The importance of size ranges in aerosol instrument intercomparisons: a case study for the Atmospheric Tomography Mission

Abstract. Aerosol intercomparisons are inherently complex as they convolve instrument-dependent detection efficiencies vs. size (which often change with pressure, temperature, or humidity) and variations in the sampled aerosol population, in addition to differences in chemical detection principles (e.g., inorganic-only nitrate vs. inorganic plus organic nitrate for two instruments). The NASA Atmospheric Tomography Mission (ATom) spanned four separate aircraft deployments which sampled the remote marine troposphere from 86∘ S to 82∘ N over different seasons with a wide range of aerosol concentrations and compositions. Aerosols were quantified with a set of carefully characterized and calibrated instruments, some based on particle sizing and some on composition measurements. This study aims to provide a critical evaluation of inlet transmissions impacting aerosol intercomparisons, and of aerosol quantification during ATom, with a focus on the aerosol mass spectrometer (AMS). The volume determined from physical sizing instruments (aerosol microphysical properties, AMP, 2.7 nm to 4.8 µm optical diameter) is compared in detail with that derived from the chemical measurements of the AMS and the single particle soot photometer (SP2). Special attention was paid to characterize the upper end of the AMS size-dependent transmission with in-field calibrations, which we show to be critical for accurate comparisons across instruments with inevitably different size cuts. Observed differences between campaigns emphasize the importance of characterizing AMS transmission for each instrument and field study for meaningful interpretation of instrument comparisons. Good agreement (regression slope =0.949 and 1.083 for ATom-1 and ATom-2, respectively; SD =0.003) was found between the composition-based volume (including AMS-quantified sea salt) and that derived from AMP after applying the AMS inlet transmission. The AMS captured, on average, 95±15 % of the standard PM1 volume (referred to as the URG Corp. standard cut 1 µm cyclone operated at its nominal efficiency). These results support the absence of significant unknown biases and the appropriateness of the accuracy estimates for AMS total mass and volume for the mostly aged air masses encountered in ATom. The particle size ranges (and their altitude dependence) that are sampled by the AMS and complementary composition instruments (such as soluble acidic gases and aerosol, SAGA, and particle analysis by laser mass spectrometry, PALMS) are investigated to inform their use in future studies.

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The Importance of Size Ranges in Aerosol Instrument Intercomparisons: A Case Study for the ATom Mission

10.5194/amt-2020-224 ◽

2020 ◽

Cited By ~ 2

Author(s):

Hongyu Guo ◽

Pedro Campuzano-Jost ◽

Benjamin A. Nault ◽

Douglas A. Day ◽

Jason C. Schroder ◽

...

Keyword(s):

Critical Evaluation ◽

Organic Nitrate ◽

Related Factors ◽

Precision Error ◽

Aerosol Mass Spectrometer ◽

Air Masses ◽

Aerosol Mass ◽

Chemical Measurements ◽

Wide Range ◽

Different Seasons

Abstract. Aerosol intercomparisons are inherently complex, as they convolve instrument-dependent detection efficiencies vs. size (which often change with pressure, temperature, or humidity) and variations on the sampled aerosol population, in addition to differences in chemical detection principles (e.g., including inorganic-only nitrate vs. inorganic plus organic nitrate for two instruments). The NASA Atmospheric Tomography Mission (ATom) spanned four separate aircraft deployments, which sampled the remote marine troposphere from 86° S to 82° N over different seasons with a wide range of aerosol concentrations and compositions. Aerosols were quantified with a set of carefully characterized and calibrated instruments, some based on particle sizing and some on composition measurements. This study aims to provide a critical evaluation of the size-related factors impacting aerosol intercomparisons, and of aerosol quantification during ATom, with a focus on the Aerosol Mass Spectrometer (AMS). The volume determined from physical sizing instruments is compared in detail with that derived from the chemical measurements of the AMS and the Single Particle Soot Photometer (SP2). Special attention was paid to characterize the upper end of the AMS size-dependent transmission with in-field calibrations, which we show to be critical for accurate comparisons across instruments with inevitably different size cuts. Observed differences between campaigns emphasize the importance of characterizing AMS transmission for each instrument and field study for meaningful interpretation of instrument comparisons. Good agreement was found between the composition-based volume (including AMS-quantified sea salt) and that derived from the size spectrometers. The very clean conditions during most of ATom resulted in substantial statistical noise (i.e., precision error), which we show to be substantially reduced by averaging at several-minute time intervals. The AMS captured, on average, 95 ± 15 % of the standard PM1 volume. These results support the absence of significant unknown biases and the appropriateness of the accuracy estimates for AMS total mass/volume for the mostly aged air masses encountered in ATom. The particle size ranges that contribute chemical composition information to the AMS and complementary composition instruments are investigated, to inform their use in future studies.

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Secondary organic aerosol formation from the β-pinene+NO<sub>3</sub> system: effect of humidity and peroxy radical fate

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-7497-2015 ◽

2015 ◽

Vol 15 (13) ◽

pp. 7497-7522 ◽

Cited By ~ 105

Author(s):

C. M. Boyd ◽

J. Sanchez ◽

L. Xu ◽

A. J. Eugene ◽

T. Nah ◽

...

Keyword(s):

Secondary Organic Aerosol ◽

Peroxy Radical ◽

Organic Aerosol ◽

Formation Mechanisms ◽

Organic Nitrate ◽

Organic Nitrates ◽

Aerosol Formation ◽

System Effect ◽

Aerosol Mass ◽

Wide Range

Abstract. The formation of secondary organic aerosol (SOA) from the oxidation of β-pinene via nitrate radicals is investigated in the Georgia Tech Environmental Chamber (GTEC) facility. Aerosol yields are determined for experiments performed under both dry (relative humidity (RH) < 2 %) and humid (RH = 50 % and RH = 70 %) conditions. To probe the effects of peroxy radical (RO2) fate on aerosol formation, "RO2 + NO3 dominant" and "RO2 + HO2 dominant" experiments are performed. Gas-phase organic nitrate species (with molecular weights of 215, 229, 231, and 245 amu, which likely correspond to molecular formulas of C10H17NO4, C10H15NO5, C10H17NO5, and C10H15NO6, respectively) are detected by chemical ionization mass spectrometry (CIMS) and their formation mechanisms are proposed. The NO+ (at m/z 30) and NO2+ (at m/z 46) ions contribute about 11 % to the combined organics and nitrate signals in the typical aerosol mass spectrum, with the NO+ : NO2+ ratio ranging from 4.8 to 10.2 in all experiments conducted. The SOA yields in the "RO2 + NO3 dominant" and "RO2 + HO2 dominant" experiments are comparable. For a wide range of organic mass loadings (5.1–216.1 μg m−3), the aerosol mass yield is calculated to be 27.0–104.1 %. Although humidity does not appear to affect SOA yields, there is evidence of particle-phase hydrolysis of organic nitrates, which are estimated to compose 45–74 % of the organic aerosol. The extent of organic nitrate hydrolysis is significantly lower than that observed in previous studies on photooxidation of volatile organic compounds in the presence of NOx. It is estimated that about 90 and 10 % of the organic nitrates formed from the β-pinene+NO3 reaction are primary organic nitrates and tertiary organic nitrates, respectively. While the primary organic nitrates do not appear to hydrolyze, the tertiary organic nitrates undergo hydrolysis with a lifetime of 3–4.5 h. Results from this laboratory chamber study provide the fundamental data to evaluate the contributions of monoterpene + NO3 reaction to ambient organic aerosol measured in the southeastern United States, including the Southern Oxidant and Aerosol Study (SOAS) and the Southeastern Center for Air Pollution and Epidemiology (SCAPE) study.

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Secondary Organic Aerosol (SOA) formation from the β-pinene + NO<sub>3</sub> system: effect of humidity and peroxy radical fate

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-2679-2015 ◽

2015 ◽

Vol 15 (2) ◽

pp. 2679-2744 ◽

Cited By ~ 6

Author(s):

C. M. Boyd ◽

J. Sanchez ◽

L. Xu ◽

A. J. Eugene ◽

T. Nah ◽

...

Keyword(s):

Secondary Organic Aerosol ◽

Peroxy Radical ◽

Organic Aerosol ◽

Formation Mechanisms ◽

Organic Nitrate ◽

Organic Nitrates ◽

Aerosol Formation ◽

System Effect ◽

Aerosol Mass ◽

Wide Range

Abstract. The formation of secondary organic aerosol (SOA) from the oxidation of β-pinene via nitrate radicals is investigated in the Georgia Tech Environmental Chamber facility (GTEC). Aerosol yields are determined for experiments performed under both dry (RH < 2%) and humid (RH = 50% and RH = 70%) conditions. To probe the effects of peroxy radical (RO2) fate on aerosol formation, "RO2 + NO3 dominant" and "RO2 + HO2 dominant" experiments are performed. Gas-phase organic nitrate species (with molecular weights of 215, 229, 231 and 245 amu) are detected by chemical ionization mass spectrometry and their formation mechanisms are proposed. The ions at m/z 30 (NO+) and m/z 46 (NO2+) contribute about 11% to the total organics signal in the typical aerosol mass spectrum, with NO+ : NO2+ ratio ranging from 6 to 9 in all experiments conducted. The SOA yields in the "RO2 + NO3 dominant" and "RO2 + HO2 dominant" experiments are comparable. For a wide range of organic mass loadings (5.1–216.1 μg m−3), the aerosol mass yield is calculated to be 27.0–104.1%. Although humidity does not appear to affect SOA yields, there is evidence of particle-phase hydrolysis of organic nitrates, which are estimated to compose 45–74% of the organic aerosol. The extent of organic nitrate hydrolysis is significantly lower than that observed in previous studies on photooxidation of volatile organic compounds in the presence of NOx. It is estimated that about 90 and 10% of the organic nitrates formed from the β-pinene + NO3 reaction are primary organic nitrates and tertiary organic nitrates, respectively. While the primary organic nitrates do not appear to hydrolyze, the tertiary organic nitrates undergo hydrolysis with a lifetime of 3–4.5 h. Results from this laboratory chamber study provide the fundamental data to evaluate the contributions of monoterpene + NO3 reaction to ambient organic aerosol measured in the southeastern United States, including the Southern Oxidant and Aerosol Study (SOAS) and the Southeastern Center for Air Pollution and Epidemiology (SCAPE) study.

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A Color Coded STEM/SEM Image Storage System

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100097880 ◽

1981 ◽

Vol 39 ◽

pp. 272-273

Author(s):

Y. Kokubo ◽

W. H. Hardy ◽

J. Dance ◽

K. Jones

Keyword(s):

Image Processing ◽

Electron Beam ◽

Storage System ◽

Particle Analysis ◽

Specific Information ◽

X Rays ◽

Sem Image ◽

Backscattered Electrons ◽

Wide Range ◽

Scanning Electron

A color coded digital image processing is accomplished by using JEM100CX TEM SCAN and ORTEC’s LSI-11 computer based multi-channel analyzer (EEDS-II-System III) for image analysis and display. Color coding of the recorded image enables enhanced visualization of the image using mathematical techniques such as compression, gray scale expansion, gamma-processing, filtering, etc., without subjecting the sample to further electron beam irradiation once images have been stored in the memory.The powerful combination between a scanning electron microscope and computer is starting to be widely used 1) - 4) for the purpose of image processing and particle analysis. Especially, in scanning electron microscopy it is possible to get all information resulting from the interactions between the electron beam and specimen materials, by using different detectors for signals such as secondary electron, backscattered electrons, elastic scattered electrons, inelastic scattered electrons, un-scattered electrons, X-rays, etc., each of which contains specific information arising from their physical origin, study of a wide range of effects becomes possible.

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Particulate organic nitrates observed in an oil and natural gas production region during wintertime

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-9313-2015 ◽

2015 ◽

Vol 15 (16) ◽

pp. 9313-9325 ◽

Cited By ~ 7

Author(s):

L. Lee ◽

P. J. Wooldridge ◽

J. deGouw ◽

S. S. Brown ◽

T. S. Bates ◽

...

Keyword(s):

Field Measurements ◽

Atomic Ratio ◽

Gas Production ◽

Heterogeneous Reactions ◽

Organic Nitrate ◽

Organic Nitrates ◽

Production Region ◽

Aerosol Mass ◽

Oil And Natural Gas ◽

Aerosol Volume

Abstract. Organic nitrates in both gas and condensed (aerosol) phases were measured during the Uintah Basin Winter Ozone Study from January to February in 2012. A high degree of correlation between total aerosol volume at diameters less than 500 nm and the particulate organic nitrate concentration indicates that organic nitrates are a consistent, if not dominant, fraction of fine aerosol mass. In contrast, a similar correlation with sub-2.5 μm aerosol volume is weaker. The C : N atomic ratio inferred from field measurements of PM2.5 and particulate organic nitrate is 34 : 1. Calculations constrained by the observations indicate that both condensation of gas-phase nitrates and heterogeneous reactions of NO3 / N2O5 are responsible for introducing organic nitrate functionality into the aerosol and that the source molecules are alkanes. Extrapolating the results to urban aerosol suggests organic nitrate production from alkanes may be a major secondary organic aerosol source.

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Organic aerosol components observed in Northern Hemispheric datasets from Aerosol Mass Spectrometry

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-4625-2010 ◽

2010 ◽

Vol 10 (10) ◽

pp. 4625-4641 ◽

Cited By ~ 677

Author(s):

N. L. Ng ◽

M. R. Canagaratna ◽

Q. Zhang ◽

J. L. Jimenez ◽

J. Tian ◽

...

Keyword(s):

Mass Spectrum ◽

Organic Aerosol ◽

Total Signal ◽

Mass Spectral ◽

Aerosol Mass ◽

Aerosol Mass Spectrometry ◽

Wide Range ◽

Triangular Region ◽

Photochemical Aging ◽

Spectral Diagnostic

Abstract. In this study we compile and present results from the factor analysis of 43 Aerosol Mass Spectrometer (AMS) datasets (27 of the datasets are reanalyzed in this work). The components from all sites, when taken together, provide a holistic overview of Northern Hemisphere organic aerosol (OA) and its evolution in the atmosphere. At most sites, the OA can be separated into oxygenated OA (OOA), hydrocarbon-like OA (HOA), and sometimes other components such as biomass burning OA (BBOA). We focus on the OOA components in this work. In many analyses, the OOA can be further deconvolved into low-volatility OOA (LV-OOA) and semi-volatile OOA (SV-OOA). Differences in the mass spectra of these components are characterized in terms of the two main ions m/z 44 (CO2+) and m/z 43 (mostly C2H3O+), which are used to develop a new mass spectral diagnostic for following the aging of OA components in the atmosphere. The LV-OOA component spectra have higher f44 (ratio of m/z 44 to total signal in the component mass spectrum) and lower f43 (ratio of m/z 43 to total signal in the component mass spectrum) than SV-OOA. A wide range of f44 and O:C ratios are observed for both LV-OOA (0.17±0.04, 0.73±0.14) and SV-OOA (0.07±0.04, 0.35±0.14) components, reflecting the fact that there is a continuum of OOA properties in ambient aerosol. The OOA components (OOA, LV-OOA, and SV-OOA) from all sites cluster within a well-defined triangular region in the f44 vs. f43 space, which can be used as a standardized means for comparing and characterizing any OOA components (laboratory or ambient) observed with the AMS. Examination of the OOA components in this triangular space indicates that OOA component spectra become increasingly similar to each other and to fulvic acid and HULIS sample spectra as f44 (a surrogate for O:C and an indicator of photochemical aging) increases. This indicates that ambient OA converges towards highly aged LV-OOA with atmospheric oxidation. The common features of the transformation between SV-OOA and LV-OOA at multiple sites potentially enable a simplified description of the oxidation of OA in the atmosphere. Comparison of laboratory SOA data with ambient OOA indicates that laboratory SOA are more similar to SV-OOA and rarely become as oxidized as ambient LV-OOA, likely due to the higher loadings employed in the experiments and/or limited oxidant exposure in most chamber experiments.

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Wintertime aerosol chemical composition, volatility, and spatial variability in the greater London area

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-1139-2016 ◽

2016 ◽

Vol 16 (2) ◽

pp. 1139-1160 ◽

Cited By ~ 17

Author(s):

L. Xu ◽

L. R. Williams ◽

D. E. Young ◽

J. D. Allan ◽

H. Coe ◽

...

Keyword(s):

Biomass Burning ◽

Solid Fuel ◽

Field Studies ◽

Rural Site ◽

Urban Site ◽

High Temporal Resolution ◽

Volatile Organics ◽

Aerosol Mass ◽

Rural And Urban ◽

Wide Range

Abstract. The composition of PM1 (particulate matter with diameter less than 1 µm) in the greater London area was characterized during the Clean Air for London (ClearfLo) project in winter 2012. Two high-resolution time-of-flight aerosol mass spectrometers (HR-ToF-AMS) were deployed at a rural site (Detling, Kent) and an urban site (North Kensington, London). The simultaneous and high-temporal resolution measurements at the two sites provide a unique opportunity to investigate the spatial distribution of PM1. We find that the organic aerosol (OA) concentration is comparable between the rural and urban sites, but the contribution from different sources is distinctly different between the two sites. The concentration of solid fuel OA at the urban site is about twice as high as at the rural site, due to elevated domestic heating in the urban area. While the concentrations of oxygenated OA (OOA) are well-correlated between the two sites, the OOA concentration at the rural site is almost twice that of the urban site. At the rural site, more than 70 % of the carbon in OOA is estimated to be non-fossil, which suggests that OOA is likely related to aged biomass burning considering the small amount of biogenic SOA in winter. Thus, it is possible that the biomass burning OA contributes a larger fraction of ambient OA in wintertime than what previous field studies have suggested. A suite of instruments was deployed downstream of a thermal denuder (TD) to investigate the volatility of PM1 species at the rural Detling site. After heating at 250 °C in the TD, 40 % of the residual mass is OA, indicating the presence of non-volatile organics in the aerosol. Although the OA associated with refractory black carbon (rBC; measured by a soot-particle aerosol mass spectrometer) only accounts for < 10 % of the total OA (measured by a HR-ToF-AMS) at 250 °C, the two measurements are well-correlated, suggesting that the non-volatile organics have similar sources or have undergone similar chemical processing as rBC in the atmosphere. Although the atomic O : C ratio of OOA is substantially larger than that of solid fuel OA and hydrocarbon-like OA, these three factors have similar volatility, which is inferred from the change in mass concentration after heating at 120 °C. Finally, we discuss the relationship between the mass fraction remaining (MFR) of OA after heating in the TD and atomic O : C of OA and find that particles with a wide range of O : C could have similar MFR after heating. This analysis emphasizes the importance of understanding the distribution of volatility and O : C in bulk OA.

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A New Way To Detect Noncovalently Bonded Complexes of Biomolecules from Liquid Micro-Droplets by Laser Mass Spectrometry

Australian Journal of Chemistry ◽

10.1071/ch05285 ◽

2006 ◽

Vol 59 (2) ◽

pp. 109 ◽

Cited By ~ 84

Author(s):

Nina Morgner ◽

Hans-Dieter Barth ◽

Bernhard Brutschy

Keyword(s):

Mass Spectrometry ◽

Quantitative Analysis ◽

Liquid Phase ◽

Laser Pulses ◽

Laser Mass Spectrometry ◽

Native Solution ◽

On Demand ◽

Ir Laser ◽

Intensity Threshold ◽

Wide Range

A new version of laser mass-spectrometry is presented, which allows the quantitative analysis of specific biocomplexes in native solution. On-demand micro droplets, injected into vacuum, are irradiated by mid IR-laser pulses. Above a certain intensity threshold they explode due to the transmitted energy, setting free a fraction of the charged biomolecules which are then mass-analyzed. Amounts of analyte in the attomolar range may be detected with the ion intensity being linear over a wide range of molarity. Evidence is given that this method is soft, tolerant against various buffers, reflects properties of the liquid phase, and suitable for studying noncovalently bonded specific complexes. This is highlighted by results from antibiotics specifically binding into the minor groove of duplex DNA.

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Maritime Aerosol Optical and Microphysical Properties in the South China Sea Under Multi-source Influence

Scientific Reports ◽

10.1038/s41598-019-54483-6 ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

Chi Zhang ◽

Hua Xu ◽

Zhengqiang Li ◽

Yisong Xie ◽

Donghui Li

Keyword(s):

South China Sea ◽

South China ◽

Volume Concentration ◽

The South China Sea ◽

Skewed Distribution ◽

The South ◽

China Sea ◽

Microphysical Properties ◽

Wide Range ◽

Fine Mode

AbstractThe South China Sea hosts a wide range of aerosol pollutants with the uneven development of socio-economic and complicated meteorology system. To fill the gap of the maritime aerosol characteristics over the sea, we selected the multi-year ground-based measurements of Taiping Site and Dongsha Site to investigate the optical and microphysical properties. In Taiping, the vast majority of aerosol optical depths (AODs) are less than 0.2, but that of Dongsha shows the wider distribution of AODs from 0 to 0.6. Angstrom Exponent frequency distribution in Taiping peaks at the range of 0.75–1.25 but that has the left-skewed distribution in Taiping Island. Moreover, there is a variation in the coarse-mode volume concentration in Taiping Island but less variation in the fine mode. The seasonal maritime aerosol properties of Taiping and Dongsha have been analyzed that can be employed as a maritime look up table (LUT) kernel in coupled atmospheric retrieval and correction algorithms.

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Characterization of nighttime formation of particulate organic nitrates based on high-resolution aerosol mass spectrometry in an urban atmosphere in China

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-5235-2019 ◽

2019 ◽

Vol 19 (7) ◽

pp. 5235-5249 ◽

Cited By ~ 8

Author(s):

Kuangyou Yu ◽

Qiao Zhu ◽

Ke Du ◽

Xiao-Feng Huang

Keyword(s):

High Resolution ◽

Organic Aerosol ◽

The United States ◽

Ozone Production ◽

Urban Site ◽

Organic Nitrate ◽

High Time Resolution ◽

Organic Nitrates ◽

Aerosol Mass

Abstract. Organic nitrates are important atmospheric species that significantly affect the cycling of NOx and ozone production. However, characterization of particulate organic nitrates and their sources in polluted atmosphere is a big challenge and has not been comprehensively studied in Asia. In this study, an aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed at an urban site in China from 2015 to 2016 to characterize particulate organic nitrates in total nitrates with a high time resolution. Based on the cross-validation of two different data processing methods, organic nitrates were effectively quantified to contribute a notable fraction of organic aerosol (OA), namely 9 %–21 % in spring, 11 %–25 % in summer, and 9 %–20 % in autumn, while contributing a very small fraction in winter. The good correlation between organic nitrates and fresh secondary organic aerosol (SOA) at night, as well as the diurnal trend of size distribution of organic nitrates, indicated a key role of nighttime local secondary formation of organic nitrates. Furthermore, theoretical calculations of nighttime SOA production of NO3 reactions with volatile organic compounds (VOCs) measured during the spring campaign were performed, resulting in three biogenic VOCs (α-pinene, limonene, and camphene) and one anthropogenic VOC (styrene) identified as the possible key VOC precursors to particulate organic nitrates. The comparison with similar studies in the literature implied that nighttime particulate organic nitrate formation is highly relevant to NOx levels. This study proposes that unlike the documented cases in the United States and Europe, modeling nighttime particulate organic nitrate formation in China should incorporate not only biogenic VOCs but also anthropogenic VOCs for urban air pollution, which needs the support of relevant smog chamber studies in the future.

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