PubMed · 5301061
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K L Swinth. 1966. Wound counting with solid state detectors. BNWL-481 4.. https://pubmed.ncbi.nlm.nih.gov/5301061/
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This study investigated the dependence of Pu3+ and Pu4+ vertical distribution on the soil characteristics in soddy and forest soil. Soil samples were analysed for organic matter and pH. Special columns with contaminated (239Pu) soil surface were kept for 326 days under field conditions. The analysis of the contaminated soil layers (5 cm each, totalling 20 cm) showed that 81% of 239Pu4+, 44% of 239Pu3+ and 82% of 239Pu4+, 61% of 239Pu3+ were accumulated in the 0-5 cm layer of soddy and forest soil. Sequential extraction of the soddy soil 30 days after surface contamination with 239Pu, 137Cs and 90Sr showed the following differences in radionuclide distribution: the largest amount of 239Pu (60%) and 137Cs (70%) were extracted from the residual fraction while 90Sr in this fraction reached only about 10%. This suggests that organic substances and some inorganic compounds, which usually are the main components of the residual fraction, affect the retention and migration of plutonium in the soil.
241Pu activity measurements in coniferous forest soil samples from Poland are presented. The results were obtained in two ways: by alpha spectrometric remeasurements of the plutonium sources 3-4 years after their preparation (i.e. by the 241Am ingrowth) and by direct measurements of 241Pu using liquid scintillation (LS) spectrometry. Both methods gave consistent results. The maximum observed activity concentration obtained by the 241Am ingrowth was (254 +/- 43) Bq/kg, and by direct measurements it was (284 +/- 31) Bq/kg (the same sample, activities calculated for May 1, 1986). Enhanced levels of 241Pu were observed in all samples from the farthest north-eastern Poland. The estimated 241Pu maximum deposition from Chernobyl fallout in this area (sum of deposition for two examined layers of one site) was (1.025 +/- 0.110) kBq/m2. This will result after 70 years in an additional 241Am activity of about (30.1 +/- 3.2) Bq/m2. The average ratio for 241Pu to total 238,239,240Pu was of the order of 25. The obtained average Chernobyl ratios for 241Pu to 239,240Pu were about 86, and those for 241Pu to 238,239,240Pu were 56.
The horizontal and depth distribution of plutonium was measured in soil east of the Rocky Flats Environmental Technology Site (formerly the Rocky Flats Plant) near Denver, Colorado, during 1992-1994. The study area was centered on the eastern plume of plutonium contamination and included transects extending from 0.2 km east of the primary origin of the contamination (the 903 Pad) to distances of up to 19 km northeast, east, southeast and south-southeast of the 903 Pad. Soil was collected in 3 cm layers down to 21 cm at exponentially increasing distances along the four transects. Plutonium concentrations decreased rapidly with depth, distance from the 903 Pad, and angle from due east. Depth distributions were independent of distance and angle from the 903 Pad, and our profile model can be used to adjust to a common basis, historical measurements made from sampling to different depths. Based on a total of approximately 1,400 independent measurements, mathematical functions were developed to describe the distance, directional, and depth relationships. These equations, combined with soil density and rock measurements, provided a new method to estimate the plutonium concentration or total deposition per unit area anywhere within the study area. Total deposition per unit area measurements at 50 sites provided an independent test of the model's predictive accuracy. Sampling coefficients of variation based on replicate samples at the main sampling locations averaged 33%, but ranged from 12 to 98%. The analytical measurement coefficient of variation averaged 8%. Mean 0-3 cm soil concentrations of (239,240)Pu among 10 Front Range "background" and 11 community locations near Rocky Flats were 2.1 and 2.3 Bq kg(-1), respectively.