404 TRANS URANIC ELEMENTS IN THE ENVIRONMENT 



Several reviews on environmental plutonium distribution and transport indicated a 

 general lack of published field data from representative areas of the United States 

 (Francis, 1973; Price, 1973; Roniney, 1977; Hanson, 1975; Hakonson, 1975). Several 

 field studies of plutonium have been initiated in the last few years to address 

 informational needs at a number of locations which encompass a wide spectrum of 

 climatic conditions ranging from deserts to humid forests and contain plutonium from 

 industrial, weapons, or accidental-release sources. 



The comparison of plutonium data from two southwest ecosystems in this chapter is 

 one step in the total synthesis of information from various regions of the United States 

 where types of ecosystems and sources of plutonium differ. The southwest United States 

 is an important study locale because of the energy activities that may develop and the 

 lack of understanding of the processes in arid systems which govern distribution and 

 transport of contaminants. In this regard studies on environmental plutonium are useful 

 to develop an understanding of patterns that are applicable to the transport and fate of 

 other materials. 



The objective of this chapter is to use existing plutonium contamination in the 

 canyon waste areas at Los Alamos and in the grasslands in the fallout zone at Trinity Site 



• To evaluate the role of environmental transport processes in distributing and 

 redistributing surface inputs of plutonium. 



• To evaluate the transport of environmental plutonium to the biosphere and the 

 relationships that lead to the potential for human exposure. 



• To compare plutonium behavior in these two major southwest ecotypes. 



The tasks in this study were to (1) document plutonium inputs where possible, 

 (2) develop an understanding of distributions by inventory of major environmental 

 components, and (3) evaluate transfers as functions of ecological variables. Plutonium, as 

 used in this chapter, denotes ^^^Pu and/or ^^^'^'**^Pu. 



Site Descriptions 



Los Alamos 



The canyons at Los Alamos, in north central New Mexico (Fig. 1), are typical of those 

 in the southwest plateau region of New Mexico, Arizona, Colorado, and Utah. They vary 

 from 10 m to over 200 m in depth and were formed by water erosion of the volcanic 

 substrate of the Pajarito Plateau. The area has a semiarid continental mountain climate 

 (Table 1) with annual precipitation ranging from about 20 to 50 cm as elevation increases 

 from 1650 to 2200 m; rainfall accounts for about 75% of the annual precipitation. 

 Drainage from the 113-km^ Laboratory site is via the many canyons that bisect the 

 plateau. The biotic resources of the canyons are diverse (Miera et al., 1977); total 

 vegetative ground cover is variable but generally high and approaches 100% in some areas 

 owing to the dense overstory, which is partly due to the industrial liquid effluents. 



Nearly all the liquid wastes generated by the Laboratory since 1943 have been 

 collected by industrial waste lines, treated (since 1951), and released into one of three 

 canyons (Fig. 1 ). The resuUs of studies in two of these canyons are emphasized in this 

 chapter since they represent the extremes in temporal use history. The oldest 

 waste-receiving area is Acid -Pueblo Canyon, which was used from 1943 to 1963 and 



