The content and composition of 19 priority polycyclic aromatic hydrocarbons (PAHs) in peat oligotrophic soils (Cryic Histosols) in the northern territories of Western Siberia were analyzed by gas chromatography in chloroform extracts. The content of PAHs in the examined soils varies from 33 to 148 ng/g. Low molecular weight (three-ring) PAHs account for 70-75% of the PAHs composition, while the total share of high molecular weight compounds does not exceed 25%. The latter are mainly represented by four-ring species, their concentrations decreasing in the sequence: f luoranthene > pyrene > chrysene. Cluster analysis (Euclidean index and pair group method) demonstrates the correlation of PAH composition with residual eutrophication and manifestation of soil degradation signs. Principal component analysis shows that phenanthrene, pyrene, and, to a lesser degree, f luoranthene and anthracene display the strongest positive correlation with the first component. The second component correlates with the contents of fluoranthene, fluorene, and naphthalene. The degradation of soil oligotrophic peat horizons accompanied by the appearance of mucky material appears as a decrease in the share of fluoranthene and an increase in the concentration of naphthalene. In oligotrophic peat horizons with the signs of residual eutrophication, the share of fluorene and naphthalene increases along with a decrease in the content of phenanthrene and fluoranthene. The diagnostic ratios identified by principal component analysis-Ant/(Ant + Phe) and Flt/Pyr-suggest a natural (petrogenic) origin of the PAHs in all examined peat soils.
