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HAZARDOUS AIR POLLUTANTS: WET REMOVAL RATES AND MECHANISMS
Citation:
Dana, M., R. Lee, AND J. Hales. HAZARDOUS AIR POLLUTANTS: WET REMOVAL RATES AND MECHANISMS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-84/113.
Description:
Fourteen hazardous organic air pollutants were evaluated for their potentials to be wet deposited by precipitation scavenging. This effort included a survey of solubilities (Henry's Law constants) in the literature, measurement of solubilities of three selected species, development and documentation of a general deposition model (MPADD) which includes dry deposition and plume depletion, and performance of scavenging field experiments to provide a data base for testing the model. Solubility parameters (dimensionless ratio of aqueous concentration to air concentration) for ethylene oxide, nitrobenzene, and methyl chloroform were measured in rainwater at two temperatures each Four field experiments were conducted: three using nitrobenzene and one involving methyl chloroform. Agreement of measured concentrations with model-calculated values was good for nitrobenzene, despite larger than desired experimental uncertainties during two of the releases. Analytical difficulties resulted in only a few measurements of methyl chloroform rainwater concentrations; these however, were in general agreement with model calculations and expectations on the basis of its much lower solubility than that of nitrobenzene. These results and sample test runs of the Multi-Pollutant Atmospheric Deposition and Depletion (MPADD) model, including dry deposition estimates, show that wet deposition should have little effect on plumes of non-reactive hazardous gases within kilometers of their sources.