and smaller by approximately the same amount within the most intense dust storms. Consequently, the vertical and horizontal transport of surface material by dust devils may in itself be an important component in the overall resuspension budget. However, of more importance is the question of transport and ultimate fate of radioactive materials by dust devils and, in general, by atmogpheric convective elements that originate in the surface boundary layer. LLL plans to make direct quantitative measurements of the amount, the distance, and the direction of dust transported from a known dust devil source region at NTS. The analysis of these data will provide estimates of the possible radicactive substances such as plutonium by dust devils. Variation in Site Characteristics The availability of plutonium for resuspension is related to a significant degree to the soil-plant surface characteristics of the plutoniumcontaminated area. This is particularly true for aged sources that are found at NTS. A number of plutonium-contaminated sites exist at NTS. Each of the sites have more-or-less different and unique characteristics that influence the availability and movement of plutonium. The proper-— ties of importance are the initial physical-chemical form of the source, source age, source strength (surface related), source area and shape, physical-chemical makeup of the soil, soil surface structure, plant coverage, animal population, climatology, and land utilization. These properties are to be intensively studied. Source Term Analysis and Redistribution of Radioactivity at NTS An evaluation of the total NTS contribution of dose to man is limited by the lack of accurate mapping of the resuspendable radioactive source material distributed throughout the site. However, elements within the NAEG program are compiling information on several radionuclides and their distribution in seil, which, if extended to all radionuclides and areas, could be the basis for input to such a mapping. Assuming that a data bank on radionuclide distribution at NTS were e modelestablished, the other necessary inpute would be a comprehensiv and an ing of the meso-scale meteorology related to wind flow at NTS, ics understanding of resuspension for the variety of source characterist present throughout the site. source This study would provide information on the relationship between future and the dose to man from existing radioactivity and possible uses. An example of an area not yet studied is the Tonopah Test Range. This area is suitable for cattle grazing. A native species of grass, not found in the GMX area, is in abundance. Also, the physical "desert pavement" characteristics are significantly different than those so far studied. The Tonopah area affords an opportunity te study a plutonium-contaminated area with surface characteristics not heretofore studied. Man-Made Effects on Redistribution Displacement of surface soil by mechanical means can increase the rate of redistribution. The impact from future uses of NTS is of particular interest. In addition to continued device testing, future use may Iinclude radicactive fuel processing, radioactive waste storage, solar energy research, and agricultural uses, Coupled with these uses are a variety of ways that sufficient mechanical disturbances to contaminated sites can result. These include construction of facilities and roads, vehicular traffic over desert pavement, and grazing by cattle. A number of the areas contaminated from past device testing and nuclear cratering events should be studied. A natural follow-up experiment in the GMX area would be to introduce a variety of man-made disturbances to the soil surface and quantitate the change in resuspension of plutonium. 282 283