Assessment Of Natural Radionuclides In Groundwater And Geothermal Fluid Of Tianjin City

Based on the Investigation Report of Tianjin Geographical Environment, theunderground water and the amount and distribution of radioactive nuclides ingeothermal fluid are explored in this paper. About519underground water samplesand281geothermal fluid samples from13districts of Tianjin were obtained bycollecting and analyzing those results of regional geological survey, hydrogeologicalsurvey, and geothermal resources survey, as well as an11919km2field investigation.The concentration of radioactive nuclides such as238U,232Th,226Ra, and40K, as wellas radon, were measured. The results are as follows:（1）The radioactive nuclides in the underground water of Tianjin are within theenvironmental background value. The specific values of238U,232Th,226Ra, and40Kare2.14μg/L,0.09μg/L,8.12mBq/L and81.8mBq/L, relatively. The average value of238U and232Th concentrations in geothermal fluid are0.28μg/L and0.12μg/L, whichare lower than the critical value, while the concentration values of226Ra and40K are170.0mBq/L and634.98mBq/L, which are higher than the environmental backgroundvalue.（2）The radon concentration values in the underground water and geothermalfluid of Tianjin are8305Bq/m3and3645Bq/m3, which are within the environmentalbackground level.（3）The average amount of radioactive nuclides taken by Tianjin civils fromunderground water is0.0607mSv, which is lower than the recommended level of0.1mSv in Guidelines for drinking-water quality,3rdedition. When the geothermal liquidis used for drinking-water, the radioactive nuclides dose rate is0.0676mSv. However,since the amount of226Ra is51.35%of the total dose rate, this geothermal liquid is notrecommended drinkable before water treatment.