scholarly journals Aircraft measurements of polar organic tracer compounds in tropospheric particles (PM<sub>10</sub>) over central China

2014 ◽  
Vol 14 (8) ◽  
pp. 4185-4199 ◽  
Author(s):  
P. Q. Fu ◽  
K. Kawamura ◽  
Y. F. Cheng ◽  
S. Hatakeyama ◽  
A. Takami ◽  
...  
Keyword(s):  
Organic Nitrogen ◽  
Ground Surface ◽  
Organic Aerosol ◽  
Central China ◽  
Gas Chromatography Mass Spectrometry ◽  
Strong Positive Correlation ◽  
Aircraft Measurements ◽  
Nitrogen Species ◽  
West China ◽  
Biological Aerosols

Abstract. Atmospheric aerosol samples were collected by aircraft at low to middle altitudes (0.8–3.5 km a.g.l.) over central East to West China during summer 2003 and spring 2004. The samples were analyzed for polar organic compounds using a technique of solvent extraction/BSTFA derivatization/gas chromatography–mass spectrometry. Biogenic secondary organic aerosol (SOA) tracers from the oxidation of isoprene were found to be more abundant in summer (3.3–138 ng m−3, mean 39 ng m−3) than in spring (3.2–42 ng m−3, 15 ng m−3), while α/β-pinene and β-caryophyllene SOA tracers showed similar abundances between these two seasons. A strong positive correlation (R2 = 0.83) between levoglucosan and β-caryophyllinic acid was found in the spring samples vs. a weak correlation (R2 = 0.17) in the summer samples, implying substantial contributions from biomass burning to the β-caryophyllinic acid production in spring. Two organic nitrogen species (oxamic acid and carbamide) were detected in the aircraft aerosol samples, and their concentrations were comparable to those of biogenic SOA tracers. Most of the primary organic aerosol (POA) and SOA tracers were less abundant at higher altitudes, suggesting they are of ground surface origin, either being directly emitted from anthropogenic/natural sources on the ground surface, or rapidly formed through photooxidation of their precursors emitted from the ground surface and then diluted during uplifting into the troposphere. This study demonstrates that primary biological aerosols, biogenic SOA, and organic nitrogen species are important components of organic aerosols in the troposphere over central China during warm seasons.

scholarly journals Aircraft measurements of polar organic tracer compounds in tropospheric particles (PM<sub>10</sub>) over Central China

2013 ◽  
Vol 13 (9) ◽  
pp. 24481-24516
Author(s):  
P. Q. Fu ◽  
K. Kawamura ◽  
Y. F. Cheng ◽  
S. Hatakeyama ◽  
A. Takami ◽  
...  
Keyword(s):  
Organic Nitrogen ◽  
Ground Surface ◽  
Organic Aerosol ◽  
Central China ◽  
Gas Chromatography Mass Spectrometry ◽  
Strong Positive Correlation ◽  
Aircraft Measurements ◽  
Nitrogen Species ◽  
West China ◽  
Biological Aerosols

Abstract. Atmospheric aerosol samples were collected by aircraft at low to middle altitudes (0.8–3.5 km a.g.l.) over Central East to West China during summer 2003 and spring 2004. The samples were analyzed for polar organic compounds using a technique of solvent extraction/BSTFA derivatization/gas chromatography-mass spectrometry. Biogenic secondary organic aerosol (SOA) tracers from the oxidation of isoprene were found to be more abundant in summer (3.3–138 ng m−3, mean 39 ng m−3) than in spring (3.2–42 ng m−3, 15 ng m−3), while α/β-pinene and β-caryophyllene SOA tracers showed similar abundance between these two seasons. A strong positive correlation (R2=0.83) between levoglucosan and β-caryophyllinic acid was found in the spring samples versus a weak correlation (R2=0.17) in the summer samples, implying substantial contributions from biomass burning to the β-caryophyllinic acid production in spring. Two organic nitrogen species (oxamic acid and carbamide) were detected in the aircraft aerosol samples and their concentrations were comparable to those of biogenic SOA tracers. Most of the POA and SOA tracers were less abundant at higher altitudes, suggesting they are of ground surface origin, either being directly emitted from anthropogenic/natural sources on the ground surface, or rapidly formed through photooxidation of their precursors emitted from the ground surface and then diluted during uplifting into the troposphere. This study demonstrates that primary biological aerosols, biogenic SOA, and organic nitrogen species are important components of organic aerosols in the troposphere over Central China.

scholarly journals Tracer-based source apportioning of atmospheric organic carbon and the influence of anthropogenic emissions on secondary organic aerosol formation in Hong Kong

2021 ◽  
Vol 21 (13) ◽  
pp. 10589-10608
Author(s):  
Yubo Cheng ◽  
Yiqiu Ma ◽  
Di Hu
Keyword(s):  
Hong Kong ◽  
Organic Carbon ◽  
Secondary Organic Aerosol ◽  
Large Fraction ◽  
Linear Regression Analysis ◽  
Temporal Trends ◽  
Organic Aerosol ◽  
Gas Chromatography Mass Spectrometry ◽  
Multivariate Linear Regression Analysis ◽  
Aerosol Formation

Abstract. Here we conducted comprehensive chemical characterization and source apportionment of 49 PM2.5 samples collected in Hong Kong. Besides the major aerosol constituents, 39 polar organic species, including 14 secondary organic aerosol (SOA) tracers of isoprene, monoterpenes, β-caryophyllene, and naphthalene, were quantified using gas chromatography–mass spectrometry (GC–MS). Six factors, i.e., SOA, secondary sulfate (SS), biomass burning (BB)/SOA, sea salt, marine vessels, and vehicle emissions, were apportioned by positive matrix factorization (PMF) as the major sources of ambient organic carbon (OC) in Hong Kong. The secondary formation, including OC from SOA, SS, and aging of BB plume, was the leading contributor to OC (51.4 %, 2.15 ± 1.37 µg C m−3) throughout the year. We then applied a tracer-based method (TBM) to estimate the SOA formation from the photo-oxidation of four selected precursors, and monoterpene SOA was the most abundant. A Kintecus kinetic model was used to examine the formation channels of isoprene SOA, and the aerosol-phase ring-opening reaction of isoprene epoxydiols (IEPOXs) was found to be the dominant formation pathway. Consistently, IEPOX tracers contributed 94 % to total GC–MS-quantified isoprene SOA tracers. The TBM-estimated secondary organic carbon (SOCTBM) and PMF-apportioned SOC (SOCPMF) showed similar temporal trends; however, SOCTBM only accounted for 26.5 % of SOCPMF, indicating a large fraction of ambient SOA was from other reaction pathways or precursors. Results of Pearson's R and multivariate linear regression analysis showed that NOx processing played a key role in both daytime and nighttime SOA production in the region. Moreover, sulfate had a significant positive linear relationship with SOCPMF and SS-related SOC, and particle acidity was significantly correlated with SOC from the aging of BB.

Pre-ozonation in the activated sludge process: fate of nitrogen species

2011 ◽  
Vol 63 (11) ◽  
pp. 2513-2519 ◽  
Author(s):  
J. H. Garcia-Orozco ◽  
A. Vargas-Martinez ◽  
M. A. Ayala-Arnez
Keyword(s):  
Activated Sludge ◽  
Organic Nitrogen ◽  
Oxygen Demand ◽  
Dry Weight ◽  
Nitrification Rate ◽  
Yield Coefficient ◽  
Base System ◽  
Nitrogen Species ◽  
Activated Sludge Reactor ◽  
Fate Of Nitrogen

The objective of this research was to include ozonation prior to an activated sludge treatment and investigate the effect on the nitrogen species, their fate and the consequences of this oxidation upon the biomass. Three parallel treatment systems were used: the base system, where feed went directly to the activated sludge reactor, and two others, where the influent was ozonated at two different dosages, 15 and 25 mg/L of influent, prior to the biological reactors. The results from the ozonation chamber show a high oxidation capacity of the entering ammonia and organic nitrogen, proportional to the ozone dose. The oxidation product was nitrate. No de-nitrification was expected because a high oxygen concentration (4 mg/L) was maintained in the reactors. The reactors receiving ozonated influent showed a lower assimilation of nitrogen by the biomass. The sludge nitrogen content resulted in 11, 9.3 and 7.4% dry-weight corresponding to no-ozone, low ozone and high ozone dosages, respectively. In spite of the lower ammonia available in the ozonated flows, the corresponding reactors showed a higher specific nitrification rate. The ozonated system also performed better in terms of chemical oxygen demand (COD) and biochemical oxygen demand (BOD5) removals, besides showing a higher true biomass yield coefficient.

scholarly journals Multi-instrument comparison and compilation of non-methane organic gas emissions from biomass burning and implications for smoke-derived secondary organic aerosol precursors

2017 ◽  
Vol 17 (2) ◽  
pp. 1471-1489 ◽  
Author(s):  
Lindsay E. Hatch ◽  
Robert J. Yokelson ◽  
Chelsea E. Stockwell ◽  
Patrick R. Veres ◽  
Isobel J. Simpson ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Biomass Burning ◽  
Secondary Organic Aerosol ◽  
Carbon Number ◽  
Time Of Flight ◽  
Organic Aerosol ◽  
Emission Factors ◽  
Gas Chromatography Mass Spectrometry ◽  
Flight Mass Spectrometry

Abstract. Multiple trace-gas instruments were deployed during the fourth Fire Lab at Missoula Experiment (FLAME-4), including the first application of proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOFMS) and comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC-TOFMS) for laboratory biomass burning (BB) measurements. Open-path Fourier transform infrared spectroscopy (OP-FTIR) was also deployed, as well as whole-air sampling (WAS) with one-dimensional gas chromatography–mass spectrometry (GC-MS) analysis. This combination of instruments provided an unprecedented level of detection and chemical speciation. The chemical composition and emission factors (EFs) determined by these four analytical techniques were compared for four representative fuels. The results demonstrate that the instruments are highly complementary, with each covering some unique and important ranges of compositional space, thus demonstrating the need for multi-instrument approaches to adequately characterize BB smoke emissions. Emission factors for overlapping compounds generally compared within experimental uncertainty, despite some outliers, including monoterpenes. Data from all measurements were synthesized into a single EF database that includes over 500 non-methane organic gases (NMOGs) to provide a comprehensive picture of speciated, gaseous BB emissions. The identified compounds were assessed as a function of volatility; 6–11 % of the total NMOG EF was associated with intermediate-volatility organic compounds (IVOCs). These atmospherically relevant compounds historically have been unresolved in BB smoke measurements and thus are largely missing from emission inventories. Additionally, the identified compounds were screened for published secondary organic aerosol (SOA) yields. Of the total reactive carbon (defined as EF scaled by the OH rate constant and carbon number of each compound) in the BB emissions, 55–77 % was associated with compounds for which SOA yields are unknown or understudied. The best candidates for future smog chamber experiments were identified based on the relative abundance and ubiquity of the understudied compounds, and they included furfural, 2-methyl furan, 2-furan methanol, and 1,3-cyclopentadiene. Laboratory study of these compounds will facilitate future modeling efforts.

scholarly journals Evidence for renoxification in the tropical marine boundary layer

2017 ◽  
Vol 17 (6) ◽  
pp. 4081-4092 ◽  
Author(s):  
Chris Reed ◽  
Mathew J. Evans ◽  
Leigh R. Crilley ◽  
William J. Bloss ◽  
Tomás Sherwen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Organic Nitrogen ◽  
Marine Boundary Layer ◽  
Model Simulation ◽  
Cape Verde ◽  
Box Model ◽  
Nitrogen Species ◽  
Dominant Source ◽  
Mixing Ratios ◽  
Solar Noon

Abstract. We present 2 years of NOx observations from the Cape Verde Atmospheric Observatory located in the tropical Atlantic boundary layer. We find that NOx mixing ratios peak around solar noon (at 20–30 pptV depending on season), which is counter to box model simulations that show a midday minimum due to OH conversion of NO2 to HNO3. Production of NOx via decomposition of organic nitrogen species and the photolysis of HNO3 appear insufficient to provide the observed noontime maximum. A rapid photolysis of nitrate aerosol to produce HONO and NO2, however, is able to simulate the observed diurnal cycle. This would make it the dominant source of NOx at this remote marine boundary layer site, overturning the previous paradigm according to which the transport of organic nitrogen species, such as PAN, is the dominant source. We show that observed mixing ratios (November–December 2015) of HONO at Cape Verde (∼ 3.5 pptV peak at solar noon) are consistent with this route for NOx production. Reactions between the nitrate radical and halogen hydroxides which have been postulated in the literature appear to improve the box model simulation of NOx. This rapid conversion of aerosol phase nitrate to NOx changes our perspective of the NOx cycling chemistry in the tropical marine boundary layer, suggesting a more chemically complex environment than previously thought.

scholarly journals Molecular markers of biomass burning and primary biological aerosols in urban Beijing: Size distribution and seasonal variation

2019 ◽  
Author(s):  
Shaofeng Xu ◽  
Lujie Ren ◽  
Yunchao Lang ◽  
Shengjie Hou ◽  
Hong Ren ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Atmospheric Aerosols ◽  
Climate Models ◽  
Aerosol Particles ◽  
Fine Fraction ◽  
Gas Chromatography Mass Spectrometry ◽  
Chemical Compositions ◽  
Urban Aerosols ◽  
Biological Aerosols ◽  
Haze Pollution

Abstract. Biomass burning and primary biological aerosol particles account for an important part of urban aerosols. Floods of studies have been conducted on the chemical compositions of fine aerosols (PM2.5) in megacities where the haze pollution is one of the severe environmental issues in China. However, little is known about their size distributions in atmospheric aerosols in the urban boundary layer. Here, size-segregated aerosol samples were collected in Beijing during haze and clear days from April 2017 to January 2018. Three anhydrosugars, six primary saccharides and four sugar alcohols in these samples were identified and quantified by gas chromatography/mass spectrometry (GC/MS). Higher concentrations of a biomass burning tracer, levoglucosan, were detected in autumn and winter than other seasons. Sucrose, glucose, fructose, mannitol and arabitol were more abundant in the bloom and glowing seasons. Particularly high level of trehalose was found in spring, which was largely associated with the Asian dust outflows. Anhydrosugars, xylose, maltose, inositol and erythritol are mainly existed in the fine mode ( 2.1 μm) between the haze and non-haze samples, while a size shift towards large particles and large GMDs in the fine fraction ( 5.8 μm. Our observations demonstrate that the sources, abundance, and chemical composition of urban aerosol particles are strongly size dependant in Beijing, which are important to better understand their environmental and health effects of urban aerosols and should be considered in air quality and climate models.

scholarly journals Multi-instrument comparison and compilation of non-methane organic gas emissions from biomass burning and implications for smoke-derived secondary organic aerosol precursors

2016 ◽  
Author(s):  
Lindsay E. Hatch ◽  
Robert J. Yokelson ◽  
Chelsea E. Stockwell ◽  
Patrick R. Veres ◽  
Isobel J. Simpson ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Biomass Burning ◽  
Secondary Organic Aerosol ◽  
Carbon Number ◽  
Time Of Flight ◽  
Organic Aerosol ◽  
Emission Factors ◽  
Gas Chromatography Mass Spectrometry ◽  
Flight Mass Spectrometry

Abstract. Multiple trace-gas instruments were deployed during the fourth Fire Lab at Missoula Experiment (FLAME-4), including the first application of proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOFMS) and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS) for laboratory biomass burning (BB) measurements. Open-path Fourier-transform infrared spectroscopy (OP-FTIR) was also deployed, as well as whole air sampling (WAS) with one-dimensional gas chromatography-mass spectrometry (GC-MS) analysis. This combination of instruments provided an unprecedented level of detection and chemical speciation. The chemical composition and emission factors (EFs) determined by these four analytical techniques were compared for four representative fuels. The results demonstrate that the instruments are highly complementary, with each covering some unique and important ranges of compositional space, thus demonstrating the need for multi-instrument approaches to adequately characterize BB smoke emissions. Emission factors for overlapping compounds generally compared within experimental uncertainty, despite some outliers, including monoterpenes. Data from all measurements were synthesized into a single EF database that includes over 500 non-methane organic gases (NMOGs) to provide a comprehensive picture of speciated, gaseous BB emissions. The identified compounds were assessed as a function of volatility; 6–11 % of the total NMOG EF was associated with intermediate volatility organic compounds (IVOCs). These atmospherically relevant compounds historically have been unresolved in BB smoke measurements and thus are largely missing from emissions inventories. Additionally, the identified compounds were screened for published secondary organic aerosol (SOA) yields. Of the total reactive carbon (defined as EF scaled by the OH rate constant and carbon number of each compound) in the BB emissions, 55–77 % was associated with compounds for which SOA yields are unknown or understudied. The best candidates for future smog chamber experiments were identified based on the relative abundance and ubiquity of the understudied compounds, and included furfural, 2-methyl furan, 2-furan methanol, and 1,3-cyclopentadiene. Laboratory study of these compounds will facilitate future modeling efforts.

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