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

2021 ◽  
Vol 21 (13) ◽  
pp. 10589-10608
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 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.

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

2021 ◽  
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.

Secondary Organic Aerosol Formation from Urban Roadside Air in Hong Kong

2019 ◽  
Vol 53 (6) ◽  
pp. 3001-3009 ◽  
Author(s):  
Tengyu Liu ◽  
Liyuan Zhou ◽  
Qianyun Liu ◽  
Berto P. Lee ◽  
Dawen Yao ◽  
...  
Keyword(s):  
Hong Kong ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Aerosol Formation ◽  
Secondary Organic Aerosol Formation

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

2012 ◽  
Vol 12 (4) ◽  
pp. 9621-9664 ◽  
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.

scholarly journals Comparison of secondary organic aerosol formation from toluene on initially wet and dry ammonium sulfate particles

2017 ◽  
Author(s):  
Tengyu Liu ◽  
Dan Dan Huang ◽  
Zijun Li ◽  
Qianyun Liu ◽  
ManNin Chan ◽  
...  
Keyword(s):  
Ammonium Sulfate ◽  
Functional Groups ◽  
Flow Reactor ◽  
Secondary Organic Aerosol ◽  
Large Fraction ◽  
Organic Aerosol ◽  
Aerosol Formation ◽  
Seed Particles ◽  
The Difference ◽  
Wet Particles

Abstract. The formation of secondary organic aerosol (SOA) has been widely studied in the presence of dry seed particles at low relative humidity (RH). At higher RH, seed particles can exist as dry or wet particles. Here, we investigated the formation of SOA from the photooxidation of toluene using an oxidation flow reactor under a range of OH exposures on initially wet or dry ammonium sulfate (AS) seed particles at an RH of 68 %. At an OH exposure of 4.66 × 1010 molecules cm -3 s, the ratio of the SOA yield on wet AS seeds to that on dry AS seeds was 1.31 ± 0.02. However, this ratio decreased to 1.01 ± 0.01 at an OH exposure of 5.28 × 1011 molecules cm -3 s. The decrease in the ratios of SOA yields as the increase of OH exposure may be due to the early deliquescence of initially dry AS seeds after coated by highly oxidized toluene-derived SOA. SOA formation lowered the deliquescence RH of AS and resulted in the uptake of water by both AS and SOA. Hence the initially dry AS seeds contained aerosol liquid water (ALW) soon after a large fraction of SOA formed and the SOA yield and ALW approached those of the initially wet AS seeds as OH exposure and ALW increased. However, a higher oxidation state of the SOA on initially wet AS seeds than that on dry AS seeds was observed at all levels of OH exposure. The difference in mass fractions of m/z 29, 43 and 44 of SOA mass spectra indicated that SOA formed on initially wet seeds may be enriched in earlier-generation products containing carbonyl functional groups at low OH exposures and later-generation products containing acidic functional groups at high exposures. Our results suggest that AS dry seeds soon turn to at least partially deliquesced particles during SOA formation and more studies on the interplay of SOA formation and ALW are warranted.

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

2012 ◽  
Vol 12 (14) ◽  
pp. 6593-6607 ◽  
Author(s):  
X. Zhang ◽  
Z. Liu ◽  
A. Hecobian ◽  
M. Zheng ◽  
N. H. Frank ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Ammonium Sulfate ◽  
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 (r2~0.7). Both components comprised a large mass fraction of PM2.5 (13% and 31%, respectively, or ~25% and 50% for WSOM and ammonium sulfate). Sulfate and WSOC both tracked ambient temperature throughout the year, suggesting the temperature effects were mainly linked to faster photochemistry and/or synoptic meteorology and less due to enhanced biogenic hydrocarbon emissions. 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 were 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 mgC 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 SOA and the roles of both biogenic and anthropogenic emissions.

scholarly journals A secondary organic aerosol formation model considering successive oxidation aging and kinetic condensation of organic compounds: global scale implications

2011 ◽  
Vol 11 (3) ◽  
pp. 1083-1099 ◽  
Author(s):  
F. Yu
Keyword(s):  
Boundary Layer ◽  
Secondary Organic Aerosol ◽  
Large Fraction ◽  
Lower Boundary ◽  
Particle Growth ◽  
Organic Aerosol ◽  
Forest Site ◽  
Aerosol Formation ◽  
Formation Model ◽  
Condensation Nuclei

Abstract. The widely used two-product secondary organic aerosol (SOA) formation model has been extended in this study to consider the volatility changes of secondary organic gases (SOG) arising from the aging process as well as the kinetic condensation of low volatile SOG (LV-SOG). In addition to semi-volatile SOG (SV-SOG) with saturation vapor pressure at 290 K (C*290) in the range of ~3 ppt–3 ppb and medium-volatile SOG (MV-SOG) with C*290 in the range of ~0.3–300 ppb, we add a third component representing LV-SOG with C*290 below ~3 ppt and design a scheme to transfer MV-SOG to SV-SOG and SV-SOG to LV-SOG associated with oxidation aging. This extended SOA formation model has been implemented in a global aerosol model (GEOS-Chem) and the co-condensation of H2SO4 and LV-SOG on pre-existing particles is explicitly simulated. We show that, over many parts of the continents, LV-SOG concentrations are generally a factor of ~2–20 higher than those of H2SO4 and the kinetic condensation of LV-SOG significantly enhances particle growth rates. Comparisons of the simulated and observed evolution of particle size distributions at a boreal forest site (Hyytiälä, Finland) clearly show that LV-SOG condensation is critical in order to bring the simulations closer to the observations. With the new SOA formation scheme, annual mean SOA mass increases by a factor of 2–10 in many parts of the boundary layer and reaches above 0.5 μg m−3 in most parts of the main continents, improving the agreement with aerosol mass spectrometer (AMS) SOA measurements. While the new scheme generally decreases the concentration of condensation nuclei larger than 10 nm by 3–30% in the lower boundary layer as a result of enhanced surface area and reduced nucleation rates, it substantially increases the concentration of cloud condensation nuclei at a water supersaturation ratio of 0.2%, ranging from ~5–20% over a large fraction of oceans and high latitude continents to more than 50% over some parts of South America, Australia, and Indonesia. Our study highlights the importance for global aerosol models to explicitly account for the oxidation aging of SOGs and their contribution to particle growth.

Assessment of biogenic secondary organic aerosol in the Himalayas

2012 ◽  
Vol 9 (3) ◽  
pp. 263 ◽  
Author(s):  
Elizabeth A. Stone ◽  
Tony T. Nguyen ◽  
Bidya Banmali Pradhan ◽  
Pradeep Man Dangol
Keyword(s):  
Organic Carbon ◽  
Fine Particles ◽  
Secondary Organic Aerosol ◽  
Monsoon Season ◽  
Late Summer ◽  
Organic Aerosol ◽  
Motor Vehicles ◽  
Gas Chromatography Mass Spectrometry ◽  
Organic Carbon Content ◽  
Aerosol Sources

Environmental contextSecondary organic aerosols derived from biogenic gases are ubiquitous in the atmosphere. We found that biogenic secondary organic aerosol in Nepal accounted for 6 to 23 % of organic carbon. Primary and secondary biogenic sources combined accounted for approximately half of the observed organic aerosol, suggesting that additional aerosol sources or precursors are significant in this region of the Himalayas. AbstractBiogenic contributions to secondary organic aerosol (SOA) in the South-East Asian regional haze were assessed by measurement of isoprene, monoterpene and sesquiterpene photooxidation products in fine particles (PM2.5) at a mid-latitude site in the Himalayas. Organic species were measured in solvent extracts of filter samples using gas chromatography–mass spectrometry (GCMS) and chemical derivatisation; this analysis was used to quantify molecular markers for primary aerosol sources – including motor vehicles, biomass burning and detritus – and SOA tracers. Authentic standards of most SOA products were not commercially available at the time of this study, so surrogate standards were used for semiquantitation. Using an empirical approach to uncertainty estimation based on homologous series of atmospherically relevant model compounds, analytical uncertainties ranged from 32 % for SOA tracers with structurally similar surrogates to more than 100 % for tracers with a poorly matched surrogate. Biogenic SOA contributions to PM2.5 organic carbon content in the 2005 monsoon and post-monsoon season ranged from 2–19 % for isoprene, 1–5 % for monoterpenes and 1–4 % for sesquiterpenes. High concentrations of isoprene derivatives in aerosol, particularly in the late summer months, point to biogenic SOA as a significant source of organic carbon in the Himalayan region.

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