Geochemical forms of 152 Eu in agricultural soils under conditions of sharp cooling or warming


Geochemical forms of 152 Eu in agricultural soils under conditions of sharp cooling or warming


Miryana Varbeva, Petya Kovacheva
Faculty of chemistry and pharmacy, University of Sofia “St. Kliment Ohridski”, Sofia


The present work aims to study the influence of the sharp warming or cooling on the geochemical forms of bonding of 152 Eu in agricultural soils. The experiment was carried out after sampling of different soil from Bulgaria and contaminating them with solution, containing 152 EuCl 3. Afterwards the samples were conditioned during one month at three temperature regimes: 40 o C, 18 о C and -18 o C. Geochemical fractionation of 152 Eu was determined by applying procedures for sequential extraction, after which the following fractions were isolated: water-soluble, exchangeable and carbonate bonded fraction; oxide bonded fraction; organic matter and sulfide bonded fraction and residual fraction. The measurements of the extracted 152 Eu were performed by gamma-spectrometer with HPGe detector. The impact of the temperature of conditioning of the contaminated soils and the soil characteristics (mechanical content, pH humus content and cation-exchange capacity) on the mobile forms of radioeuropium were considered. The results has showed that the mobile fraction of 152 Eu is highest in the soil which has very low cation exchange capacity and high sand content. The sharp temperature decrease caused increase of the exchangeable and carbonate-bonded fraction of radioeuropium in the studied soils. The obtained results can be used for evaluation of the transfer of europium from soils to the crops and within the food chain in case of contamination under the conditions of sharp change of the environmental temperature.
Keywords: Eu-152, soils, geochemical forms, temperature changes