Characterization of contemporary aeolian dust deposition on mountain glaciers of western China

From 2008 to 2010, a total of 15 snow pit samples were collected from 13 mountain glaciers in western China. In this study these samples are used to determine the spatial distribution of insoluble particle concentrations and dust deposition fluxes in western China. The results show that the mass concentrations of insoluble particles exhibit high spatial variation and strongly decrease （by a factor of approximately 50） from the north （Tienshan Mountains） to the south （Himalayas）. However, the insoluble particles concentrations at the southeastern Tibetan Plateau （TP） sites are also high and ap- proximately 30 times greater than those in the Himalayas. The spatial distribution of the dust flux is similar to that of the mass concentrations; however, the high dust deposition rate in the southeastern TP is very significant as a result of the extensive snow accumulation （precipitation） in this region. The average sizes of the insoluble particles at each site generally exhibit bimodal distributions with peaks at approximately 5 μm and 10 μm, which can be explained as re- sulting from dust emissions from regional and local sources, respectively. The enrichment factors for most of the elements measured in insoluble particles are less than 10 at all of the study sites, indicating primarily crustal sources. However, the sites located in the peripheral mountains of western China, such as the Tienshan Mountains and the Himalayas, are characterized by high levels of certain enrichment elements （e.g., Cu, Zn, Cr, and V） indicative of sources related to the long-range transport of pollutants.

The acid cleaning method of labware for trace element analysis in snow and ice samples

Acid cleaning processes were performed on a class 100 laminar flow clean bench assembled inside a class 1000 clean room.The ultrapure water was produced by Millipore RO (Reverse Osmosis) and Milli-Q water purification systems.The three purity grades of nitric acid used for cleaning include Merck reagent grade HNO3,Fisher 'TraceMetal' grade HNO3,and the purest Fisher 'Optima' grade HNO3.The various bottles,containers and other labware,which are in contact with the samples,are made of low-density polyethylene (LDPE) and FEP or PFA Teflon materials.The acid cleaning procedures of the bottles and other containers follow a successive four times cleaning through immersion in increasing purity of nitric acid baths at different concentrations during four weeks.The first acid bath is performed at room temperature,but the following three acid baths are heated on ceramic hotplates with a surface temperature of 45℃.In order to verify the efficiency of the acid cleaning method,cleaned bottles underwent a blank determination procedure using ELAN 6100 inductively coupled plasma spectrometry (ICP-MS).Results show that most measured trace elements are not detected and the elements detected are at very low concentrations.The blank values are comparable with that of bottles cleaned at Korea Polar Research Institute (KOPRI).Although the acid cleaning method is developed mainly for reliable measurements of trace elements in snow and ice samples,it can also be used for investigations of trace elements in other environmental samples.

Spatial variations of Pb,As,and Cu in surface snow along the transect from the Zhongshan Station to Dome A,East Antarctica

The spatial distributions of lead, arsenic, and copper （Pb, As, and Cu, respectively） in surface snow along the transect from the Zhongshan Station to Dome A, East Antarctica, are presented. The mean concentrations of Pb, As, and Cu are 1.04±1.56 pg/g, 0.39±0.08 pg/g, and 11.2±14.4 pg/g, respectively. It is estimated that anthropogenic contributions are dominant for Pb, As, and Cu. Spatially, Pb concentrations show an exponentially decreasing trend from the coast inland, while a moderate decreasing trend is observed for Cu concentrations in the coastal area （below 2,000 m above sea level （a.s.1.））. In the intermediate area （2,000-3,000 m a.s.1.）, the concentrations and enrichment factors of all these elements show high variability due to the complicated characteristics of climate and environment. On the inland plateau （above 3,000 m a.s.1.）, the high concentrations of As and Pb are induced by high deposition efficiency, the existence of polar stratospheric precipitation, and the different fraction deposition to East Antarctica. The extremely high concentrations with maximum values of 9.59 pg/g and 69.9 pg/g for Pb and Cu, respectively, are suggested to result mainly from local human activities at the station. Our results suggest that source, transport pathway, and deposition pattern, rather than distance from the coast or altitude, lead to the spatial distributions of Pb, As, and Cu; and it is further confirmed by spatial variations of the three metals deposited over the whole continent of Antarctica.

Methods for extraction of microorganism DNA from glacier surface snow

In order to thoroughly investigate the diversity of glacier microorganisms, four DNA extraction methods with differem lysis pat- terns were tested and two screened methods （the Bosshard-Bano method and the Zhou method） were optimized for the most ef- fective form of the filter membrane （cut vs. uncut）, the DNA extraction method, and the precipitation method. The two optimized methods were then compared with the commercial Mo-Bio DNA extraction kit, and the results showed that the kit was generally suitable for extraction of microorganism DNA fi＇om glacier surface snow. Procedurally, it was found that a modified Boss- hard-Bano method （i.e., cutting the filter membrane into pieces, using a specific lysis pattern [lysozyme （5 mg/mL）-protease K （ 1 mg/mL）-CTAB （ 1%）-SDS （ 1%）], performing the extraction only once by chloroform-isoamyl alcohol （24： 1）, and conducting DNA precipitation by pure ethanol） was also an effective and less expensive method for extraction of microorganism DNA from glacier surface snow.

Major advances in studies of the physical geography and living environment of China during the past 70 years and future prospects

The natural environment provides material essentials for human survival and development. The characteristics,processes, regional differentiation and forcing mechanisms of the elements of the natural environment(e.g. geomorphology,climate, hydrology, soil, etc.) are the main objects of research in physical geography. China has a complex natural environment and huge regional differentiation and therefore it provides outstanding reserach opportunities in physical geography. This review summarizes the most important developments and the main contributions of research in the physical geography and human living environment in China during the past 70 years. The major topics addressed are the uplift of the Tibetan Plateau and the evolution of its cryosphere, the development of fluvial systems, the acidification of the vast arid region of the Asian interior, variations in the monsoon and westerly climate systems on multiple timescales, the development of lakes and wetlands, the watershed system model, soil erosion, past human-environment interactions, biogeography, and physical geographic zonality. After briefly introducing international research developments, we review the history of research in physical geography in China, focusing on the major achievements and major academic debates, and finally we summarize the status of current research and the future prospects. We propose that in the context of the national demand for the construction of an ecological civilization, we should make full use of the research findings of physical geography, and determine the patterns and mechanisms of natural environmental processes in order to continue to promote the continued contribution of physical geography to national development strategies, and to further contribute to the theory of physical geography from a global perspective.

Recent change of the ice core accumulation rates on the Qinghai-Tibetan Plateau

Three ice cores recovered from the Himalayas (i.e. the East Rongbuk Glacier and the Far East Rongbuk Glacier at Mt. Qomolangma (Everest), and the Dasuopu Glacier at Xixiabangma) show a sharp decline in the accumulation rates since the 1950s, which is consistent with the precipitation fluctuation over India and the low northern latitude zone (5°-35癗). Correspondingly, an increasing trend is observed for the ice core accumulations from the central and northern Qinghai-Tibetan Plateau (i.e. the Xiao Dongkemadi Glacier in the central Tanggula Mountains, the Guliya Ice Cap in the western Kunlun Mountains, and the Dunde Ice Cap in the Qilian Mountains) since the 1950s, which is consistent with the precipitation fluctuation over the middle-high northern latitude zone (35°-70°N). However, the variation magnitude of the high-elevation ice core accumulations is more significant than that of precipitation at the low-eleva- tion places, suggesting its extra sensitivity of high-elevation areas to climatic change.

Abundance and community of snow bacteria from three glaciers in the Tibetan Plateau

Bacterial abundance and diversity in snow of East Rongbuk, Laohugou and Halluogou glaciers on the Tibetan Plateau were investigated through epifluorescence microscope and denaturing gradient gel electrophoresis. Cell abundance ranged from 4.0 × 10^3 to 290.2 × 10^3 cells/mL. The phylogenetic trees placed the 16S rRNA sequences in four major groups： Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. Brevundimonas, Flavobacterium, Hymenobacter, Bacillus, Polaromonas, Rhodoferax and Streptomyces were widely distributed bacteria in glaciers from different cold regions. The remaining five genera of Hylemonella, Delftia, Zoogloea, Blastococcus and Rhodococcus were endemism, only recovered from our investigated glaciers. It is proposed that the three glaciers on the Tibetan Plateau provide a specific ecological niche for prolonging survival of diverse microbial lineages.