Fossil and Non-Fossil Sources of Different Carbonaceous Fractions in Fine and Coarse Particles by Radiocarbon Measurement

Abstract

ABSTRACT. Radiocarbon offers a unique possibility for unambiguous source apportionment of carbonaceous particles due to a direct distinction of non-fossil and fossil carbon. In this work, particulate matter of different size fractions was collected at 4 sites in Switzerland to examine whether fine and coarse carbonaceous particles exhibit different fossil and contemporary sources. Elemental carbon (EC) and organic carbon (OC) as well as water-soluble OC (WSOC) and water-insoluble OC (WINSOC) were separated and determined for subsequent 14 C measurement. In general, both fossil and non-fossil fractions in OC and EC were found more abundant in the fine than in the coarse mode. However, a substantial fraction (~20 ± 5%) of fossil EC was found in coarse particles, which could be attributed to traffic-induced non-exhaust emissions. The contribution of biomass burning to coarse-mode EC in winter was relatively high, which is likely associated to the coating of EC with organic and/or inorganic substances emitted from intensive wood burning. Further, fossil OC (i.e. from vehicle emissions) was found to be smaller than non-fossil OC due to the presence of primary biogenic OC and/or growing in size of wood-burning OC particles during aging processes. 14 C content in WSOC indicated that the second organic carbon rather stems from non-fossil precursors for all samples. Interestingly, both fossil and non-fossil WINSOC concentrations were found to be higher in fine particles than in coarse particles in winter, which is likely due to primary wood burning emissions and/or secondary formation of WINSOC.

Source Apportionment Using Radiocarbon and Organic Tracers for PM2.5 Carbonaceous Aerosols in Guangzhou, South China: Contrasting Local- and Regional-Scale Haze Events

“…This is comparable to previous studies conducted in European urban cities such as Goẗeborg (55 ± 8%) 15 and Zurich (70 ± 7%). 37 Most of the WSOC (67 ± 3%) is derived from nonfossil fuel emission sources in this study, which is reasonable because OC directly emitted from the combustion of fossil fuel is mainly water insoluble. 10 However, these values are lower than those observed in European and American cities (∼70−85%); 10,15,37 this variation is likely because more SOC is derived from fossil fuels in Guangzhou, given that WSOC is a good tracer for SOC in urban regions.…”

“…37 Most of the WSOC (67 ± 3%) is derived from nonfossil fuel emission sources in this study, which is reasonable because OC directly emitted from the combustion of fossil fuel is mainly water insoluble. 10 However, these values are lower than those observed in European and American cities (∼70−85%); 10,15,37 this variation is likely because more SOC is derived from fossil fuels in Guangzhou, given that WSOC is a good tracer for SOC in urban regions. 11,39 As expected, in Guangzhou, EC is largely dominated by the combustion of fossil fuel (71 ± 10%), which is comparable to other studies performed in cities around the world, such as Beijing (83 ± 4%), 22 Goẗeborg (89 ± 3%), 15 Zurich (75 ± 5%), 40 and represents a value much higher than found in samples collected at rural stations (25−50%) in southern China 24 and southern Asia (45−52%).…”

“…The trend of f m (WSOC) > f m (WIOC) > f m (EC) has also been observed in other urban regions, such as Goẗeborg and Zurich. 15,37 Because EC is formed only by primary emission, is inert in ambient air and originates from wood burning or fossil fuel combustion only, f m (EC) particularly tracks the change of these PM 2.5 sources. Its high relative standard deviation of 35% shows a large variability of wood burning and fossil impacts.…”

Origin Identification of Carbonaceous Aerosol Particles by Carbon Isotope Ratio Analysis

“…Most radiocarbon measurements have been performed on the PM 2.5 and PM 10 carbonaceous aerosol samples (Gelencsér et al, 2007;Schichtel et al, 2008;Fushimi et al, 2011;Glasius et al, 2011;Dusek et al, 2013). However, 14 C analysis of PM 1 is not so common (Endo et al, 2004;Minguillón et al, 2011;Zhang et al, 2013). Taking into account that PM 1 fraction is combustion-derived aerosol particles the 14 C analysis in PM 1 samples could give more conclusive information on the sources of carbonaceous aerosol particles.…”

High Contribution of Biomass Combustion to PM2.5 in the City Centre of Naples (Italy)

“…There has been a great effort in Europe to characterize carbonaceous aerosol sources, both in urban areas [29][30][31][32][33][34][35][36][37] and at background or rural sites [29,33,[38][39][40][41]. The carbonaceous composition of PM 2.5 has been studied at different sites in Italy [42][43][44][45][46][47].…”