scholarly journals Sources and formation of carbonaceous aerosols in Xi'an, China: primary emissions and secondary formation constrained by radiocarbon

2020 ◽  
Author(s):  
Haiyan Ni ◽  
Ru-Jin Huang ◽  
Ulrike Dusek
Keyword(s):  
Biomass Burning ◽  
Coal Combustion ◽  
Vehicle Emissions ◽  
Fossil Fuel ◽  
Fuel Combustion ◽  
Warm Period ◽  
Water Soluble ◽  
Formation Mechanisms ◽  
Carbonaceous Aerosols ◽  
Fossil Fuel Combustion

<p>To investigate the sources and formation mechanisms of carbonaceous aerosols, a major contributor to severe particulate air pollution, radiocarbon (<span><sup>14</sup>C</span>) measurements were conducted on aerosols sampled from November 2015 to November 2016 in Xi'an, China. Based on the <span><sup>14</sup>C</span> content in elemental carbon (EC), organic carbon (OC) and water-insoluble OC (WIOC), contributions of major sources to carbonaceous aerosols are estimated over a whole seasonal cycle: primary and secondary fossil sources, primary biomass burning, and other non-fossil carbon formed mainly from secondary processes. Primary fossil sources of EC were further sub-divided into coal and liquid fossil fuel combustion by complementing <span><sup>14</sup>C</span> data with stable carbon isotopic signatures.</p><p>The dominant EC source was liquid fossil fuel combustion (i.e., vehicle emissions), accounting for 64 % (median; 45 %–74 %, interquartile range) of EC in autumn, 60 % (41 %–72 %) in summer, 53 % (33 %–69 %) in spring and 46 % (29 %–59 %) in winter. An increased contribution from biomass burning to EC was observed in winter (<span>∼28</span> %) compared to other seasons (warm period; <span>∼15</span> %). In winter, coal combustion (<span>∼25</span> %) and biomass burning equally contributed to EC, whereas in the warm period, coal combustion accounted for a larger fraction of EC than biomass burning. The relative contribution of fossil sources to OC was consistently lower than that to EC, with an annual average of <span>47±4</span> %. Non-fossil OC of secondary origin was an important contributor to total OC (<span>35±4</span> %) and accounted for more than half of non-fossil OC (<span>67±6</span> %) throughout the year. Secondary fossil OC (SOC<span><sub>fossil</sub></span>) concentrations were higher than primary fossil OC (POC<span><sub>fossil</sub></span>) concentrations in winter but lower than POC<span><sub>fossil</sub></span> in the warm period.</p><p>Fossil WIOC and water-soluble OC (WSOC) have been widely used as proxies for POC<span><sub>fossil</sub></span> and SOC<span><sub>fossil</sub></span>, respectively. This assumption was evaluated by (1) comparing their mass concentrations with POC<span><sub>fossil</sub></span> and SOC<span><sub>fossil</sub></span> and (2) comparing ratios of fossil WIOC to fossil EC to typical primary OC-to-EC ratios from fossil sources including both coal combustion and vehicle emissions. The results suggest that fossil WIOC and fossil WSOC are probably a better approximation for primary and secondary fossil OC, respectively, than POC<span><sub>fossil</sub></span> and SOC<span><sub>fossil</sub></span> estimated using the EC tracer method.</p>

scholarly journals Sources and formation of carbonaceous aerosols in Xi'an, China: primary emissions and secondary formation constrained by radiocarbon

2019 ◽  
Vol 19 (24) ◽  
pp. 15609-15628 ◽  
Author(s):  
Haiyan Ni ◽  
Ru-Jin Huang ◽  
Junji Cao ◽  
Jie Guo ◽  
Haoyue Deng ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Coal Combustion ◽  
Vehicle Emissions ◽  
Fossil Fuel ◽  
Fuel Combustion ◽  
Warm Period ◽  
Water Soluble ◽  
Formation Mechanisms ◽  
Carbonaceous Aerosols ◽  
Fossil Fuel Combustion

Abstract. To investigate the sources and formation mechanisms of carbonaceous aerosols, a major contributor to severe particulate air pollution, radiocarbon (14C) measurements were conducted on aerosols sampled from November 2015 to November 2016 in Xi'an, China. Based on the 14C content in elemental carbon (EC), organic carbon (OC) and water-insoluble OC (WIOC), contributions of major sources to carbonaceous aerosols are estimated over a whole seasonal cycle: primary and secondary fossil sources, primary biomass burning, and other non-fossil carbon formed mainly from secondary processes. Primary fossil sources of EC were further sub-divided into coal and liquid fossil fuel combustion by complementing 14C data with stable carbon isotopic signatures. The dominant EC source was liquid fossil fuel combustion (i.e., vehicle emissions), accounting for 64 % (median; 45 %–74 %, interquartile range) of EC in autumn, 60 % (41 %–72 %) in summer, 53 % (33 %–69 %) in spring and 46 % (29 %–59 %) in winter. An increased contribution from biomass burning to EC was observed in winter (∼28 %) compared to other seasons (warm period; ∼15 %). In winter, coal combustion (∼25 %) and biomass burning equally contributed to EC, whereas in the warm period, coal combustion accounted for a larger fraction of EC than biomass burning. The relative contribution of fossil sources to OC was consistently lower than that to EC, with an annual average of 47±4 %. Non-fossil OC of secondary origin was an important contributor to total OC (35±4 %) and accounted for more than half of non-fossil OC (67±6 %) throughout the year. Secondary fossil OC (SOCfossil) concentrations were higher than primary fossil OC (POCfossil) concentrations in winter but lower than POCfossil in the warm period. Fossil WIOC and water-soluble OC (WSOC) have been widely used as proxies for POCfossil and SOCfossil, respectively. This assumption was evaluated by (1) comparing their mass concentrations with POCfossil and SOCfossil and (2) comparing ratios of fossil WIOC to fossil EC to typical primary OC-to-EC ratios from fossil sources including both coal combustion and vehicle emissions. The results suggest that fossil WIOC and fossil WSOC are probably a better approximation for primary and secondary fossil OC, respectively, than POCfossil and SOCfossil estimated using the EC tracer method.

scholarly journals Sources and formation of carbonaceous aerosols in Xi'an, China: primary emissions and secondary formation constrained by radiocarbon

2019 ◽  
Author(s):  
Haiyan Ni ◽  
Ru-Jin Huang ◽  
Junji Cao ◽  
Jie Guo ◽  
Haoyue Deng ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Coal Combustion ◽  
Vehicle Emissions ◽  
Fossil Fuel ◽  
Fuel Combustion ◽  
Warm Period ◽  
Formation Mechanisms ◽  
Carbonaceous Aerosols ◽  
Fossil Fuel Combustion ◽  
Relative Contribution

Abstract. To investigate the sources and formation mechanisms of carbonaceous aerosols, a major contributor to severe particulate air pollution, radiocarbon (14C) measurements were conducted on aerosols sampled from November 2015 to November 2016 in Xi'an, China. Based on the 14C content in elemental carbon (EC), organic carbon (OC) and water-insoluble OC (WIOC), contributions of major sources to carbonaceous aerosols are estimated over a whole seasonal cycle: primary and secondary fossil sources, primary biomass burning, and other non-fossil carbon formed mainly from secondary processes. Primary fossil sources of EC were further sub-divided into coal and liquid fossil fuel combustion by complementing 14C data with stable carbon isotopic signatures. The dominant EC source was liquid fossil fuel combustion (i.e., vehicle emissions), accounting for 64 % (median; 45–74 %, interquartile range) of EC in autumn, 60 % (41–72 %) in summer, 53 % (33–69 %) in spring and 46 % (29–59 %) in winter, respectively. An increased contribution from biomass burning to EC was observed in winter (~ 28 %) compared to other seasons (warm period; ~ 15 %). In winter, coal combustion (~ 25 %) and biomass burning equally contributed to EC, whereas in the warm period, coal combustion accounted for a larger fraction of EC than biomass burning. The relative contribution of fossil sources to OC was consistently lower than that to EC, with an annual average of 47 ± 4 %. Non-fossil OC of secondary origin was an important contributor to total OC (35 ± 4%) and accounted for more than half of non-fossil OC (67 ± 6%) throughout the year. Secondary fossil OC (SOCfossil) concentrations were higher than primary fossil OC (POCfossil) concentrations in winter, but lower than POCfossil in the warm period. Fossil WIOC and water-souble OC (WSOC) have been widely used as proxies for POCfossil and SOCfossil, respectively. This assumption was evaluated by (1) comparing their mass concentrations with POCfossil and SOCfossil, and (2) comparing ratios of fossil WIOC to fossil EC to typical primary OC to EC ratios from fossil sources including both coal combustion and vehicle emissions. The results suggest that fossil WIOC and fossil WSOC are probably a better approximation for primary and secondary fossil OC, respectively, than POCfossil and SOCfossil estimated using the EC tracer method.

scholarly journals Measurement report: dual-carbon isotopic characterization of carbonaceous aerosol reveals different primary and secondary sources in Beijing and Xi'an during severe haze events

2020 ◽  
Vol 20 (24) ◽  
pp. 16041-16053
Author(s):  
Haiyan Ni ◽  
Ru-Jin Huang ◽  
Max M. Cosijn ◽  
Lu Yang ◽  
Jie Guo ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Coal Combustion ◽  
Fossil Fuel ◽  
Fuel Combustion ◽  
Carbonaceous Aerosol ◽  
Carbonaceous Aerosols ◽  
Fossil Fuel Combustion ◽  
Aerosol Formation ◽  
Haze Pollution ◽  
Isotopic Characterization

Abstract. To mitigate haze pollution in China, a better understanding of the sources of carbonaceous aerosols is required due to the complexity in multiple emissions and atmospheric processes. Here we combined the analysis of radiocarbon and the stable isotope 13C to investigate the sources and formation of carbonaceous aerosols collected in two Chinese megacities (Beijing and Xi'an) during severe haze events of a “red alarm” level from December 2016 to January 2017. The haze periods with daily PM2.5 concentrations as high as ∼ 400 µg m−3 were compared to subsequent clean periods (i.e., PM2.5 less than median concentrations during the winter 2016/2017) with PM2.5 concentrations below 100 µg m−3 in Xi'an and below 20 µg m−3 in Beijing. In Xi'an, liquid fossil fuel combustion was the dominant source of elemental carbon (EC; 44 %–57 %), followed by biomass burning (25 %–29 %) and coal combustion (17 %–29 %). In Beijing, coal combustion contributed 45 %–61 % of EC, and biomass burning (17 %–24 %) and liquid fossil fuel combustion (22 %–33 %) contributed less. Non-fossil sources contributed 51 %–56 % of organic carbon (OC) in Xi'an, and fossil sources contributed 63 %–69 % of OC in Beijing. Secondary OC (SOC) was largely contributed by non-fossil sources in Xi'an (56±6 %) and by fossil sources in Beijing (75±10 %), especially during haze periods. The fossil vs. non-fossil contributions to OC and EC did not change drastically during haze events in both Xi'an and Beijing. However, compared to clean periods, the contribution of coal combustion to EC during haze periods increased in Xi'an and decreased in Beijing. During clean periods, primary OC from biomass burning and fossil sources constituted ∼ 70 % of OC in Xi'an and ∼ 53 % of OC in Beijing. From clean to haze periods, the contribution of SOC to total OC increased in Xi'an but decreased in Beijing, suggesting that the contribution of secondary organic aerosol formation to increased OC during haze periods was more efficient in Xi'an than in Beijing. In Beijing, the high SOC fraction in total OC during clean periods was mainly due to an elevated contribution from non-fossil SOC. In Xi'an, a slight day–night difference was observed during the clean period with enhanced fossil contributions to OC and EC during the day. This day–night difference was negligible during severe haze periods, likely due to the enhanced accumulation of pollutants under stagnant weather conditions.

Dual-carbon isotopic characterization of carbonaceous aerosol reveals different primary and secondary sources in Beijing and Xi’an during severe haze events

2021 ◽  
Author(s):  
Haiyan Ni ◽  
Ru-Jin Huang ◽  
Ulrike Dusek
Keyword(s):  
Biomass Burning ◽  
Coal Combustion ◽  
Fossil Fuel ◽  
Fuel Combustion ◽  
Carbonaceous Aerosol ◽  
Carbonaceous Aerosols ◽  
Fossil Fuel Combustion ◽  
Aerosol Formation ◽  
Haze Pollution ◽  
Isotopic Characterization

<p>To mitigate haze pollution in China, a better understanding of the sources of carbonaceous aerosols is required due to the complexity in multiple emissions and atmospheric processes. Here we combined the analysis of radiocarbon and the stable isotope <sup>13</sup>C to investigate the sources and formation of carbonaceous aerosols collected in two Chinese megacities (Beijing and Xi’an) during severe haze events of “red alarm” level from December 2016 to January 2017. The haze periods with daily PM<sub>2.5</sub> concentrations as high as ~400 µg m<sup>-3</sup> were compared to subsequent clean periods (i.e., PM<sub>2.5 </sub>< median concentrations during the winter 2016/2017), with PM<sub>2.5 </sub>concentrations<sub></sub>below 100 µg m<sup>-3</sup> in Xi’an and below 20 µg m<sup>-3</sup> in Beijing. In Xi’an, liquid fossil fuel combustion was the dominant source of elemental carbon (EC; 44%–57%), followed by biomass burning (25%–29%) and coal combustion (17%–29%). In Beijing, coal combustion contributed 45%–61% of EC and biomass burning (17%–24%) and liquid fossil fuel combustion (22%–33%) contributed less. Non-fossil sources contributed 51%–56% of organic carbon (OC) in Xi’an and fossil sources contributed 63%–69% of OC in Beijing. Secondary OC (SOC) was largely contributed by non-fossil sources in Xi’an (56 ± 6%) and by fossil sources in Beijing (75 ± 10%), especially during haze periods. The fossil vs. non-fossil contributions to OC and EC did not change drastically during haze events in both Xi’an and Beijing. However, compared to clean periods, the contribution of coal combustion to EC during haze periods increased in Xi’an and decreased in Beijing. During clean periods, primary OC from biomass burning and fossil sources constituted ~70% of OC in Xi’an and ~53% of OC in Beijing. From clean to haze periods, the contribution of SOC to total OC increased in Xi’an, but decreased in Beijing, suggesting that contribution of secondary organic aerosol formation to increased OC during haze periods was more efficient in Xi’an than in Beijing. In Beijing, the high SOC fraction in total OC during clean periods was mainly due to elevated contribution from non-fossil SOC. In Xi’an, a slight day-night difference was observed during the clean period, with enhanced fossil contributions to OC and EC during the day. This day-night difference was negligible during severe haze periods, likely due to enhanced accumulation of pollutants under stagnant weather conditions.</p>

scholarly journals Measurement report: Dual-carbon isotopic characterization of carbonaceous aerosol in Beijing and Xi'an: distinctions in primary versus secondary sources

2020 ◽  
Author(s):  
Haiyan Ni ◽  
Ru-Jin Huang ◽  
Max M. Cosijn ◽  
Lu Yang ◽  
Jie Guo ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Coal Combustion ◽  
Fossil Fuel ◽  
Fuel Combustion ◽  
Carbonaceous Aerosol ◽  
Carbonaceous Aerosols ◽  
Fossil Fuel Combustion ◽  
Aerosol Formation ◽  
Haze Pollution ◽  
Isotopic Characterization

Abstract. To mitigate haze pollution in China, a better understanding of the sources of carbonaceous aerosols is required due to the complexity in multiple emissions and atmospheric processes. Here we combined the analysis of radiocarbon and the stable isotope 13C to investigate the sources and formation of carbonaceous aerosols collected in two Chinese megacities (Beijing and Xi’an) during severe haze events of “red alarm” level from December 2016 to January 2017. In Xi’an, liquid fossil fuel combustion was the dominant source of elemental carbon (EC; 44 %–57 %), followed by biomass burning (25 %–29 %) and coal combustion (17 %–29 %). In Beijing, coal combustion contributed 45%–61% of EC and biomass burning (17 %–24 %) and liquid fossil fuel combustion (22 %–33 %) contributed less. Non-fossil sources contributed 51 %–56 % of organic carbon (OC) in Xi’an and fossil sources contributed 63 %–69 % of OC in Beijing. Secondary OC (SOC) was largely contributed by non-fossil sources in Xi’an (56 ± 6 %) and by fossil sources in Beijing (75 ± 10 %), especially during haze periods. The fossil vs. non-fossil contributions to OC and EC did not change drastically during haze events in both Xi’an and Beijing. However, compared to clean periods, the contribution of coal combustion to EC during haze periods increased in Xi’an and decreased in Beijing. During clean periods, primary OC from biomass burning and fossil sources constituted ~ 70 % of OC in Xi’an and ~ 53 % of OC in Beijing. From clean to haze periods, the contribution of SOC to total OC increased in Xi’an, but decreased in Beijing, suggesting that contribution of secondary organic aerosol formation to increased OC during haze periods was more efficient in Xi’an than in Beijing. In Beijing, the high SOC fraction in total OC during clean periods was mainly due to elevated contribution from non-fossil SOC. In Xi’an, a slight day-night difference was observed during clean period, with enhanced fossil contributions to OC and EC during the day. This day-night difference was negligible during severe haze periods, likely due to enhanced accumulation of pollutants under stagnant weather conditions.

scholarly journals Fossil fuel combustion, biomass burning and biogenic sources of fine carbonaceous aerosol in the Carpathian Basin

2019 ◽  
Author(s):  
Imre Salma ◽  
Anikó Vasanits-Zsigrai ◽  
Attila Machon ◽  
Tamás Varga ◽  
István Major ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Fossil Fuel ◽  
Fuel Combustion ◽  
Carpathian Basin ◽  
Water Soluble ◽  
Total Carbon ◽  
Carbonaceous Aerosol ◽  
City Centre ◽  
Fossil Fuel Combustion ◽  
Regional Background

Abstract. Fine-fraction aerosol samples were collected, air pollutants and meteorological properties were measured in-situ in regional background environment of the Carpathian Basin, a suburban area and central part of its largest city, Budapest in each season for 1 year-long time interval. The samples were analysed for PM2.5 mass, organic carbon (OC), elemental carbon (EC), water-soluble OC (WSOC), radiocarbon, levoglucosan (LVG) and its stereoisomers, and some chemical elements. Carbonaceous aerosol species made up 36 % of the PM2.5 mass with a modest seasonal variation and with a slightly increasing tendency from the regional background to the city centre (from 32 to 39 %). Coupled radiocarbon-LVG marker method was applied to apportion the total carbon (TC = OC + EC) into contributions of EC and OC from fossil fuel (FF) combustion (ECFF and OCFF, respectively), EC and OC from biomass burning (BB) (ECBB and OCBB, respectively) and OC from biogenic sources (OCBIO). Fossil fuel combustion showed rather constant daily or seasonal mean contributions (of 35 %) to the TC in the whole year in all atmospheric environments, while the daily contributions of BB and biogenic sources changed radically (from

scholarly journals Source apportionment of carbonaceous aerosols in Xi'an, China: insights from a full year of measurements of radiocarbon and the stable isotope <sup>13</sup>C

2018 ◽  
Vol 18 (22) ◽  
pp. 16363-16383 ◽  
Author(s):  
Haiyan Ni ◽  
Ru-Jin Huang ◽  
Junji Cao ◽  
Weiguo Liu ◽  
Ting Zhang ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Coal Combustion ◽  
Stable Carbon Isotopes ◽  
Fossil Fuel ◽  
Stable Carbon Isotope ◽  
Fuel Combustion ◽  
Fossil Fuel Combustion ◽  
Stable Carbon ◽  
Source Contributions ◽  
Secondary Formation

Abstract. Sources of organic carbon (OC) and elemental carbon (EC) in Xi'an, China, are investigated based on 1-year radiocarbon and stable carbon isotope measurements. The radiocarbon results demonstrate that EC is dominated by fossil sources throughout the year, with a mean contribution of 83±5 % (7±2 µg m−3). The remaining 17±5 % (1.5±1 µg m−3) is attributed to biomass burning, with a higher contribution in the winter (∼24 %) compared to the summer (∼14 %). Stable carbon isotopes of EC (δ13CEC) are enriched in winter (-23.2±0.4 ‰) and depleted in summer (-25.9±0.5 ‰), indicating the influence of coal combustion in winter and liquid fossil fuel combustion in summer. By combining radiocarbon and stable carbon signatures, relative contributions from coal combustion and liquid fossil fuel combustion are estimated to be 45 % (median; 29 %–58 %, interquartile range) and 31 % (18 %–46 %) in winter, respectively, whereas in other seasons more than one half of EC is from liquid fossil combustion. In contrast with EC, the contribution of non-fossil sources to OC is much larger, with an annual average of 54±8 % (12±10 µg m−3). Clear seasonal variations are seen in OC concentrations both from fossil and non-fossil sources, with maxima in winter and minima in summer because of unfavorable meteorological conditions coupled with enhanced fossil and non-fossil activities in winter, mainly biomass burning and domestic coal burning. δ13COC exhibited similar values to δ13CEC, and showed strong correlations (r2=0.90) in summer and autumn, indicating similar source mixtures with EC. In spring, δ13COC is depleted (1.1 ‰–2.4 ‰) compared to δ13CEC, indicating the importance of secondary formation of OC (e.g., from volatile organic compound precursors) in addition to primary sources. Modeled mass concentrations and source contributions of primary OC are compared to the measured mass and source contributions. There is strong evidence that both secondary formation and photochemical loss processes influence the final OC concentrations.

scholarly journals Source apportionment of carbonaceous aerosols in Xi’an, China: insights from a full year of measurements of radiocarbon and the stable isotope <sup>13</sup>C

2018 ◽  
Author(s):  
Haiyan Ni ◽  
Ru-Jin Huang ◽  
Junji Cao ◽  
Ting Zhang ◽  
Meng Wang ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Coal Combustion ◽  
Stable Carbon Isotopes ◽  
Fossil Fuel ◽  
Stable Carbon Isotope ◽  
Fuel Combustion ◽  
Fossil Fuel Combustion ◽  
Stable Carbon ◽  
Source Contributions ◽  
Secondary Formation

Abstract. Sources of organic carbon (OC) and elemental carbon (EC) in Xi’an, China are investigated based on one-year radiocarbon and stable carbon isotope measurements. The radiocarbon results demonstrate that EC is dominated by fossil sources throughout the year, with a mean contribution of 83 ± 5 % (7 ± 2 µg m−3). The remaining 17 ± 5 % (1.5 ± 1 µg m−3) is attributed to biomass burning, with higher contribution in the winter (~ 24 %) compared to the summer (~ 14 %). Stable carbon isotopes of EC (δ13CEC) are enriched in winter (−23.20 ± 0.35 ‰) and depleted in summer (−25.94 ± 0.46 ‰), indicating the influence of coal combustion in winter and liquid fossil fuel combustion in summer. By combining radiocarbon and stable carbon signatures, relative contributions from coal combustion and liquid fossil fuel combustion are estimated as 45 % (29–58 %, interquartile range) and 31 % (18–46 %) in winter, respectively, whereas in other seasons more than one half of EC are from liquid fossil combustion. In contrast with EC, the contribution of non-fossil sources to OC is much larger, with an annual average of 54 ± 8 % (12 ± 10 µg m−3). Clear seasonal variations are seen in OC concentrations both from fossil and non-fossil sources, with maxima in winter and minima in summer, because of unfavourable meteorological conditions coupled with enhanced fossil and non-fossil activities in winter, mainly biomass burning and domestic coal burning. δ13COC exhibited similar values with δ13CEC, and showed strong correlations (r2 = 0.90) in summer and autumn, indicating similar source mixtures with EC. In spring, δ13COC is depleted (1.1–2.4 ‰) compared to δ13CEC, indicating the importance of secondary formation of OC (e.g., from volatile organic compound precursors) in addition to primary sources. Modelled mass concentrations and source contributions of primary OC are compared to the measured mass and source contributions. There is strong evidence that both secondary formation and photochemical loss processes influence the final OC concentrations.

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