Dry Deposition of Gas-Phase Polycyclic Aromatic Hydrocarbons to Greased Surrogate Surfaces

Abstract

Recently, greased surrogate surfaces h ave been successfully used to ( ) directly measure the dry deposition of semivolatile organic chemicals SVOCs . However, it has been dif® cult to interpret these measurements because the extent to which the grease used to collect the deposited particles absorbs the gas phase SVOCs is not clear. In this study, the partitioning between polycyclic aromatic ( ) hydrocarbons PAHs in the vapor phase and grease used on surrogate surfaces was investigated. This interaction was parameterized by de® ning a partition factor as the ratio between the individual PAH air phase equilibrium concentration and the PAH grease ph ase equilibrium concentration multiplied by the square root of the PAH diffusion coef® cient in the grease. This factor was used to estimate the vapor phase PAH deposition to greased surrogate surfaces deployed in the ® eld for periods between 1 and 5 days. For these samples, naphthalene h ad the largest gas phase deposition to the grease while¯uorene had the lowest. Th e amount of deposited PAH attributable to gas phase deposition was not signi® cant compared to particle deposition. Th e air r r r r r grease partition factor was found to be correlatedto its octanol r r r r r air partition coef® cient r ) 77% .

Dry deposition fluxes and velocities of polychlorinated biphenyls (PCBs) associated with particles

“…Dry deposition has gained a great deal of interest from researchers due to its effects on the environment and consequently there have been significant efforts to measure or estimate dry deposition using a variety of techniques (Ogura et al, 2001;Pryor and Barthelmie, 2000;Drooge et al, 2001;Yang et al, 1999;Fang et al, 1999;Bidleman, 1988;Grainer and Chevreuil, 1997;Miller et al, 2001;Shahin et al, 1999;Pirrone et al, 1995;Hoff et al, 1996). The amount of dry deposition is a function of contaminant concentration and characteristics, atmospheric conditions and the receptor surface (Hoff et al, 1996;Zannetti, 1990;Holsen et al, 1991;Murphy et al, 1981).…”

“…The collection surface was designed based on wind tunnel studies to have minimum flow disruption and therefore, an estimation of the lower limit for dry deposition flux would be provided (Holsen et al, 1991). The deposition plate with greased strips has been successfully used as a surrogate surface to directly assess particulate fluxes of both organic and inorganic air pollutants (Noll et al, 1990;Tasdemir, 1997;Yi et al, 1997;Franz et al, 1998;Shahin et al, 1999;Odabasi et al, 1999;Vardar et al, 2002).…”

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

“…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.…”

Mass transfer coefficients for polycyclic aromatic hydrocarbons (PAHs) to the water surface sampler:

“…Estimated quantities absorbed by grease were not signi"cant and measured particulate phase #uxes were not corrected for this artifact (Odabasi et al, 1999a). Shahin et al (1999) also reported that the amount of deposited PAH due to gas-phase deposition was not signi"cant compared to particle deposition. It was assumed that reactive losses of deposited PAHs from dry deposition plates due to exposure to solar radiation and atmospheric oxidants during sampling were insigni"cant.…”