Accumulation of 134Cs from contaminated soils in different sorts of oats

The accumulation of radioisotopes in agricultural crops depends on the soil properties, the plant biological characteristics and environmental conditions. The aim of the study carried out was to determine the absorption of 134Cs from different types of soil contaminated, its accumulation in different plant organs of oats during the vegetation period, and also the influence of different sorts on the extent of absorption. Vegetation pot experiments with three sorts of oats cultivated in Bulgaria were carried out: Model farm-4, VV-16 and VV-17. The plants were grown in the fallow of two types of soils representative for the country: black earth from an experimental field in Gorni Dybnik (Pleven region) and maroon soil from an experimental field in Primorsko (Burgas region). The experiments were set up in pots with capacity of 5 kg soil under controlled conditions. Before sowing of the seeds the soil was contaminated with an aqueous solution of 134Cs with activity of of 2.7 MBq/pot. Each experiment was repeated four times. The plants were grown to a stage of complete maturity. Gammaspectrometrical analysis on the epigeous plant organs (leaves, stem and grains) with multichannel system 'Canberra' with Germanium detector of 25% efficacy was performed. A 'coefficient of accumulation' expressing the relationship between activity in 1g plant mass and 1 g soil for assessment of the cumulation of the radioisotope in the different plant organ has been determined. The results obtained show that: 1. 134Cs is unevenly distributed in the different plant organs with the highest accumulation in the vegetation ones and the lowest - in the grains; 2. The highest degree of accumulation of 134Cs has been detected at the sort VV-15 and the lowest - at VV-16 and 3. Depending on the soil properties the accumulation of 134Cs in the different sorts of oat is not equal. The plants grown on maroon soil extract more intensively the radioisotope in comparison to those grown on leached black earth. (author)