UPTAKE OF TRANSURANIC NUCLIDES FROM SOIL BY PLANTS 339 



TABLE 1 ^ 3 ^ -2 ^ °Pu and ^ '^ ' Am Concentrations and 

 Ratios of Desert Soils from the Nevada Test Site and the 

 Tonopah Test Range Used in the Soybean Experiment* 



Concentration, nCi/g 

 (dry weight) 



Soil source 2 39,24opy ^^^\m Pu/Am 



Area 11 B 2.8 ±0.41 0.44 ± 0.06 6.5 + 0.17 



Area 11 C 9.6+1.3 1.8 ± 0.20 5.2 ±0.17 



Area 11 D 4.6 ± 0.24 0.87 ± 0.06 5.2 ±0.12 



Area 13 ' 6.0 ± 0.93 1.1 ±0.11 5.6 ± 0.27 



Qean Slate 1 4.3 ± 0.57 0.23 ± 0.03 19.0 ± 0.33 



aeanSlate2 15.0 ± 3.6 0.72 ±0.13 21.0+1.9 



Qean Slate 3 11.0+1.6 0.59 ± 0.07 19.0 ±0.67 



Double Track 5.9 ± 0.79 0.28 ± 0.03 21.0 ± 0.88 



* Values are means ±1 standard error. 



eight fallout areas at which FIDLER activity readings ranged from 20,000 to 30,000 cpm 

 are given in Table 1. These soils were used for the soybean experiment. The soUs used for 

 the alfalfa and barley experiments were collected at a greater distance from ground zero 

 in Area 13 and consequently had much lower ^ ^^Pu and ^"^^ Am contents. 



Soils collected from an intermediate contamination zone in Area 13 were subdivided 

 into twelve 20-kg lots and mixed thoroughly with given amendments in a Patterson— 

 Kelley blender for 1 lir before subdividing the mixture into six 3.2-kg lots for potting. 

 The soil amendments consisted of nitrogen fertiUzer (at a rate equal to 200 kg N/ha as 

 NH4NO3), 2% agricultural-grade sulfur (to reduce pH from 7.6 to 5.4), and 57o OM (as 

 alfalfa meal). The treatments were done in three separate sets of three replications per 

 treatment and with and without DTPA (72 pots in total). Soil was potted in plastic pots 

 that were sleeved inside plastic buckets and covered with 5 cm of siUca sand to prevent 

 soil-particle resuspension. The soil activity levels turned out to be much lower than had 

 been anticipated. Consequently the plant materials from all rephcates grown on similar 

 treatments of the three sets had to be combined to produce an adequate sample size for 

 radioassay. Barley plants were grown first. They were harvested in the dough stage by 

 cutting at about 5 cm above the top of the sand layer and were divided into straw and 

 fruit head samples. Alfalfa was grown next. Tluee successive cuttings of foliage were 

 made in the quarter-bloom stage; then the plants were harvested and combined like the 

 barley plants. 



Soils collected from eight different plutonium fallout areas on the NTS and the 

 Tonopah Test Range were used for the pot-culture experiments with soybeans. These 

 soils received only the DTPA chelate (200 ppm) amendment. The eight soils were again 

 arranged in three sets each, containing three replicates, with and without DTPA (144 pots 

 in total). Soil processing and potting and plant harvesting and preparation for radioassay 

 were done as indicated for the barley and alfalfa experiments. The soybean plants were 

 grown to maturity, harvested, and separated into fruit pods and foliage (leaf and stem). 

 All samples were radioassayed for ^"^^ Am and ^•'^Pu at LFE, Richmond, Cahf. (Majors 

 etal., 1973), 



