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2017, 9 (5) Online: 01 October 2017 Previous issue Next issue
  • The temporal and spatial variation of positive degree-day factors on the Koxkar Glacier over the south slope of the Tianshan Mountains, China, from 2005 to 2010
  • Min Xu, HaiDong Han, ShiChang Kang
  • DOI: 10.3724/SP.J.1226.2017.00425
  • 2017, Vol.9 (5): 425–431 Abstract ( 35) HTML PDF (3039 KB) ( 41 )
  • The degree-day model is one important method to estimate glacier melt, which is based on the specific relationship between glacial melting and the sum of daily mean temperatures above the melting point. According to the observation data on the Koxkar Glacier (KG) from 2005 to 2010, we analyzed the temporal and spatial variation of degree-day factors (DDF) and its influential factors. The results indicate that the average value of DDF was 7.2~10.4 mm/(℃·d) on the KG from 2005 to 2010. It showed a decreasing trend between 3,700 m and 4,200 m, and the deceasing trend was more obvious in the upper part of the KG. On a spatial scale, the DDF increased evidently with increasing altitude. The DDF ranged from 3.6 to 9.3 mm/(℃·d) at 3,700 m a.s.l., with the average value of 9.3 mm/(℃·d). It varied from 6.9 to 13.0 mm/(℃·d) at 4,000 m a.s.l., with the average value of 10.2 mm/(℃·d). During the period of ablation, the fluctuation of DDF was not significant at the lower altitude (3,700 m a.s.l.), but it decreased at the higher altitudes (4,000 m a.s.l. and 4,200 m a.s.l.). The debris changes the transmission of heat, which accelerates the melting of a glacier; and the DDF showed high value. This paper will provide the reference for temporal-spatial parameterization schemes of DDF on Tuomuer glaciers of the Tianshan Mountains.
  • Changes of glacier area in the Xiying River Basin, East Qilian Mountain, China
  • YuShuo Liu, Xiang Qin, WenTao Du
  • DOI: 10.3724/SP.J.1226.2017.00432
  • 2017, Vol.9 (5): 432–437 Abstract ( 30) HTML PDF (7907 KB) ( 18 )
  • The Xiying River, one of eight tributaries of the Shiyang River, located at Lenglongling, east Qilian Mountain, is formed by the confluence of Luotuo, Qingyang, Ningchan, and Shuiguan rivers. In the Xiying River Basin, where have 42 glaciers which toward NE in the majority. In this study, three Landsat images and two topographic maps were used to extract boundaries by artificial vector quantization. Results show that glacier area in Xiying Basin increased slightly around 1987, since then, has been reduced considerably. From 1956/1972 to 2008, glacier area in Xiying River Basin was reduced by 20.76%, nine glaciers have disappeared, and below 4,100 m a.s.l., there is no ice cover. Variation tendency of glacier retreat was obviously controlled by orientation. Temperature increase especially after 1987 is the main reason of glacier shrinkage, where glaciers in the Xiying River Basin are more sensitive to climate change.
  • A mathematical approach to evaluate maximum frost heave of unsaturated silty clay
  • Lin Geng, XianZhang Ling, Liang Tang, Jun Luo, XiuLi Du
  • DOI: 10.3724/SP.J.1226.2017.00438
  • 2017, Vol.9 (5): 438–446 Abstract ( 43) HTML PDF (2776 KB) ( 55 )
  • Maximum frost heave of unsaturated frost-susceptible soils, in conjunction with a high water table, is an important consideration for the design of foundations in seasonally frozen regions. Therefore, it is necessary to evaluate accurately and efficiently the maximum frost heave for a given soil. For this purpose, a series of one-sided freezing experiments was conducted on unsaturated silty clay in an open system. Multistage cooling of sufficient duration was applied to the soil sample's top, while constant above-zero temperatures were maintained at the bottom. Then, a simple methodology for calculating maximum frost heave at a given cooling temperature was derived utilizing information obtained within the limited time allotted for each stage. On this basis, an empirical equation for defining maximum frost heave as a function of cooling temperature and overburden pressure was determined. Overall, this study provides a simple and practical procedure that is applicable to the evaluation of maximum frost heave of unsaturated frost-susceptible soils.
  • Characteristics of thawed interlayer and its effect on settlement beneath embankment in permafrost regions—A case study for the Qinghai-Tibet Highway
  • ZhiZhong Sun, HongLei Wang, WenJie Feng, YongZhi Liu, ShuJuan Zhang
  • DOI: 10.3724/SP.J.1226.2017.00447
  • 2017, Vol.9 (5): 447–454 Abstract ( 33) HTML PDF (2827 KB) ( 23 )
  • Based on ground temperatures and deformations monitored at the Xieshuihe site along the Qinghai-Tibet Highway (QTH) in permafrost regions from 2004 to 2015, variation of artificial permafrost table (APT), maximum frozen depth (MFD), thawed interlayer thickness (TIT) and ground temperature beneath embankment is analyzed, respectively. The results indicate that under the embankment, the change of APT occurred from October to December of that year and presented a deepening trend. The change of MFD occurred from April to June of that year with no obvious change trend, and TIT had an increasing trend year by year, which mainly resulted from the deepening artificial permafrost table. Mean annual ground temperature at 0.5 m depth was 3.91℃ higher beneath the embankment center than that under the natural field. The rising ground temperature at shallow layer of embankment resulted in the development of thawed interlayer beneath the embankment and warming of underlying permafrost. Embankment settlement is closely associated with TIT. Greater settlement easily occurs when permafrost with higher ice content exists under the thawed interlayer, and in turn the settlement is smaller when permafrost with lower ice content exists under the thawed interlayer.
  • Chemistry and environmental significance of aerosols collected in the eastern Tianshan
  • XiaoYu Zhang, ShengJie Wang, Xin Zhang, Ping Zhou, Shuang Jin, ZhongQin Li, Nozomu Takeuchi
  • DOI: 10.3724/SP.J.1226.2017.00455
  • 2017, Vol.9 (5): 455–466 Abstract ( 36) HTML PDF (7413 KB) ( 7 )
  • 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.; FuKang 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.; WangFeng 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.
  • Contamination and risk assessment of heavy metals in farmland soils of Baghrash County, Xinjiang, Northwest China
  • Ajigul Mamut, Mamattursun Eziz, Anwar Mohammad, Mattohti Anayit, Atiyagul Rixit
  • DOI: 10.3724/SP.J.1226.2017.00467
  • 2017, Vol.9 (5): 467–475 Abstract ( 35) HTML PDF (2876 KB) ( 34 )
  • Soil pollution significantly reduces environmental quality. In this study, farmland soil samples were collected from 25 sites in Baghrash County, Northwest China; and the concentrations of eight heavy-metal elements (arsenic, As; cadmium, Cd; chromium, Cr; copper, Cu; manganese, Mn; nickel, Ni; lead, Pb; zinc, Zn) were determined by standard methods. The spatial distribution, contamination level, and ecological risk stature of heavy metals were analyzed based on GIS technology, the Geo-accumulation Index (Igeo), the Pollution Load Index (PLI), and the Potential Ecological Risk Index (RI). Results indicated that (1) The average concentrations of Cd exceeded 12.12 times the allowed national standard for soil environmental quality of China. The average concentrations of Cd, Cr, Ni, Pb, and Zn exceeded the background values of irrigation soils in Xinjiang by 60.58, 1.25, 1.50, 4.95, and 5.10 times, respectively. (2) The pollution order of the average value of Igeo for heavy metals was ranked as Cd > Zn > Pb > Ni > Cr > Cu > As > Mn. The individual potential ecological risk index for heavy metals was ranked in the order of Cd > As > Ni > Cu > Pb > Cr > Zn. The average PLI for the study area showed a heavy pollution level, while the average RI showed a considerable ecological risk stature, as compared to the classification standard. (3) The spatial distribution patterns of eight heavy metal elements were substantially heterogeneous. The moderately polluted areas with moderate potential ecological risks were distributed in the southern parts of the study area, whereas the heavily polluted areas with considerable potential ecological risks were distributed in the northern parts. Overall, it was observed that Cd contributed most to the PLI and RI of the farmland soils in Baghrash County. The pollution risk of Cd should be a major concern, and human activities in the region should be cautious.
  • Complex network analysis of climate change in the Tarim River Basin, Northwest China
  • ZuHan Liu, JianHua Xu, WeiHong Li
  • DOI: 10.3724/SP.J.1226.2017.00476
  • 2017, Vol.9 (5): 476–487 Abstract ( 49) HTML PDF (2933 KB) ( 20 )
  • The complex network theory provides an approach for understanding the complexity of climate change from a new perspective. In this study, we used the coarse graining process to convert the data series of daily mean temperature and daily precipitation from 1961 to 2011 into symbol sequences consisting of five characteristic symbols (i.e., R, r, e, d and D), and created the temperature fluctuation network (TFN) and precipitation fluctuation network (PFN) to discover the complex network characteristics of climate change in the Tarim River Basin of Northwest China. The results show that TFN and PEN both present characteristics of scale-free network and small-world network with short average path length and high clustering coefficient. The nodes with high degree in TFN are RRR, dRR and ReR while the nodes with high degree in PFN are rre, rrr, eee and err, which indicates that climate change modes represented by these nodes have large probability of occurrence. Symbol R and r are mostly included in the important nodes of TFN and PFN, which indicate that the fluctuating variation in temperature and precipitation in the Tarim River Basin mainly are rising over the past 50 years. The nodes RRR, DDD, ReR, RRd, DDd and Ree are the hub nodes in TFN, which undertake 19.71% betweenness centrality of the network. The nodes rre, rrr, eee and err are the hub nodes in PFN, which undertake 13.64% betweenness centrality of the network.
  • Palynological assemblage in the late Early Cretaceous from Sikouzi Section, Liupanshan Group, Central China and its implication to paleoenvironment change
  • Qiang Zhu, Shuang Dai, YongBo Huang, JunWei Liu
  • DOI: 10.3724/SP.J.1226.2017.00488
  • 2017, Vol.9 (5): 488–494 Abstract ( 31) HTML PDF (7782 KB) ( 4 )
  • The Cretaceous (ca. 145 Ma~65 Ma) was characterized by remarkable greenhouse conditions which was more server than present greenhouse gas emissions. However, this special climate condition is mainly documented from marine records. The information derived from continental sediments including terrestrial vegetation is relatively scarce. Here, we report on a palynological study of 17 samples from the Lower Cretaceous Liupanshan Group of the Sikouzi Section (spanning 116 Ma~103 Ma), Liupanshan Basin and analyzed for paleoclimate implications. The palynoflora is diverse, dominated by Classopollis (Cheirolepidiaceae), with abundant ferns and rare angiosperms. The dominant ferns are from Lygodiaceae and Schizaeaceae. The palynological data shows that the Early Cretaceous floras are derived from various settings, i.e., the Coniferales on high elevation mountains, Cheirolepidiaceae along low hills near lakes, ferns in marsh wetlands, and algae in fresh water lakes. The palynoflora indicates that the climate in the Liupanshan area is hot and dry, and the palaeogeography is characterized by complex and various outlook during the Early Cretaceous, furthermore, climate evolution revealed by the vegetation can be divided into two stages during this period. From 116 Ma to 112 Ma, the concentration of thermophilic and xerophilous species such as Cheirolepidiaceae and Schizaeaceae were relatively low, conifers increased significantly, and fern concentration remained steady. This ecosystem suggests a humid and cold climate during this period. From 112 Ma to 103 Ma, the concentration of Cheirolepidiaceae and Schizaeaceae was relatively high, and conifers decreased significantly. Compared to the upper stage, the total percentage of Lygodiaceae spores were relatively low. Vegetation change during this period may indicate an increased trend of a dry and hot environment in this region. The trend of climate change recorded by the pollen assemblages during this period coincide with global sea surface temperature fluctuation. Thus, climate change recorded by the palynological assemblage in the Sikouzi section correlates well with global climate change during the Early Cretaceous.
  • Intrastorm stemflow variability of a xerophytic shrub within a water-limited arid desert ecosystem of northern China
  • YaFeng Zhang, XinPing Wang, YanXia Pan, Rui Hu
  • DOI: 10.3724/SP.J.1226.2017.00495
  • 2017, Vol.9 (5): 495–502 Abstract ( 37) HTML PDF (3289 KB) ( 41 )
  • An increasing number of studies in recent years has elucidated distinguishable effects of stemflow on hydrology and biogeochemistry within a variety of ecosystems. Nonetheless, no known studies have investigated the temporal variability of stemflow volume within discrete rainfall events for xerophytic shrubs. Here, stemflow was monitored at 5-min intervals using a tipping-bucket rain gage during the 2015 growing season for a xerophytic shrub (Caragana korshinskii) within a water-limited arid desert ecosystem of northern China. We characterized the stemflow temporal variability, along with rainfall, and found the temporal heterogeneity of rainfall clearly affected the timing of stemflow inputs into basal soil within discrete rainfall events. The rainfall threshold value for stemflow generation is not a constant value but a range (0.6~2.1mm, with an average of 1.1 mm) across rainfall events and is closely associated with the antecedent dry period. Time lags existed between the onset of rainfall and the onset of stemflow, and between rainfall peaks and stemflow peaks. Our findings are expected to be helpful for an improved process-based understanding of the temporal stemflow yield of xerophytic shrubs within water-limited arid desert ecosystems.
  • High-quality draft genome sequence of Streptomyces agglomeratus 5-1-8 with strong anti-MRSA ability, isolated from the frozen soil of Tibet in China
  • XiMing Chen, Ling Zhang, HaiLi Sun, ShuYan Li, SiJing Chang, QingFeng Zhang, BingLin Zhang, Tuo Chen, GuangXiu Liu, Paul Dyson
  • DOI: 10.3724/SP.J.1226.2017.00503
  • 2017, Vol.9 (5): 503–510 Abstract ( 22) HTML PDF (2710 KB) ( 20 )
  • Streptomyces agglomeratus 5-1-8 with strong anti methicillin-resistant Staphylococcus aureus (MRSA) ability, isolated from the frozen soil of Tibet in China, has a strong ability to kill the multi-drugs-resistant MRSA. To identify the second-ary metabolism ability of this strain, we describe here the phenotypic characteristics of this strain, along with its high-quality draft genome sequence, its annotation, and analysis. The 7.1M draft genome encodes 6,284 putative open reading frames (ORFs), of which 4,416 ORFs were assigned with clusters of orthologous genes (COG) categories. Also, 65 tRNA genes and 24 rRNA operons were identified. The genome contains 12 gene clusters involved in antibiotics production and 1 gene cluster involved in anticancer-compounds production; 4 gene clusters belong to polyketides and nonribosomal peptides, 1 gene cluster belong to the butyrolactone, 4 gene clusters belong to the bacteriocin or lantipeptide, and 3 gene clusters belong to the others. This genome-sequence data will facilitate efforts to probe the potential of new antibiotics to kill multi-drugs-resistant MRSA.