2014—2017年青海东部农业区饮用水与部分生物样品中放射性水平调查

Investigation on radiation levels in drinking water and some biological samples in agricultural areas of Eastern Qinghai from 2014-2017

目的了解青海东部农业区部分生物样品中放射性水平,掌握青海东部农业区饮用水、菠菜、小麦中天然放射性本底数据。方法通过对海晏、湟源、湟中、西宁、平安、互助、乐都、民和饮用水(枯水期和丰水期)、菠菜和小麦样品的采集制备,用HPGeγ能谱、低本底α、β测量仪分析测量,给出青海东部农业区饮用水和部分生物样品中的放射性核素含量和水平。结果2014—2017年青海东部农业区枯水期饮用水中总α、总β放射性比活度平均值分别为0.14、0.13Bq/L;丰水期总α、总β放射性比活度平均值分别为0.13、0.12Bq/L;菠菜和小麦中238U、137Cs比活度均在仪器的探测下限以下,波菜中232Th、226Ra和40K比活度分别为(0.356±0.120)、(0.465±0.065)、(138.148±25.267)Bq/kg,小麦中232Th、226Ra、40K比活度分别为(0.284±0.110)、(0.289±0.136)、(99.065±12.667)Bq/kg,菠菜中232Th、226Ra、40K比活度高于小麦。结论各地区此次动态监测未发现人工放射性核素的污染,属天然本底水平。

[Objective]To understand the radiation levels in some biological samples in agricultural areas of Eastern Qinghai,obtain the data of natural radioactive background in drinking water,spinach and wheat.[Methods]The samples of drinking water (dry season and wet season),spinach and wheat were collected from Haiyan,Huangyuan,Huangzhong,Xining,Ping'an,Huzhu,Ledu and Minhe,and measured by HPGe γ spectrum,low background α and β measuring instruments,to obtain the levels of radionuclides in drinking water and some biological samples in agricultural areas of Eastern Qinghai.[Results]The mean value of specific activity of total alpha and total beta in drinking water during the dry period of 2014-2017 in the agricultural area of Eastern Qinghai was 0.14 Bq/L and 0.13 Bq/L respectively,while that during the wet period was 0.13Bq/L and 0.12Bq/L respectively. The specific activity of 238U and 137Cs in spinach and wheat was lower than the lower limit of the instrument. The specific activity of 232Th,226Ra and 40K in spinach was (0.356±0.120)Bq/kg,(0.465±0.0648) Bq/kg and (138.148±25.267)Bq/kg,respectively. The specific activity of 232Th, 226Ra and 40K in wheat was(0.284±0.110)Bq/kg,(0.289±0.136)Bq/kg and(99.065±12.667)Bq/kg,respectively. The specific activity of 232Th,226Ra and 40K in spinach were higher than those in wheat.[Conclusion]No contamination of artificial radionuclides has been found in this dynamic monitoring in all regions,which belongs to natural background level.