用AMS法测量新疆和湖北两地土壤样品中的钚  

Study on Plutonium in Terrestrial Soil Samples in China by AMS Method

作　　者：董微[1] 杨益隆[1] 郭秋菊[1] 

机构地区：[1]北京大学物理学院核物理与核技术国家重点实验室,北京100871

出　　处：《辐射防护》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)

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.

关 键 词：钚 加速器质谱 ^239+240Pu ^240Pu/239Pu 土壤 

分 类 号：TL942.1[核科学技术—辐射防护及环境保护]