Aerosol samples were collected in the Shiyi Glacier, Qilian Mountains from July 24 to August 19, 2012 and analyzed for major water-soluble ionic species(F-, Cl-, NO2-, NO3-, SO42-, Na+, NH4+, K+, Mg2+and Ca2+) by ion chromatography. SO42-and NH4+were the most abundant components of all the anions and cations, with average concentrations of 94.72 and 54.26 neq/m3, respectively, accounting for 34% and 20% of the total water-soluble ions analyzed. These mean ion concentrations were generally comparable with the background conditions in remote sites of the Qilian Mountains, but were much lower than those in certain cities in China. The particles were grouped into two dominant types according to their morphology and EDX signal: Si-rich particles and Fe-rich particles. Backward air mass trajectory analysis suggested that inland cities may contribute some anthropogenic pollution to this glacier, while the arid and semi-arid regions of central Asia were the primary sources of the mineral particles.
Aerosol samples were collected at altitudes from 584 m a.s.l.to 3,804 m a.s.l.at seven sites of the eastern Tianshan.The occurrence,distribution,and possible sources of 47 trace metals—including alkali metals and alkali earth metals,transition metals,lanthanoids,and heavy metals—were investigated.It was found that four sampling sites(Shuinichang,1,691 m a.s.l.;Urumqi City,809 m a.s.l.;Fu Kang Station,584 m a.s.l.;and Bogeda Glacier No.4,3,613 m a.s.l.)were contaminated mainly by heavy metals.Other three high-altitude sites(Urumqi Glacier No.1,3,804 m a.s.l.;Wang Feng road-maintenance station,3,039 m a.s.l.;and Tianshan Glaciology Station,2,135 m a.s.l.)were not polluted.The aerosol particles were clustered into two dominant types:crust-originated particles and pollution-derived particles.Aerosols from UG1,WF,and TGS were characterized by crust-originated particles such as clay,plagioclase,dolomite,alkali feldspar,and biotite;while those from SNC,Urumqi,FK,and BG4 were characterized by high content of Cl-rich particles,S-rich particles,and soot.The backward-trajectories results indicated that air masses arriving at SNC,Urumqi,FK,and BG4 were identified as the more polluted source,when compared to the short-range air mass transport from the North to UGI and WF.Relatively lower altitude,as well as terrain blocking,might be another important reason for the gradient difference in pollution influence among these seven places in the Urumqi River Basin.
For most mountain glaciers,chemical components in snowfall are subject to the elution process under the influences of meltwater before they are preserved in ice,creating difficulties for interpreting ice core records.To understand the formation process of ice core records and analyze the influences of meteorological factors on the ice core resolution,we measured ion concentrations of snowpacks from 2003 to 2006 in the PGPI(Program for Glacier Processes Investigation)site of Urumqi Glacier No.1.The ion concentration variation in snowpack exhibits apparent seasonality.In summer,the higher snowmelt rates due to air temperature rise intensify dilution and lead to an exponential decrease in ion concentrations as the accumulated positive temperature increases.In winter,the snow ion concentrations are stable and low as a result of reduced temperature and rare precipitation.Many ions from summer precipitation are leached out by meltwater,and only the precipitation that occurs at the end of the wet season can be preserved.Through tracking the evolution of magnesium ion peaks in the snowpack,it is concluded that the ice core resolution is one year on Urumqi Glacier No.1,albeit 70%of the concentration information is lost.
Daily samples of aerosol（n=27） were collected from September 21 st to October 4th, 2013 in Fukang（44.17°N, 88.45°E, 475 m a.s.l.）, Xinjiang, Northwest China. The enrichment factors（EFc） of selected 49 elements showed that the aerosols had extremely high concentrations of heavy metals, probably indicating their anthropogenic origins. Morphology of individual aerosol particles was determined by scanning electron microscopy and energy-dispersive X-ray microanalysis. Based on morphology and elemental composition, the particles were clustered into three dominant types：（Ⅰ） crustal originated particles： Si/Al-rich particles（36%） and Si/Fe-rich particles（24%）;（Ⅱ） mixed source particles; and（Ⅲ） pollution derived particles： Pb-rich particles（10%）. The backward trajectories were calculated using the HYSPLIT model, and the results indicated the different anthropogenic sources for heavy metals in Fukang aerosols. Air mass from north was identified as the most polluted source when compared to south and west.
Chemical records from alpine ice cores provide an invaluable source of paleoclimatic and environ- mental information. Not only the atmospheric chemical composition but also depositional and post-depositional processes are recorded within snow/tim strata. To interpret the environmental and climatic significance of ice core records, we studied the variability of glacier snowpack chemistry by investigating homogeneous snowpacks from October 2003 to September 2006 on Urumqi Glacier No. 1 in eastern Tianshan Mountains, Central Asia. Principle Component Analysis of ionic species in dry and wet seasons revealed the impact of meltwater in redistributing ions in the snowpacks. The 1st, 2nd and 3rd principle components for dry seasons differ significantly, reflecting complex associations between depositional or/and post-depositional processes. The variability trend of ionic concentrations during the wet seasons was found to fit a Gauss Function with significant parameters. The elution factor revealed that more than half of ions are leached out during the wet seasons. Differences with respect to ion snowpack mo- bility were found. Of the ions studied SO42- was the most mobile and Mg2＋ the least mobile. A threshold relationship between air temperatures and the elution process was investigated over the study period. The results indicate that the strong melt/ablation processes and iconic redistribution occur at a threshold air temperature of 0℃. The study found that surface melt on the snowpacks is the main factor causing the alteration of the snowpack chemistry. Rainfall also has an impact on the chemistry but plays a less significant role than the surface melt.
The profound impacts exerted by climate warming on the Tibetan Plateau have been documented extensively, but the biogeochemical responses remain poorly understood. This study was aimed at seasonal variations of total organic carbon(TOC) and total organic nitrogen(TON) in stream water at two gauging sections(TTH, ZMD) in the upper basin of Yangtze River(UBYA) and at fourgauging sections(HHY, JM, JG, TNH) in the upper basin of Yellow River(UBYE) in 2013. Results showed that concentrations of TON exhibit higher values in spring and winter and lower values in summer. TOC exhibits higher concentrations in spring or early summer and lower concentrations in autumn or winter. Seasonal variations of TOC and TON fluxes are dominated by water flux. In total, the UBYE and UBYA delivers 55,435 tons C of organic carbon and 9,872 tons N of organic nitrogen to downstream ecosystems in 2013. Although the combined flux ofTOC from UBYA and UBYE is far lower than those from large rivers, their combined yields is higher than, or comparable with, those from some large rivers(e.g. Nile, Orange, Columbia), implying that organic carbon from the Tibetan Plateau may exert a potentially influence on regional and/or global carbon cycles in future warming climate.
LI Xiang-yingDING Yong-jianHAN Tian-dingXU Jian-zhongKANG Shi-changWU Qing-baiMika Sillanp??YU Zhong-boYU Cong-rong
