Impact of afforestation on long term 137Cs and 90Sr recycling from a waste burial in the Chernobyl Red Forrest

Following the Chernobyl reactor fire in April 1986, acute irradiation caused complete decay of pine trees in forest located in direct vicinity of ChNPP. The so-called "Red Forest", a 1500 ha of Scots pine stand where the absorbed doses values exceeded the destructive value for coniferous species (> 60 Gy), is still today one of the most contaminated terrestrial ecosystems on Earth. Emergency clean-up activities consisted of in situ burial of contaminated topsoil layers and dead trees in about two hundred sub-surface trenches involving 1 million m3 of radioactive materials. The trenches of Red Forest waste dump were then covered with 20-30 cm layer of "clean" sand and the site was revegetated with a mixture of pine, birch and bushes to prevent secondary contamination due to soil erosion or wind resuspension (Kozubov and Taskaev, 2002).