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

• Investigations of 137Cs and 40K were performed in different ecological conditions.
• The data indicate a diverse biological metabolism of 137Cs and 40K in plant species.
• A pronounced association between 137Cs and 40K in soil and plants is not statistically significant.
• A competitive relationship exists between 137Cs and 40K in plants as well as in the soil.
• The ratio of 137Cs/40K in plants can be applied in evaluating the influence of plant contamination.

Long-term investigations (1996–2008) were conducted into the 137Cs and 40K in the soil of forests, swamps and meadows in different regions of Lithuania, as well as in the plants growing in these media. The 137Cs and 40K activity concentrations, the 137Cs/40K 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 137Cs and 40K accumulation, the transfer from soil to roots and translocation within the plants depend on the plant species and environmental ecological conditions. The 137Cs/40K 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 137Cs and 40K in plants and soil is different. Different accumulations and translocations of investigated radionuclides in the same plant species indicate diverse biological metabolism of 137Cs and its chemical analogue 40K in plants. A competitive relationship exists between 137Cs and 40K in plants as well as in the soil.