Prior to LLL involvement in the NAEG program, Livermore had carried out resuspension studies related to nuclear cratering experiments and accidental releases from nuclear device tests. One of these studies was in conjunction with the Schooner cratering experiment (Anspaugh et al., 1969; Anspaugh et ai,, 1971; and Anspaugh et al., in press). Radioactivity measurements were made on an arc approximately 50 miles from the Schooner surface ground zero (SGZ). Some of the highest readings were obtained in the vicinity of the Queen City Summit outetide the northern boundaries of NTS. Based upon conjecture that the high readings were caused by unique interactions between wind flow and topography at the Queen City Summit region which had existed during the Schooner cloud passage, it was hypothesized that similar conditions could have existed during atwospheric device testings in previous years at NIS which could have resulted in unusually high plutonium depositions at the same site. Consequently, soil samples were analyzed for plutonium and data were obtained in support of the hypothesis. Plutonium levels in seil at Queen City Summit were found to be 100 times over the average background levels in U.S. sof]. Subsequent measurements were made by the Environmental Protection Agency's National Envtronmental Research Laboratory, Las Vegas (formerly the U.S. Public Health Service), which confirmed the LLL's earlier findings. These findings added impetus to carry out resuspension studies at NTS. Subsequent to starting the plutonium resuspension field studies, the opportunity arose to conduct a long-term experiment using the radioactivity deposited on the soil surface during the Baneberry accidental venting (Anspaugh et al., in press). The incident occurred in December, 1970. The study was carried out over approximately a one-year period. The study was directed at observing the resuspension of radioactivity as a function of time. Following the Baneberry study, efforts were directed toward designing a series of experiments at plutonium-contaminated areas on NTS. A joint proposal from LLL and NOAA/ARL outlining the experimental plan was submitted for AEC review, Early in 1972, research, development, and procurement were started on special apparatus needed to carry out the experiment. This included developing ultrahigh-volume air samplers, in-situ particle spectrometers, light-scattering-type particle counters, and establishing a micrometecrology field laboratory. A plutonium-contaminated site was selected and surveyed for layout of the experiment. RESUSPENSION EXPEREMENT: GMX-AREA 5 out a series of experiments involving plutonium and high explosives. At no time were nuclear detonations involved. These plutonium-high explosive tests started in late 1954 and ended in early 1956. Thus, as of thie date, the mean life of the plutonium source at GMX ia 18 years. Following the 1954-1956 serfes of tests, the highly contaminated area was fenced off and remained essentially undisturbed. Various groups within the NAEG program have gathered data which support the resuspension studies. These data include the areal distribution of plutonium, the distribution and concentration of plutonium within the soil, and a population census of vegetation covering the GMX study area. The initial resuspension experiment was designed with the goal of devel' oping a model to predict air concentrations of plutonium, given the source characteristics and relevant meteorological parameters. The objective was then to conduct a series of measurements within and downwind of the plutonium source. This was to be done during a period of time when the winds were consistent. Examination of several years of wind data showed that this was possible for a 2-4 hr period. The experiment waa laid out as shown in Fig. 2. The line showing the sampling stations ja located at 020° true, which corresponds to the mean direction of winds over 10 mph from March 24 to August 3, 1971, at the GMX site. the Micrometeorological measurements were directed at characterizing driving forces; i.e., winds, turbulence, and related parameters that up are considered to be most likely related to moving or picking discussed particles from the desert pavement. These measurements are olin detail by Kennedy and Booth (this report). The main micrometeor as shown ogy station waa established 1200 ft downwind from GZ, at R-1, ft, 2400 in Fig. 2. Air-sampling stations were established at GZ, 1200 stations, ft, and 4800 ft from GZ. In addition to the downwind sampling and in control stations were established upwind from GZ, at Mercury, identiLivermore, California. These background stations utilized the cal type of ultrahigh-volume air sampler. hr, the various During a field experiment, which usually lasted from 1-4 -volume micrometeorological parameters were recorded and the ultrahigh zed to start air samplers were operated. All the samplers were synchroni ts, particle spectrum and stop together. Concurrent with these measuremen using the Climet analyses at various heights above the ground were made ng in time with particle analyzer (Koval, this report). Also overlappi 900 ft upwind these measurements, background air samples were collected . from GZ; at Mercury, Nevada; and in Livermore, California g particles Saltation/creep samplers have been installed for collectin , this report). These that roll or bounce on the soil surface (Reichman field experiments. samplers as yet have not been integrated into the use the instruIt ig planned to finish evaluation studies in 1974 and ments shortly afterwards. The GMX Site, in Area 5, was selected for conducting the first plutonium resuspension experiment. This area had previously been used for carrying 276