scholarly journals Secondary Organic Aerosols from OH Oxidation of Cyclic Volatile Methyl Siloxanes as an Important Si Source in the Atmosphere

2021 ◽  
Author(s):  
Chong Han ◽  
Hongxing Yang ◽  
Kun Li ◽  
Patrick Lee ◽  
John Liggio ◽  
...  
Keyword(s):  
Mass Spectra ◽  
Flow Reactor ◽  
Organic Aerosols ◽  
Consumer Products ◽  
Environmental Risks ◽  
Chemical Compositions ◽  
Source Strength ◽  
Urban Centers ◽  
Yield Data ◽  
Yield Decrease

Abstract. Cyclic volatile methyl siloxanes (cVMS) are active ingredients in widely used consumer products, which can volatilize into the atmosphere, thus attracting much attention due to their potential environmental risks. While in the atmosphere the cVMS undergo oxidation yielding both gaseous and particulate products. The aerosol yields and compositions from the OH oxidation of four cVMS (D3-D6) were determined under low and high-NOx conditions in an oxidation flow reactor. The aerosol yields progressively increased from D3 to D6, consistent with the volatilities and molecule weights of these cVMS. NOx can restrict the formation of SOA, leading to lower SOA yields under high-NOx conditions than under low-NOx conditions, with a yield decrease between 0.05–0.30 depending on the cVMS. Ammonium sulfate seeds exhibited minor impacts on SOA yields under low-NOx conditions, but significantly increased the SOA yields in the oxidation of D3-D5 at short photochemical ages under high-NOx conditions. The mass spectra of the SOA showed a dependence of its chemical compositions on OH exposure. At high exposures, equivalent to photochemical ages of > 6 days in the atmosphere, D4-D6 SOA mainly consisted of CxHy and CxHyOzSin under low-NOx conditions, whereas they primarily contained NmOz, CxHy, CxHyO1, CxHyO>1 and CxHyOzSin under high-NOx conditions. Using the yield data from the present study and reported cVMS annual production, a global cVMS-derived SOA source strength is estimated to be 0.16 Tg yr−1, distributed over major urban centers.

scholarly journals Source apportionment of fine organic aerosols in Beijing

2009 ◽  
Vol 9 (21) ◽  
pp. 8573-8585 ◽  
Author(s):  
Q. Wang ◽  
M. Shao ◽  
Y. Zhang ◽  
Y. Wei ◽  
M. Hu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Particulate Organic Matter ◽  
Biomass Burning ◽  
Fine Particles ◽  
Organic Aerosols ◽  
Gas Chromatography Mass Spectrometry ◽  
Chemical Compositions ◽  
Vehicle Exhaust ◽  
Coal Burning ◽  
Alkanoic Acids

Abstract. Fine particles (PM2.5, i.e., particles with an aerodynamic diameter of ≤2.5 μm) were collected from the air in August 2005, August–September 2006, and January–February 2007, in Beijing, China. The chemical compositions of particulate organic matter in the ambient samples were quantified by gas chromatography/mass spectrometry. The dominant compounds identified in summertime were n-alkanoic acids, followed by dicarboxylic acids and sugars, while sugars became the most abundant species in winter, followed by polycyclic aromatic hydrocarbons, n-alkanes, and n-alkanoic acids. The contributions of seven emission sources (i.e., gasoline/diesel vehicles, coal burning, wood/straw burning, cooking, and vegetative detritus) to particulate organic matter in PM2.5 were estimated using a chemical mass balance receptor model. The model results present the seasonal trends of source contributions to organic aerosols. Biomass burning (straw and wood) had the highest contribution in winter, followed by coal burning, vehicle exhaust, and cooking. The contribution of cooking was the highest in summer, followed by vehicle exhaust and biomass burning, while coal smoke showed only a minor contribution to ambient organic carbon.

Source Attribution of Submicron Organic Aerosols during Wintertime Inversions by Advanced Factor Analysis of Aerosol Mass Spectra

2008 ◽  
Vol 42 (1) ◽  
pp. 214-220 ◽  
Author(s):  
Valentin A. Lanz ◽  
M. Rami Alfarra ◽  
Urs Baltensperger ◽  
Brigitte Buchmann ◽  
Christoph Hueglin ◽  
...  
Keyword(s):  
Factor Analysis ◽  
Mass Spectra ◽  
Organic Aerosols ◽  
Source Attribution ◽  
Aerosol Mass

Highly oxygenated molecules and their chemistry in polluted urban environments

2020 ◽  
Author(s):  
Qi Chen ◽  
Xi Cheng ◽  
Yongjie Li ◽  
Yan Zheng ◽  
Keren Liao ◽  
...  
Keyword(s):  
Mass Spectra ◽  
Flow Reactor ◽  
Particle Growth ◽  
Urban Environments ◽  
Oxidation Products ◽  
Initial Particle ◽  
Positive Matrix ◽  
Ionization Time ◽  
Flight Mass Spectrometry ◽  
Aerosol Mass

<p>Highly oxygenated molecules (HOMs) are important atmospheric oxidation products that may contribute to new particle formation and initial particle growth. Thousands of such compounds were quantified in both winter and summer of 2016 in Beijing by using online nitrate ion chemical ionization time-of-flight mass spectrometry. Positive-matrix factorization of the time series of the high-resolution mass spectra identified at least 10 major groups of gaseous HOMs in Beijing. We compared these PMF factors with the HOMs produced in a Potential Aerosol Mass (PAM) flow reactor in the laboratory from the oxidation of typical biogenic and aromatic precursors under various oxidation conditions. Our results show that four of the ten PMF factors perhaps correspond to biogenic precursors, and another four factors are likely related to aromatic precursors. The chemistry of these aromatic HOMs are discussed based on the results from the PAM experiments.</p>

Evaluating the risks associated with nanomaterials

2017 ◽  
Author(s):  
K. Thomas ◽  
N. Monteiro-Riviere ◽  
D. Warheit ◽  
N. Savage
Keyword(s):  
Exposure Assessment ◽  
Research Priorities ◽  
Industrial Applications ◽  
Consumer Products ◽  
Environmental Risks ◽  
Consumer Electronics ◽  
Systematic Evaluation ◽  
Pulmonary Exposure ◽  
Therapeutic Delivery

This article discusses the risks associated with nanomaterials. The use of nanomaterials in consumer products and industrial applications is becoming more prevalent owing to their range of benefits. Nanomaterials have found uses in energy production, home appliances, water treatment, novel therapeutic delivery techniques and dietary supplements, consumer electronics, and sports equipment. While considerable attention has been given to the likely commercial advantages associated with nanomaterials, less emphasis has been placed on the development of a systematic approach for characterizing the human health and environmental risks from exposure to nanomaterials. This article first considers the use of nanomaterials in consumer products and the characterization of nanomaterials before describing a systematic evaluation of the hazards associated with nanomaterials. It also examines pulmonary exposure assessment and dermal exposure assessment, along with risk assessment for exposure to nanomaterials. Finally, it outlines research priorities for the development of more refined estimates of nanomaterial risk.

scholarly journals Hydrocarbon-like and oxygenated organic aerosols in Pittsburgh: insights into sources and processes of organic aerosols

2005 ◽  
Vol 5 (5) ◽  
pp. 8421-8471 ◽  
Author(s):  
Q. Zhang ◽  
D. R. Worsnop ◽  
M. R. Canagaratna ◽  
J.-L. Jimenez
Keyword(s):  
Organic Carbon ◽  
Mass Spectra ◽  
Organic Aerosols ◽  
Organic Aerosol ◽  
Particle Formation ◽  
Total Carbon ◽  
New Particle Formation ◽  
Aerosol Mass ◽  
Diurnal Profile ◽  
Mass Concentrations

Abstract. A recently developed algorithm (Zhang et al., 2005) has been applied to deconvolve the mass spectra of organic aerosols acquired with the Aerosol Mass Spectrometer (AMS) in Pittsburgh during September 2002. The results are used here to characterize the mass concentrations, size distributions, and mass spectra of hydrocarbon-like and oxygenated organic aerosol (HOA and OOA, respectively). HOA accounts for 34% of the measured organic aerosol mass and OOA accounts for 66%. The mass concentrations of HOA demonstrate a prominent diurnal profile that peaks in the morning during the rush hour and decreases with the rise of the boundary layer. The diurnal profile of OOA is relatively flat and resembles those of SO42− and NH4+. The size distribution of HOA shows a distinct ultrafine mode that is commonly associated with fresh emissions while OOA is generally concentrated in the accumulation mode and appears to be mostly internally mixed with the inorganic ions, such as SO42− and NH4+. These observations suggest that HOA is likely primary aerosol from local, combustion-related emissions and that OOA is secondary organic aerosol (SOA) influenced by regional contributions. There is strong evidence of the direct correspondence of OOA to SOA during an intense new particle formation and growth event, when condensational growth of OOA was observed. The mass spectrum of OOA of this new particle formation event is very similar to the OOA spectrum of the entire study, which strongly suggests that most OOA during this study is SOA. O3 appears to be a poor indicator for SOA concentration while SO42− is a relatively good surrogate for this dataset. Since the diurnal averages of HOA tightly track those of CO during day time, oxidation/aging of HOA appears to be very small on the time scale of several hours. Based on extracted mass spectra and the likely elemental compositions of major m/z's, the organic mass to organic carbon ratios (OM:OC) of HOA and OOA are estimated at 1.2 and 2.2 μg/μg C, respectively, leading to an average OM:OC ratio of 1.8 for submicron OA in Pittsburgh during September. The C:O ratio of OOA is estimated at 1:0.8. The carbon contents in HOA and OOA calculated accordingly correlate well to primary and secondary organic carbon, respectively, estimated by the OC/EC tracer technique (assuming POC-to-EC ratio=1). In addition, the total carbon concentrations calculated from the AMS data agree well with those measured by the Sunset Laboratory Carbon analyzer (r2=0.87; slope=1.01±0.11).

scholarly journals Direct links between hygroscopicity and mixing state of ambient aerosols: Estimating particle hygroscopicity from their single particle mass spectra

2020 ◽  
Author(s):  
Xinning Wang ◽  
Xiaofei Wang ◽  
Xin Yang
Keyword(s):  
Single Particle ◽  
Mass Spectra ◽  
Temporal Variations ◽  
Particle Mass ◽  
Back Trajectory ◽  
Chemical Compositions ◽  
Ambient Aerosols ◽  
Spectra Analysis ◽  
Ambient Particles ◽  
Back Trajectory Analysis

Abstract. Hygroscopicity plays a crucial role in determining aerosol optical properties and aging processes in the atmosphere. We investigated submicron aerosol hygroscopicity and composition by connecting an aerosol time-of-flight mass spectrometer (ATOFMS) to the downstream of a hygroscopic tandem differential mobility analyzer (HTDMA), to simultaneously characterize hygroscopicities and chemical compositions of ambient aerosols in Shanghai, China. Major particle types, including biomass burning, EC, Dust/Ash, organics particles, cooking particles and sea salt, were shown to have distinct hygroscopicity distributions. It is also found that particles with stronger hygroscopicities were more likely to have higher effective densities. Based on the measured hygroscopicity-composition relations, we developed a statistical method to estimate ambient particle hygroscopicity just from their mass spectra. This method was applied to another ambient ATOFMS dataset sampled from September 12nd to 28th, 2012 in Shanghai, and it is found that ambient particles were present in three major hygroscopicity modes, whose growth factors at relative humidity 85 % peaked at 1.05, 1.42 and 1.60, respectively. The temporal variations of the estimated particle hygroscopicity were consistent with the back-trajectory analysis and atmospheric visibility observations. These hygroscopicity estimation results with single particle mass spectra analysis can provide critical information on particulate water content, particle source apportionment and aging processes.

scholarly journals Hydrocarbon-like and oxygenated organic aerosols in Pittsburgh: insights into sources and processes of organic aerosols

2005 ◽  
Vol 5 (12) ◽  
pp. 3289-3311 ◽  
Author(s):  
Q. Zhang ◽  
D. R. Worsnop ◽  
M. R. Canagaratna ◽  
J. L. Jimenez
Keyword(s):  
Organic Carbon ◽  
Mass Spectra ◽  
Organic Aerosols ◽  
Organic Aerosol ◽  
Total Carbon ◽  
Direct Estimate ◽  
Entire Study ◽  
Aerosol Mass ◽  
Diurnal Profile ◽  
Mass Concentrations

Abstract. A recently developed algorithm (Zhang et al., 2005) has been applied to deconvolve the mass spectra of organic aerosols acquired with the Aerosol Mass Spectrometer (AMS) in Pittsburgh during September 2002. The results are used here to characterize the mass concentrations, size distributions, and mass spectra of hydrocarbon-like and oxygenated organic aerosol (HOA and OOA, respectively). HOA accounts for 34% of the measured organic aerosol mass and OOA accounts for 66%. The mass concentrations of HOA demonstrate a prominent diurnal profile that peaks in the morning during the rush hour and decreases with the rise of the boundary layer. The diurnal profile of OOA is relatively flat and resembles those of SO42− and NH4+. The size distribution of HOA shows a distinct ultrafine mode that is commonly associated with fresh emissions while OOA is generally concentrated in the accumulation mode and appears to be mostly internally mixed with the inorganic ions, such as SO42− and NH4+. These observations suggest that HOA is likely primary aerosol from local, combustion-related emissions and that OOA is secondary organic aerosol (SOA) influenced by regional contributions. There is strong evidence of the direct correspondence of OOA to SOA during an intense new particle formation and growth event, when condensational growth of OOA was observed. The fact that the OOA mass spectrum from this event is very similar to that from the entire study suggests that the majority of OOA in Pittsburgh is likely SOA. O3 appears to be a poor indicator for OOA concentration while SO42− is a relatively good surrogate for this dataset. Since the diurnal averages of HOA track those of CO during day time, oxidation/aging of HOA appears to be very small on the time scale of several hours. Based on extracted mass spectra and the likely elemental compositions of major m/z's, the organic mass to organic carbon ratios (OM:OC) of HOA and OOA are estimated at 1.2 and 2.2 μg/μgC, respectively, leading to an average OM:OC ratio of 1.8 for submicron OA in Pittsburgh during September. The C:O ratio of OOA is estimated at 1:0.8. The carbon contents in HOA and OOA estimated accordingly correlate well to primary and secondary organic carbon, respectively, estimated by the OC/EC tracer technique (assuming POC-to-EC ratio=1). In addition, the total carbon concentrations estimated from the AMS data agree well with those measured by the Sunset Laboratory Carbon analyzer (r2=0.87; slope=1.01±0.11). Our results represent the first direct estimate of the OM:OC ratio from highly time-resolved chemical composition measurements.

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