[Concentration and Source of Dissolved Organic Carbon in Snowpits of the Tibetan Plateau].

Snowpit samples of three glaciers (Laohugou NO. 12 Glacier (LHG), Small Dongkemadi Glacier on Mount Tanggula (TGL) and East Ronghuk Glacier on Mount Everest (ZF)) in the Tibetan Plateau were collected. Concentrations of DOC and major ions were analyzed. The results showed that average DOC concentrations of the snowpits of LHG, TGL and ZF were (250.30 +/- 157.10), (216.92 +/- 142.82) and (152.50 +/- 56.11) microg x L(-1), respectively. DOC of TGL and ZF accounted for large parts of total values of DOC and ions. Correspondingly, DOC of LHG accounted for small part (only 5%), because LHG was located at north China and intensively influenced by natural mineral dust, which caused high concentrations of Ca2+ (the highest value could reach 5299.18 microg x L(-1)) and consequently low percentage of DOC of snowpit samples. Correlation and PCA analyses were used to study the sources of DOC. DOC was significantly correlated with Ca2+, Mg2+, K+ and SO4(2-). Additionally, PCA further indicated that the main potential source of DOC was the natural source of mineral dust. Meanwhile, anthropogenic pollutants (e.g., biomass, fossil combustion and agricultural related pollutants) could also not be ignored. Moreover, the carbon depositional fluxes of three snowpits were roughly estimated, and the values of LHG, TGL and ZF snowpits were 189.23, 132.76 and 128.44 mg (m2 x a)(-1), respectively, which played a significant role in the carbon cycle in this region and was also helpful for the study of glaciers fluctuation.

[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.