Concentrations, sources, and spatial distribution of individual polycyclic aromatic hydrocarbons (PAHs) in agricultural soils in the Eastern part of the EU: Poland as a case study.

Soils from agricultural areas receive unsatisfactory attention as regards the contamination with organic pollutants. To answer those needs the contents of the sixteen individual PAH compounds were determined (GC/MS technique) in agricultural soils in Poland. The samples (n=216) were collected from the upper layer of arable land in the year 2005. Half of the samples represented typical rural areas, while the rest derived from the territories potentially subjected to the urban/industrial pressure of various intensity. The mean (geometric) content of individual compounds varied from 1 microg kg(-1) for acenaphtylene to 55 microg kg(-1) for fluoranthene with the highest contributions (11.6%-12.9%) of phenanthrene, fluoranthene and pyrene. Higher molecular weight PAHs (4 rings) were strongly linked mutually and with the summation operator 16PAHs. They contributed substantially (73%) to the overall content of PAHs, which implies domination of anthropogenic sources. The calculated molecular indexes suggest that most of those PAHs derive from the combustion of coal, the main energy source in Poland. Simultaneously, the concentrations of lower molecular weight compounds seem to reflect the background, "natural" PAH compounds, which represent mainly atmospherically distributed emission. The division of the samples into groups describing geographical regions and landscape type enabled evaluation of the spatial trends in contamination of soils with PAH compounds. The most pronounced effect of spatial parameters corresponded to PAHs >4 rings, while lower molecular weight compounds showed more homogeneous concentration through the country.