Effect of foliage surface wetness on the deposition of ozone
This study investigated the influence of foliage surface wetness on the deposition of ozone onto vegetation. Outdoor data, above and within a deciduous forest canopy, showed ozone deposition was affected by solar radiation, wind speed and ambient ozone concentration. Ozone deposition deep in the canopy was small compared to the upper canopy, because of the larger biological sink for ozone in the upper canopy. Substantial ozone deposition occurred while the forest canopy remained wet with either dew or rain water, nighttime and daytime. The ozone deposition onto hypostomatous red maple (Acer rubrum) and amphistomatous hybrid poplar (Populus deltoides tricocarpa) leaves was determined under controlled conditions. The ozone deposition onto wet maple leaves increased after water spraying. Nighttime measurements demonstrated that the enhanced deposition onto wet maple leaves was largely controlled by the chemistry of the solution on leaves. Small ozone deposition reductions were measured after poplar leaves became wet during daytime conditions. Little deposition was detected onto wet poplar leaves during the night, indicating that leaf water chemistry was less important as an ozone sink for poplar leaves. Water from poplar leaves offered little ozone sink whereas water from maple leaves was more effective in scavenging ozone. Data from outdoor and indoor experiments were incorporated in a one-dimensional model to further investigate the contribution of foliage wetness (dew) on the deposition of ozone onto vegetation. The model assumed that the deposition can be found from the ratio of the ozone concentration gradient and the sum of resistances to the transfer along the source-to-sink pathway. The modeled and measured deposition velocities compared reasonably well when the forest remained either dry or wet with dew. The indoor and outdoor studies demonstrate foliage wetness is an important factor in determining the ozone deposition to natural vegetated surfaces.
- Research Organization:
- Guelph Univ., ON (Canada)
- OSTI ID:
- 5413664
- Resource Relation:
- Other Information: Thesis (Ph.D.). Order No. DANN72267
- Country of Publication:
- United States
- Language:
- English
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