Soil concentration, vertical distribution and inventory of plutonium, 241Am, 90Sr, and 137Cs in the Marche Region of Central Italy

Soil concentrations of Pu239+240, Pu-238, Am-241, Sr-90, and Cs-137 are investigated in the Marche Region of Central Italy. Mean values in uncultivated soils (0.721. +/- 0.456, 0.023 +/- 0.014, 0.241 +/- 0.165, 5.40 +/- 3.32, and 62.3 +/- 33.9 Bq kg(-1), respectively) are 3.5-8 times higher than the corresponding values in cultivated soils (0.147 +/- 0.054, 0.005 +/- 0.002, 0.047 +/- 0.021, 1.53 +/- 0.44, and 7.70 +/- 2.07 Bq kg(-1)). Radionuclide inventories and ratios are consistent with values reported by the United Nations Scientific Committee on:the Effect of Atomic Radiation for this latitude (40-50 degrees N). This suggests that radiocontamination in this region:is mainly due to atmospheric deposition of nuclear weapon test fallout. The vertical distribution of these radionuclides is also studied. The results show that, with the exception of Sr-90 (68%), more than 90% of these radionuclides are contained in the first 20 cm of soil and that mobility follows the order Sr-90 > Am-241 > Pu239+240, Pu-238 > Cs-137.