Polynuclear aromatic hydrocarbons (PAHs) in global background soils.

The levels and distribution of polynuclear aromatic hydrocarbons (PAHs) were investigated in global background soil samples. Total PAH concentrations (sum of 15 compounds) ranged over 5 orders of magnitude, from <1 to 7,840 (mean 328) ng g(-1) dry weight. The order was generally Europe > North America > Asia > Oceania > Africa > South America. Proximity to long-term emissions sources and locations susceptible to high atmospheric depositional inputs tended to have higher concentrations. A broad positive correlation was obtained between population density and soil PAH concentrations (i.e. source-related factors). However, concentrations were also influenced by the holding capacity of the soils (i.e. sink-related factors) with statistically significant correlations observed between PAHs and soil organic matter (SOM), and black carbon (BC).