Date of Award
Master of Science (MS)
Civil and Environmental Engineering
Cliff I. Davidson
Dry Deposition, Dry Deposition Velocity, Inorganic Anion, Surrogate Surface, Washoff
Surrogate surfaces are used to measure atmospheric dry deposition of contaminants, and are sometimes designed intentionally with simple geometry to estimate the lower limit of the flux to any surface. However, most surrogate surfaces have a small collection area: long periods of dry weather may be needed to obtain sufficient deposited contaminants to be detected and quantified, and such exposure periods may not be common in wet climates. In this study, two relatively large surrogate surfaces—disks with surface areas > 1 m2—were designed to measure dry deposition of F-, Cl-, SO42-, and NO3- in Syracuse, NY. Results indicate that good reproducibility is possible for measurements with exposure periods of 2-6 days. Computational Fluid Dynamics modeling shows that the boundary layer thickness varies somewhat over the disk, but average fluxes to different sections of the disk differ by only 8%. This study also proposes a new method to measure dry deposition to urban surfaces by measuring the removal of dry deposited material in runoff samples collected from an urban surface during a rainstorm at various time steps. For this method to work, the amount of dry deposited mass must be substantially greater than the amount contributed by precipitation. As an example calculation, the amount of SO42- deposited to the roof of the War Memorial Arena in downtown Syracuse, NY is estimated using dry deposition data from the disks and compared to the amount of SO42- in the precipitation for a hypothetical storm. The results show that it may be possible to measure the removal of SO42- and other contaminants from the roof by stormwater runoff during a subsequent rainstorm.
Johnson, Alexander J., "Measuring Atmospheric Dry Deposition to Urban Surfaces" (2018). Theses - ALL. 265.