scholarly journals Diurnal variations of organic molecular tracers and stable carbon isotopic compositions in atmospheric aerosols over Mt. Tai in North China Plain: an influence of biomass burning

2012 ◽  
Vol 12 (4) ◽  
pp. 9079-9124
Author(s):  
P. Q. Fu ◽  
K. Kawamura ◽  
J. Chen ◽  
J. Li ◽  
Y. L. Sun ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
North China Plain ◽  
North China ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Total Carbon ◽  
Stable Carbon ◽  
Isotopic Compositions ◽  
Carbon Isotopic

Abstract. Organic tracer compounds of tropospheric aerosols, as well as organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and stable carbon isotope ratios (δ13C) of total carbon (TC) have been investigated for aerosol samples collected during early and late periods of Mount Tai eXperiment 2006 (MTX2006) field campaign in North China Plain. Total solvent extracts were investigated by gas chromatography/mass spectrometry. More than 130 organic compounds were detected in the aerosol samples. They were grouped into twelve organic compound classes, including biomass burning tracers, biogenic primary sugars, biogenic secondary organic aerosol (SOA) tracers, and anthropogenic tracers such as phthalates, hopanes and polycyclic aromatic hydrocarbons (PAHs). In early June when the field burning activities of wheat straws in North China Plain were very active, the total identified organics (2090 ± 1170 ng m−3) were double those in late June (926 ± 574 ng m−3). All the compound classes were more abundant in early June than in late June, except phthalate esters, which were higher in late June. Levoglucosan (88–1210 ng m−3, 403 ng m−3) was found as the most abundant single compound in early June, while diisobutyl phthalate was the predominant species in late June. During the biomass-burning period in early June, the diurnal trends of most of the primary and secondary organic aerosol tracers were characterized by the concentration peaks observed at mid-night or in early morning, while in late June most of the organic species peaked in late afternoon. This suggests that smoke plumes from biomass burning can uplift the aerosol particulate matter to a certain altitude and then transported to and encountered the summit of Mt. Tai during nighttime. On the basis of the tracer-based method for the estimation of biomass-burning OC, fungal-spore OC and biogenic secondary organic carbon (SOC), we estimate that an average of 24% (up to 64%) of the OC in the Mt. Tai aerosols was due to biomass burning in early June, followed by the contribution of isoprene SOC (mean 4.3%). In contrast, isoprene SOC was the main contributor (6.6%) to OC, and only 3.0% of the OC was due to biomass burning in late June. In early June, δ13C of TC (−26.6‰ to −23.2‰, mean −25.0‰) were lower than those (−23.9‰ to −21.9‰, mean −22.9‰) in late June. In addition, a strong anti-correlation was found between levoglucosan and δ13C values. This study demonstrates that crop-residue burning activities can significantly enhance the organic aerosol loading and alter the organic molecular compositions and stable carbon isotopic compositions of aerosol particles in the troposphere over North China Plain.

scholarly journals Diurnal variations of organic molecular tracers and stable carbon isotopic composition in atmospheric aerosols over Mt. Tai in the North China Plain: an influence of biomass burning

2012 ◽  
Vol 12 (18) ◽  
pp. 8359-8375 ◽  
Author(s):  
P. Q. Fu ◽  
K. Kawamura ◽  
J. Chen ◽  
J. Li ◽  
Y. L. Sun ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
North China Plain ◽  
North China ◽  
Carbon Isotopic Composition ◽  
Organic Aerosol ◽  
Stable Carbon ◽  
Carbon Isotopic ◽  
The North ◽  
The North China Plain

Abstract. Organic tracer compounds, as well as organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and stable carbon isotope ratios (δ13C) of total carbon (TC) have been investigated in aerosol samples collected during early and late periods of the Mount Tai eXperiment 2006 (MTX2006) field campaign in the North China Plain. Total solvent-extractable fractions were investigated by gas chromatography/mass spectrometry. More than 130 organic compounds were detected in the aerosol samples. They were grouped into twelve organic compound classes, including biomass burning tracers, biogenic primary sugars, biogenic secondary organic aerosol (SOA) tracers, and anthropogenic tracers such as phthalates, hopanes and polycyclic aromatic hydrocarbons (PAHs). In early June when the field burning activities of wheat straws in the North China Plain were very active, the total identified organics (2090 ± 1170 ng m−3) were double those in late June (926 ± 574 ng m−3). All the compound classes were more abundant in early June than in late June, except phthalate esters, which were higher in late June. Levoglucosan (88–1210 ng m−3, mean 403 ng m−3) was found as the most abundant single compound in early June, while diisobutyl phthalate was the predominant species in late June. During the biomass-burning period in early June, the diurnal trends of most of the primary and secondary organic aerosol tracers were characterized by the concentration peaks observed at mid-night or in early morning, while in late June most of the organic species peaked in late afternoon. This suggests that smoke plumes from biomass burning can uplift the aerosol particulate matter to a certain altitude, which could be further transported to and encountered the summit of Mt. Tai during nighttime. On the basis of the tracer-based method for the estimation of biomass-burning OC, fungal-spore OC and biogenic secondary organic carbon (SOC), we estimate that an average of 24% (up to 64%) of the OC in the Mt. Tai aerosols was due to biomass burning in early June, followed by the contribution of isoprene SOC (mean 4.3%). In contrast, isoprene SOC was the main contributor (6.6%) to OC, and only 3.0% of the OC was due to biomass burning in late June. In early June, δ13C of TC (−26.6 to −23.2‰, mean −25.0‰) were lower than those (−23.9 to −21.9‰, mean −22.9‰) in late June. In addition, a strong anti-correlation was found between levoglucosan and δ13C values. This study demonstrates that crop-residue burning activities can significantly enhance the organic aerosol loading and alter the organic composition and stable carbon isotopic composition of aerosol particles in the troposphere over the North China Plain.

scholarly journals Molecular distribution and stable carbon isotopic compositions of dicarboxylic acids and related SOA from biogenic sources in the summertime atmosphere of Mt. Tai in the North China Plain

2018 ◽  
Author(s):  
Jingjing Meng ◽  
Gehui Wang ◽  
Zhanfang Hou ◽  
Xiaodi Liu ◽  
Benjie Wei ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Isotopic Fractionation ◽  
Dicarboxylic Acids ◽  
Photochemical Oxidation ◽  
Photochemical Degradation ◽  
Stable Carbon ◽  
Δ13c Values ◽  
Isotopic Compositions ◽  
Carbon Isotopic

Abstract. Abstract: Molecular distributions and stable carbon isotopic (δ13C values) compositions of dicarboxylic acids and related SOA in PM2.5 aerosols collected on a day/night basis at the summit of Mt. Tai (1534 m  a.s.l.) in the summer of 2016 were analyzed to investigate the sources and photochemical aging process of organic aerosols in the forested highland region of North China Plain. The molecular distributions of dicarboxylic acids and related SOA are characterized by the dominance of oxalic acid (C2), followed by malonic (C3), succinic (C4) and azelaic (C9) acids. The concentration ratios of C2/C4, diacid-C/OC and C2/total diacids are larger in daytime than in nighttime, suggesting that the daytime aerosols are more photochemically aged than those in nighttime due to the higher temperatures and stronger solar radiation. Both ratios of C2/C4 (R2 > 0.5) and C3/C4 (R2 > 0.5) correlated strongly with the ambient temperature, indicating that SOA in the mountaintop atmosphere are mainly derived from the photochemical oxidation of local emissions rather than long-range transport. The mass ratios of C9/C6, C9/Ph, Gly/mGly and the strong linear correlation of major dicarboxylic acids and related SOA with biogenic precursors further suggest that aerosols in this region are mainly originated from biogenic sources (i.e., tree emissions). C2 concentrations correlated well with aerosol pH, indicating that particle acidity favors the organic acid formation. The stable carbon isotopic compositions (δ13C) of the dicarboxylic acids are higher in daytime than in nighttime with the highest value (−16.5 ± 1.9 ‰) found for C2 and the lowest value (−25.2 ± 2.7 ‰) found for C9. An increase in δ13C values of C2 along with increases in C2/Gly and C2/mGly ratios was observed, largely due to the isotopic fractionation during photochemical degradation of the precursors.

scholarly journals Chemical and isotopic composition of secondary organic aerosol generated by <i>α</i>-pinene ozonolysis

2016 ◽  
Author(s):  
Carl Meusinger ◽  
Ulrike Dusek ◽  
Stephanie M. King ◽  
Rupert Holzinger ◽  
Thomas Rosenørn ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Isotopic Composition ◽  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Isotope Effects ◽  
Isotope Analysis ◽  
Carbon Isotopic Composition ◽  
Organic Aerosol ◽  
Total Carbon ◽  
Carbon Isotopic

Abstract. Secondary organic aerosol (SOA) plays a central role in air pollution and climate. However, an exact description of the sources and mechanisms leading to SOA is elusive despite decades of research. Stable isotope analysis may help to constrain atmospheric SOA budgets but the isotope effects associated with the underlying processes have to be determined in order to do so. In this paper, SOA formation from ozonolysis of α-pinene – an important precursor and perhaps the best-known model system used in laboratory studies – was investigated using stable carbon isotope analysis, position-specific isotope analysis (PSIA), and high-resolution chemical analysis based on a thermal-desorption proton-transfer-reaction mass-spectrometer (PTR-MS). SOA was formed in a constant-flow chamber under dark, dry and low-NOx conditions, with OH scavengers in the absence of seed particles. Product SOA was collected on doubly-stacked quartz filters (front and back filters). During analysis, the filters were heated stepwise over the range of 100–400 °C to desorb organic compounds that were (i) detected using PTR-MS for chemical analysis and to determine the O:C ratio, and (ii) converted to CO2 for 13C analysis. In addition, the total carbon isotopic composition of selected samples was measured. For the first time PSIA has been performed for α-pinene. More than 400 ions in the mass range from 39–800 Da were detected and quantified using the PTR-MS. The largest mass fraction desorbed from the filters at 150 °C. The measured O:C ratio of front filter material increased from 0.18 to 0.25 as the desorption temperature was raised from 100 to 250 °C. The rising trend is consistent with the fact that functionalization decreases the volatility of chemical species. At temperatures above 250 °C the O:C ratio of thermally desorbed material, presumably from oligomeric precursors, was constant. The observation of a number of components across the full range of desorption temperatures suggests that they are generated by thermal decomposition of oligomers. SOA on front filters was enriched in 13C by 0.2–2.9 ‰ relative to the initial α-pinene, at all desorption temperatures. The total carbon isotopic composition was similar to the enrichment of the major fraction desorbing at 150 °C. Gas-phase compounds desorbing from the back filters showed much lower concentrations but were depleted in 13C by 0.7 ‰ compared to the initial α-pinene and by 1.9 ‰ compared to the corresponding front filter. PSIA showed that the isotope enrichment at individual carbon positions in α-pinene ranged from −6.9 to +10.5 ‰ relative to the bulk composition. However, there was not a clear mechanistic connection between those values and the observed isotopic enrichment of bulk SOA. Instead, fragmentation reactions favouring the loss of small, isotopically light products to the gas phase are consistent with the observations. In monoterpene ozonolysis, functionalization is known to follow fragmentation, however it is the fragmentation step that seems to govern the isotope budget. The isotope effect associated with oligomerization is small. The suggested isotope effects are important for the interpretation of isotopic compositions of ambient aerosol.

scholarly journals Springtime carbon episodes at Gosan background site revealed by total carbon, stable carbon isotopic composition, and thermal characteristics of carbonaceous particles

2011 ◽  
Vol 11 (5) ◽  
pp. 13867-13910
Author(s):  
J. Jung ◽  
K. Kawamura
Keyword(s):  
Citric Acid ◽  
Organic Carbon ◽  
Isotopic Composition ◽  
Thermal Evolution ◽  
Carbon Isotopic Composition ◽  
Organic Aerosols ◽  
Total Carbon ◽  
Stable Carbon ◽  
Carbon Isotopic ◽  
Airborne Pollens

Abstract. In order to investigate the carbon episodes at Gosan background super-site (33.17° N, 126.10° E) in East Asia during spring of 2007 and 2008, total suspended particles (TSP) were collected and analyzed for particulate organic carbon, elemental carbon, total carbon (TC), total nitrogen (TN), and stable carbon isotopic composition (δ13C) of TC. The carbon episodes at the Gosan site were categorized as long-range transported anthropogenic pollutant (LTP) from Asian continent, Asian dust (AD) accompanying with LTP, and local pollen episodes. The stable carbon isotopic composition of TC (δ13CTC) was found to be lowest during the pollen episodes (range: −26.2 ‰ to −23.5 ‰, avg.: −25.2 ± 0.9 ‰), followed by the LTP episodes (range: −23.5 ‰ to −23.0 ‰, avg.: −23.3 ± 0.3 ‰) and the AD episodes (range: −23.3 to −20.4 %, avg.: −21.8 ± 2.0 ‰). The δ13CTC of the airborne pollens (−28.0 ‰) collected at the Gosan site showed value similar to that of tangerine fruit (−28.1 ‰) produced from Jeju Island. Based on the carbon isotope mass balance equation and the TN and TC regression approach, we found that ∼40–45 % of TC in the TSP samples during the pollen episodes was attributed to airborne pollens from Japanese cedar trees planted around tangerine farms in Jeju Island. The δ13C of citric acid in the airborne pollens (−26.3 ‰) collected at the Gosan site was similar to that in tangerine fruit (−27.4 ‰). The negative correlation between the citric acid-carbon/TC ratios and δ13CTC were obtained during the pollen episodes. These results suggest that citric acid emitted from tangerine fruit may be adsorbed on the airborne pollens and then transported to the Gosan site. Based on the thermal evolution pattern of organic aerosols during the carbon episodes, we found that organic aerosols originated from East China are more volatile on heating and are more likely to form pyrolized organic carbon than the pollen-enriched organic aerosols and organic aerosols originated from Northeast China. Since thermal evolution patterns of organic aerosols are highly influenced by their molecular weight, they can be used as additional information on the formation of secondary organic aerosols during the long-range atmospheric transport and the source regions of organics.

scholarly journals Ubiquitous Influence of Wildfire Emissions and Secondary Organic Aerosol on Summertime Atmospheric Aerosol in the Forested Great Lakes Region

2017 ◽  
Author(s):  
Matthew J. Gunsch ◽  
Nathaniel W. May ◽  
Miao Wen ◽  
Courtney L. H. Bottenus ◽  
Daniel J. Gardner ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Great Lakes ◽  
Long Range ◽  
Mass Spectrometer ◽  
Biomass Burning ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Great Lakes Region ◽  
Aerosol Mass ◽  
Biomass Burning Particles

Abstract. Long-range aerosol transport affects locations hundreds of kilometers from the point of emission, leading to distant particle sources influencing rural environments that have few major local sources. Source apportionment was conducted using real-time aerosol chemistry measurements made in July 2014 at the forested University of Michigan Biological Station near Pellston, Michigan, a site representative of the remote forested Great Lakes region. Size-resolved chemical composition of individual 0.5–2.0 μm particles was measured using an aerosol time-of-flight mass spectrometer (ATOFMS), and non-refractory aerosol mass less than 1 μm (PM1) was measured by a high resolution aerosol mass spectrometer (HR-AMS). The field site was also influenced by air masses transporting Canadian wildfire emissions and urban pollution from Milwaukee and Chicago. During wildfire influenced periods, 0.5–2.0 μm particles were primarily aged biomass burning particles (88 % by number). These particles were heavily coated with secondary organic aerosol (SOA) formed during transport, with organics (average O/C ratio of 0.8) contributing 89 % of the PM1 mass. During urban-influenced periods, organic carbon, elemental carbon/organic carbon, and aged biomass burning particles were identified, with inorganic secondary species (ammonium, sulfate, and nitrate) contributing 41 % of the PM1 mass, indicative of atmospheric processing. With current models under-predicting organic carbon (OC) in this region and biomass burning being the largest combustion contributor to SOA by mass, these results highlight the importance for regional chemical transport models to accurately predict the impact of long-range transported particles on air quality in the upper Midwest United States, particularly considering increasing intensity and frequency of Canadian wildfires.

scholarly journals Molecular distribution and stable carbon isotopic compositions of dicarboxylic acids and related SOA from biogenic sources in the summertime atmosphere of Mt. Tai in the North China Plain

2018 ◽  
Vol 18 (20) ◽  
pp. 15069-15086 ◽  
Author(s):  
Jingjing Meng ◽  
Gehui Wang ◽  
Zhanfang Hou ◽  
Xiaodi Liu ◽  
Benjie Wei ◽  
...  
Keyword(s):  
Azelaic Acid ◽  
North China Plain ◽  
North China ◽  
Organic Aerosols ◽  
Dicarboxylic Acids ◽  
Stable Carbon ◽  
Δ13c Values ◽  
Carbon Isotopic ◽  
The North ◽  
The North China Plain

Abstract. Molecular distributions and stable carbon isotopic (δ13C values) compositions of dicarboxylic acids and related secondary organic aerosols (SOA) in PM2.5 aerosols collected on a day/night basis at the summit of Mt. Tai (1534 m a.s.l.) in the summer of 2016 were analyzed to investigate the sources and photochemical aging process of organic aerosols in the forested highland region of the North China Plain. The molecular distributions of dicarboxylic acids and related SOA are characterized by the dominance of oxalic acid (C2), followed by malonic (C3), succinic (C4) and azelaic (C9) acids. The concentration ratios of C2 ∕ C4, diacid-C ∕ OC and C2 ∕ total diacids are larger in the daytime than in the nighttime, suggesting that the daytime aerosols are more photochemically aged than those in the nighttime due to the higher temperature and stronger solar radiation. Both ratios of C2 ∕ C4 (R2>0.5) and C3 ∕ C4 (R2>0.5) correlated strongly with the ambient temperatures, indicating that SOA in the mountaintop atmosphere are mainly derived from the photochemical oxidation of local emissions rather than long-range transport. The mass ratios of azelaic acid to adipic acid (C9 ∕ C6), azelaic acid to phthalic aid (C9 ∕ Ph) and glyoxal to methylglyoxal (Gly ∕ mGly) and the strong linear correlations of major dicarboxylic acids and related SOA (i.e., C2, C3, C4, ωC2, Pyr, Gly and mGly) with biogenic precursors (SOA tracers derived from isoprene, α/β-pinene and β-caryophyllene) further suggest that aerosols in this region are mainly originated from biogenic sources (i.e., tree emissions). C2 concentrations correlated well with aerosol pH, indicating that particle acidity favors the organic acid formation. The stable carbon isotopic compositions (δ13C) of the dicarboxylic acids are higher in the daytime than in the nighttime, with the highest value (-16.5±1.9 ‰) found for C2 and the lowest value (-25.2±2.7 ‰) found for C9. An increase in δ13C values of C2 along with increases in C2 ∕ Gly and C2 ∕ mGly ratios was observed, largely due to the isotopic fractionation effect during the precursor oxidation process.

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