The influence of surface structure on predicted particle dry deposition to natural grass canopies

Equations describing particle transport to surfaces by diffusion, interception, impaction, and sedimentation have been used to predict dry deposition onto five wild grass canopies. Detailed measurements of plant height and spacing, width of stems, leaves, and inflorescences, and wind data collected within and above each canopy have been applied as model input data. The resulting curves of deposition velocity versus particle diameter have then been used with size distribution data from the literature for Pb and sulfate to predict overall dry deposition. Results of these calculations suggest a wide range of dry deposition velocities of 0.05 to 1 cm s^-1 for these species, the variation resulting from differences in surface structure and size distribution characteristics. At least 40% of the mass deposition of lead and sulfate results from the largest 10% of the airborne material.