scholarly journals PM<sub>2.5</sub> pollution in a megacity of southwest China: source apportionment and implication

2014 ◽  
Vol 14 (16) ◽  
pp. 8679-8699 ◽  
Author(s):  
J. Tao ◽  
J. Gao ◽  
L. Zhang ◽  
R. Zhang ◽  
H. Che ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Coal Combustion ◽  
Southwest China ◽  
Anthropogenic Sources ◽  
Chemical Components ◽  
Emission Sources ◽  
Annual Average ◽  
Iron And Steel ◽  
Pmf Model ◽  
Steel Manufacturing

Abstract. Daily PM2.5 (aerosol particles with an aerodynamic diameter of less than 2.5 μm) samples were collected at an urban site in Chengdu, an inland megacity in southwest China, during four 1-month periods in 2011, with each period in a different season. Samples were subject to chemical analysis for various chemical components ranging from major water-soluble ions, organic carbon (OC), element carbon (EC), trace elements to biomass burning tracers, anhydrosugar levoglucosan (LG), and mannosan (MN). Two models, the ISORROPIA II thermodynamic equilibrium model and the positive matrix factorization (PMF) model, were applied to explore the likely chemical forms of ionic constituents and to apportion sources for PM2.5. Distinctive seasonal patterns of PM2.5 and associated main chemical components were identified and could be explained by varying emission sources and meteorological conditions. PM2.5 showed a typical seasonality of waxing in winter and waning in summer, with an annual mean of 119 μg m−3. Mineral soil concentrations increased in spring, whereas biomass burning species elevated in autumn and winter. Six major source factors were identified to have contributed to PM2.5 using the PMF model. These were secondary inorganic aerosols, coal combustion, biomass burning, iron and steel manufacturing, Mo-related industries, and soil dust, and they contributed 37 ± 18, 20 ± 12, 11 ± 10, 11 ± 9, 11 ± 9, and 10 ± 12%, respectively, to PM2.5 masses on annual average, while exhibiting large seasonal variability. On annual average, the unknown emission sources that were not identified by the PMF model contributed 1 ± 11% to the measured PM2.5 mass. Various chemical tracers were used for validating PMF performance. Antimony (Sb) was suggested to be a suitable tracer of coal combustion in Chengdu. Results of LG and MN helped constrain the biomass burning sources, with wood burning dominating in winter and agricultural waste burning dominating in autumn. Excessive Fe (Ex-Fe), defined as the excessive portion in measured Fe that cannot be sustained by mineral dust, is corroborated to be a straightforward useful tracer of iron and steel manufacturing pollution. In Chengdu, Mo / Ni mass ratios were persistently higher than unity, and considerably distinct from those usually observed in ambient airs. V / Ni ratios averaged only 0.7. Results revealed that heavy oil fuel combustion should not be a vital anthropogenic source, and additional anthropogenic sources for Mo are yet to be identified. Overall, the emission sources identified in Chengdu could be dominated by local sources located in the vicinity of Sichuan, a result different from those found in Beijing and Shanghai, wherein cross-boundary transport is significant in contributing pronounced PM2.5. These results provided implications for PM2.5 control strategies.

scholarly journals PM<sub>2.5</sub> pollution in a megacity of southwest China: source apportionment and implication

2014 ◽  
Vol 14 (4) ◽  
pp. 5147-5196 ◽  
Author(s):  
J. Tao ◽  
J. Gao ◽  
L. Zhang ◽  
R. Zhang ◽  
H. Che ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Coal Combustion ◽  
Southwest China ◽  
Anthropogenic Sources ◽  
Chemical Components ◽  
Emission Sources ◽  
Annual Average ◽  
Iron And Steel ◽  
Pmf Model ◽  
Steel Manufacturing

Abstract. Daily PM2.5 (aerosol particles with an aerodynamic diameter of less than 2.5 μm) samples were collected at an urban site in Chengdu, an inland megacity in southwest China, during four one-month periods in 2011, with each period in a different season. Samples were subjected to chemical analysis for various chemical components ranging from major water-soluble ions, organic carbon (OC), element carbon (EC), trace elements to biomass burning tracers, anhydrosugar levoglucosan (LG) and mannosan (MN). Two models, ISORROPIA-II thermodynamic equilibrium model and positive matrix factorization (PMF) model, were applied to explore the likely chemical forms of ionic constituents and to apportion sources for PM2.5. Distinctive seasonal patterns of PM2.5 and associated main chemical components were identified and could be explained by varying emission sources and meteorological conditions. PM2.5 showed a typical seasonality of waxing in winter and waning in summer, with an annual mean of 119 μg m−3. Mineral soil concentrations increased in spring whereas biomass burning species elevated in autumn and winter. Six major source factors were identified to have contributed to PM2.5 using the PMF model. These were secondary inorganic aerosols, coal combustion, biomass burning, iron and steel manufacturing, Mo-related industries, and soil dust, and they contributed 37 ± 18%, 20 ± 12%, 11 ± 10%, 11 ± 9%, 11 ± 9%, and 10 ± 12%, respectively, to PM2.5 masses on annual average, while exhibiting large seasonal variability. On annual average, the unknown emission sources that were not identified by the PMF model contributed 1 ± 11% to the measured PM2.5 mass. Various chemical tracers were used for validating PMF performance. Antimony (Sb) was suggested to be a suitable tracer of coal combustion in Chengdu. Results of LG and MN helped constrain the biomass burning sources, with wood burning dominating in winter and agricultural waste burning dominating in autumn. Excessive Fe (Ex-Fe), defined as excessive portion in measured Fe that cannot be sustained by mineral dust, is corroborated to be a straightforward useful tracer of iron and steel manufacturing pollution. In Chengdu, Mo/Ni mass ratios were persistently higher than unity, and considerably distinct from those usually observed in ambient airs. V/Ni ratios averaged at only 0.7. Results revealed that heavy oil fuel combustion should not be a vital anthropogenic source, and additional anthropogenic sources for Mo are yet to be identified. Overall, the emission sources identified in Chengdu could be dominated by local sources located in the vicinity of Sichuan, a result differed from those found in Beijing and Shanghai, wherein cross-boundary transport is significant in contributing pronounced PM2.5. These results provided implications for PM2.5 control strategies.

scholarly journals Seasonal variations in high time-resolved chemical compositions, sources, and evolution of atmospheric submicron aerosols in the megacity Beijing

2017 ◽  
Vol 17 (16) ◽  
pp. 9979-10000 ◽  
Author(s):  
Wei Hu ◽  
Min Hu ◽  
Wei-Wei Hu ◽  
Jing Zheng ◽  
Chen Chen ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Coal Combustion ◽  
Fine Particles ◽  
Liquid Water Content ◽  
Urban Site ◽  
Chemical Components ◽  
Chemical Compositions ◽  
Average Mass ◽  
Four Seasons ◽  
Secondary Formation

Abstract. A severe regional haze problem in the megacity Beijing and surrounding areas, caused by fast formation and growth of fine particles, has attracted much attention in recent years. In order to investigate the secondary formation and aging process of urban aerosols, four intensive campaigns were conducted in four seasons between March 2012 and March 2013 at an urban site in Beijing (116.31° E, 37.99° N). An Aerodyne high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS) was deployed to measure non-refractory chemical components of submicron particulate matter (NR-PM1). The average mass concentrations of PM1 (NR-PM1+black carbon) were 45.1 ± 45.8, 37.5 ± 31.0, 41.3 ± 42.7, and 81.7 ± 72.4 µg m−3 in spring, summer, autumn, and winter, respectively. Organic aerosol (OA) was the most abundant component in PM1, accounting for 31, 33, 44, and 36 % seasonally, and secondary inorganic aerosol (SNA, sum of sulfate, nitrate, and ammonium) accounted for 59, 57, 43, and 55 % of PM1 correspondingly. Based on the application of positive matrix factorization (PMF), the sources of OA were obtained, including the primary ones of hydrocarbon-like (HOA), cooking (COA), biomass burning OA (BBOA) and coal combustion OA (CCOA), and secondary component oxygenated OA (OOA). OOA, which can be split into more-oxidized (MO-OOA) and less-oxidized OOA (LO-OOA), accounted for 49, 69, 47, and 50 % in four seasons, respectively. Totally, the fraction of secondary components (OOA+SNA) contributed about 60–80 % to PM1, suggesting that secondary formation played an important role in the PM pollution in Beijing, and primary sources were also non-negligible. The evolution process of OA in different seasons was investigated with multiple metrics and tools. The average carbon oxidation states and other metrics show that the oxidation state of OA was the highest in summer, probably due to both strong photochemical and aqueous-phase oxidations. It was indicated by the good correlations (r = 0.53–0.75, p < 0.01) between LO-OOA and odd oxygen (Ox =  O3 + NO2), and between MO-OOA and liquid water content in aerosols. BBOA was resolved in spring and autumn, influenced by agricultural biomass burning (e.g., field preparation burnings, straw burning after the harvest). CCOA was only identified in winter due to domestic heating. These results signified that the comprehensive management for biomass burning and coal combustion emissions is needed. High concentrations of chemical components in PM1 in Beijing, especially in winter or in adverse meteorological conditions, suggest that further strengthening the regional emission control of primary particulate and precursors of secondary species is expected.

scholarly journals Seasonal variations of high time-resolved chemical compositions, sources and evolution for atmospheric submicron aerosols in the megacity Beijing

2017 ◽  
Author(s):  
Wei Hu ◽  
Min Hu ◽  
Wei-Wei Hu ◽  
Jing Zheng ◽  
Chen Chen ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Coal Combustion ◽  
Fine Particles ◽  
Urban Site ◽  
Chemical Components ◽  
Chemical Compositions ◽  
Average Mass ◽  
Four Seasons ◽  
Secondary Formation ◽  
Autumn And Winter

Abstract. Severe regional haze problem in the megacity Beijing and surrounding areas, caused by fast formation and growth of fine particles, has attracted much attention in recent years. In order to investigate the secondary formation and aging process of urban aerosols, four intensive campaigns were conducted in four seasons between March 2012 and March 2013 at an urban site in Beijing (116.31° E, 37.99° N). An Aerodyne high resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS) and other relevant instrumentations for gaseous and particulate pollutants were deployed. The average mass concentrations of submicron particulate matter (PM1) were 45.1±45.8, 37.5±31.0, 41.3±42.7, and 81.7±72.4 μg m−3 in spring, summer, autumn and winter, respectively. Organic aerosol (OA) was the most abundant component in PM1, accounting for 31, 33, 44 and 36 % seasonally, and secondary inorganic aerosol (SNA, sum of sulfate, nitrate and ammonium) accounted for 59, 57, 43, and 55 % of PM1 correspondingly. Based on the application of positive matrix factorization (PMF), the sources of OA were obtained, including the primary ones of hydrocarbon-like (HOA), cooking (COA), biomass burning OA (BBOA) and coal combustion OA (CCOA), and secondary component oxygenated OA (OOA). OOA, usually composed of more-oxidized (MO-OOA) and less-oxidized OOA (LO-OOA), accounted for 63, 69, 47 and 50 % in four seasons, respectively. Totally, the fraction of secondary components (OOA+SNA) contributed about 60–80 % to PM1, suggesting that secondary formation played an important role in the PM pollution in Beijing, and primary sources were also non-negligible. The evolution process of OA in different seasons was investigated with multiple metrics and tools. The average carbon oxidation states and other metrics show that the oxidation state of OA was the highest in summer, probably due to both strong photochemical and aqueous-phase oxidations. BBOA and CCOA were only resolved in autumn and winter, respectively, consistent with the agricultural activities (e.g., straw burning after the harvest in suburban areas) in autumn and domestic heating in winter, signifying that the comprehensive management for the emissions from biomass burning and coal combustion are needed. High concentrations of chemical components in PM1 in Beijing, especially in winter or in adverse meteorological conditions, suggest that further strengthening the regional emission control of primary particulate and precursors of secondary species is expected.

scholarly journals Isotopic partitioning of nitrogen in PM<sub>2.5</sub> at Beijing and a background site of China

2016 ◽  
Author(s):  
Yan-Li Wang ◽  
Xue-Yan Liu ◽  
Wei Song ◽  
Wen Yang ◽  
Bin Han ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Coal Combustion ◽  
Fertilizer Application ◽  
Anthropogenic Sources ◽  
Organic N ◽  
Ambient Atmosphere ◽  
Qinghai Province ◽  
Background Site ◽  
15N Enrichment ◽  
Animal Wastes

Abstract. Using isotope mixing model (IsoSource) and natural δ15N method, this study evaluated contributions of major sources to N of PM2.5 at Beijing (collected during a severe haze episode of January 22nd–30th, 2013) and a background site (Menyuan, Qinghai province; collected from September to October of 2013) of China. At Beijing, δ15N values of PM2.5 (−4.1 – +13.5 ‰; mean = +2.8 ± 6.4 ‰) distributed within the range reported for major anthropogenic sources (including NH3 and NO2 from coal combustion, vehicle exhausts and domestic wastes/sewage). However, δ15N values of PM2.5 at the background site (+8.0 – +27.9 ‰; mean = +18.5 ± 5.8 ‰) were significantly higher than that of potential sources (including NH3 and NO2 from biomass burning, animal wastes, soil N cycle, fertilizer application, and organic N of soil dust). Evidences from molecular ratios of NH4+ to NO3− and/or SO42− in PM2.5, NH3 to NO2 and/or SO2 in ambient atmosphere suggested that the equilibrium of NH3 ↔ NH4 + caused apparent 15N enrichment only in NH4 + of PM2.5 at the background site due to more abundant NH3 than SO2 and NO2. Therefore, a net 15N enrichment (33 ‰) was assumed for NH3 sources of background PM2.5 when fractional contributions were estimated by IsoSource model. Results showed that 41 %, 30 % and 14 % of N in PM2.5 of Beijing originated from coal combustion, vehicle exhausts and domestic wastes/sewage, respectively. Background PM2.5 derived N mainly from biomass burning (58 %), animal wastes (15 %) and fertilizer application (9 %). These results revealed the regulation of the stoichiometry between ammonia and acidic gases on δ15N signals in PM2.5. Emissions of NO2 from coal combustion and NH3 from urban transportation should be strictly controlled to advert the risk of haze episodes in Beijing.

scholarly journals Source Apportionment and Toxic Potency of Polycyclic Aromatic Hydrocarbons (PAHs) in the Air of Harbin, a Cold City in Northern China

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 297
Author(s):  
Haitao Liu ◽  
Bo Li ◽  
Hong Qi ◽  
Lixin Ma ◽  
Jianzhong Xu ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Biomass Burning ◽  
Aromatic Hydrocarbons ◽  
Coal Combustion ◽  
Treatment Plant ◽  
Sampling Period ◽  
Vehicle Exhaust ◽  
Pmf Model ◽  
Polycyclic Aromatic ◽  
Toxicity Equivalent

A total of 68 PUF samples were collected seasonally from 17 sampling sites in Harbin, China from May 2016 to April 2017 for analyzing 15 congeners of gaseous polycyclic aromatic hydrocarbons (Σ15PAHs). An improved non-negative matrix (NMF) model and a positive matrix factorization (PMF) model were used to apportion the sources of PAHs. The carcinogenic risk due to exposure to PAHs was estimated by the toxicity equivalent of BaP (BaPeq). The results showed that the average concentration of Σ15PAHs was 68.3 ± 22.3 ng/m3, and the proportions of 3-ring, 4-ring, 5-ring, and 6-ring PAHs were 64.4%, 32.6%, 2.10%, and 0.89%, respectively. Among the six typical functional areas in Harbin, the Σ15PAHs concentrations were 98.1 ± 76.7 ng/m3, 91.2 ± 76.2 ng/m3, 71.4 ± 75.6 ng/m3, 67.9 ± 65.6 ng/m3, 42.6 ± 34.7 ng/m3, and 38.5 ± 38.0 ng/m3 in the wastewater treatment plant, industrial zone, business district, residential area, school, and suburb, respectively. During the sampling period, the highest concentration of Σ15PAHs was in winter. The improved NMF model and PMF model apportioned the PAHs into three sources including coal combustion, biomass burning, and vehicle exhaust. The contributions of coal combustion, biomass burning, and vehicle exhausts were 34.6 ± 3.22%, 48.6 ± 4.03%, and 16.8 ± 5.06%, respectively. Biomass burning was the largest contributor of Σ15PAHs concentrations in winter and coal combustion contributed significantly to the concentrations in summer. The average ΣBaPeq concentration was 0.54 ± 0.23 ng/m3 during the sampling period, high concentrations occurred in the cold season and low levels presented in the warm period. Vehicle exhaust was the largest contributor to the ΣBaPeq concentration of PAHs in Harbin.

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