title: Seasonality of the air-forest canopy exchange of persistent organic pollutants.
abstract: 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 Fwere 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 modelframeworkthatincludesthe 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.
authors.affiliation: Centre for Chemicals Management, Environmental Science Department, Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK. L.nizzetto@lancaster.ac.uk
authors.forename: Luca
authors.initials: L
authors.lastname: Nizzetto
authors.forename: Andrew
authors.initials: A
authors.lastname: Jarvis
authors.forename: Pietro A
authors.initials: PA
authors.lastname: Brivio
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Jones
authors.forename: Antonio
authors.initials: A
authors.lastname: Di Guardo
mesh_terms: D000388:Air; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis*; D008956:Models, Chemical; D018515:Plant Leaves / Q000737:chemistry*; D011078:Polychlorinated Biphenyls / Q000032:analysis*; D012621:Seasons; D014197:Trees / Q000737:chemistry*
chemical_list: D004785:Environmental Pollutants; D011078:Polychlorinated Biphenyls