PROTOTYPE MAPPING OF RADON POTENTIALS IN FLORIDA by : Kirk K . Nielson Randall

A prototype map of radon potentials in Alachua County, Florida is being developed to demonstrate the feasibility of defining geographic criteria for implementing radon-protective building construction standards. Because of regulatory needs and sensitivities, the map is being developed independent of institutional boundaries or of particular present radon limits. I t defines the radon source potentials as the average rate at which radon would enter a reference house that is modeled on specific soil profiles that are defined in the existing county soil survey. Radon transport parameters (diffusion coefficients and air permeabilities) for each soil layer a t each location are defined from soil densities, textures, and moisture properties in the soil survey data base. Parent radium concentrations and radon emanation coefficients were measured in 323 soil samples obtained from archived materials from the county survey reference pedon sites and from supplementary borings. Radium concentrations are mainly associated with clayey materials from the Hawthorne formation. Relatively high radon emanation coefficients were observed, averaging 0.48 20.16. The high emanation coefficients are attributed to predominant radium mineralization in the Hawthorne-related surface coatings in sandy soils. Radon potentials 01 approximately 3 mCi y'l per pCi g"l ^ ~ a are estimated to correspond to uniform sandy soils to give an indoor radon concentration of 2 pCi cl. This project is funded by the U. S. Environmental Protection Agency (EPA) and the Florida Department of Community Maim (DCA). This paper has been reviewed in accordance with the U.S. Environmental Protection Agency's peer and administrative review policies and approved for presentation and publication.