Calculated results are shown with the one-sigma radiowere calculated. chemical counting statistic limits around each data point. If limits are symplotting the within are limits counting not shown, the radiochemical bol. Implications of Concentration Profiles Airborne concentration profiles are the airborne concentrations in either uCi/cm? or uCi/g as a function of height. In some cases, airborne concentration profiles of plutonium-239 and americium-241 can be interConcentration profiles preted in terms of possible resuspension sources. are influenced by the extent and variation of the resuspension source, deposition between the resuspension source and sampling location, and by meteorological parameters such as wind speed and atmospheric stability. For example, the concentration profile for an infinite source would show the pCi/em? decreasing with increasing height. For an upwind source and simultaneous airborne plume depletion by deposition, the maximum airborne concentration in wCi/cm? will be at some elevated height. Similarly for airborne concentration profiles in uCi/g, the airborne concentration is influenced by sampling both the soil from the contaminant resuspension source as well as airborne soil transported from uncontaminated surfaces. An attempt will be made to interpret the experimental concentration profiles in terms of these possible sources. Each interpretation of the observed concentration profiles carries one qualification: that these average profiles are for samples collected for all wind speeds and directions. Thus, sources of airborne plutonium-239 and americium-241 cannot be identified with respect to direction from the air sampling location. Small Particle Concentration in uCi/cm? Airborne concentrations in wCi/em? for "small" particles are shown in Fig. 2. The relative plutonium-239 and americium-241 concentrations for "small" particles show distinctly different concentration profiles. The plutonium-239 airborne concentration was 1.4 x 107!7 yci/em? (maximum) at 1.9 m and decreased with increasing height up to 91 m. From 91 m to 122 m, the plutonium-239 concentration increased. In contrast to the decrease, there was a maximum americium-241 concentration of 9.6 x 107!7 uCi/em? at a 9l-m height. It is unknown why the plutonium-239 airborne concentration in pCi/cem? for "small" particles at 122 m was greater than at 91 m. The increased airborne concentration at 122 m is attributed in part to a greater plutonium-239 yCi/g at 122 m than at 91m. unexplained, Although the increase is an increased concentration was also observed (Sehmel and Lloyd, 1976) at Rocky Flats for sampling heights between 10 and 30 m. In contrast to the plutonium-239 concentration profile, the americium-241 concentration profile in wCi/em? for "small" particles suggests a surface depletion of the airborne plume. This concentration profile indicates either an upwind resuspension source or an elevated release. In any event, the americium-241 source was not determined. 711