TY - JOUR

T1 - Seasonality of air-forest canopy exchange of persistent organic pollutants

AU - Nizzetto, Luca

AU - Jarvis, Andrew

AU - Brivio, Pietro A.

AU - Jones, Kevin C.

AU - Di Guardo, Antonio

PY - 2008/12/1

Y1 - 2008/12/1

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=57449087897&partnerID=8YFLogxK

U2 - 10.1021/es802019g

DO - 10.1021/es802019g

M3 - Journal article

VL - 42

SP - 8778

EP - 8783

JO - Environmental Science and Technology

JF - Environmental Science and Technology

SN - 0013-936X

IS - 23

ER -