摘要
采用加速器质谱(Accelerator Mass Spectrometry,AMS)方法测量了我国新疆维吾尔自治区(罗布泊附近)和湖北省(襄樊和荆门)两地不同深度土壤样品中钚的比活度(239+240Pu)和240Pu/239Pu同位素比。测量结果显示:新疆表层土壤239+240Pu比活度为0.010～0.827mBq/g,240Pu/239Pu比值范围为0.155～0.214。新疆罗布泊附近两处钻芯土壤采样点的239+240Pu沉积通量分别为16.7Bq/m2和55.4Bq/m2。新疆土壤中钚比活度随土壤深度的分布呈现出两种模式:①比活度峰值出现在土壤表层以下,之后随深度呈指数方式衰减;②比活度从表层开始指数方式衰减。湖北省两处钻芯土壤采样所得土壤中239+240Pu沉积通量分别为44.9Bq/m2和54.6Bq/m2,239+240Pu比活度峰值在2～4cm和4～6cm出现,大小分别为0.418mBq/g和0.502mBq/g。两处土壤中240Pu/239Pu比值分别在0.170～0.210和0.186～0.220范围内。两地结果显示我国陆地土壤中240Pu/239Pu同位素比值均与全球沉降结果吻合。
To study Pu concentrations and its isotope ratio distributions present in China,then to identify its source and understand the characterization of Pu in the environment,the 239＋240Pu activity and 240Pu/239Pu atom ratio in soil samples from Xinjiang Autonomous Region and Hubei Province in China were investigated using Accelerator Mass Spectrometry （AMS）.The 239＋240Pu activity and the 240Pu/239Pu atom ratio in surface soils in Xinjiang ranged from 0.010 to 0.827 mBq/g and 0.155 to 0.214,respectively.The 239＋240Pu inventories of two core soil samples in the surrounding areas of Lop Nor in Xinjiang were 16.7 Bq/m2 and 55.4 Bq/m2,respectively.Vertical profile of 239＋240Pu activity in the core soils collected from Xinjiang exhibited two different patterns：1） The maximum concentration appeared below surface and then decreased nearly exponentially with increasing depth;2） The 239＋240Pu activity decreased nearly exponentially from surface with increasing depth.The 239＋240Pu inventories of two core soil samples collected from Hubei were 44.9 Bq/m2 and 54.6 Bq/m2,respectively.And the maximum concentration appeared in 2—4 cm and 4—6 cm,which were 0.418 mBq/g and 0.502 mBq/g,respectivelly.The 240Pu/239Pu atom ratio of core soil samples ranged from 0.170 to 0.210 and from 0.186 to 0.220.It was suggested that the 240Pu/239Pu atom ratio in soils of China was similar to global fallout values,and the local effects of China＇s atmospheric nuclear tests on terrestrial in China were not observed.
出处
《辐射防护》
CAS
CSCD
北大核心
2010年第3期175-180,共6页
Radiation Protection
基金
国家自然科学基金资助项目(项目编号:10775007)
国家基础学科人才培养基金(北京大学核物理基地:J0730316)
