RESUSPENSION ELEMENT STATUS REPORT, MAY, 1975* NEVADA APPLIED ECOLOGY GROUP L. R. Anspaugh and P. L. Phelps Division of Biomedical and Environmental Research Lawrence Livermore Laboratory Livermore, California ABSTRACT The resuspension-inhalation pathway is generally regarded as the critical pathway for a few radionuclides of very low biological availability, such as plutonium. The primary goal of the resuspension element program is to develop a general model for the predictionof the average concentration of resuspended contaminants. This report briefly summarizes past accomplishments, current studies, and future plans of the resuspension project being conducted at the Nevada Test Site. Past accomplishments have been: measurement of the concentra- tion of resuspended 239 Pu over short time periods of consistent meteorology with concomitant detailed micrometeorological measurements; development of two interim predictive models and derivation of protective guidelines for soil contamination with 2395. derivation of parameterizations of resuspended soil concentrations and fluxes as functions of friction velocity and soil erodibility; test of applicability of these parameterizations to the resuspension of Pu; and development of an integrated approach to a general resuspension model. Current studies include: test of the resuspended soil concen- tration and flux parameterizations at a variety of Test Site locations; development of an airborne platform for the study of mass fluxes produced by episodic events such as dust devils; development of a computer-controlled sampling system for testing model validity; addditional data analysis of collected data; and development of *A preprint of this report appeared as UCRL-76823. 91