Resolving Chernobyl vs. global fallout contributions in soils from Poland using Plutonium atom ratios measured by inductively coupled plasma mass spectrometry

Plutonium in Polish forest soils and the Bor za Lasem peat bog is resolved between Chernobyl and global fallout contributions via inductively coupled plasma mass spectrometric measurements of Pu-240/Pu-239 and Pu-241/Pu-239 atom ratios in previously prepared NdF3 a spectrometric sources. Compared to global fallout, Chernobyl Pu exhibits higher abundances of Pu-240 and Pu-241. The ratios Pu-240/Pu-239 and Pu-241/Pu-239 co-vary and range from 0.186 to 0.348 and 0.0029 to 0.0412, respectively, in forest Soils (Pu-241/Pu-239 = 0.2407x[Pu-240/Pu-239] - 0.0413; r(2) = 0.9924). Two-component mixing models are developed to apportion Pu239+240 and 241 Pu activities; various estimates of the percentage of Chernobyl-derived Pu239+240 activity in forest soils range from <10% to >90% for the sample set. The Pu-240/Pu-239-Pu-241/Pu-239 atom ratio mixing line extrapolates to estimate Pu-241/Pu-239 and the Pu-241/Pu239+240 activity ratio for the Chernobyl source term (0.123 +/- 0.007; 83 +/- 5; 1 May 1986). Sample Pu-241 activities, calculated using existing alpha spectrometric Pu239+240 activities, and the Pu-240/Pu-239 and Pu-241/Pu-239 atom ratios, agree relatively well with previous liquid scintillation spectrometry measurements. Chernobyl Pu is most evident in locations from northeastern Poland. The Pu-241 activities and/or the Pu-241/Pu-239 atom ratios are more sensitive than Pu-240/Pu-239 or Pu-238/Pu239+240 activity ratios at detecting small Chernobyl Pu239+240 inputs, found in southern Poland. The mass spectrometric data show that the Pu-241 activity is 40-62% Chernobyl-derived in southern Poland, and 58-96% Chernobyl in northeastern Poland. The Bor za Lasem peat bog (49.42degrees N, 19.75degrees E), located in the Orawsko-Nowotarska valley of southern Poland, consists of global fallout Pu. (C) 2003 Elsevier Ltd. All rights reserved.