Trends in alkanes and PAHs in airborne particulate matter from Oporto and Vienna: identification and comparison.

A total of 56 weekly samples from Oporto and 40 from Vienna were collected and analysed, for 23 n-alkanes and 16 polycyclic aromatic hydrocarbons (PAH), by GC-MS after extraction with a toluene/methanol mixture. Total and elemental carbon were in the same range of values for both sampling sites. Although parts of the spectrum of species in both sampling sites were constant over the sampling period there is no evidence for suggesting a universal tracer for alkanes. For both Oporto and Vienna, Principal Component Analysis (PCA) identified two PCs and in both cases the first PC contained only PAHs while the second contained only alkanes. This separation between alkanes and PAHs and the observation of an alternating pattern with higher concentrations of odd carbon numbered from C27 to C30 (natural emissions from biological origin) is believed to result from a separation between anthropogenic and biological contributions associated with the first and second PC, respectively.