Accumulation of persistent organic pollutants in canopies of different forest types: Role of species composition and altitudinal-temperature gradient

Leaves from the dominant tree species in three different alpine forests were sampled along an altitudinal gradient and analyzed for HCB, α- and γ-HCH, and PCBs. The mean canopy concentration was calculated, considering the relative abundance of each species in the respective forest Compound fractionation occurred in the vegetation along the altitudinal/temperature gradient. Results were compared with air concentrations and in-field plant/air partition coefficients (KPA) were calculated for each species; this showed differences between broadleaves and needles. The mean canopy/air partition coefficient (KCA) was also calculated by averaging results from single species. The variability of persistent organic pollutants distribution in canopies is discussed considering two main factors, the altitudinal/temperature gradient and the species composition. The latter is responsible for most of the concentration variability of the more volatile compounds. A model to calculate dry gaseous deposition to different forest canopies is presented.