scholarly journals Source apportionment of fine organic aerosol in Mexico City during the MILAGRO experiment 2006

2008 ◽  
Vol 8 (5) ◽  
pp. 1249-1259 ◽  
Author(s):  
E. A. Stone ◽  
D. C. Snyder ◽  
R. J. Sheesley ◽  
A. P. Sullivan ◽  
R. J. Weber ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Mexico City ◽  
Large Fraction ◽  
Optical Filter ◽  
Soxhlet Extraction ◽  
Water Soluble ◽  
Motor Vehicles ◽  
Balance Model ◽  
Urban Site ◽  
Peripheral Site

Abstract. Organic carbon (OC) comprises a large fraction of fine particulate matter (PM2.5) in Mexico City. Daily and select 12-h PM2.5 samples were collected in urban and peripheral sites in Mexico City from 17–30 March 2006. Samples were analyzed for OC and elemental carbon (EC) using thermal-optical filter-based methods. Real-time water-soluble organic carbon (WSOC) was collected at the peripheral site. Organic compounds, particularly molecular markers, were quantified by soxhlet extraction with methanol and dichloromethane, derivitization, and gas chromatography with mass spectrometric detection (GCMS). A chemical mass balance model (CMB) based on molecular marker species was used to determine the relative contribution of major sources to ambient OC. Motor vehicles, including diesel and gasoline, consistently accounted for 49% of OC in the urban area and 32% on the periphery. The daily contribution of biomass burning to OC was highly variable, and ranged from 5–26% at the urban site and 7–39% at the peripheral site. The remaining OC unapportioned to primary sources showed a strong correlation with WSOC and was considered to be secondary in nature. Comparison of temporally resolved OC showed that contributions from primary aerosol sources during daylight hours were not significantly different from nighttime. This study provides quantitative understanding of the important sources of OC during the MILAGRO 2006 field campaign.

scholarly journals Source apportionment of fine organic aerosol in Mexico City during the MILAGRO Experiment 2006

2007 ◽  
Vol 7 (4) ◽  
pp. 9635-9661 ◽  
Author(s):  
E. A. Stone ◽  
D. C. Snyder ◽  
R. J. Sheesley ◽  
A. P. Sullivan ◽  
R. J. Weber ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Mexico City ◽  
Large Fraction ◽  
Optical Filter ◽  
Soxhlet Extraction ◽  
Water Soluble ◽  
Motor Vehicles ◽  
Balance Model ◽  
Urban Site ◽  
Peripheral Site

Abstract. Organic carbon (OC) comprises a large fraction of fine particulate matter (PM2.5) in Mexico City. Daily and select 12-h PM2.5 samples were collected in urban and peripheral sites in Mexico City from 17–30 March 2006. Samples were analyzed for OC and elemental carbon (EC) using thermal-optical filter-based methods. Real-time water-soluble organic carbon (WSOC) was collected at the peripheral site. Organic compounds, particularly molecular markers, were quantified by soxhlet extraction with methanol and dichloromethane, derivitization, and gas chromatography with mass spectrometric detection (GCMS). A chemical mass balance model (CMB) based on molecular marker species was used to determine the relative contribution of major sources to ambient OC. Motor vehicles, including diesel and gasoline, consistently accounted for 47% of OC in the urban area and 31% on the periphery. The daily contribution of biomass burning to OC was highly variable, and ranged from 5–30% at the urban site and 11–50% at the peripheral site. The remaining OC unapportioned to primary sources showed a strong correlation with WSOC and was considered to be secondary in nature. Comparison of temporally resolved OC showed that contributions from primary aerosol sources during daylight hours were not significantly different from nighttime. This study provides quantitative understanding of the important sources of OC during the MILAGRO 2006 field campaign.

scholarly journals Characteristics of PM2.5 Chemical Compositions and Their Effect on Atmospheric Visibility in Urban Beijing, China during the Heating Season

2018 ◽  
Vol 15 (9) ◽  
pp. 1924 ◽  
Author(s):  
Xing Li ◽  
Shanshan Li ◽  
Qiulin Xiong ◽  
Xingchuan Yang ◽  
Mengxi Qi ◽  
...  
Keyword(s):  
Fine Particles ◽  
Inorganic Ions ◽  
Water Soluble ◽  
Motor Vehicles ◽  
Urban Site ◽  
Chemical Compositions ◽  
Heating Season ◽  
Atmospheric Visibility ◽  
Visibility Impairment ◽  
Mass Concentrations

Beijing, which is the capital of China, suffers from severe Fine Particles (PM2.5) pollution during the heating season. In order to take measures to control the PM2.5 pollution and improve the atmospheric environmental quality, daily PM2.5 samples were collected at an urban site from 15 November to 31 December 2016, characteristics of PM2.5 chemical compositions and their effect on atmospheric visibility were analyzed. It was found that the daily average mass concentrations of PM2.5 ranged from 7.64 to 383.00 μg m−3, with an average concentration of 114.17 μg m−3. On average, the Organic Carbon (OC) and Elemental Carbon (EC) contributed 21.39% and 5.21% to PM2.5, respectively. Secondary inorganic ions (SNA: SO42− + NO3− + NH4+) dominated the Water-Soluble Inorganic Ions (WSIIs) and they accounted for 47.09% of PM2.5. The mass concentrations of NH4+, NO3− and SO42− during the highly polluted period were 8.08, 8.88 and 6.85 times greater, respectively, than during the clean period, which contributed most to the serious PM2.5 pollution through the secondary transformation of NO2, SO2 and NH3. During the highly polluted period, NH4NO3 contributed most to the reconstruction extinction coefficient (b′ext), accounting for 35.7%, followed by (NH4)2SO4 (34.44%) and Organic Matter (OM: 15.24%). The acidity of PM2.5 in Beijing was weakly acid. Acidity of PM2.5 and relatively high humidity could aggravate PM2.5 pollution and visibility impairment by promoting the generation of secondary aerosol. Local motor vehicles contributed the most to NO3−, OC, and visibility impairment in urban Beijing. Other sources of pollution in the area surrounding urban Beijing, including coal burning, agricultural sources, and industrial sources in the Hebei, Shandong, and Henan provinces, released large amounts of SO2, NH3, and NO2. These, which were transformed into SO42−, NH4+, and NO3− during the transmission process, respectively, and had a great impact on atmospheric visibility impairment.

scholarly journals An optimized tracer-based approach for estimating organic carbon emissions from biomass burning in Ulaanbaatar, Mongolia

2020 ◽  
Vol 20 (5) ◽  
pp. 3231-3247 ◽  
Author(s):  
Jayant Nirmalkar ◽  
Tsatsral Batmunkh ◽  
Jinsang Jung
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Quantitative Estimation ◽  
Water Soluble ◽  
Atmospheric Particulate Matter ◽  
Coefficient Of Determination ◽  
Urban Site ◽  
Air Sampler ◽  
Novel Approach ◽  
The Impact

Abstract. The impact of biomass burning (BB) on atmospheric particulate matter of <2.5 µm diameter (PM2.5) at Ulaanbaatar, Mongolia, was investigated using an optimized tracer-based approach during winter and spring 2017. Integrated 24 h PM2.5 samples were collected on quartz-fiber filters using a 30 L min−1 air sampler at an urban site in Ulaanbaatar. The aerosol samples were analyzed for organic carbon (OC) and elemental carbon (EC), anhydrosugars (levoglucosan, mannosan, and galactosan), and water-soluble ions. OC was found to be the predominant species, contributing 64 % and 56 % to the quantified aerosol components in PM2.5 in winter and spring, respectively. BB was identified as a major source of PM2.5, followed by dust and secondary aerosols. Levoglucosan ∕ mannosan and levoglucosan ∕ K+ ratios indicate that BB in Ulaanbaatar mainly originated from the burning of softwood. Because of the large uncertainty associated with the quantitative estimation of OC emitted from BB (OCBB), a novel approach was developed to optimize the OC ∕ levoglucosan ratio for estimating OCBB. The optimum OC ∕ levoglucosan ratio in Ulaanbaatar was obtained by regression analysis between OCnon-BB (OCtotal–OCBB) and levoglucosan concentrations that gives the lowest coefficient of determination (R2) and slope. The optimum OC ∕ levoglucosan ratio was found to be 27.6 and 18.0 for winter and spring, respectively, and these values were applied in quantifying OCBB. It was found that 68 % and 63 % of the OC were emitted from BB during winter and spring, respectively. This novel approach can also be applied by other researchers to quantify OCBB using their own chemical measurements. In addition to OCBB, sources of OCnon-BB were also investigated through multivariate correlation analysis. It was found that OCnon-BB originated mainly from coal burning, vehicles, and vegetative emissions.

scholarly journals Fossil and non-fossil sources of organic carbon (OC) and elemental carbon (EC) in Göteborg, Sweden

2009 ◽  
Vol 9 (5) ◽  
pp. 1521-1535 ◽  
Author(s):  
S. Szidat ◽  
M. Ruff ◽  
N. Perron ◽  
L. Wacker ◽  
H.-A. Synal ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Elemental Carbon ◽  
Latin Hypercube Sampling ◽  
Water Soluble ◽  
Total Carbon ◽  
Rural Site ◽  
Urban Site ◽  
Winter Period ◽  
Back Trajectories ◽  
Wood Burning

Abstract. Particulate matter was collected at an urban site in Göteborg (Sweden) in February/March 2005 and in June/July 2006. Additional samples were collected at a rural site for the winter period. Total carbon (TC) concentrations were 2.1–3.6 μg m−3, 1.8–1.9 μg m−3, and 2.2–3.0 μg m−3 for urban/winter, rural/winter, and urban/summer conditions, respectively. Elemental carbon (EC), organic carbon (OC), water-insoluble OC (WINSOC), and water-soluble OC (WSOC) were analyzed for 14C in order to distinguish fossil from non-fossil emissions. As wood burning is the single major source of non-fossil EC, its contribution can be quantified directly. For non-fossil OC, the wood-burning fraction was determined independently by levoglucosan and 14C analysis and combined using Latin-hypercube sampling (LHS). For the winter period, the relative contribution of EC from wood burning to the total EC was >3 times higher at the rural site compared to the urban site, whereas the absolute concentrations of EC from wood burning were elevated only moderately at the rural compared to the urban site. Thus, the urban site is substantially more influenced by fossil EC emissions. For summer, biogenic emissions dominated OC concentrations most likely due to secondary organic aerosol (SOA) formation. During both seasons, a more pronounced fossil signal was observed for Göteborg than has previously been reported for Zurich, Switzerland. Analysis of air mass origin using back trajectories suggests that the fossil impact was larger when local sources dominated, whereas long-range transport caused an enhanced non-fossil signal. In comparison to other European locations, concentrations of levoglucosan and other monosaccharide anhydrides were low for the urban and the rural site in the area of Göteborg during winter.

scholarly journals Fossil and non-fossil sources of organic carbon (OC) and elemental carbon (EC) in Göteborg, Sweden

2008 ◽  
Vol 8 (4) ◽  
pp. 16255-16289 ◽  
Author(s):  
S. Szidat ◽  
M. Ruff ◽  
L. Wacker ◽  
H.-A. Synal ◽  
M. Hallquist ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Elemental Carbon ◽  
Latin Hypercube Sampling ◽  
Water Soluble ◽  
Rural Site ◽  
Urban Site ◽  
Winter Period ◽  
Back Trajectories ◽  
Relative Contribution ◽  
Wood Burning

Abstract. Particulate matter was collected at an urban site in Göteborg (Sweden) in February/March 2005 and in June/July 2006. Additional samples were collected at a rural site for the winter period. Elemental carbon (EC), organic carbon (OC), water-insoluble OC (WINSOC), and water-soluble OC (WSOC) were analyzed for 14C in order to distinguish fossil from non-fossil emissions. As wood burning is the single major source of non-fossil EC, its contribution can be quantified directly. For non-fossil OC, the wood burning fraction was determined independently by levoglucosan and 14C analysis and combined using Latin-hypercube sampling (LHS). For the winter period, the relative contribution of EC from wood burning to the total EC was >3 times higher at the rural site compared to the urban site, whereas the absolute concentrations of EC from wood burning were comparable at both sites. Thus, the urban site is substantially more influenced by fossil EC emissions. For summer, biogenic emissions dominated OC concentrations most likely due to secondary organic aerosol (SOA) formation. During both seasons, a more pronounced fossil signal was observed for Göteborg than has previously been reported for Zurich, Switzerland. Analysis of air mass origin using back trajectories suggests that the fossil impact was larger when local sources dominated, whereas long-range transport caused an enhanced non-fossil signal. In comparison to other European locations, concentrations of levoglucosan and other monosaccharide anhydrides were low for the urban and the rural site in the area of Göteborg during winter. The comparison of summer and winter results provides insight into the annual cycle of anthropogenic vs. biogenic contributions to the atmospheric aerosol.

scholarly journals Source apportionment of carbonaceous aerosols in Beijing with radiocarbon and organic tracers: insight into the differences between urban and rural sites

2021 ◽  
Vol 21 (10) ◽  
pp. 8273-8292
Author(s):  
Siqi Hou ◽  
Di Liu ◽  
Jingsha Xu ◽  
Tuan V. Vu ◽  
Xuefang Wu ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Biomass Burning ◽  
Fine Particles ◽  
Water Soluble ◽  
Carbonaceous Aerosol ◽  
Balance Model ◽  
Gas Chromatography Mass Spectrometry ◽  
Urban Site ◽  
Carbonaceous Aerosols ◽  
Carbonaceous Particles

Abstract. Carbonaceous aerosol is a dominant component of fine particles in Beijing. However, it is challenging to apportion its sources. Here, we applied a newly developed method which combined radiocarbon (14C) with organic tracers to apportion the sources of fine carbonaceous particles at an urban (IAP) and a rural (PG) site of Beijing. PM2.5 filter samples (24 h) were collected at both sites from 10 November to 11 December 2016 and from 22 May to 24 June 2017. 14C was determined in 25 aerosol samples (13 at IAP and 12 at PG) representing low pollution to haze conditions. Biomass burning tracers (levoglucosan, mannosan, and galactosan) in the samples were also determined using gas chromatography–mass spectrometry (GC-MS). Higher contributions of fossil-derived OC (OCf) were found at the urban site. The OCf / OC ratio decreased in the summer samples (IAP: 67.8 ± 4.0 % in winter and 54.2 ± 11.7 % in summer; PG: 59.3 ± 5.7 % in winter and 50.0 ± 9.0 % in summer) due to less consumption of coal in the warm season. A novel extended Gelencsér (EG) method incorporating the 14C and organic tracer data was developed to estimate the fossil and non-fossil sources of primary and secondary OC (POC and SOC). It showed that fossil-derived POC was the largest contributor to OC (35.8 ± 10.5 % and 34.1 ± 8.7 % in wintertime for IAP and PG, 28.9 ± 7.4 % and 29.1 ± 9.4 % in summer), regardless of season. SOC contributed 50.0 ± 12.3 % and 47.2 ± 15.5 % at IAP and 42.0 ± 11.7 % and 43.0 ± 13.4 % at PG in the winter and summer sampling periods, respectively, within which the fossil-derived SOC was predominant and contributed more in winter. The non-fossil fractions of SOC increased in summer due to a larger biogenic component. Concentrations of biomass burning OC (OCbb) are resolved by the extended Gelencsér method, with average contributions (to total OC) of 10.6 ± 1.7 % and 10.4 ± 1.5 % in winter at IAP and PG and 6.5 ± 5.2 % and 17.9 ± 3.5 % in summer, respectively. Correlations of water-insoluble OC (WINSOC) and water-soluble OC (WSOC) with POC and SOC showed that although WINSOC was the major contributor to POC, a non-negligible fraction of WINSOC was found in SOC for both fossil and non-fossil sources, especially during winter. In summer, a greater proportion of WSOC from non-fossil sources was found in SOC. Comparisons of the source apportionment results with those obtained from a chemical mass balance model were generally good, except for the cooking aerosol.

scholarly journals Emission and chemistry of organic carbon in the gas and aerosol phase at a sub-urban site near Mexico City in March 2006 during the MILAGRO study

2008 ◽  
Vol 8 (6) ◽  
pp. 21265-21312 ◽  
Author(s):  
J. A. de Gouw ◽  
D. Welsh-Bon ◽  
C. Warneke ◽  
W. C. Kuster ◽  
L. Alexander ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Organic Carbon ◽  
Mexico City ◽  
Organic Aerosol ◽  
Early Morning ◽  
Diurnal Variations ◽  
Urban Site ◽  
Secondary Formation ◽  
The Us ◽  
Emission Ratios

Abstract. Volatile organic compounds (VOCs) and carbonaceous aerosol were measured at a sub-urban site near Mexico City in March of 2006 during the MILAGRO study (Megacity Initiative: Local and Global Research Objectives). Diurnal variations of hydrocarbons, elemental carbon (EC) and hydrocarbon-like organic aerosol (HOA) were dominated by a high peak in the early morning when local emissions accumulated in a shallow boundary layer, and a minimum in the afternoon when the emissions were diluted in a significantly expanded boundary layer and, in case of the reactive gases, removed by OH. In comparison, diurnal variations of species with secondary sources such as the aldehydes, ketones, oxygenated organic aerosol (OOA) and water-soluble organic carbon (WSOC) stayed relatively high in the afternoon indicating strong photochemical formation. Emission ratios of many hydrocarbon species relative to CO were higher in Mexico City than in the US, but we found similar emission ratios for most oxygenated VOCs and organic aerosol. Secondary formation of acetone may be more efficient in Mexico City than in the US, due to higher emissions of alkane precursors from the use of liquefied petroleum gas. Secondary formation of organic aerosol was similar between Mexico City and the US. Combining the data for all measured gas and aerosol species, we describe the budget of total observed organic carbon (TOOC), and find that the enhancement ratio of TOOC relative to CO is conserved between the early morning and mid afternoon despite large compositional changes. Finally, the influence of biomass burning is investigated using the measurements of acetonitrile, which was found to correlate with levoglucosan in the particle phase. Diurnal variations of acetonitrile indicate a contribution from local burning sources. Scatter plots of acetonitrile versus CO suggest that the contribution of biomass burning to the enhancement of most gas and aerosol species was not dominant and perhaps not dissimilar from observations in the US.

scholarly journals Source apportionment of fine organic carbon at an urban site of Beijing using a chemical mass balance model

2021 ◽  
Vol 21 (9) ◽  
pp. 7321-7341
Author(s):  
Jingsha Xu ◽  
Di Liu ◽  
Xuefang Wu ◽  
Tuan V. Vu ◽  
Yanli Zhang ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Mass Balance ◽  
Source Apportionment ◽  
Biomass Burning ◽  
Coal Combustion ◽  
Fine Particles ◽  
Inorganic Ions ◽  
Balance Model ◽  
Urban Site ◽  
Chemical Mass Balance

Abstract. Fine particles were sampled from 9 November to 11 December 2016 and 22 May to 24 June 2017 as part of the Atmospheric Pollution and Human Health in a Chinese Megacity (APHH-China) field campaigns in urban Beijing, China. Inorganic ions, trace elements, organic carbon (OC), elemental carbon (EC), and organic compounds, including biomarkers, hopanes, polycyclic aromatic hydrocarbons (PAHs), n-alkanes, and fatty acids, were determined for source apportionment in this study. Carbonaceous components contributed on average 47.2 % and 35.2 % of total reconstructed PM2.5 during the winter and summer campaigns, respectively. Secondary inorganic ions (sulfate, nitrate, ammonium; SNA) accounted for 35.0 % and 45.2 % of total PM2.5 in winter and summer. Other components including inorganic ions (K+, Na+, Cl−), geological minerals, and trace metals only contributed 13.2 % and 12.4 % of PM2.5 during the winter and summer campaigns. Fine OC was explained by seven primary sources (industrial and residential coal burning, biomass burning, gasoline and diesel vehicles, cooking, and vegetative detritus) based on a chemical mass balance (CMB) receptor model. It explained an average of 75.7 % and 56.1 % of fine OC in winter and summer, respectively. Other (unexplained) OC was compared with the secondary OC (SOC) estimated by the EC-tracer method, with correlation coefficients (R2) of 0.58 and 0.73 and slopes of 1.16 and 0.80 in winter and summer, respectively. This suggests that the unexplained OC by the CMB model was mostly associated with SOC. PM2.5 apportioned by the CMB model showed that the SNA and secondary organic matter were the two highest contributors to PM2.5. After these, coal combustion and biomass burning were also significant sources of PM2.5 in winter. The CMB results were also compared with results from the positive matrix factorization (PMF) analysis of co-located aerosol mass spectrometer (AMS) data. The CMB model was found to resolve more primary organic aerosol (OA) sources than AMS-PMF, but the latter could apportion secondary OA sources. The AMS-PMF results for major components, such as coal combustion OC and oxidized OC, correlated well with the results from the CMB model. However, discrepancies and poor agreements were found for other OC sources, such as biomass burning and cooking, some of which were not identified in AMS-PMF factors.

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