Semivolatiles in the Forest Environment - The Case of PAHs

Forests are an important sink for semivolatile organic compounds (SVOCs) due to the great aerodynamic roughness of woodland landscape which enhances downward fluxes of both gaseous and particle-bound pollutants and the slow turnover of soil organic content. In particular, Polycyclic Aromatic Hydrocarbons (PAHs) are the most abundant persistent organic toxics in forests. Due to their lipophilic properties PAHs accumulate in soil, sediment and living organisms. PAHs emitted to the atmosphere by combustion processes are transported by air masses and are subject to dry or wet deposition. In forests PAHs are mainly present in the soil compartment, therefore the forest biomass can be regarded as a pump of pollutants from the atmosphere to the soil from which chemicals can return to the atmosphere only with difficulty. In the atmosphere, the main processes responsible for PAH degradation are photolysis and oxidation by gaseous pollutants, while microbial metabolism is the major process for the degradation of PAHs in soil.JRC.DDG.F.9-Sustainable Transport (Ispra