EDUCATION OF ANALYTICAL METHOD FOR THE MIGRATION STUDY OF ENVIRONMENTAL PLUTONIUM

1945年8月9日，在日本长崎引爆钚（10 ~ 15公斤）原子弹，释放出人工单剂量污染物。一部分，1.2千克的239Pu被裂变，释放出21千吨TNT能量以及各种裂变产物。其余未消耗的可裂变物质239+240Pu， 13.8 kg (3.49 x 10^<13>Bq)，与裂变产物137Cs， 23.4 g （7.44 x 10^<13>Bq）一起分散到大气中。239+240Pu和137Cs的命运是通过分析局部和全局沉降物来研究的。239+240Pu在震源以东2.8 km处的最高浓度为64.5 mBq/g (181 mBq/cm2)， 137Cs的最高浓度为188 mBq/g （526 mBq/cm2）。239+240Pu的沉降总量为37.5 g (9.48 x 10^<10>Bq)， 137Cs的沉降总量为3.14 mg （5.88 x 10^<10>Bq）。239+240Pu和137Cs的局部沉降与放射性核素释放总量的比例分别为0.27%和0.134%。分析技术的最新进展使1945年在北极冰芯层中检测到长崎爆炸释放的人工放射性核素成为可能。239+240Pu和137Cs是通过收集加拿大埃尔斯米尔岛阿加西冰帽上的10个冰芯来测量的。239+240Pu沉积0.16 μBq/cm2, 137Cs沉积20 μBq/cm2。在大气试验中，239+240Pu和137Cs的沉积变化超过100次，其中239+240Pu和137Cs的峰值均在1962年出现，分别超过50 μBq/cm2和800 μBq/cm2。通过分析北极地区的数据，可以得到许多关于全球长途运输、核武器发展史等方面的新信息。

An artificial single dose contaminant was released at Nagasaki, Japan on August 9,1945 detonating Plutonium (10-15kg) atomic bomb. A portion, 1.2 kg of 239Pu was fissioned releasing 21 kt TNT energy along with various fission products. The rest of the unexpended fissile material, 239+240Pu, 13.8 kg (3.49 x 10^<13> Bq), was dispersed into the atmosphere along with a fission product, 137Cs, 23.4 g (7.44 x 10^<13>Bq). The fate of 239+240Pu and 137Cs was investigated by analysing both local and global fallout. The highest concentration of 239+240Pu was 64.5 mBq/g (181 mBq/cm2) while it was 188 mBq/g (526 mBq/cm2) for 137Cs both at 2.8 km east from the hypocentre. The total amount of deposition in the local fallout region of 264 km2 was 37.5 g (9.48 x 10^<10>Bq) for 239+240Pu and 3.14 mg (5.88 x 10^<10>Bq) for 137Cs. The ratio of the local fallout against the total amount of the radionuclides released was 0.27% for 239+240Pu and 0.134% for 137Cs. Recent advancements in analytical technology made it possible for artificial radionuclides released from the Nagasaki explosion to be detected in the Arctic ice core layer of 1945. The 239+240Pu and the 137Cs, were measured by collecting 10 ice cores on the Agassiz ice cap, Ellesmere Island, Canada. The deposition was 0.16 μBq/cm2 for 239+240Pu and 20 μBq/cm2 for 137Cs. During the atmospheric testing, the deposition of 239+240Pu and 137Cs varied more than 100 times with the highest peaks of over 50 μBq/cm2 for 239+240Pu and over 800 μBq/cm2 for 137Cs both occurred in 1962. Analyzing Arctic data, there are many new information for long global transport, the history of nuclear weapons development etc.