Evaluation Of Natural Radioactivity Level And Health Risk In Water Body Of Water Sources In Guangdong Province

Based on the monitoring research and evaluation of natural radioactivity levels in water bodies of water sources in Guangdong Province,this paper has been clear about the total radioactivity level of prefecture-level cities,water systems and water sources as well as the specific natural radionuclide species and concentration level with studies on their variation rules.This paper provides a scientific basis for the safety supervision and management of the water source and technical support for the effective disposal of drinking water safety accidents.Besides,the basic database of drinking water source radioactivity in Guangdong Province is established to provide environmental background data for the decision-making of emergency accident disposal.It also gives an intuitive explanation for the people’s understanding of the impact of drinking water radiation on health.A total of 191 selected water sources over the entire province are sampled once in high-water period and low-water period,respectively.The samples are collected and processed according to the nation-level Radioactivity Index of Standard Monitoring Method for Drinking Water（GB/T 5750.13-2006）.The totalandradioactivity levels are measured by PIC-MDS-4 low flowing gas meter ofand.The concentrations of ²³⁸U and ²³²Th are measured by inductively coupled plasma mass spectrometer（ICP-MS）while those of ²⁶²Ra and ⁴⁰K by high purity germanium（HPGe）spectrometer（GMX40P）.The totalandradioactivity levels are evaluated according to the Standard for Drinking Water（GB 5749-2006）,and then the impact of natural radionuclides in water body of water source on residents is measured by introducing the health hazard risk evaluation model.A total of 382 samples are collected in high-water period and low-water period.Among them,377 samples are used for total radioactivity research,including 189 samples collected in high-water period and 188 samples collected in low-water period.In general,the totalradioactivity level in wet season is（0.042±0.064）Bq/L（0.008-0.402 Bq/L）,and the totalradioactivity level is（0.118±0.128）Bq/L（0.014-0.848 Bq/L）.The totalradioactivity level in dry season is（0.033±0.060）Bq/L（0.008-0.582 Bq/L）,and the totalradioactivity level is（0.108±0.091）Bq/L（0.014-0.637 Bq/L）.Regardless of periods,the overall radioactivity level is higher in the cities and rivers of west Guangdong.The totalαandβradioactivity levels of groundwater are higher than those of river water and lake and reservoir water in both wet season and dry season.The overall radioactivity level of groundwater in Guangdong Province is in the middle of the national level compared with that of national environmental radiation report and that of other areas of China.All natural radionuclides are positively correlated with the total alpha and total beta radioactivity levels.Among them,the natural radionuclides 238U,232Th,and 226Ra have a high correlation with the total alpha radioactivity level,and the correlation between each nuclide and the total beta radioactivity level Overall not high.Based on the health risk evaluation model,it reveals that the risk of health hazard（carcinogenesis）is generally negligible,and only part of groundwater samples have certain potential risks for children and adolescents.It is found through in-depth comparison that the risk of health hazards（carcinogenesis）of natural radionuclides in all types of water sources in all basins is shown below,i.e.children group>adolescent group>adult group by age group;the potential health risk caused by all the natural radionuclide species is listed below,i.e.²²⁶Ra>⁴⁰K>²³²Th>²³⁸U.Among them,²²⁶Ra is as high as over 70%in the whole age group,which are the two most important natural radionuclides causing the risk of health hazard（carcinogenesis）.In this paper,the natural radioactivity level in water body of water source in Guangdong Province is obtained through sampling experiment and analysis.Its overall level is lower than the national standard of drinking water in China,and the total radioactivity level of the water systems and groundwater sources in west Guangdong is higher than that of other water systems and water sources;based on the health risk evaluation model,the health risk caused by natural radionuclides in the source water of the whole province is generally negligible,and the risk value of the young children group is slightly higher than that of the other two groups.Routine monitoring should focus on levels of ²²⁶Ra.