scholarly journals Formation and characteristics of secondary aerosols in an industrialized environment during cold seasons

2018 ◽  
Author(s):  
Yangzhou Wu ◽  
Xinlei Ge ◽  
Junfeng Wang ◽  
Yafei Shen ◽  
Zhaolian Ye ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Soot Particle ◽  
Oxidation Degree ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Fine Aerosol ◽  
Secondary Aerosols ◽  
Photochemical Processing ◽  
The One ◽  
Phase Chemistry

Abstract. Secondary aerosols including inorganic and organic components often dominate the fine aerosol mass, it is thus important to elucidate the formation and characteristics of these species. In this work, we measured the submicron aerosols (PM1) by using an Aerodyne high resolution soot-particle aerosol mass spectrometer in suburban Nanjing, China. The site was surrounded by industry plants, and the measurement was conducted during cold seasons (February–March 2015). We found that under such environment, the PM1 was predominantly comprised of secondary species (on average 63.2 % from ammonium sulfate and nitrate). Results show that moisture plays a key role to enhance both nitrate and sulfate formations. The moisture promotes the gas-particle partitioning and nocturnal heterogeneous production of nitrate, while transformation of SO2 into sulfate directly in aqueous phase is more significant. The organic aerosol (OA) occupied ~1/4 of total PM1 mass, and the primary OA (POA) and secondary OA (SOA) contributions were almost equal. A specific industry-related OA was separated and a modified graphical method was introduced to describe the evolution of OA. Results further show that the most abundant OA factor, which is the one with highest oxidation degree, is also mainly driven by aqueous-phase processing, while the other two less oxygenated SOA factors are mainly governed by photochemical processing. Peak sizes of sulfate, nitrate and OA all shifted towards larger sizes with the increases of relative humidity, reflecting the effects of aqueousphase processing too. Aqueous-phase driven secondary aerosols were found to be very important in enhancing the PM1 pollution, while photochemical processed SOA was important to OA pollution, leading to a fresher OA at higher OA concentrations. We further demonstrated influences of the aqueous-phase processing and photochemical processing on formation of secondary aerosols by using two typical cases, respectively. This paper highlights the importance of aqueous-phase chemistry on sulfate and nitrate formations, and that different portions of SOA can be dominated by different mechanisms in an industrialized environment.

scholarly journals Seasonal differences in formation processes of oxidized organic aerosol near Houston, TX

2018 ◽  
Author(s):  
Qili Dai ◽  
Benjamin C. Schulze ◽  
Xiaohui Bi ◽  
Alexander A. T. Bui ◽  
Fangzhou Guo ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Organic Aerosol ◽  
Liquid Water Content ◽  
Ratio Method ◽  
Organic Nitrate ◽  
Aerosol Formation ◽  
Light Rain ◽  
Aerosol Mass ◽  
Secondary Aerosols ◽  
Phase Chemistry

Abstract. Submicron aerosol was measured to the southwest of Houston, Texas during winter and summer 2014 to investigate its seasonal variability. Data from a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) indicated that organic aerosol (OA) was the largest component of non-refractory submicron particulate matter (NR-PM1) (on average, 46 ± 13 % and 55 ± 18 % of the NR-PM1 mass loading in winter and summer, respectively). Positive matrix factorization (PMF) analysis of the OA mass spectra demonstrated that two classes of oxygenated OA (less and more-oxidized OOA, LO and MO) together dominated OA mass in summer (77 %) and accounted for 42 % of OA mass in winter. The fraction of LO-OOA (out of total OOA) is higher in summer (69 %) than in winter (44 %). Secondary aerosols (sulfate + nitrate + ammonium + OOA) accounted for ~ 76 % and 89 % of NR-PM1 mass in winter and summer, respectively, indicating NR-PM1 mass was driven mostly by secondary aerosol formation regardless of the season. The mass loadings and diurnal patterns of these secondary aerosols show a clear winter/summer contrast. Organic nitrate (ON) concentrations were estimated using the NOx+ ratio method, with an average contribution of ~ 15 % and 37 % to OA during winter and summer campaign, respectively. The estimated ON in summer strongly correlated with LO-OOA (r = 0.73) and was enhanced at nighttime. The relative importance of aqueous-phase chemistry and photochemistry in processing OOA was investigated by examining the relationship of aerosol liquid water content (LWC) and the sum of ozone (O3) and nitrogen dioxide (NO2) (Ox = O3 + NO2) with LO-OOA and MO-OOA. The processing mechanism of LO-OOA apparently depended on relative humidity (RH). In periods of RH  80 %, these effects were opposite that of low RH periods. Both photochemistry and aqueous-phase processing appear to facilitate MO-OOA formation except during periods of high LWC, which is likely a result of wet removal during periods of light rain. The nighttime increases of MO-OOA during winter and summer were 0.013 and 0.01 μg MO-OOA per μg of LWC, respectively. The increase of LO-OOA was larger than that for MO-OOA, with increase rates of 0.033 and 0.055 μg LO-OOA per μg of LWC at night during winter and summer, respectively. On average, the mass concentration of LO-OOA in summer was elevated by nearly 1.2 μg m−3 for a ~ 20 μg change in LWC, which is accompanied by a 40 ppb change in Ox.

scholarly journals Collection efficiency of the soot-particle aerosol mass spectrometer (SP-AMS) for internally mixed particulate black carbon

2014 ◽  
Vol 7 (12) ◽  
pp. 4507-4516 ◽  
Author(s):  
M. D. Willis ◽  
A. K. Y. Lee ◽  
T. B. Onasch ◽  
E. C. Fortner ◽  
L. R. Williams ◽  
...  
Keyword(s):  
Laser Beam ◽  
Black Carbon ◽  
Mass Spectrometer ◽  
Soot Particle ◽  
Collection Efficiency ◽  
Particle Beam ◽  
Aerosol Mass Spectrometer ◽  
Coated Particles ◽  
Aerosol Mass ◽  
Wide Range

Abstract. The soot-particle aerosol mass spectrometer (SP-AMS) uses an intra-cavity infrared laser to vaporize refractory black carbon (rBC) containing particles, making the particle beam–laser beam overlap critical in determining the collection efficiency (CE) for rBC and associated non-refractory particulate matter (NR-PM). This work evaluates the ability of the SP-AMS to quantify rBC and NR-PM mass in internally mixed particles with different thicknesses of organic coating. Using apparent relative ionization efficiencies for uncoated and thickly coated rBC particles, we report measurements of SP-AMS sensitivity to NR-PM and rBC, for Regal Black, the recommended particulate calibration material. Beam width probe (BWP) measurements are used to illustrate an increase in sensitivity for highly coated particles due to narrowing of the particle beam, which enhances the CE of the SP-AMS by increasing the laser beam–particle beam overlap. Assuming complete overlap for thick coatings, we estimate CE for bare Regal Black particles of 0.6 ± 0.1, which suggests that previously measured SP-AMS sensitivities to Regal Black were underestimated by up to a factor of 2. The efficacy of the BWP measurements is highlighted by studies at a busy road in downtown Toronto and at a non-roadside location, which show particle beam widths similar to, but greater than that of bare Regal Black and coated Regal Black, respectively. Further BWP measurements at field locations will help to constrain the range of CE for fresh and aged rBC-containing particles. The ability of the SP-AMS to quantitatively assess the composition of internally mixed particles is validated through measurements of laboratory-generated organic coated particles, which demonstrate that the SP-AMS can quantify rBC and NR-PM over a wide range of particle compositions and rBC core sizes.

Soot Particle Aerosol Mass Spectrometer: Development, Validation, and Initial Application

2012 ◽  
Vol 46 (7) ◽  
pp. 804-817 ◽  
Author(s):  
T. B. Onasch ◽  
A. Trimborn ◽  
E. C. Fortner ◽  
J. T. Jayne ◽  
G. L. Kok ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Soot Particle ◽  
Aerosol Mass Spectrometer ◽  
Initial Application ◽  
Aerosol Mass

scholarly journals Technical note: A new approach to discriminate different black carbon sources by utilising fullerene and metals in positive matrix factorisation analysis of high-resolution soot particle aerosol mass spectrometer data

2021 ◽  
Vol 21 (13) ◽  
pp. 10763-10777
Author(s):  
Zainab Bibi ◽  
Hugh Coe ◽  
James Brooks ◽  
Paul I. Williams ◽  
Ernesto Reyes-Villegas ◽  
...  
Keyword(s):  
High Resolution ◽  
Black Carbon ◽  
Source Apportionment ◽  
Atmospheric Aerosol ◽  
Soot Particle ◽  
Organic Aerosol ◽  
Positive Matrix ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Matrix Factorisation

Abstract. Atmospheric aerosol particles are known to have detrimental effects on human health and climate. Black carbon is an important constituent of atmospheric aerosol particulate matter (PM), emitted from incomplete combustion. Source apportionment of BC is very important, to evaluate the influence of different sources. The high-resolution soot particle aerosol mass spectrometer (HR-SP-AMS) instrument uses a laser vaporiser, which allows the real-time detection and characterisation of refractory black carbon (rBC) and its internally mixed particles such as metals, coating species, and rBC subcomponents in the form of HOA + fullerene. In this case study, the soot data were collected by using HR-SP-AMS during Guy Fawkes Night on 5 November 2014. Positive matrix factorisation was applied to positively discriminate between different wood-burning and bonfire sources for the first time, which no existing black carbon source apportionment technique is currently able to do. Along with this, the use of the fullerene signals in differentiating between soot sources and the use of metals as a tracer for fireworks has also been investigated, which did not significantly contribute to the rBC concentrations. The addition of fullerene signals and successful positive matrix factorisation (PMF) application to HR-SP-AMS data apportioned rBC into more than two sources. These bonfire sources are HOA + fullerene, biomass burning organic aerosol, more oxidised oxygenated organic aerosol (MO-OOA), and non-bonfire sources such as hydrocarbon-like OA and domestic burning. The result of correlation analysis between HR-SP-AMS data and previously published Aethalometer, MAAP, and CIMS data provides an effective way of gaining insights into the relationships between the variables and provide a quantitative estimate of the source contributions to the BC budget during this period. This research study is an important demonstration of using HR-SP-AMS for the purpose of BC source apportionment.

Aerosol Measurements by Soot Particle Aerosol Mass Spectrometer: a Review

2020 ◽  
Vol 6 (4) ◽  
pp. 440-451
Author(s):  
Yunjiang Zhang ◽  
Junfeng Wang ◽  
Shijie Cui ◽  
Dan Dan Huang ◽  
Xinlei Ge
Keyword(s):  
Mass Spectrometer ◽  
Soot Particle ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass

Particle detection using the dual-vaporizer configuration of the soot particle Aerosol Mass Spectrometer (SP-AMS)

2020 ◽  
pp. 1-14
Author(s):  
Anita M. Avery ◽  
Leah R. Williams ◽  
Edward C. Fortner ◽  
Wade A. Robinson ◽  
Timothy B. Onasch
Keyword(s):  
Mass Spectrometer ◽  
Soot Particle ◽  
Particle Detection ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass

scholarly journals Mixing state of carbonaceous aerosol in an urban environment: single particle characterization using the soot particle aerosol mass spectrometer (SP-AMS)

2015 ◽  
Vol 15 (4) ◽  
pp. 1823-1841 ◽  
Author(s):  
A. K. Y. Lee ◽  
M. D. Willis ◽  
R. M. Healy ◽  
T. B. Onasch ◽  
J. P. D. Abbatt
Keyword(s):  
Cluster Analysis ◽  
Urban Environment ◽  
Mass Spectrometer ◽  
Single Particle ◽  
Soot Particle ◽  
Organic Aerosol ◽  
Mixing State ◽  
Aerosol Mass Spectrometer ◽  
Mass Spectral ◽  
Aerosol Mass

Abstract. Understanding the impact of atmospheric black carbon (BC)-containing particles on human health and radiative forcing requires knowledge of the mixing state of BC, including the characteristics of the materials with which it is internally mixed. In this study, we examine the mixing state of refractory BC (rBC) and other aerosol components in an urban environment (downtown Toronto) utilizing the Aerodyne soot particle aerosol mass spectrometer equipped with a light scattering module (LS-SP-AMS). k-means cluster analysis was used to classify single particle mass spectra into chemically distinct groups. One resultant particle class is dominated by rBC mass spectral signals (C1+ to C5+) while the organic signals fall into a few major particle classes identified as hydrocarbon-like organic aerosol (HOA), oxygenated organic aerosol (OOA), and cooking emission organic aerosol (COA). A gradual mixing is observed with small rBC particles only thinly coated by HOA (~ 28% by mass on average), while over 90% of the HOA-rich particles did not contain detectable amounts of rBC. Most of the particles classified into other inorganic and organic particle classes were not significantly associated with rBC. The single particle results also suggest that HOA and COA emitted from anthropogenic sources were likely major contributors to organic-rich particles with vacuum aerodynamic diameter (dva) ranging from ~ 200 to 400 nm. The similar temporal profiles and mass spectral features of the organic classes identified by cluster analysis and the factors from a positive matrix factorization (PMF) analysis of the ensemble aerosol data set validate the interpretation of the PMF results.

scholarly journals Elemental analysis of Oxygenated Organic Coating on Black Carbon Particles using a Soot-Particle Aerosol Mass Spectrometer

2020 ◽  
Author(s):  
Mutian Ma ◽  
Laura-Hélèna Rivellini ◽  
YuXi Cui ◽  
Megan D. Willis ◽  
Rio Wilkie ◽  
...  
Keyword(s):  
Black Carbon ◽  
Mass Spectrometer ◽  
Elemental Analysis ◽  
Soot Particle ◽  
Organic Coatings ◽  
Laser Vaporization ◽  
Scaling Factors ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Relative Errors

Abstract. Chemical characterization of organic coatings is important to advance our understanding of the physio-chemical properties and environmental fate of black carbon (BC) particles. The soot-particle aerosol mass spectrometer (SP-AMS) has been utilized for this purpose in recent field studies. The laser vaporization (LV) scheme of SP-AMS can heat BC cores gradually until they are completely vaporized, during which organic coatings can be vaporized at temperatures lower than that of the thermal vaporizer (TV) used in a standard high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) that employs flash vaporization. This work investigates the effects of vaporization schemes on fragmentation and elemental analysis of known oxygenated organic species using three SP-AMS instruments. We show that LV can reduce fragmentation of organic molecules. Substantial enhancement of C2H3O+/CO2+ and C2H4O2+ signals was observed for most of the tested species when the LV scheme was used, suggesting that the observational frameworks based using HR-ToF-AMS field data may not be directly applicable for evaluating the chemical evolution of oxygenated organic aerosol (OOA) components coated on ambient BC particles. The uncertainties of H:C and O:C determined by the improved-ambient (I-A) method for both LV and TV approaches were similar, with scaling factors of 1.10 for H:C and 0.89 for O:C were determined to facilitate more direct comparisons between observations from the two vaporization schemes. Furthermore, the I-A method was updated based on the multilinear regression model for the LV scheme measurements. The updated parameters can reduce the relative errors of O:C from −26.3 % to 5.8 %, whereas the relative errors of H:C remain roughly the same. Applying the scaling factors and the updated parameters for the I-A method to ambient data, we found that even though the time series of OOA components determined by the LV and TV schemes are strongly correlated at the same location, OOA coatings were likely less oxygenated compared to those externally mixed with BC.

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