Chemometric interpretation of vertical profiles of radionuclides in soils near a Spanish coal-fired power plant.

The study of the vertical distribution of seven radionuclides in soils around a coal fired power plant in a mountain region in the north of Spain has been performed, in order to know if some deposition and migration of these radionuclides has taken place. Thirteen profiles of 30 cm depth have been selected, and every fraction of 5 cm has been analyzed until of a total of 72 soil samples. The activity concentration of (238)U, (226)Ra, (210)Pb, (232)Th, (224)Ra, (40)K and (137)Cs has been measured by gamma-ray spectrometry. The data were analyzed using multivariate statistical techniques, founding the best result when using a simple two-factor model, which can explain the 81.1% of the total variance. Additionally, on the basis of the significant differences found in the concentration of lead in the soil top and deep layers, the evaluation of excess of (210)Pb and the K-parameter was done. A good correlation between the excess of (210)Pb and the concentration of anthropogenic radionuclide (137)Cs in surface soil was found. These results confirm the atmospheric deposition of lead as a decay product of exhaled Rn.