Study On The Radioactivity Level Of The Surrounding Environment Of A Phosphate Rock In Southwest China

In this dissertation,a phosphorite area in Southwest China is the research area.We got datas on soil permeability,soil radon concentration and natural radionuclide content in the study area based on existing geological datas,field works and indoor measurement,we can know the degree of environmental radiation pollution,and there're some conclusions:First of all,we studied the permeability of soil gas in study area.The Qiong Zhu Si Formation belong phosphate layer with high level soil gas permeability.Therefore,the radon produced by natural radionuclides in the soil of the phosphate rock and its surrounding areas is easily precipitated from the soil into the air,and it is easy to cause certain radioactive pollution to the environment.We studied soil radon concentration by Rad7 instrument,and found the average soil radon concentration in the Qiong Zhu Si Formation is obviously higher than that of the other Formation,and the maximum soil radon concentration measurement point is located in the Qiong Zhu Si Formation,which proves that the high gas permeability formation is easily affected by the radiation of soil radon and its daughters.Combined with the field gamma ray spectrum data and indoor high-purity germanium gamma spectrum data,we can know that The high content of Uranium in the study area is mainly concentrated in the phosphorite area,and the Uranium content in the study area is about 2.7 times that of the world average.Thorium has no obvious distribution rules.The average value of Thorium in the study area is about 1.8 times that of the world average,slightly higher than the world level and the average distribution in the whole research area.The average Kalium content in the study area is close to the average Kalium content in the whole country.The contents of Thorium and Kalium in the study area were normal,while the Uranium content in the soil containing phosphate rock was high,and the phosphate rock area belonged to the high Uranium area.The air absorption dose rate by field gamma spectrum data shows that the air absorption dose rate in the study area is far beyond the national average air absorption dose rate and the world average air absorption dose rate.The high air absorbed dose rate is also concentrated in the phosphate rock strata.The highest air absorbed dose rate appears in the Qiong Zhu Si Formation,up to 189 nGy/h,it is three times the national average,indicating that the environmental radioactivity level around the phosphate rock is relatively high.