Distribution characteristic of trace elements in pastures from Tibet

7 kinds trace elements of 43 species in 3 families of pastures from Tibet, including iron (Fe), manganese (Mn), molybdenum (Mo), copper (Cu), zinc (Zn), selenium (Se) and cobalt (Co), were determined to study the distribution characteristic of trace elements in pastures among different families and genus. The results showed that the distribution of trace elements in pastures from Tibet presented certain regularity. Overall, the content of Fe was the highest, the content of Zn was the second, and the content of Se was the lowest. Among 3 families, Gramineae pastures had low Fe content, but high Zn and Cu content, whereas Chenopodiaceae pastures had low content of Zn and Cu, but high content of Fe and Mn. The contents of most of trace elements in Leguminosae pastures were at mediate levels. In cultivated pastures from Tibet, the contents of Fe, Zn and Cu were all high levels; Co content was middle level; but the levels of Mn, Se and Mo contents were not the same among different families.