In order to understand the potential influence of pollution from human activity on the natural cycle of trace elements in the at- mosphere over the eastern Kunlun mountains, north-eastern part of the Qinghai-Tibetan Plateau, concentrations of Al, Fe, Ba, Cd, Co, Cr, Cu, Li, Ni, Zn, Pb, Sb, Sr, U and V in a 75 cm-deep snow pit recovered from 5,800 m a.s.l. of the Yuzhu Peak Glacier on October 25, 2009, were determined by a sector field inductively coupled plasma mass spectrometry. The results indicate that con- centrations of the measured trace elements vary by orders of magnitude from one element to another ranging from the minimum value 1.2 pg/g (U) to the maximum value 293 ng/g (Fe); the value of Max/Min ranges from 7 pg/g (Sd) to 358 pg/g (Li). EFc val- ues of measured trace elements show that there are other important sources except dust for Cd, Sb, Zn, Pb and Cu. Comparison of the concentrations of the measured trace elements with those in other areas in the Tibetan Plateau indicates that trace element con- centrations for Yuzhu Peak are lower than those in east Tianshan and Muztagh Ata (Pamirs). Concentrations of some trace ele- ments are also lower than those in East Rongbuk Glacier. However, concentrations of all measured trace elements are extensively higher than those in Greenland and the Antarctic.
YueFang Li XiaoLan Shi NingLian Wang JianChen Pu TanDong Yao
We report on the concentration and compositional features of n-alkanes of natural and anthropogenic origins in the snow samples collected from the Qiyi glacier in the Qilian Mountains, the Yuzhufeng glacier in eastern Kunlun Mountains, the Xiaodongkemadi glacier in the Tanggula Mountains, and the Gurenhekou glacier in the Nyainqêntanglha Range. The results indicate a decrease in the total n-alkane concentration (T-HCs) from the northeast to the south over the Tibetan Plateau. The T-HCs in these studied areas were close to those in the Belukha and Sofiyskiy glacier, Russian Alati Mountains and the Dasuopu glacier in the Himalaya but were much higher than those in the Greenland ice sheet, suggesting that the mountain glaciers in the Asian continent may receive a higher loading of n-alkanes than the Greenland ice core. Moreover, the compositional characteristics of n-alkanes indicated that the n-alkanes in the studied areas were probably originated from the plant waxes as well as the fossil-fuel combustion exhaust, whereas the contribution from the lower organisms was small. In addition, the plant wax (Cn(wax)) and anthropogenic (non-Cn(wax)) contributions revealed that fast industrialization may have significant effects on the organic pollutant composition in glacier over the Tibetan Plateau and its circumference environment. Particularly, except for the Yuzhufeng glacier, the ΣnC21-/ΣnC22+ and (nC15+nC17+nC19)/(nC27+nC29+nC31) ratio decreased from the Qiyi glacier to the Gurenhekou glacier over the Tibetan Plateau, while the carbon preference index (CPI) values increased. These results indicate a decrease in terrigenous input while an increase in marine input from the northeast to the south over the Tibetan Plateau. These two ratios can be used as the climatic and environmental change indicators.
LI QuanLianWANG NingLianWU XiaoBoPU JianChenHE JianQiaoXIE Jun
Diurnal minor and trace elements in glacial outflow water draining the Qiyi Glacier and associated hydrological controls as well as the filtration effects on water chemistry were examined. Results show that major ions, Li, Sr, and Ba are exported predominately as mobile monovalent or divalent ions and are controlled by hydrological variations over the diurnal cycle exhibiting an inverse concentration with discharge, suggesting that Li, Sr, and Ba can be used as tracers in subglacial hydrological investigations. Conversely, other elements (e.g. Fe, Al, and Cr) exhibit variations that are not strongly correlated with the discharge reflecting the physicochemical controls. The non-filtered operation appears not to strongly influence Sr and Ba, but has an effect on some elements such as Fe, Al, V, Ti, and Co, indicating that these changed elements are transported in particulate forms and thus their concentrations are highly dependent on particulate numbers in solutions. This implies that the immediate filtration after sampling is essential in hydrochemical studies at Alpine glacial basins due to subsequent mineral dissolution.
LI XiangYingQIN DaHeJING ZheFanLI YueFangWANG NingLian
Although previous investigations of the trace elements in snow and ice from the Qinghai-Tibetan Plateau obtained interesting information about pollution from human activities on the plateau, most were based on traditional acidification methods.To emphasize the influence of the different sample-preparation methods on the records of trace elements and rare earth elements, snow samples were collected from glaciers on the Qinghai-Tibetan Plateau in China and prepared using two methods: traditional acidification and total digestion. Concentrations of 18 trace elements(Al, Ti, Fe, Rb, Sr, Ba, V, Cr, Mn, Li,Cu, Co, Mo, Cs, Sb, Pb, Tl, and U), along with 14 rare earth elements(REEs: La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er,Tm, Yb, and Lu), Y, and Th in the snow samples, were measured using inductively coupled plasma-sector field mass spectrometry(ICP-SFMS). The results showed that the mass fraction of the trace elements(defined as ratio of concentration in the acid-leachable fraction to that in the digested sample) such as Mo, Ti, Al, Rb, and V, varied from 0.06 to 0.5. The mass fraction of other trace elements varied from about 0.6 to more than 0.9; those of the REEs, Y, and Th varied from 0.34 to0.75. Lower mass fractions will lead to an overestimated contribution of other sources, especially human activities, and the underestimated fluxes of these trace elements(especially REEs, Y, and Th, as well as dust) if the REEs are used as the proxy for the crust dust. The two sample-preparation methods exhibited different REE normalized distribution patterns,REE ratios, and provenance-tracing results. The REE normalized distribution patterns and proxies in the digested samples are more reliable and integrated than those found in traditional acidification method for dust-provenance tracing.
