CMAQ Model Performance Enhanced When In-Cloud Secondary Organic Aerosol is Included: Comparisons of Organic Carbon Predictions with Measurements

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.

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Diurnal variations of organic molecular tracers and stable carbon isotopic compositions in atmospheric aerosols over Mt. Tai in North China Plain: an influence of biomass burning

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-9079-2012 ◽

2012 ◽

Vol 12 (4) ◽

pp. 9079-9124

Author(s):

P. Q. Fu ◽

K. Kawamura ◽

J. Chen ◽

J. Li ◽

Y. L. Sun ◽

...

Keyword(s):

Organic Carbon ◽

Biomass Burning ◽

North China Plain ◽

North China ◽

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Total Carbon ◽

Stable Carbon ◽

Isotopic Compositions ◽

Carbon Isotopic

Abstract. Organic tracer compounds of tropospheric aerosols, as well as organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and stable carbon isotope ratios (δ13C) of total carbon (TC) have been investigated for aerosol samples collected during early and late periods of Mount Tai eXperiment 2006 (MTX2006) field campaign in North China Plain. Total solvent extracts were investigated by gas chromatography/mass spectrometry. More than 130 organic compounds were detected in the aerosol samples. They were grouped into twelve organic compound classes, including biomass burning tracers, biogenic primary sugars, biogenic secondary organic aerosol (SOA) tracers, and anthropogenic tracers such as phthalates, hopanes and polycyclic aromatic hydrocarbons (PAHs). In early June when the field burning activities of wheat straws in North China Plain were very active, the total identified organics (2090 ± 1170 ng m−3) were double those in late June (926 ± 574 ng m−3). All the compound classes were more abundant in early June than in late June, except phthalate esters, which were higher in late June. Levoglucosan (88–1210 ng m−3, 403 ng m−3) was found as the most abundant single compound in early June, while diisobutyl phthalate was the predominant species in late June. During the biomass-burning period in early June, the diurnal trends of most of the primary and secondary organic aerosol tracers were characterized by the concentration peaks observed at mid-night or in early morning, while in late June most of the organic species peaked in late afternoon. This suggests that smoke plumes from biomass burning can uplift the aerosol particulate matter to a certain altitude and then transported to and encountered the summit of Mt. Tai during nighttime. On the basis of the tracer-based method for the estimation of biomass-burning OC, fungal-spore OC and biogenic secondary organic carbon (SOC), we estimate that an average of 24% (up to 64%) of the OC in the Mt. Tai aerosols was due to biomass burning in early June, followed by the contribution of isoprene SOC (mean 4.3%). In contrast, isoprene SOC was the main contributor (6.6%) to OC, and only 3.0% of the OC was due to biomass burning in late June. In early June, δ13C of TC (−26.6‰ to −23.2‰, mean −25.0‰) were lower than those (−23.9‰ to −21.9‰, mean −22.9‰) in late June. In addition, a strong anti-correlation was found between levoglucosan and δ13C values. This study demonstrates that crop-residue burning activities can significantly enhance the organic aerosol loading and alter the organic molecular compositions and stable carbon isotopic compositions of aerosol particles in the troposphere over North China Plain.

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Atmospheric oxidation of isoprene and 1,3-butadiene: influence of aerosol acidity and relative humidity on secondary organic aerosol

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-3773-2015 ◽

2015 ◽

Vol 15 (7) ◽

pp. 3773-3783 ◽

Cited By ~ 17

Author(s):

M. Lewandowski ◽

M. Jaoui ◽

J. H. Offenberg ◽

J. D. Krug ◽

T. E. Kleindienst

Keyword(s):

Organic Carbon ◽

Secondary Organic Aerosol ◽

Absolute Humidity ◽

Organic Aerosol ◽

Photochemical Oxidation ◽

Pronounced Increase ◽

Acid Sensitivity ◽

Aerosol Acidity ◽

Acidic Sulfate ◽

Secondary Organic Carbon

Abstract. The effects of acidic seed aerosols on the formation of secondary organic aerosol (SOA) have been examined in a number of previous studies, several of which have observed strong linear correlations between the aerosol acidity (measured as nmol H+ m−3 air sample volume) and the percent change in secondary organic carbon (SOC). The measurements have used several precursor compounds representative of different classes of biogenic hydrocarbons including isoprene, monoterpenes, and sesquiterpenes. To date, isoprene has displayed the most pronounced increase in SOC, although few measurements have been conducted with anthropogenic hydrocarbons. In the present study, we examine several aspects of the effect of aerosol acidity on the secondary organic carbon formation from the photooxidation of 1,3-butadiene, and extend the previous analysis of isoprene. The photooxidation products measured in the absence and presence of acidic sulfate aerosols were generated either through photochemical oxidation of SO2 or by nebulizing mixtures of ammonium sulfate and sulfuric acid into a 14.5 m3 smog chamber system. The results showed that, like isoprene and β-caryophyllene, 1,3-butadiene SOC yields linearly correlate with increasing acidic sulfate aerosol. The observed acid sensitivity of 0.11% SOC increase per nmol m−3 increase in H+ was approximately a factor of 3 less than that measured for isoprene. The results also showed that the aerosol yield decreased with increasing humidity for both isoprene and 1,3-butadiene, although to different degrees. Increasing the absolute humidity from 2 to 12 g m−3 reduced the 1,3-butadiene yield by 45% and the isoprene yield by 85%.

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Spatial and seasonal variations of fine particle water-soluble organic carbon (WSOC) over the Southeastern United States: implications for secondary organic aerosol formation

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-9621-2012 ◽

2012 ◽

Vol 12 (4) ◽

pp. 9621-9664 ◽

Cited By ~ 3

Author(s):

X. Zhang ◽

Z. Liu ◽

A. Hecobian ◽

M. Zheng ◽

N. H. Frank ◽

...

Keyword(s):

Organic Carbon ◽

Fine Particles ◽

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Water Soluble ◽

Aerosol Formation ◽

Southeastern Us ◽

Urban Rural ◽

Water Soluble Organic Carbon ◽

Soluble Organic Carbon

Abstract. Secondary organic aerosol (SOA) in the Southeastern US is investigated by analyzing the spatial-temporal distribution of water-soluble organic carbon (WSOC) and other PM2.5 components from 900 archived 24 h Teflon filters collected at 15 urban or rural EPA Federal Reference Method (FRM) network sites throughout 2007. Online measurements of WSOC at an urban/rural-paired site in Georgia in the summer of 2008 are contrasted to the filter data. Based on FRM filters, excluding biomass-burning events (levoglucosan < 50 ng m−3), WSOC and sulfate were highly correlated with PM2.5 mass and both comprised a large mass fraction of PM2.5 (13% and 35%, respectively). Sulfate and WSOC both tracked ambient temperature throughout the year, suggesting the temperature effects were mainly on the photochemical processes that lead to secondary formation. FRM WSOC, and to a lesser extent sulfate, were spatially homogeneous throughout the region, yet WSOC was moderately enhanced (27%) in locations of greater predicted isoprene emissions in summer. A Positive Matrix Factorization (PMF) analysis identified two major source types for the summer WSOC; 22% of the WSOC were associated with ammonium sulfate, and 56% of the WSOC was associated with brown carbon and oxalate. A small urban excess of FRM WSOC (10%) was observed in the summer of 2007, however, comparisons of online WSOC measurements at one urban/rural pair (Atlanta/Yorkville) in August 2008 showed substantially greater difference in WSOC (31%) relative to the FRM data, suggesting a low bias for urban filters. The measured Atlanta urban excess, combined with the estimated boundary layer heights, gave an estimated Atlanta daily WSOC production rate in August of 0.55 mg C m−2 h−1 between mid-morning and mid-afternoon. This study characterizes the regional nature of fine particles in the Southeastern US, confirming the importance of secondary organic aerosol and the roles of both biogenic and anthropogenic emissions.

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

10.5194/acp-2021-32 ◽

2021 ◽

Cited By ~ 1

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 μgC 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 monoterpenes 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 (IEPOX) was found to be the dominant formation pathway. Consistently, IEPOX tracers contributed 94 % of total GC-MS quantified isoprene SOA tracers. The TBM-estimated SOC (SOCTBM) and PMF-resolved 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/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. SOA formation through nighttime NO3 oxidation of biogenic VOCs, especially monoterpenes, may have made a considerable contribution to the SOA loading in Hong Kong. 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.

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Gas/particle partitioning of water-soluble organic aerosol in Atlanta

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-635-2009 ◽

2009 ◽

Vol 9 (1) ◽

pp. 635-671 ◽

Cited By ~ 2

Author(s):

C. J. Hennigan ◽

M. H. Bergin ◽

A. G. Russell ◽

A. Nenes ◽

R. J. Weber

Keyword(s):

Organic Carbon ◽

Liquid Water ◽

Fine Particle ◽

Mass Concentration ◽

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Water Soluble ◽

Formation Mechanisms ◽

Main Process ◽

Aerosol Mass Concentration

Abstract. Gas and particle-phase organic carbon compounds soluble in water (e.g., WSOC) were measured simultaneously in Atlanta throughout the summer of 2007 to investigate gas/particle partitioning of ambient secondary organic aerosol (SOA). Previous studies have established that, in the absence of biomass burning, particulate WSOC (WSOCp) is mainly from secondary organic aerosol (SOA) production. Comparisons between WSOCp, organic carbon (OC) and elemental carbon (EC) indicate that WSOCp was a nearly comprehensive measure of SOA in the Atlanta summertime. To study SOA formation mechanisms, WSOC gas-particle partitioning was investigated as a function of temperature, RH, NOx, O3, and organic aerosol mass concentration. Identifying a clear temperature effect on partitioning was confounded by other temperature-dependent processes, which likely included the emissions of biogenic SOA precursors and photochemical SOA formation. Relative humidity data indicated a linear dependence between partitioning and fine particle liquid water. Lower NOx concentrations were associated with greater partitioning to particles, but WSOC partitioning had no visible relation to O3 or fine particle OC mass concentration. There was, however, a relationship between WSOC partitioning and the WSOCp concentration, suggesting a compositional dependence between partitioning semi-volatile gases and the phase state of the aerosol. Combined, the overall results suggest that partitioning to liquid water, followed by heterogeneous reactions may represent the main process by which SOA is formed in urban Atlanta during summer.

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Receptor modelling of secondary particulate matter at UK sites

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-27255-2012 ◽

2012 ◽

Vol 12 (10) ◽

pp. 27255-27295

Author(s):

A. Charron ◽

C. Degrendele ◽

B. Laongsri ◽

R. M. Harrison

Keyword(s):

Organic Carbon ◽

Secondary Organic Aerosol ◽

Concentration Field ◽

Organic Aerosol ◽

Rural Site ◽

Regional Influence ◽

Secondary Organic Carbon ◽

The One ◽

Atmospheric Formation ◽

Made In

Abstract. Complementary approaches have been taken to better understand the sources and their spatial distribution for secondary inorganic (nitrate and sulphate) and secondary organic aerosol sampled at a rural site (Harwell) in the southern United Kingdom. A concentration field map method was applied to 1581 daily samples of chloride, nitrate and sulphate from 2006 to 2010, and 982 samples for organic carbon and elemental carbon from 2007 to 2010. This revealed a rather similar pattern of sources for nitrate, sulphate and secondary organic carbon within western/central Europe, which in the case of nitrate and sulphate, correlated significantly with EMEP emissions maps of NOx and SO2. A slightly more southerly source emphasis for secondary organic carbon may reflect the contribution of biogenic sources. Trajectory clusters confirm this pattern of behaviour with a major contribution from mainland European sources. Similar behaviours of, on the one hand, sulphate and organic carbon and, on the other hand, EC and nitrate showed that the former are more subject to regional influence than the latter in agreement with the slower atmospheric formation of sulphate and secondary organic aerosol than for nitrate, and the local/mesoscale influences upon primary EC. In a separate study, measurements of sulphate, nitrate, elemental and organic carbon were made in 100 simultaneously collected samples at Harwell and at a suburban site in Birmingham (UK). This showed a significant correlation in concentrations between the two sites for all of the secondary constituents, further indicating secondary organic aerosol to be a regional pollutant behaving similarly to sulphate and nitrate.

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Ubiquitous Influence of Wildfire Emissions and Secondary Organic Aerosol on Summertime Atmospheric Aerosol in the Forested Great Lakes Region

10.5194/acp-2017-786 ◽

2017 ◽

Author(s):

Matthew J. Gunsch ◽

Nathaniel W. May ◽

Miao Wen ◽

Courtney L. H. Bottenus ◽

Daniel J. Gardner ◽

...

Keyword(s):

Organic Carbon ◽

Great Lakes ◽

Long Range ◽

Mass Spectrometer ◽

Biomass Burning ◽

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Great Lakes Region ◽

Aerosol Mass ◽

Biomass Burning Particles

Abstract. Long-range aerosol transport affects locations hundreds of kilometers from the point of emission, leading to distant particle sources influencing rural environments that have few major local sources. Source apportionment was conducted using real-time aerosol chemistry measurements made in July 2014 at the forested University of Michigan Biological Station near Pellston, Michigan, a site representative of the remote forested Great Lakes region. Size-resolved chemical composition of individual 0.5–2.0 μm particles was measured using an aerosol time-of-flight mass spectrometer (ATOFMS), and non-refractory aerosol mass less than 1 μm (PM1) was measured by a high resolution aerosol mass spectrometer (HR-AMS). The field site was also influenced by air masses transporting Canadian wildfire emissions and urban pollution from Milwaukee and Chicago. During wildfire influenced periods, 0.5–2.0 μm particles were primarily aged biomass burning particles (88 % by number). These particles were heavily coated with secondary organic aerosol (SOA) formed during transport, with organics (average O/C ratio of 0.8) contributing 89 % of the PM1 mass. During urban-influenced periods, organic carbon, elemental carbon/organic carbon, and aged biomass burning particles were identified, with inorganic secondary species (ammonium, sulfate, and nitrate) contributing 41 % of the PM1 mass, indicative of atmospheric processing. With current models under-predicting organic carbon (OC) in this region and biomass burning being the largest combustion contributor to SOA by mass, these results highlight the importance for regional chemical transport models to accurately predict the impact of long-range transported particles on air quality in the upper Midwest United States, particularly considering increasing intensity and frequency of Canadian wildfires.

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