SIMPLIFIED AND SENSITIVE ANALYSIS OF ORGANICALLY BOUND TRITIUM IN TREE-RINGS TO RETROSPECT ENVIRONMENTAL TRITIUM LEVELS

In order to estimate the environmental tritium level retrospectively, the authors tried to establish a simplified and sensitive method for determination of organically bound tritium in tree rings. Organically bound tritium as low as approx. 1 Bq L(-1) was determined with sufficient reproducibility, after combusting 25 g of dried wood without isolating cellulose. In Japan, this tree ring analysis reproduced the historical fallout tritium levels during 1961-87 in the general environment and detected a probable local effect of tritium discharge from nuclear facilities retrospectively.