Effectiveness of tree rings for recording Pu history at Nagasaki, Japan

Changes in the distribution of radiocesium in the wood of Japanese cedar trees from 2011 to 2013

“…In the reports, 137 Cs existed in annual rings formed before the fallout, which suggested that 137 Cs moves easily within the wood. Kudo et al (1993) found that 40 years after local fallout, 137 Cs concentration in heartwood of Japanese cedar was higher than that in sapwood, and similar results were reported by others (Momoshima et al, 1995;Mahara et al, 1995;Kagawa et al, 2002).…”

“…The distribution of the radioactive materials in the wood of Japanese cedar trunks has been examined in annual rings for the purpose of understanding changes caused by the fallout derived from the atomic bomb in Japan and experiments with nuclear weapons (Kudo et al, 1993;Momoshima et al, 1995;Mahara et al, 1995;Kagawa et al, 2002). In the reports, 137 Cs existed in annual rings formed before the fallout, which suggested that 137 Cs moves easily within the wood.…”

Radial distributions of Cd in stems of oak trees (Quercus robur L.) re-analyzed after 10 years

“…Annual growth rings of trees have been tentatively used as a material for biomonitoring historical trends in trace element pollution (Berish and Ragsdale 1985;Queirolo et al 1990;Yanosky and Vroblesky 1992;Kudo et al 1993). Usually element concentrations in dated annual growth rings were analyzed and the results plotted along a time axis showing the years of wood growth.…”

Aging Effect of 137Cs Obtained from 137Cs in the Kanto Loam Layer from the Fukushima Nuclear Power Plant Accident and in the Nishiyama Loam Layer from the Nagasaki A-bomb Explosion

“…We assumed that 137 Cs and Pu were deposited at Nishiyama at the same rate as local fallouts, and that the deposition area was 100 km 2 (within a radius of 1 -10 km from the detonation hypocenter, Kudo et al 16 ). Although the amount of Pu in the Nagasaki A-bomb is classified, Kudo et al 13 estimated that the mass of Pu in the A-bomb ranged between the critical mass of 4.5 and 15 kg. Based on this estimated Pu amount, we assumed that the local deposition rate of 137 Cs was 0.…”

“…11 On the other hand, on August 9, 1945, a plutonium A-bomb exploded 500 m above Urakami in Nagasaki city at 11:02 LT. Half an hour after the detonation, large quantities of fission products and unfissioned plutonium in the form of fallout reached the ground (the so-called black rain). The greatest Pu and 137 Cs depositions were found at Nishiyama in an eastern suburb of Nagasaki city, 2.8 km east of the hypocenter, [12][13][14][15][16][17][18] strongly suggesting that the local fallout was not deposited as dust or aerosol particles, but as precipitate. 16 The Tokyo metropolitan area belongs to the Kanto loam region, which mainly consists of clays derived from weathered volcanic ash.…”