Measurement of 239Pu in Soil and Plants in the Nishiyama District of Nagasaki

Abstract

Nishiyama district in Nagasaki is located approximately 3000 m east of the hypocenter of the atomic bomb that was dropped on 9 August 1945. This district is also known as an area where there was a concentrated radioactive fallout with the black rain that was carried by a westerly wind. The Nagasaki atomic bomb was a Pu bomb, and the fallout must have included 239Pu without fission in addition to fission products. The presence of 239Pu in Nishiyama district has been confirmed previously. In this study, the distribution of 239 + 240Pu concentration in the uncultivated soil and the transfer factor of 239 + 240Pu to agricultural products in Nishiyama district were examined. The concentration of 239 + 240Pu in the uncultivated soil was 20 Bq kg-1, which was approximately eight times as high as that in the control districts. The transfer factor of 239 + 240Pu to agricultural products was 10(-4) - 10(-3), which was 1/100-1/200 of that of 137Cs.

Distribution of nuclear bomb Pu in Nishiyama area, Nagasaki, estimated by accurate and precise determination of 240Pu/239Pu ratio in soils

“…The highest 239þ240 Pu activity concentration in surface 0e5 cm, 59.9 AE 0.81 Bq/kg (dry weight), was observed at N1 on the slope 300 m west from the Nishiyama reservoir (2.4 km east from the hypocenter). This value is comparable with the values reported before (Mahara and Miyahara, 1984;Okajima et al, 1990). The concentration decreased sharply with increasing distance from the Nishiyama reservoir, and reached the same range as global fallout Pu in surface soil of Japanese forests, 0.15e4.31 Bq/kg (dry weight) (Muramatsu et al, 2003).…”

“…1b and c. As reported in previous papers (e.g. Yamamoto et al, 1983Yamamoto et al, , 1985Okajima et al, 1990;Kudo et al, 1991), high concentrations of Pu isotopes in soils around the Nishiyama reservoir were observed. The highest 239þ240 Pu activity concentration in surface 0e5 cm, 59.9 AE 0.81 Bq/kg (dry weight), was observed at N1 on the slope 300 m west from the Nishiyama reservoir (2.4 km east from the hypocenter).…”

“…At the time of detonation of the Pu nuclear weapon over Nagasaki city on August 9, 1945, radionuclide contaminated rain, so-called ''black rain'', was deposited on the Nishiyama area, about 3 km east from the hypocenter. Several studies have demonstrated that the area was contaminated by Pu isotopes (Yamamoto et al, 1983(Yamamoto et al, , 1985Okajima et al, 1990;Kudo et al, 1991). However, the data for the 240 Pu/ 239 Pu ratio are rather scarce, and there are only limited studies describing the present situation of the contamination after 60 years from the bombing.…”

Distribution and source of 129 I, 239 ,240 Pu, 137 Cs in the environment of Lithuania

“…The half-life of cesium-137 is relatively short (30.1y), nevertheless it is still possible to use this radionuclide for identification of source of the contamination. The main source of this isotope in the environment were the Chernobyl accident and nuclear weapon testing [17]- [20]. The 239,240 Pu/ 137 Cs activity ratio of 0.018 and 238 Pu/ 137 Cs activity ratio of 0.00068 the representative value of global fallout in soil were determined by Bunzl and Kracke in 1988 [21].…”

Measurement of Nagasaki Pu Global Transport Rates, Comparing with SO2 from Historic Volcanic Eruptions

“…A review article entitled "Plutonium in the Environment" (Harley6» stimulated studies for Nagasaki. Yamamoto et al7> and Okajima et al 8 ) measured plutonium concentrations in environmental samples around the city of Nagasaki and found that there were some elevated levels of 239+24~and 137CS. They were, however, not able to recognize the degree of scientific importance of the radioactive residues from the first Pu A-bomb explosion with a human loss.…”