Abstract:Radionuclide uranium in soil is one of the main natural radiation contributors. When the uranium content in soil is abnormal, its chemical toxicity and radioactivity can pose a serious threat to human health. Cities are densely populated areas, so it is important to determine the level of uranium content in soil of urban radioactive geological survey, which can provide basic data support for urban planning areas and potential planning areas. Taking a city soil as the research object, the mechanism of uranium migration and transformation in urban soil during radioactive geological survey was analyzed by static adsorption test and simulated rainfall dynamic elution test. The results show that adding Cu ions can reduces the soil''s adsorption rate by 9.7%. The initial uranium concentration, adsorption time, and particle size indicate that the negative point charge of uranyl ion adsorbed in soil is limited. The soil''s uranium adsorption capacity is strongest at pH values between 4 and 6. SEM analysis reveals that after uranium adsorption, the soil surface changes from uneven and porous to smooth, with reduced and smaller porosity. The leaching kinetics of uranium at different pH values is consistent with bi-constant kinetic model, and the release of uranium from soil surface shows a slight curvilinear characteristic. Under natural acidic conditions with a pH value of 4 to 6, when the content of uranium in the solution is greater than that in the soil, the soil will absorb the uranyl ions from the solution. When the content of uranium in the solution is less than that in the soil, the uranyl ions in the soil are easily released into the solution. This study provides a theoretical basis for urban radioactive geological surveys.