Abstract:In order to disclose the distribution characteristic and sources of selenium (Se) excess soils in Daba Mountain area of southern Ankang and lay the foundation for the rational development and planning of Se-enriched soils, rock and soil samples were collected and Se contents were determined, and the distribution characteristics and correlation between Se contents in rocks and soils were analyzed. The results show that soil Se is ranged from 0.000 07 to 36.69 mg/kg with an average of 0.84 mg/kg. Two NW-SE oriented high Se regions are found there. Se-enriched soil is occupied 73.09% of the total area, and Se excess soils are distributed in patches and spots with an area of 0.91%. Rock Se is ranged from 0.005 to 68.75 mg/kg with a mean of 5.83 mg/kg. Rock Se are obviously higher in the upper Sinian Dengying formation and the lower Cambrian Lujiaping formation and the lower Silurian Banjiuguan formation in the deep-water sedimentary environment than in other formations. Se is higher in slate, siliceous rock, dolomite and syenite porphyry, especially in pyrite and stone coal, and rock and soil Se contents have significant positive correlation. Se excess soils are distributed in patches and spots in Shuang’an, Hanwang, Huangu, Donghe, Haoping, Wamiao, Maliu, Maoba, Gaotan and Jieling in Ziyang County, Zuolong and Chengguan in Langao County, Chengguan in Zhenping County. Soil Se is mainly derived from rocks, and the main sources of Se excess soil are carbonaceous slate with high Se content in the upper Sinian Dengying formation, Se-rich pyrite, carbonaceous slate, carbonaceous slate, siliceous slate, carbonaceous siliceous rock and siliceous rock in the lower Cambrian Lujiaping formation, Se-rich stone coal, carbonaceous slate and carbonaceous siliceous slate in the lower Silurian Banjiuguan formation.