Based on more recent knowledge, changing criteria, and further FIDLER develop- ment, the FIDLER may prove to be of greater value than was believed originally. For example, if a "level of no concern" is set within the detection range of the FIDLER, the number of samples subjected to radiochemistry could be substan- tially reduced if the FIDLER were used and hence there would be a resultant reduction in analytical costs. Mound Sampling Certain studies present unique sampling requirements such as those associated with blow-sand mounds. Blow-sand mounds may constitute as much as 20-30% of a study area. The mound may be considered as composed of layers which have been intermittently deposited by wind. The structure is complicated by the dynamic nature of the mound in that deposition and removal are coexistent. Many mounds have been created or altered by animal activities. The mound may be an accumulator of windblown radionuclides; a knowledge of associated concen- trations is necessary to a calculation of inventory. The location and concen- tration of radionuclides within the mound and the proximity of radionuclides to the root zone are also important. The Soils Element submitted a procedure for mound sampling to NAEG in March, 1974. The procedure was developed such that simple or complex missions could be satisfied. Procedures were submitted by other Elements, and an integrated version of the proposed methods was used in the summer of 1974 in a pilot study titled Mound Study #1. Profile samples were obtained from a series of mounds and adjacent desert pavement in Area 11 and assayed by Ge(Li) spectrometric techniques for 241lam to predict the distribution of plutonium within the mound. Figure 1 presents one typical pair of mound and desert pavement profiles. It will be noted that in this mound, the surface of the surrounding desert pavement is below the desert pavement datum found under the mound, possibly indicating erosion of the surrounding desert pavement during and after mound formation. Further, radioactivities below the desert pavement datum within the mound and those in the desert pavement surrounding the mound correlate very well below the 2 cm depth. Based on the data obtained, two possible explanations for the observed 24lam distribution are (1) that the radioactivity was deposited prior to mound formation and (2) that the mound may have dynamically moved in the direction of the sampling point covering an already contaminated surface with additional contaminated material. A second point to note is the higher radioactivity associated with the mound than that associated with the surrounding desert pavement. Since the mounds are formed from a relatively narrow range of particles, it can be assumed that 241am and consequently plutonium is associated with soil particles which fall within that range. It was concluded from Mound Study #1 that mounds are an important sink for radioactivity; hence, their contribution to inventory may be important. A second study related to mound sampling (Mound Study #2) was initiated in FY 1976 to determine the contribution of plutonium and 24lam in the mound to total inventory. Sampling and analysis are progressing; results are not available at this time. 22