Patterns of PAH distribution in karst sinkhole soils (Polar Urals)

This work was the first comprehensive study of polycyclic aromatic hydrocarbons (PAHs) accumulation in soils of karst sinkholes and in background soils of the Polar Urals. Principal component analysis and cluster analysis were used to assess the distribution patterns of PAHs. PAH concentrations were measured in 53 soil samples collected from plant communities of two habitat types: dryad-green moss-lichen tundra and herb-grass meadow. We found karst processes influenced contents of PAHs, especially in the deepest sinkholes where the increased PAH contents were mainly due to surface erosion. The shifted peaks of PAH accumulation along the soil profile were found at the slopes of sinkholes. This was possibly due to more active PAH migration and stratification of soil horizons. We also identified the relationship between accumulation of PAHs and species composition of plant communities. PCA analysis showed relationships between soil PAHs, organic carbon and organic nitrogen that were explained mainly by the formation of PAHs from high molecular weight organic substances, humic acids and lignin. Paleocoals also affected the PAH contents in soils. Calculated diagnostic ratios of PAHs indicated their pedogenic origin.