The Radioactive Level Of Fresh-water From Source-area Of Drinking-water In Guangdong Province

It was to monitor and evaluate the radioactive level of centralized drinking water sources in various prefecture-level cities in Guangdong Province to grasp the level and dynamic change of total alpha and total beta radioactivity of drinking water sources.To provide basic data for establishing the emergency system of radioactive safety and working mechanism of drinking water.According to the implementation of water quality monitoring program of the centralized drinking water source in Guangdong Province,taking full account of the natural environment around the drinking water source,the changes that affect radionuclides of the drinking water and other factors to select reservoir water,river water and groundwater as the type of studied water.The fifty drinking water sources in twenty-two prefecture-level cities in Guangdong Province as sampling point after optimizing selection.They were sampled in the wet season（May）and the dry season（November）.BH1227 low background alpha-beta admeasuring apparatus is used to measure it,while 241 Am is used as the total alpha standard reference materials and 40 K is used as total beta standard reference materials of radioactivity measurement.Uranium（U）was measured by WGJ-III trace uranium analyzer,thorium（Th）was measured by Spectrophotometric.The research results indicated that:（1）The average radioactivity of total alpha and total beta in these 100 water samples were respectively 0.055±0.072 Bq·L^-1(0.007⁰.411 Bq·L^-1)and 0.117±0.083 Bq·L^-1(0.020⁰.397 Bq·L^-1);The average of β/α is 2.13;The mass concentration of U and Th were respectively 0.28±0.33 μg·L^-1(0.02¹.34 μg·L^-1)and 0.16±0.39 μg·L^-1(0.04².90 μg·L^-1).（2）By comparing the wet and dry periods,the radioactivity of total alpha were respectively 0.054±0.072 Bq·L^-1 and 0.056±0.072 Bq·L^-1,the radioactivity of total beta were respectively 0.118±0.086 Bq·L^-1 and 0.116±0.082 Bq·L^-1.（3）By comparing different water samples,the average concentration of total alpha and total beta radioactivity of groundwater is the highest,they were respectively 0.214±0.051 Bq·L^-1 and 0.333±0.057 Bq·L^-1;then the reservoir water,they were respectively 0.064±0.101 Bq·L^-1 and 0.109±0.072 Bq·L^-1.The lowest was the River water,they were respectively 0.036±0.020 Bq·L^-1 and 0.101±0.059 Bq·L^-1.However,the order of the concentration of U and Th in the three types of water samples is not consistent with the order of total α and total β radioactivity concentration.The order of the content of U is the river water > reservoir water > groundwater,the order of the content of Th is the reservoir water > river water > groundwater.（4）According to the standard of total alpha radioactivity ≤ 0.5 Bq·L^-1 and total beta radioactivity ≤ 1 Bq·L^-1 in the "Standard for Drinking Water"（GB5749-2006）,the total alpha and total beta radioactivity concentrations of all water samples were not exceeded.Among them,the total alpha and total beta radioactivity of Xinxihe Reservoir in Jieyang city,and the groundwater of Zhanjiang city,reservoir water of Zhuhai were relatively high.The concentration of U and Th in the water samples of Xinxihe Reservoir in Jieyang City is also the highest.The main conclusions:（1）No matter what kind of water type,there was no significant difference in the total alpha and total beta radioactivity levels between the wet water and the dry season.（2）The order of total α and total β radioactivity radioactivity levels of the three types of water samples is the groundwater > reservoir water > river water,the order of the content of U is the river water > reservoir water > groundwater,the order of the content of Th is the reservoir water > river water > groundwater.（3）The radioactivity level of groundwater is the highest in the all water samples.In order to reduce the annual effective dose of residents due to drinking water every year,the drinking water conditions in rural areas should be improved.（4）As the regular of change between total α,total β radioactivity level and mass concentration of U and Th is not consistent,it is recommended to increase 226 Ra and 40 K and other radionuclide measurements to ensure that the concentration of nuclide in drinking water as low as possible.（5）Drinking water sources in Guangdong Province are not polluted by radionuclides and are at normal levels of natural radioactive background.