Factors affecting the source identification and distribution of polycyclic aromatic compounds in environmental compartments of the Lake Baikal area

The aim of this study was to reveal factors causing the differences in the distribution and origin of polycyclic aromatic hydrocarbons (PAHs) among air, water, soil and sediments. The concentrations of twelve priority PAHs in samples were measured. It was observed that PAH concentrations in all ecosystem compartments increased with a decrease in distance from settlements. PAH concentrations also increased with an age of PAHs. It was proved that unlike air and water the ratio between gas phase and particle phase PAHs in bottom sediments and soils does not change over time. It was found that due to PAH partitioning among ecosystem compartments, the hydrophobic particle phase PAHs were fixed in soils and bottom sediments, whereas water-soluble particle/gas phase PAHs were leached from soil to rivers and lakes. It was also found that the precision of PAH source identification using the diagnostic ratio (DR) approach depends on the similarity of physicochemical properties of diagnostic PAHs and on their affinity to the predominant phase of the studied ecosystem compartment. The inconsistency between contributions of DR-derived and real PAH sources to the pollution of environmental compartments is probably conditioned by the inconsistence between literature-derived DRs and DRs characteristic for local sources.