Can barium and strontium be used as tracers for radium in soil–plant transfer studies?

Radium is one of the prominent potential contaminants linked with industries extracting or processing material containing naturally occurring radionuclides. In this study we investigate if 133Ba and 85Sr can be used as tracers for predicting 226Ra soil-to-plant transfer. Three soil types were artificially contaminated with these radionuclides and transfer to ryegrass and clover was studied. Barium is considered a better tracer for radium than strontium, given the significant linear correlation found between the Ra and Ba-TF. For strontium, no such correlation was found. The relationship between soil characteristics and transfer factors was investigated. Cation exchange capacity, exchangeable Ca + Mg content and soil pH did not seem to influence Ra, Ba or Sr uptake in any clear way. A significant relation (negative power function) was found between the bivalent (Ca + Mg) concentration in the soil solution and the Ra-TF. A similar dependency was found for the Sr and Ba-TF, although less significant.