RELATIONSHIP OF MICROBIAL PROCESSES 329 



<=> <=> O cr>:;- XYLEM EXUDATE to 6.3 hr 



15,200 (d/min) ml-1 



6.3 to 9.8 hr 37,400 (d/min) m|-l 



<=> '='* 9.8 to 14.7 hr 43,900 (d/min) ml-i 



14.7 to 26.7 hr 60,100 (d/min) ml-i 



® CONTROL, Pu-DTPA 50,000 (d/min) ml-i 



c=:)C3 ^z^ CONTROL PLANT XYLEM 50,000 



i EXUDATE PLUS Pu(N03)4 (d/min) ml 



ORIGIN 



(+) -*■ TLE, 40 mm ► Q 



Fig. 10 Thin-layer electrophoretic behavior of plutonium in soybean xylem exudates. 

 [From Wildung, Drucker, and Au (1977).] 



tissues grown on plutonium-containing soil. In these studies gut absorption of plutonium 

 gavaged in inorganic solution and plutonium fed in alfalfa tissue was compared for rats 

 (nonherbivorous) and guinea pigs (herbivorous). In both rats and guinea pigs, absorption 

 through the gastrointestinal tract of plutonium incorporated in alfalfa tissue was greater 

 (7.7 to 53 times) than that by gavaging inorganic Pu(IV) solutions (Sullivan and Garland, 

 1977). Uptake by rats fed alfalfa containing the plutonium exceeded that from gavaging 

 Pu(IV) nitrate or Pu(IV) citrate but was less than that resuhing from gavaging Pu(VI) 

 nitrate (Table 8). Uptake was higher when stems and leaves were fed than when leaves 

 only were fed. Several variables, including animal species, duration of feeding, and types 

 of plant tissues fed, were evaluated, but, as a result of the small number of animals that 

 could be used, the limited quantity of tissues, and variability, further studies are required 

 to evaluate the statistical significance of individual variables. 



PreUminary chemical characterization (T. R. Garland, K. M. McFadden, and R. E. 

 Wildung, unpublished) of the form of plutonium present in the alfalfa tissue fed to the 

 rodents indicated that the plutonium was more soluble in stems than in leaves, perhaps by 



