Polycyclic aromatic hydrocarbons in crude oils from Poland

The content of 17 polycyclic aromatic hydrocarbons (PAHs) in oil samples derived from all three oil-bearing regions of Poland, i.e. from the Carpathians, the Carpathian Foredeep and the Polish Lowlands (the Fore-Sudetic-Wielkopolska, the Western Pomeranian and the Peribaltic areas), were determined. The concentrations of PAHs determined in these crude oils varied from 22.85 to 332.45 ppm. The average content of PAHs in crude oils from the Carpathians and the Carpathian Foredeep (191.18 ppm) was several times higher than that in crude oils from the Polish Lowlands (44.70 ppm); there was throughout, though, a relatively small variability in the content of perylene, varying from 0.50 to 0.80 ppm. Of PAH compounds determined, the largest share was occupied by 3-cyclic hydrocarbons (an average of 72%) and 4-cyclic (about 24%), whereas the content of 5- and 6-cyclic hydrocarbons did not exceed 3%. Phenanthrene and fluorene were prevailing PAH compounds. The diverse PAH composition in oil samples from the Polish Lowlands compared to those from the Carpathians and the Carpathian Foredeep seems to have resulted more from the composition of original organic matter than from the course of geochemical and biochemical processes (which occur during biomass decay) and the subsequent migration of these compounds in rock formations.