Analysis of the potential disadvantages of chemical countermeasures against the transfer of radiocaesium to plants

¹ LARUEX, Dept. of Applied Physics, C.U.M., University of Extremadura, c/ Sta. Teresa de Jornet 38, 06080 Mérida (Badajoz), Spain
² LARUEX, Dept. of Applied Physics, Faculty of Veterinary Science, University of Extremadura, Avda. de la Universidad s/n, 10071 Cáceres, Spain
³ Dept. of Physics of Life and Environment, Horia Hulubei National Institute of Research and Development for Physics and Nuclear Engineering, Box MG-6, 077125 Mägurele-Bucharest, Romania

Corresponding author: fguillen@unex.es

Abstract

Countermeasures to reduce the transfer of a radionuclide from soil to plants are usually based on saturating the soil with a stable element that is a chemical analogue of that radionuclide. But when a radioactive contamination event occurs, it is seldom due to the evacuation of a pure radionuclide such as ¹³⁷Cs. Instead, a mixture of radionuclides may be released into the environment. The countermeasures applied to reduce the transfer of one of them may also influence other radionuclides. We have developed an experimental procedure to check whether radiocaesium countermeasures are appropriate when other radionuclides are also involved, or have some disadvantages that may limit their use. It consists of growing wheat seeds under controlled laboratory conditions using Neubauer's plantlet method. This method has been in use for many years as a small-scale screening procedure to check a soil's capacity to provide the potassium that plants need as a nutrient. In particular, we used it to study the effectiveness and the disadvantages of the application of a potassium salt fertilizer to a soil contaminated with ¹³⁴Cs, ⁹⁰Sr, and ⁶⁰Co. This countermeasure indeed reduced the uptake of ¹³⁴Cs, but it also enhanced the uptake of ⁶⁰Co. This enhancement was higher for the wheat stems than for the roots. For ⁹⁰Sr, there was observed a slight increase due to the fertilizer.