Deposition of Polybrominated Diphenyl Ethers, Polychlorinated Biphenyls, and Polycyclic Aromatic Hydrocarbons to a Boreal Deciduous Forest

• Published in: Environmental science & technology Vol. 41; no. 2; pp. 534 - 540
• Main Authors: Su, Yushan, Wania, Frank, Harner, Tom, Lei, Ying D
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.01.2007
• Subjects: Air Pollutants - analysis; Animal and plant ecology; Animal, plant and microbial ecology; Applied sciences; Atmospheric chemistry; Atmospheric pollution; Biological and medical sciences; Canada; Climate; Environmental Monitoring - statistics & numerical data; Exact sciences and technology; Forests; Fundamental and applied biological sciences. Psychology; Gas Chromatography-Mass Spectrometry; Herbivores; Hydrocarbons; Models, Theoretical; Particulate Matter - analysis; PCB; Phenyl Ethers - analysis; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Polybrominated Biphenyls - analysis; Polybrominated diphenyl ethers; Polychlorinated biphenyls; Polycyclic aromatic hydrocarbons; Polycyclic Aromatic Hydrocarbons - analysis; Sedimentation & deposition; Synecology; Terrestrial ecosystems; Trees - chemistry; Trees - growth & development; Velocity; VOCs; Volatile organic compounds; Canada; Great Lakes of America; North America; Ontario; America; Germany; Terrestrial environment; Boreal forest; Deciduous forest; Atmospheric fallout; Ether; Hydrocarbon; Pollutant behavior; Organic bromine compounds; Partition coefficient; Volatile organic compound; Deposition rate; Polycyclic aromatic compound; Low volatile compound; Polychlorobiphenyl; Organic chlorine compounds; Dry deposition; Persistent organic pollutant; Air biosphere interaction; Aerosols; Air pollution; Aromatic compound; Interception; Organic compounds; Canopy(vegetation)
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es0622047

The atmospheric deposition of several groups of semi-volatile organic compounds to a deciduous forest in Canada was determined using an indirect technique based on ratios of measured canopy interception and air concentrations. Air (gas and particle phase) and bulk deposition were sampled for 14 months from October 2001 to December 2002 at both a forest and a nearby clearing, and extracts were quantified for polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). Long-term average dry deposition velocities for vapors and particle-bound species were then derived for the canopy growing period. The mean dry gaseous deposition velocity for PBDEs and PCBs to the Canadian deciduous forest was 2.7 ± 0.52 cm·s-1, which is similar to the only other measured value for a deciduous canopy. Particle-bound deposition velocities to the canopy due to diffusion and impaction were 0.8 cm·s-1 for the PBDEs and 0.11 cm·s-1 for the PAHs. Differences in the particle-bound deposition velocities between PBDEs and PAHs and between deciduous canopies in Canada and Germany are explainable by differences in particle size distribution. The interception/concentration ratios for several PAHs were too low to be interpretable as dry gaseous deposition velocities. This is likely because the measured deposition flux under the canopy was less than the deposition flux to the canopy, possibly as a result of photodegradation in the canopy. From the ratio of canopy interception and average gas-phase concentration of less chlorinated PCBs, a predictive relationship between the canopy/air partition coefficient K PA and the octanol/air partition coefficient K OA was derived (K PA = 110 K OA 0.67). Despite differences in local climate and canopy composition and structure, the deposition velocities and the canopy uptake capacity measured in Canada were remarkably similar to those reported in Germany, lending credibility to the suggestion that high gaseous deposition velocities are common throughout boreal and temperate deciduous forests. These extraordinarily high deposition velocities of semi-volatile organic compounds to deciduous forest canopies are at the core of the hypothesis of a significant filter effect of forests on a regional and global scale.