Accumulation and translocation peculiarities of 137Cs and 40K in the soil – plant system

Abstract Long-term investigations (1996–2008) were conducted into the 137 Cs and 40 K in the soil of forests, swamps and meadows in different regions of Lithuania, as well as in the plants growing in these media. The 137 Cs and 40 K activity concentrations, the 137 Cs/ 40 K activity concentration ratio and accumulation, and translocation in the system, i.e. from the soil to plant roots to above-ground plant part of these radionuclides, were evaluated after gamma-spectrometric measurements using a high purity germanium (HPGe) detector. Based on the obtained data, it can be asserted that in the tested plant species, the 137 Cs and 40 K accumulation, the transfer from soil to roots and translocation within the plants depend on the plant species and environmental ecological conditions. The 137 Cs/ 40 K activity concentration ratios in the same plant species in different regions of Lithuania are different and this ratio depends on the biotope (forest, swamp or meadow) in which the plant grows and on the location of the growing region. Based on the determined trends of statistically reliable inverse dependence between the activity concentrations in both soil and plants, it can be stated that the exchange of 137 Cs and 40 K in plants and soil is different. Different accumulations and translocations of investigated radionuclides in the same plant species indicate diverse biological metabolism of 137 Cs and its chemical analogue 40 K in plants. A competitive relationship exists between 137 Cs and 40 K in plants as well as in the soil.