Survey of natural radionuclide contents in soil in tibet autonomous region

The methods and results of survey of natural radionuclides in soil in Tibet autonomous region is reported. The collecting points of soil are same as the measuring points of γ radiation dose rate of environmental ground. 247 soil samples were collected, of which 203 points were sited in uniformly distributed networks of size 50 x 50 km2, 44 points were more densely distributed according to the geology, types of soil and conditions of cultivation. the results show that the area-weighted mean and point-weighted mean of 238U, was 47.7 and 48.8 Bq·kg-1; 232Th, 69.7 and 72.5 Bq·kg-1; 226Ra, 43.0 and 44.9 Bq·kg-1; 40K, 626.8 and 633.2 Bq·kg-1. The contents of 238U, 232Th, 226Ra in soil in north part of autonomous region are higher than that in south part of the region. The content of 40K in north-west part is higher than that in south-east part