Article

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

Atmospheric Chemistry and Physics (Impact Factor: 4.88). 08/2008; 8:16255-16289. DOI: 10.5194/acpd-8-16255-2008
Source: DOAJ

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.

Full-text

Available from: H.-A. Synal, Mar 30, 2015
0 Bookmarks
 · 
152 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Radiocarbon (14C) analysis is a unique tool to distinguish fossil/non-fossil sources of carbonaceous aerosols. We present 14C-measurements of organic and total carbon (OC, TC) on highly time resolved filters (3–4 h, typically 12 h or longer have been reported) from 7 days collected during CalNex-2010, in Pasadena. Average non-fossil contributions of 58% ± 15% and 51% ± 15% were found for OC and TC, respectively. Results indicate that non-fossil carbon is a major constituent of the background aerosol, evidenced by its nearly constant concentration (2–3 μgC m−3). Cooking is estimated to contribute at least 25% to non-fossil OC, underlining the importance of urban non-fossil OC sources. In contrast, fossil OC concentrations have prominent and consistent diurnal profiles, with significant afternoon enhancements (~3 μgC m−3), following the arrival of the western Los Angeles (LA) basin plume with the sea breeze. A corresponding increase in semi-volatile oxygenated OC and organic vehicular emissions markers and their photochemical reaction products occurs. This suggests that the increasing OC is mostly from fresh anthropogenic secondary OC (SOC) from mainly fossil precursors formed in the western LA basin plume. We note that in several European cities where the diesel passenger car fraction is higher, SOC is 20% less fossil, despite 2–3 times higher elemental carbon concentrations, suggesting that SOC formation from gasoline emissions most likely dominates over diesel in the LA basin. This would have significant implications for our understanding of the on-road vehicle contribution to ambient aerosols and merits further study.
    06/2014; 119(11). DOI:10.1002/2013JD021114
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Abstract Carbonaceous aerosol sources were investigated by measuring the stable carbon isotope ratio (δ13CTC) in size segregated aerosol particles. The samples were collected with a micro-orifice uniform deposit impactor (MOUDI) in 11 size intervals ranging from 0.056 μm to 18 μm. The aerosol particle size distribution obtained from combined measurements with a scanning mobility particle sizer (SMPS; TSI 3936) and an aerosol particle sizer (APS; TSI 3321) is presented for comparison with MOUDI data. The analysis of δ13CTC values revealed that the total carbonaceous matter in size segregated aerosol particles significantly varied from -23.4 ± 0.1 ‰ in a coarse mode to -30.1 ± 0.5 ‰ in a fine mode. A wide range of the δ13CTC values of size segregated aerosol particles suggested various sources of aerosol particles contributing to carbonaceous particulate matter. Therefore, the source mixing equation was applied to verify the idea of mixing of two sources: continental non-fossil and fossil fuel combustion. The obtained δ13CTC value of aerosol particles originating from fossil fuel combustion was -28.0 — -28.1 ‰, while the non-fossil source δ13CTC value was in the range of -25.0 — -25.5 ‰. The two source mixing model applied to the size segregated samples revealed that the fossil fuel combustion source contributed from 100 % to 60 % to the carbonaceous particulate matter in the fine mode range (Dp < 1 μm). Meanwhile the second, continental non-fossil, source was the main contributor in the coarse fraction (Dp > 2 μm). The particle range from 0.5 to 2.0 μm was identified as a transition region where two sources almost equally contributed to carbonaceous particulate matter. The proposed mixing model offers an alternative method for determining major carbonaceous matter sources where radiocarbon analysis may lack the sensitivity (as in size segregated samples).
    Atmospheric Research 05/2015; DOI:10.1016/j.atmosres.2015.01.014 · 2.42 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We conducted a source apportionment and investigated the atmospheric behavior of carbonaceous aerosols during hazy and normal days using radiocarbon (14C) and biomass burning/secondary organic aerosol (SOA) tracers during winter in Guangzhou, China. Haze episodes were formed either abruptly by local emissions or through the accumulation of particles transported from other areas. The average contributions of fossil carbon to elemental carbon (EC), water-insoluble organic carbon (WIOC), and water-soluble organic carbon (WSOC) were 71±10%, 40±6% and 33±3%, respectively. High contributions of fossil carbon to EC (80-90%) were observed for haze samples that were substantially impacted by local emissions, as were the highest (lowest) ratios for NO3-/SO42- (OC/EC), which indicates that these particles mainly came from local vehicle exhaust. Low contributions of fossil carbon to EC (60-70%) were found for haze particles impacted by regional transport. Secondary organic carbon (SOC) calculated using SOA tracers accounts for only ~20% of the SOC estimated by 14C, which is probably because some important volatile organic carbons are not taken into account in the SOA tracer calculation method and because of the large discrepancy in ambient conditions between the atmosphere and smog chambers. A total of 33±11% of the SOC was of fossil origin, a portion of which could be influenced by humidity.
    Environmental Science and Technology 09/2014; 48(20). DOI:10.1021/es503102w · 5.48 Impact Factor