Long-term cycling of 137Cs in Pinus Kesiya at Wat Chan Thailand

Surface soil and above-ground parts of Pinus kesiya (Three-needled pine) were collected at Wat Chan pine forest to study cycling of Cs-137. Cs-137 derived from nuclear weapons tests up to 1963 was found to have accumulated at a shallow depth (<5 cm) in the forest soil. Calculated total deposition of Cs-137 was in the range of previous studies and could be used as a reference for nuclear test deposition of Cs-137 fallout in northern Thailand and nearby locations. Potassium in soil does not appear to be a good indicator for long-term radiocaesium cycling. Finally, 'available' stable caesium (Cs-133) in the soil was found to be an appropriate indicator for studying uptake of Cs-137 by Pinus kesiya at Wat Chan.