Abstract:

The iodine content and distributing pattern in the bedrock, soil, crop, spring and main rivers of Daba Mountains (South Qinling Mountains)region were studied.The result show s that iodine content in this region is not balanced and most area is short of iodine, specifically in the distributing area of limestone and sandstone as well as the upper part of big hill.The iodine content in the bedrock,w hich are mainly early Paleozoic st rata, is high, it is about 0.7～ 1.9 mg/ kg, among them, the igneous rock, specifically the diabase is more rich in iodine,it is about 1.4 ～ 1.9 mg/ kg.The iodine content of soil is 0.2 ～ 2.2mg/ kg ;the iodine content of potato is 8 ～ 180μg/ kg.The iodine content of the soil and crop that is dist ributing in the area of igneous rock is rich in iodine if the hill is not more steep and cranny is not developed.The iodine content of the soil and crop that is in the dist ributing area of sandstone and limestone is the lowest in this region.So, the iodine content in the soil, crop and spring is closely related with the iodine content and lithologic character of the bedrock and geog raphical condition in these region and simultaneously closely related with the distributing pattern of the cretinism in the region

Key words: iodine, distributing pattern, endemic cretinism, South Shaanxi Province,Daba Mountains