Impact of Scots pine (Pinus sylvestris L.) plantings on long term 137Cs and 90Sr recycling grom a waste burial site in the Chernobyl Red Forest

Plantings of Scots pine on a waste burial site in the Chernobyl Red Forest wash shown to influence the long term redistribution of radioactivity contained in sub-surfaces trenches. After 15 years of growth, aboveground biomass of the average tree had accumulated 1.7 times more 137Cs than that of trees growing off the trench, and 5.4 times more 90Sr. At the scale of the trench, tree contamination corresponds to 0.024% of the 137Cs and 2.52% of the 90Sr contained in the buried waste material. A quantitative description of the radionuclide cycling showed a potential for trees to annually extract up to 0.82% of the 90Sr pool in the trench and 0.0038% of the 137Cs. A preferential 90Sr uptake from the deep soil is envisioned while pine roots would take up 137Cs mostly from less contaminated shallow soil layers. Using a prospective calculation model, we estimated that maximum 90Sr cycling can be expected to occur at 40 years post-planting, resulting in 12% of the current 90Sr content in the trench transferred to surface soils through biomass turnover and 7% stored in tree biomass.