[Study on soil element background values of the Hoh Xil area in north Tibet]

Hoh Xil locates at northern part of the Tibetan Plateau. Twenty five surface soil samples were collected from this area in 2007 and 32 elements were analyzed and compared to the element contents of Yarlung Zangbo river sediment, background element value of the Tibetan surface soil and the Chinese Continental crust contents. The results showed that the element contents of the < 20 microm fraction were higher than those of bulk samples; Contents of many elements of this study were similar to those of the Tibetan soil. Meanwhile, contents of Ca and As of the studied area were higher than those of Chinese continental crust, resulting mainly from local alpine arid climate and widely distributed the rocks that enriched in As, respectively. The EOF analysis of the contents of bulk soil samples revealed the sources and chemical properties of studied elements: many elements such as Al, Fe, Ga inherit the characteristics of the parent rocks of this region. Meanwhile, elements with an active chemical property and the element Zr that specially existed in the heavy minerals also had a certain contribution to the contents. The contents of B and Cs revealed contribution of hot springs to the soil of studied area.