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Seasonality of air-forest canopy exchange of persistent organic pollutants

Research output: Contribution to journalJournal article

<mark>Journal publication date</mark>1/12/2008
<mark>Journal</mark>Environmental Science and Technology
Issue number23
Number of pages6
Pages (from-to)8778-8783
<mark>Original language</mark>English


Forest canopies represent an extensive organic surface available for partitioning of semivolatile organic pollutants with the atmosphere. To date, the ability of forests to sequester such compounds (the so-called “forest filter effect”) has been investigated using indirect methods that yield time integrated deposition fluxes and scenario-dependent deposition velocities. In the present study, experimental data collected at three different alpine forest sites were used to assess the dynamics of PCB deposition fluxes (F, ng m−2 d−1) during the growing season. Estimated values of F were consistent with previously reported data. Furthermore, this study showed that maximum levels of F in late spring can be a factor of 1.4−3.4 higher than their seasonal mean value. These data, in conjunction with a simple model framework that includes the main forcing parameters of air concentration, temperature, foliage structure, and biomass dynamics, are used to estimate the plant−air mass transfer coefficient (kU, m d−1) and its variation with time in one of the forests. kU did not appear to significantly vary during the season, and its mean seasonal value ranged between 43 and 95 m d−1 for selected compounds. The proposed framework was successfully applied to predict the variation in canopy concentration with time in the other two forests.