Seasonal variations of naturally occurring radionuclides and 137cs in the leaves of deciduous tree species at sites of background radioactivity levels

Activity concentration of natural radionuclides and 137Cs were studied in leaves of the deciduous trees. In the spring and autumn season, leaves were collected in the area of normal background radiation levels represented by city parks in a multi-year period (2002-2012). Measurements by means of gamma-ray spectrometry showed 226Ra and 210Pb seasonal accumulation in leaves, while 238U and 235U could be detected only in autumn. Difference between seasons was not found significant for 40K and 137Cs. The study of radionuclides transfer factors was conducted by analyzing its relationships with basic soil properties at the beginning and the end of the vegetation period. © 2019, Editura Academiei Romane. All rights reserved.