Long-term effects of fallout Cs-137 on treesAim of the study137Cs activities in trees are examined in commercial forest stands to provide information for assessment of radioactivity in timber and wood fuels. The project aims to find out (1) how 137Cs activities in trees vary between forest stands of different age, (2) how 137Cs activities in trees change in the course of time (in the long term) and (3) how the forest site type affects the 137Cs activities in trees. ImplementationThe project has been started in 1997 in co-operation with Finnish forest industries. The study sites are located in Central Finland which is a part of the area that was contaminated with 137Cs from the Chernobyl fallout in 1986. The studied forests are spruce or pine dominated coniferous forests growing on dryish or moist sites on mineral soil. The study sites represent common forest types in Southern and Central Finland. The tree stands represent three different development classes. The sampling of trunk wood and other parts of trees has been carried out in 1999 and 2005 at six sites. The 137Cs activities in samples have been determined using gamma-ray spectrometry. The samples of soil and ground vegetation have been collected and analysed, too. The 137Cs distributions in trees and soil have been obtained by these sample measurements. Dissemination and exploitation of the resultsThe results will be published in scientific journals or in the STUK A-report series and they will be communicated to the Finnish forest industries involved in the project. The results can be used for evaluation of radioactivity in domestic wood products, and in models developed for exposure assessment. CollaboratorsFinnish forest industries TimetableThe project was discontinued in 2001 - 2003 due to execution of other projects. The existing data will be analysed and a summary of results will be prepared. The sampling and 137Cs determination of samples will continue until enough data on 137Cs activities have been obtained to draw conclusions on the questions addressed in the objectives of the project. Responsible scientistsVirve Vetikko and Aino Rantavaara Page updated 15/05/2009
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