广州市北部土壤天然放射性水平研究

Studies on natural radioactivity of soil in North of Guangzhou

用高纯锗γ能谱分析仪测量了广州市北部土壤中放射性核素238U,226Ra,232Th和40K的含量,分别为167.5（43.0～605.0）Bq/kg,171.7（47.8～603.6）Bq/kg,183.2（45.4～447.1）Bq/kg和871.7（70.5～1967.2）Bq/kg,与全国和广东省的平均值相比明显偏高.测量了采样点1m高空气γ辐射吸收剂量率,并与利用Beck公式的计算值进行了对比,计算值普遍高于实际测量值.还计算了等效镭浓度、外照射指数和年有效剂量率,平均值分别为502.0Bq/kg,1.4,284.7μSv/a,表明广州市的γ辐射外照射水平远高于全国和广东省平均值.

The contents of radioactive nuclides 238U,226Ra,232Th and 40K in soils in northern Guangzhou were measured using an HPGe γ-ray spectrometer.The measured activity concentrations of 238U,226Ra,232Th and 40K were 167.5（43.0-605.0）,171.7（47.8-603.6）,183.2（45.4~447.1） and 871.7（70.5~1967.2） Bq/kg,respectively,which were evidently higher than the average values of Guangdong Province and countrywide.The absorbed dose rates in air from γ radiation above the sampling points were determined and found to be generally lower than the predicted values based on the Beck formula.The calculated mean values of radium equivalent activity,external hazard index and annual effective dose rate were 502.0 Bq/kg,1.4 and 284.7 μSv/a,respectively.The results indicate that the levels of gamma radiation external irradiation and natural radioactivity in soils of northern Guangzhou are much higher compared with the average values of nationwide and Guangdong.