Determination of multiple organic matter sources in aerosol PM10 from Wroclaw, Poland using molecular and stable carbon isotope compositions

The natural and anthropogenic contributions of hydrocarbon groups (aliphatic and aromatic), as well as total organic carbon, in atmospheric PM10 dust (particulate matter <10 mu m) collected from Wroclaw (SW Poland) were assessed using combined molecular (gas chromatography mass spectrometry - GC-MS) and stable carbon isotopic (isotope-ratio mass spectrometry - IR-MS) analyses. The PM10 samples were taken in the seasonal sampling program in 2007, and represent air pollution from all months of the year. The delta C-13 values of the total carbon varied seasonally from -27.6 to -25.3 parts per thousand. The isotopic mass balance calculations confirmed greater coal burning input, reaching 70.5%, in the heating season and dominant transported sources 47.5% in the vegetative season. The data obtained for the aliphatic fractions: carbon preference index (CPI), carbon number maximum (C-max), wax n-alkane contents (%WNA), and delta C-13 values of the aliphatic fractions (-36.6 to -29.4 parts per thousand), indicated a dominant anthropogenic origin (gasoline/diesel/coal combustion) and a lesser biogenic input (biomass burning and natural organic matter). Petroleum and coal combustion emissions were confirmed by the presence of hopanes and moretanes. The molecular analysis of the concentrations and diagnostic ratios of the polycyclic aromatic hydrocarbons (PAHs) and the delta C-13 values of the aromatic fractions (-35.4 to -26.8 parts per thousand) indicated that the main PAH sources were also collectively from combustion of liquid fuels and coal. Based on PAH discrimination diagrams it is also clear that the main organic carbon source is derived from coal, biomass and petroleum combustion in both seasons. However, taking into account the PAH concentrations during the vegetative and heating seasons, coal and biomass burning seem to be their major source. Additionally, the polar organic compounds (mainly levoglucosan) confirmed a significant contribution from biomass burning to the total anthropogenic input. The general conclusion derived from coupling of organic tracer analysis and carbon isotopic data of PM10 was that the total carbon (including insoluble soot) is likely derived from fossil fuel combustion, while the extractable organic matter is a mixture from different sources with significant inputs of biomass burning. We have also shown that dominant organic tracers do not always represent the major input source in aerosol PM and the unresolved part of the organic matter (soot) is important in the carbon budget. (C) 2014 Elsevier Ltd. All rights reserved.