Diurnal Variations of Individual Organic Compound Constituents of Ultrafine and Accumulation Mode Particulate Matter in the Los Angeles Basin

2004 ◽  
Vol 38 (5) ◽  
pp. 1296-1304 ◽  
Author(s):  
Philip M Fine ◽  
Bhabesh Chakrabarti ◽  
Meg Krudysz ◽  
James J. Schauer ◽  
Constantinos Sioutas
Keyword(s):  
Particulate Matter ◽  
Los Angeles ◽  
Organic Compound ◽  
Diurnal Variations ◽  
Los Angeles Basin ◽  
Accumulation Mode

scholarly journals The Pasadena Aerosol Characterization Observatory (PACO): chemical and physical analysis of the Western Los Angeles basin aerosol

2011 ◽  
Vol 11 (15) ◽  
pp. 7417-7443 ◽  
Author(s):  
S. P. Hersey ◽  
J. S. Craven ◽  
K. A. Schilling ◽  
A. R. Metcalf ◽  
A. Sorooshian ◽  
...  
Keyword(s):  
Los Angeles ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Organic Mass ◽  
Los Angeles Basin ◽  
Aerosol Composition ◽  
Accumulation Mode ◽  
California Institute Of Technology ◽  
Aerosol Characterization ◽  
Marine Layer

Abstract. The Pasadena Aerosol Characterization Observatory (PACO) represents the first major aerosol characterization experiment centered in the Western/Central Los Angeles Basin. The sampling site, located on the campus of the California Institute of Technology in Pasadena, was positioned to sample a continuous afternoon influx of transported urban aerosol with a photochemical age of 1–2 h and generally free from major local contributions. Sampling spanned 5 months during the summer of 2009, which were broken into 3 regimes on the basis of distinct meteorological conditions. Regime I was characterized by a series of low pressure systems, resulting in high humidity and rainy periods with clean conditions. Regime II typified early summer meteorology, with significant morning marine layers and warm, sunny afternoons. Regime III was characterized by hot, dry conditions with little marine layer influence. Regardless of regime, organic aerosol (OA) is the most significant constituent of nonrefractory submicron Los Angeles aerosol (42, 43, and 55 % of total submicron mass in regimes I, II, and III, respectively). The overall oxidation state remains relatively constant on timescales of days to weeks (O:C = 0.44 ± 0.08, 0.55 ± 0.05, and 0.48 ± 0.08 during regimes I, II, and III, respectively), with no difference in O:C between morning and afternoon periods. Periods characterized by significant morning marine layer influence followed by photochemically favorable afternoons displayed significantly higher aerosol mass and O:C ratio, suggesting that aqueous processes may be important in the generation of secondary aerosol and oxidized organic aerosol (OOA) in Los Angeles. Online analysis of water soluble organic carbon (WSOC) indicates that water soluble organic mass (WSOM) reaches maxima near 14:00–15:00 local time (LT), but the percentage of AMS organic mass contributed by WSOM remains relatively constant throughout the day. Sulfate and nitrate reside predominantly in accumulation mode aerosol, while afternoon SOA production coincides with the appearance of a distinct fine mode dominated by organics. Particulate NH4NO3 and (NH4)2SO4 appear to be NH3-limited in regimes I and II, but a significant excess of particulate NH4+ in the hot, dry regime III suggests less SO42− and the presence of either organic amines or NH4+-associated organic acids. C-ToF-AMS data were analyzed by Positive Matrix Factorization (PMF), which resolved three factors, corresponding to a hydrocarbon-like OA (HOA), semivolatile OOA (SV-OOA), and low-volatility OOA (LV-OOA). HOA appears to be a periodic plume source, while SV-OOA exhibits a strong diurnal pattern correlating with ozone. Peaks in SV-OOA concentration correspond to peaks in DMA number concentration and the appearance of a fine organic mode. LV-OOA appears to be an aged accumulation mode constituent that may be associated with aqueous-phase processing, correlating strongly with sulfate and representing the dominant background organic component. Periods characterized by high SV-OOA and LV-OOA were analyzed by filter analysis, revealing a complex mixture of species during periods dominated by SV-OOA and LV-OOA, with LV-OOA periods characterized by shorter-chain dicarboxylic acids (higher O:C ratio), as well as appreciable amounts of nitrate- and sulfate-substituted organics. Phthalic acid was ubiquitous in filter samples, suggesting that PAH photochemistry may be an important SOA pathway in Los Angeles. Aerosol composition was related to water uptake characteristics, and it is concluded that hygroscopicity is largely controlled by organic mass fraction (OMF). The hygroscopicity parameter κ averaged 0.31 ± 0.08, approaching 0.5 at low OMF and 0.1 at high OMF, with increasing OMF suppressing hygroscopic growth and increasing critical dry diameter for CCN activation (Dd). An experiment-averaged κorg of 0.14 was calculated, indicating that the highly-oxidized organic fraction of aerosol in Los Angeles is appreciably more hygroscopic than previously reported in urban areas. Finally, PACO will provide context for results forthcoming from the CalNex field campaign, which involved ground sampling in Pasadena during the spring and summer of 2010.

scholarly journals Oxidative potential of coarse particulate matter (PM10–2.5) and its relation to water solubility and sources of trace elements and metals in the Los Angeles Basin

2015 ◽  
Vol 17 (12) ◽  
pp. 2110-2121 ◽  
Author(s):  
Farimah Shirmohammadi ◽  
Sina Hasheminassab ◽  
Dongbin Wang ◽  
Arian Saffari ◽  
James J. Schauer ◽  
...  
Keyword(s):  
Trace Elements ◽  
Particulate Matter ◽  
Los Angeles ◽  
Elemental Composition ◽  
Water Solubility ◽  
Los Angeles Basin ◽  
Oxidative Potential ◽  
Coarse Particulate Matter

Elemental composition of CPM was highly associated with ROS activity.

scholarly journals Particulate Matter Modeling in the Los Angeles Basin Using SAQM-AERO

2000 ◽  
Vol 50 (1) ◽  
pp. 32-42 ◽  
Author(s):  
Prasad Pai ◽  
Krishnakumar Vijayaraghavan ◽  
Christian Seigneur
Keyword(s):  
Particulate Matter ◽  
Los Angeles ◽  
Los Angeles Basin

scholarly journals The Pasadena Aerosol Characterization Observatory (PACO): chemical and physical analysis of the Western Los Angeles Basin aerosol

2011 ◽  
Vol 11 (2) ◽  
pp. 5867-5933 ◽  
Author(s):  
S. P. Hersey ◽  
J. S. Craven ◽  
K. A. Schilling ◽  
A. R. Metcalf ◽  
A. Sorooshian ◽  
...  
Keyword(s):  
Los Angeles ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Physical Analysis ◽  
Organic Mass ◽  
Los Angeles Basin ◽  
Accumulation Mode ◽  
California Institute Of Technology ◽  
Aerosol Characterization ◽  
Marine Layer

Abstract. The Pasadena Aerosol Characterization Observatory (PACO) represents the first major aerosol characterization experiment centered in the Western/Central Los Angeles Basin. The sampling site, located on the campus of the California Institute of Technology in Pasadena, was positioned to sample a continuous afternoon influx of transported urban aerosol with a photochemical age of 1–2 h and generally free from major local contributions. Sampling spanned 5 months during the summer of 2009, which were broken into 3 regimes on the basis of distinct meteorological conditions. Regime I was characterized by a series of low pressure systems, resulting in high humidity and rainy periods with clean conditions. Regime II typified early summer meteorology, with significant morning marine layers and warm, sunny afternoons. Regime III was characterized by hot, dry conditions with little marine layer influence. Organic aerosol (OA) is the most significant constituent of Los Angeles aerosol (42, 43, and 55% of total submicron mass in regimes I, II, and III, respectively), and that the overall oxidation state remains relatively constant on timescales of days to weeks (O:C = 0.44 ± 0.08, 0.55 ± 0.05, and 0.48 ± 0.08 during regimes I, II, and III, respectively), with no difference in O:C between morning and afternoon periods. Periods characterized by significant morning marine layer influence followed by photochemically favorable afternoons displayed significantly higher aerosol mass and O:C ratio, suggesting that aqueous processes may be important in the generation of secondary aerosol and oxidized organic aerosol (OOA) in Los Angeles. Water soluble organic mass (WSOM) reaches maxima near 14:00–15:00 local time (LT), but the percentage of AMS organic mass contributed by WSOM remains relatively constant throughout the day. Sulfate and nitrate reside predominantly in accumulation mode aerosol, while afternoon SOA production coincides with the appearance of a distinct fine mode dominated by organics. Particulate NH4NO3 and (NH4)2SO4 appear to be NH3-limited in regimes I and II, but a significant excess of particulate NH4+ in the hot, dry regime III suggests less marine SO42− and the presence of organic amines. Positive Matrix Factorization (PMF) analysis of C-ToF-AMS data resolved three factors, corresponding to a hydrocarbon-like OA (HOA), semivolatile OOA (SV-OOA), and low-volatility OOA (LV-OOA). HOA appears to be a periodic plume source, while SV-OOA exhibits a strong diurnal pattern correlating with ozone. Peaks in SV-OOA concentration correspond to peaks in DMA number concentration and the appearance of a fine organic mode. LV-OOA appears to be an aged accumulation mode constituent that may be associated with aqueous-phase processing, correlating strongly with sulfate and representing the dominant background organic component. Filter analysis revealed a complex mixture of species during periods dominated by SV-OOA and LV-OOA, with LV-OOA periods characterized by shorter-chain dicarboxylic acids (higher O:C ratio), as well as appreciable amounts of nitrate- and sulfate-substituted organics. Phthalic acid was ubiquitous in filter samples, suggesting that PAH photochemistry may be an important SOA pathway in Los Angeles. Water uptake characteristics indicate that hygroscopicity is largely controlled by organic mass fraction (OMF). The hygroscopicity parameter κ averaged 0.31 ± 0.08, approaching 0.5 at low OMF and 0.1 at high OMF, with increasing OMF suppressing hygroscopic growth and increasing critical dry diameter for CCN activation (Dd). Finally, PACO will provide context for results forthcoming from the CalNex field campaign, which involved ground sampling in Pasadena during the spring and summer of 2010.

Size Distribution of Diesel Particulate Matter From a Heavy Duty Diesel Engine During FTP Transient Cycle

2004 ◽  
Author(s):  
Emre Tatli ◽  
Nigel N. Clark ◽  
Richard J. Atkinson ◽  
Gregory J. Thompson
Keyword(s):  
New York ◽  
Particulate Matter ◽  
Los Angeles ◽  
Size Distributions ◽  
Heavy Duty ◽  
Accumulation Mode ◽  
Particulate Size ◽  
Heavy Duty Diesel ◽  
Vehicle Activity ◽  
Average Size

Researchers concerned both with diesel exhaust health effects and with mechanisms of particulate matter (PM) formation have an interest in gaining understanding of PM size distributions from heavy-duty on-road diesel engines. Prior research has been done on particulate size measurement but the results fall short in understanding PM size distributions because of the response time or size range of the instruments used. This study reports the transient size distributions of PM from a 1992 Detroit Diesel Series 60 on an engine dynamometer from a full flow dilution tunnel for a FTP Transient Cycle using a Cambustion ® Differential Mobility spectrometer (DMS 500). The size bins selected for this study for the nucleation and accumulation modes were 20nm and 60nm bins, respectively. The accumulation mode during the accelerations and the nucleation mode during the decelerations were clearly observed from the distributions with respect to time. Distributions were also observed during the test cycle showing the transition between the two modes. From the results obtained from the analysis, no strong correlation between the 60nm particles and engine speed was observed even though higher counts of accumulation particles were observed at the same time that the vehicle activity occurred. Similarly, there was no correlation between the accumulation mode particles and power. When the distributions of nucleation and accumulation mode particles were plotted against each other, there was no correlation or anti-correlation. The average size distributions were also analyzed during the four periods of the FTP Transient cycle and the highest counts were observed during the Los Angeles Freeway (LAF) period. Also, higher counts at the second New York Non Freeway (NYNF) were observed during the cycle.

Redox activity of airborne particulate matter at different sites in the Los Angeles Basin

2005 ◽  
Vol 99 (1) ◽  
pp. 40-47 ◽  
Author(s):  
Arthur K. Cho ◽  
Constantinos Sioutas ◽  
Antonio H. Miguel ◽  
Yoshito Kumagai ◽  
Debra A. Schmitz ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Los Angeles ◽  
Airborne Particulate Matter ◽  
Redox Activity ◽  
Airborne Particulate ◽  
Los Angeles Basin
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