PLUTONIUM IN A GRASSLAND ECOSYSTEM 423 



Navratil and Baldwin (1976) found that filtering the contaminated oil through a 

 O.Ol-jum filter removed only about 50% of the plutonium. This result strongly suggested 

 that about half the plutonium was in a relatively large particulate form whereas the other 

 half was associated with very small particles. Fission-track analysis of the filtered oil 

 confirmed that the remaining plutonium was monomeric. It is doubtful that the barrels 

 consistently held the above proportions of particulate and nonparticulate plutonium 

 oxide, but each probably contained some plutonium cliloride. 



J. M. Cleveland (personal communication) also suggested that the filtered 3-ium 

 plutonium particles might combine to form larger aggregates of the metal. Of course, the 

 size and binding tenacity of 1,hese conglomerates are unknown. 



Methods 



Two macroplots were chosen for intensive sampling of plutonium in soil, vegetation, and 

 litter. The locations of these macroplots relative to the supposed plutonium source, the 

 barrel storage area, and the prevailing wind are shown in Fig. 2. A sampling grid was 

 superimposed over each macroplot. The macroplot 1 grid was approximately 0.75 ha 



N 



1 km 



ACROPLOT 1 



ASPHALT BARREL 

 STORAGE PAD 



SECURITY 

 FENCE 



Fig. 2 Schematic representation of the southeast comer of the Rocky Flats Plant 

 indicating the location of study macroplots and sampling transects. The wind rose 

 indicates the relative magnitudes of wind velocities during 1974. 



