Measuring atmospheric dry deposition with large surrogate surfaces for improved time resolution. (1st February 2019)

• Record Type: Journal Article
• Authors: Johnson, Alexander J.; Davidson, Cliff I.
• Is Part Of: Atmospheric environment. Volume 198(2019)
• Page Start: 489
• Page End: 495
• Publication Date: 2019-02-01
• Subjects: Dry deposition -- Surrogate surface -- Aerosol -- Anion; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2018.10.055
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: 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 m 2 —were designed to measure dry deposition of F −, Cl −, SO4 2−, and NO3 − in Syracuse, NY. Results indicate that good reproducibility is possible for measurements with exposure periods of 2–6 days. The ranges of dry deposition velocities for each species are as follows: F − (0.6–2.5 cm/s), Cl − (1.9–9.2 cm/s), SO4 2− (0.11–1.8 cm/s), and NO3 − (0.1–1.1 cm/s). Fluxes were also measured to four separate sections of the disk; results suggest that deposition varies somewhat across the disk in a way that is consistent with boundary layer thickness predicted by Computational Fluid Dynamics modeling. Graphical abstract: Highlights: Two large disks measured dry deposition of atmospheric anions for short dry periods. Dry deposition velocities were obtained for F −, Cl −, SO4 2−, and NO3 − . Winter deposition of Cl − and SO4 2− substantially exceeded summer and fall deposition. Fluxes were measured to sections of the disks to check uniformity in deposition. Fluxes measured to different sections of the disks varied, but not greatly.