Abstract: The natural radioactivities of radionuclides in the soil of Maoniuping REE deposit were measured using gamma ray spectroscopy with its internal and external exposure index, γ exposure rate and γ external exposure effective dose calculated accordingly and then compared with that of the Baiyun Obo rare earth mining area and Xiazhuang uranium ore field in Guangdong. Results show that the main value of γ exposure rate (177.16 Gy/h) is higher than the national reference value (81.50 nGy/h), international reference value (80.00 nGy/h), Baiyun Obo rare earth mining area reference value (120.00 nGy/h) and Xiazhuang uranium ore field reference value (124.00 nGy/h)in Guangdong as well. The natural radioactivity level of study area still lies within normal range because its internal and external exposure index, γ exposure rate and gamma external exposure effective dose are within the national referenced range. Rare earth mining contributes to the higher soil natural radioactivity level of the study area; Large area exposed in Triassic crown west granite rock mass in the study area also leads to a higher natural radioactivity level of soil than Baiyun Obo rare earth mining area and Xiazhuang uranium ore field in Guangdong.

Key words: energy spectrum, γ exposure rate, annual effective dose, radioactivity level