Dry deposition of gas-phase polycyclic aromatic hydrocarbons to greased surrogate surfaces

Recently, greased surrogate surfaces have been successfully used to directl y measure the dry deposition of semivolatile organic chemicals (SVOCs). How ever, it has been difficult to interpret these measurements because the ext ent to which the grease used to collect the deposited particles absorbs the gas phase SVOCs is not clear. In this study, the partitioning between poly cyclic aromatic hydrocarbons (PAHs) in the vapor phase and grease used on s urrogate surfaces was investigated. This interaction was parameterized by d efining a partition factor as the ratio between the individual PAH air phas e equilibrium concentration and the PAH grease phase equilibrium concentrat ion multiplied by the square root of the PAR diffusion coefficient in the g rease. This factor was used to estimate the vapor phase PAH deposition to g reased surrogate surfaces deployed in the field for periods between 1 and 5 days. For these samples, naphthalene had the largest gas phase deposition to the grease while fluorene had the lowest. The amount of deposited PAH at tributable to gas phase deposition was not significant compared to particle deposition. The air/grease partition factor was found to be con elated to its octanol/air partition coefficient (r(2) > 77%).