广西乐业天坑群中苔藓的放射性核素分析

为探究广西喀斯特地貌对放射性核素分布及当地环境放射性的影响，利用高纯锗探测器对广西喀斯特地区的大曹天坑和邓家坨天坑采集来的苔藓样品中⁷Be、⁴⁰K、²³⁸U、²³²Th、²²⁶Ra、²¹⁰Pb和¹³⁷Cs的放射性比活度进行测量与分析。结果表明：在苔藓植物中, ⁷Be的放射性比活度为202.3-698.8 Bq/kg [平均值：(430.7±169.7) Bq/kg，n=7]；⁴⁰K为33.7-159.9 Bq/kg [平均值：(91.6±44.1) Bq/kg, n=7]；²³⁸U为检测限(3.0 Bq/kg)至54.4 Bq/kg [平均值：(16.9±23.6) Bq/kg，n=7]；²³²Th为1.2-42.5 Bq/kg [平均值：(14.7±15.9) Bq/kg, n=7]；²²⁶Ra为0.7-48.4 Bq/kg [平均值：(16.9±20.3) Bq/kg，n=7]；²¹⁰Pb为284.1-950.5 Bq/kg [平均值：(555.5±231.0) Bq/kg, n=7]； ¹³⁷Cs为检测限(0.1 Bq/kg)至2.3 Bq/kg [平均值：(1.1±0.9) Bq/kg，n=7]。对比后发现所有测得的数据均在正常范围内，表明天坑这一喀斯特地貌对放射性核素的分布并没有显著影响，该地区也不存在其他污染来源，同时为我国南方喀斯特地区大气示踪提供数据支撑。

Radionuclide Analysis of Moss in the Leye Tiankeng Group in Guangxi

In order to explore the influence of karst landform on the distribution of radionuclides and the radioactivity of local environment in Guangxi, the specific activities of ⁷Be, ⁴⁰K, ²³⁸U, ²³²Th, ²²⁶Ra, ²¹⁰Pb and ¹³⁷Cs in moss samples collected from Dacao Tiankeng and Dengjiatuo Tiankeng in karst area of Guangxi were measured and analyzed for the first time by using high-purity germanium detector. The results showed that the specific activity of ⁷Be in bryophytes ranged from 202.3 to 698.8 Bq/kg [mean: (430.7±169.7) Bq/kg, n=7]. ⁴⁰K: 33.7-159.9 Bq/kg [mean: (91.6±44.1) Bq/kg, n=7];²³⁸U was the detection limit (3.0 Bq/kg) to 54.4 Bq/kg [mean: (16.9±23.6) Bq/kg, n=7]. ²³²Th was 1.2-42.5 Bq/kg [mean: (14.7±15.9) Bq/kg, n=7]. ²²⁶Ra was 0.7-48.4 Bq/kg [mean: (16.9±20.3) Bq/kg, n=7]. ²¹⁰Pb was 284.1-950.5 Bq/kg [mean: (555.5±231.0) Bq/kg, n=7];¹³⁷Cs was the detection limit (0.1 Bq/kg) to 2.3 Bq/kg [mean: (1.1±0.9) Bq/kg, n=7]. After comparison, it is found that all the measured data are within the normal range, indicating that the karst landform of the Tiankeng has no significant effect on the distribution of radionuclides, and there are no other sources of pollution in the area. At the same time, it provides data support for atmospheric tracing in the karst area of southern China.