Accumulation and transfer of 137Cs and 90Sr in the plants of the forest ecosystem near the Ignalina Nuclear Power Plant

The radioecological state of the forest ecosystem in the vicinity of the Ignalina Power Plant prior to decommissioning was analysed with specific emphasis on 137Cs and 90Sr activity concentrations in plant species growing in two reference sampling sites (Tilze and Grikiniskes). In the period of 1996–2008 the mean contamination of plants with 137Cs was from 45 to 119 Bq/kg and with 90Sr – from 3 to 42 Bq/kg. Measured 137Cs TF values for soil-root transfer mainly ranged between 1.0–1.4, except for Calamagrostis arundinacea which had a TF value of 0.1. On average, the 137Cs TF value from root to shoot was 1.7 fold higher than for soil to root transfer. 90Sr TF values (soil-root) were in the range of 1.2–1.8 but for Calluna vulgaris it was 0.2. The mean root to shoot TF value for 90Sr was 7.7 fold higher. These results indicate the higher 90Sr bioavailability than that of 137Cs in the forested area. The Grikiniskes reference site is located nearby the Ignalina NPP, specifically the heated water outlet channel, which results in altered microclimatic conditions. These specific microclimatic conditions result in relationships between 137Cs TF (soil-root) values and pH, moisture and organic matter content in the soil at Grikiniskes which appear to be different to those at the Tilze reference sampling site.

► The state of the forest ecosystem prior to decommissioning of the NPP was analysed.
► Results indicate the higher 90Sr bioavailability than that of 137Cs.
► Contribution of 137Cs of different origin in plants was calculated.