Rates of Dry Deposition Determined Using Wet/Dry Collectors

Abstract

Daily samples of dryfall were collected during the June 1982 Dry Deposition MeasurementIntercomparison Study at Champaign, Illinois, using six Aerochem Metrics wet/dry collectors. Upon completion of the field experiment, these samples were analyzed at the Environmental Measurements Laboratory for pH and for their concentrations of major inorganic constituents. Contamination by rain and bird droppings rendered a number of dryfall samples unusuable. When data for these samples were removed, the remaining data displayed acceptable precision for sulfate, calcium, and magnesium. The measured deposition rates varied between 7 and 73 ng/m2/s for sulfate, between 7 and 44 for calcium, and between 0.8 and 8.1 for magnesium. The precision of the data for ammonium, nitrate, and phosphate was poor, so we have not calculated deposition rates for these constituents. The measurements of the atmospheric concentrations of sulfate reported by the Illinois State Water Survey have been used to calculate deposition velocities for particulate sulfate for 18 daily samples, even though the aerosol sampler and the dry bucket of the wet/dry collector may not sample the same size population of particulates. These velocities ranged from 0.1 to 1.2 cm/s, with a median value of 0.4 cm/s and a mean of 0.45+0.31 cm/s. The estimation of rates of dry deposition during the June 1982 dry deposition intercomparison study at Champaign, Illinois, Illinois State Water Survey, Champaign, 1983. Ton, N., J. A. Eastman, and H. Sievering, Dry loading collection efficiency of sulfate and soil aeresol by a passive sampler, EOS-Trans. AGU, 64, 198, 1983. Volchok, H. L., and G. de Planque (eds.), EML Procedures Manual, USDOERep.'HASL-300, 25th ed.,

Atmospheric depositional characteristics of beryllium 7 and lead 210 along the southeastern Virginia coast

“…The wet-only collector was exposed to the atmosphere only during precipitation events. The bulk collector was exposed to the atmosphere continuously, thus enabling the collection of both wet and dry fallout [Feely et al, 1985].…”

Dry Deposition of Particulate Polychlorinated Biphenyls and Polycyclic Aromatic Hydrocarbons to Lake Michigan

“…Nevertheless, surrogate collection devices have been deployed to estimate dry deposition to various ecosystems. Such devices include wet/dry collectors of various configurations (31)(32)(33)(34)(35)(36), moss bags (37), glass fiber filters (16,32,38,39), Petri dishes (39,40), water surfaces (41,42), "Frisbee"-shaped air foils (43)(44)(45)(46), and aluminum, glass, or Mylar plates coated with grease, glycerin, mineral oil, or other material to prevent bounce-off (15)(16)(17)(47)(48)(49)(50)(51). Surrogate surfaces are reproducible and can be deployed in large spatial arrays to estimate particle deposition (40) and to evaluate regional and temporal trends.…”

Diurnal and seasonal variability in size-dependent atmospheric deposition fluxes of polycyclic aromatic hydrocarbons in an urban center

“…First, previous sampling was often conducted with a single sample integrating over many days (Feely et al, 1985;Golomb et al, 1997;Terzi and Samara, 2005), which concealed the diurnal variability stemming from meteorological factors, such as the turbulent mixing and changes in the depth of the atmospheric boundary layer. Degradation of SVOCs on the sampling medium was also a possibility during long-term sampling but not accounted for, resulting in underestimated deposition fluxes.…”

“…Dry deposition fluxes of semivolatile organic compounds (SVOCs), substantially influenced by particle size and meteorological conditions (Sheu et al, 1996), have been extensively measured worldwide. Surrogate receptors (mostly polyvinyl chloride plates smeared with silicon grease and water-filled platters) (Holsen and Noll, 1992;Sheu et al, 1996;Franz et al, 1998;Odabasi et al, 1998;Shahin et al, 1999;Tasdemir and Esen, 2007) and automated wet/dry deposition collectors (Feely et al, 1985;Golomb et al, 1997;Terzi and Samara, 2005) have been used to measure dry deposition fluxes. However, surrogate receptors seldom reasonably represent natural surfaces; therefore the results cannot be extrapolated to natural deposition with confidence.…”