric water soluble organic carbon (WSOC), which dissolves into clouds, fogs and aerosol liquid water. In this study, we examined the molecular composition and evolution of a WSOC mixture extracted from fresh biomass burning aerosols upon photolysis, using direct infusion electrospray ionization high-resolution mass spectrometry (ESI-HRMS) and liquid chromatography coupled with mass spectrometry (LC/ESI-HRMS). For comparison, two typical phenolic compounds (i.e., phenol and guaiacol) emitted from lignin pyrolysis in combination with hydrogen peroxide (H2O2) as a typical OH radical precursor, were exposed to simulated sunlight irradiation. The photochemistry of both, the phenols (photo-oxidation) and WSOC mixture (direct photolysis) can produce a series of highly oxygenated compounds which in turn increases the degree of oxidation of organic composition and acidity of the bulk solution. In particular, the LC/ESI-HRMS technique revealed significant photochemical evolution on the WSOC composition, e.g., the photodegradation of low oxygenated species and the formation of highly oxygenated products. We also tentatively compared the mass spectra of photolytic time-profile extract with each other for a more comprehensive description of the photolytic evolution. The calculated average oxygen-to-carbon (O / C) ratios of oxygenated compounds in bulk extract increases from 0.38 ± 0.02 to 0.44 ± 0.02 (mean±standard deviation) while the intensity (S / N)-weighted average O / C (O / Cw) increases from 0.45 ± 0.03 to 0.53 ± 0.06 as the time of irradiation extends from 0 to 12 h. These findings indicate that the water soluble organic fraction of fresh combustion-derived aerosols have the potential to form more oxidized organic matter, accounting for the highly oxygenated nature of atmospheric organic aerosols.

scholarly journals An optimized tracer-based approach for estimating organic carbon emissions from biomass burning in Ulaanbaatar, Mongolia

2020 ◽  
Vol 20 (5) ◽  
pp. 3231-3247 ◽  
Author(s):  
Jayant Nirmalkar ◽  
Tsatsral Batmunkh ◽  
Jinsang Jung
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Quantitative Estimation ◽  
Water Soluble ◽  
Atmospheric Particulate Matter ◽  
Coefficient Of Determination ◽  
Urban Site ◽  
Air Sampler ◽  
Novel Approach ◽  
The Impact

Abstract. The impact of biomass burning (BB) on atmospheric particulate matter of <2.5 µm diameter (PM2.5) at Ulaanbaatar, Mongolia, was investigated using an optimized tracer-based approach during winter and spring 2017. Integrated 24 h PM2.5 samples were collected on quartz-fiber filters using a 30 L min−1 air sampler at an urban site in Ulaanbaatar. The aerosol samples were analyzed for organic carbon (OC) and elemental carbon (EC), anhydrosugars (levoglucosan, mannosan, and galactosan), and water-soluble ions. OC was found to be the predominant species, contributing 64 % and 56 % to the quantified aerosol components in PM2.5 in winter and spring, respectively. BB was identified as a major source of PM2.5, followed by dust and secondary aerosols. Levoglucosan ∕ mannosan and levoglucosan ∕ K+ ratios indicate that BB in Ulaanbaatar mainly originated from the burning of softwood. Because of the large uncertainty associated with the quantitative estimation of OC emitted from BB (OCBB), a novel approach was developed to optimize the OC ∕ levoglucosan ratio for estimating OCBB. The optimum OC ∕ levoglucosan ratio in Ulaanbaatar was obtained by regression analysis between OCnon-BB (OCtotal–OCBB) and levoglucosan concentrations that gives the lowest coefficient of determination (R2) and slope. The optimum OC ∕ levoglucosan ratio was found to be 27.6 and 18.0 for winter and spring, respectively, and these values were applied in quantifying OCBB. It was found that 68 % and 63 % of the OC were emitted from BB during winter and spring, respectively. This novel approach can also be applied by other researchers to quantify OCBB using their own chemical measurements. In addition to OCBB, sources of OCnon-BB were also investigated through multivariate correlation analysis. It was found that OCnon-BB originated mainly from coal burning, vehicles, and vegetative emissions.

scholarly journals Contribution of dissolved organic matter to submicron water-soluble organic aerosols in the marine boundary layer over the eastern equatorial Pacific

2016 ◽  
Author(s):  
Yuzo Miyazaki ◽  
Sean Coburn ◽  
Kaori Ono ◽  
David T. Ho ◽  
R. Bradley Pierce ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Organic Carbon ◽  
Marine Boundary Layer ◽  
Organic Aerosols ◽  
Equatorial Pacific ◽  
Water Soluble ◽  
Total Carbon ◽  
Stable Carbon ◽  
Study Region ◽  
Eastern Equatorial Pacific

Abstract. Stable carbon isotopic compositions of water-soluble organic carbon (WSOC) and organic molecular markers were measured to investigate the relative contributions of the sea-surface sources to the water-soluble fraction of submicron organic aerosols collected over the eastern equatorial Pacific during the Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated VOCs (TORERO)/KA-12-01 cruise. On average, the water-soluble organic fraction of the total carbon (TC) mass in submicron aerosols was ~ 30–35 % in the open oceans, whereas it was ~ 60 % in the coastal oceans. The average stable carbon isotope ratio of WSOC (δ13CWSOC) was −19.8 ± 2.0 ‰, which was systematically higher than that of TC (δ13CTC) (−21.8 ± 1.4 ‰). We found that in both coastal and open oceans, the δ13CWSOC was close to the typical values of δ13C for dissolved organic carbon (DOC), ranging from −22 ‰ to −20 ‰ in surface seawater of tropical Pacific oceans. This suggests an enrichment of marine biological products in WSOC aerosols in the study region regardless of the oceanic area. In particular, enhanced levels of WSOC and biogenic organic marker compounds together with high values of WSOC/TC (~ 60 %) and δ13CWSOC were observed over upwelling areas and phytoplankton blooms, which was attributed to planktonic tissues being more enriched in δ13C. The δ13C analysis estimated that on average, marine sources contribute ~ 90 ± 25 % of the aerosol carbon, indicating the predominance of marine-derived carbon in the submicron WSOC. This conclusion is supported by Lagrangian trajectory analysis, which suggests that the majority of the sampling points on the ship had been exposed to marine boundary layer air for more than 80 % of the time during the previous 7 days. The combined analysis of the δ13C and monosaccharides, such as glucose and fructose, indicated that DOC concentration was the major factor controlling the concentration levels of the submicron WSOC regardless of the oceanic areas over the study region.

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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