Transfer factors of 226Ra, 232Th and 40K from soil to pasture-grass in the northeastern of Turkey

The uptake of natural radioactivity by pasture-grass collected from seven different grasslands of Digor was calculated. The activities of Ra-226, Th-232 and K-40 in pasture-grass were in the range of 21.8 +/- 6.3-49.6 +/- 13.4, 51.9 +/- 13.2-127.7 +/- 23.8 and 309.5 +/- 33.5-807.3 +/- 64.4Bqkg(-1), respectively. The soil to pasture-grass transfer factors were evaluated and determined to be in the range from 0.26 +/- 0.13 to 0.69 +/- 0.34, 0.64 +/- 0.27 to 1.99 +/- 0.40 and 0.64 +/- 0.014 to 1.40 +/- 0.032 for Ra-226, Th-232 and K-40, respectively. The distribution of Ra-226 and Th-232 in different parts of pasture-grass indicated a decreasing tendency in order of root>stem>leaf. K-40 mainly accumulated in stem of pasture-grass and is followed by declining trend stem>leaf>root.