Fossil vs. non-fossil sources of fine carbonaceous aerosols in four Chinese cities during the extreme winter haze episode in 2013

Abstract

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The importance of non-fossil sources in carbonaceous aerosols in a megacity of central China during the 2013 winter haze episode: A source apportionment constrained by radiocarbon and organic tracers

“…These carbon particles in the atmosphere have two sources: fossil fuel (FF, e.g., from traffic exhaust, coal combustion, industry) and non-fossil (NF, e.g., from open/forest fire, biofuel burning, biogenic emission) emissions. Their unambiguous source apportionment has been conducted in recent years by the measurements of radiocarbon ( 14 C) (Gustafsson et al, 2009, Szidat et al, 2009Chen et al, 2013;Liu et al, 2013;Huang et al, 2014;Liu et al, 2014;Zotter et al, 2014a;Andersson et al, 2015;Zhang et al, 2015). This radioisotope (half-life ¼ 5730 years) enables a distinction between FF and NF sources because 14 C is absent in FF, but present at the current ambient level in NF materials.…”

“…Chen et al (2013) first systematically investigated the 14 C signals of EC (or black carbon) in Beijing, Shanghai, and Xiamen, and found that 83e86% of EC was associated with FF combustion during the 2009e2010 winter, with the remainder derived from biomass burning (BB). Zhang et al (2015) analyzed the 14 C levels of OC and EC in four Chinese citieseBeijing, Xi'an, Guangzhou, and Shanghaieand found that the contributions of FF sources to OC and EC were 35e49% and 57e80%, respectively, in January 2013. Andersson et al (2015) found that during this haze period FF sources on average contributed 74%, 68% and 68% to EC in Beijing, Shanghai and Guangzhou, respectively.…”

“…Previous 14 C-related studies also have displayed this difference. For example, the contribution of FF sources to OC in Beijing was 58% , whereas it was <40% in Guangzhou on average Zhang et al, 2015). Thus, this large-scale haze crisis was very likely caused by the convergence of materials from numerous point sources in regions with different sources.…”

Analysis of Long-Range Transport Effects on PM2.5 during a Short Severe Haze in Beijing, China

“…Under the synoptic condition, winds at the surface layer were very weak with the wind speed lower than 2.0 m s relative humidity was usually 100%. The high-pressure, weak winds and high relative humidity were unfavorable for the dispersion of pollutants (Gao et al, 2015;Zhang et al, 2015a) which caused the accumulation of pollutants in Beijing. Furthermore, the previous source regions totally shifted from northwesterly to southerly.…”

Seasonal variations and source apportionment of complex polycyclic aromatic hydrocarbon mixtures in particulate matter in an electronic waste and urban area in South China

“…Thus, the OC/EC ratios in the urban air (4.10 ± 2.26) were significantly lower than those in the rural air (5.82 ± 2.51) (p b0.001). This was probably due to more PM associated with fossil emissions from coal combustion and vehicle exhaust in the urban area than in the e-waste area, which are thought to be the primary sources of EC (Liu et al, 2014;Zhang et al, 2015) and/or different emission sources of PM at the two sites. In addition, at both urban and rural sites, the OC/EC ratios in dry seasons (winter and fall) (4.30 ± 1.49 and 7.33 ± 2.46, respectively) were significantly higher than those in wet seasons (summer and spring) (3.02 ± 2.28 and 5.18 ± 1.72, respectively).…”