Change Analysis of Three Major Antarctic Ice Shelves Based on Multi-source Remote Sensing Data     

Wu Chenxi  Liu Shijie  Tian Yixiang  Tong Xiaohua 《地球科学进展》2016,31(2):206-212

In recent years, melting and calving happen in the Antarctic ice shelves. In this paper, seven periods of coastlines were applied to provide an analysis of the ice front changes of Ross, Filchner-Ronne and Amery ice shelves with the inclusion of 1997 and 2000 Radarsat products, 2003/2004 and 2008/2009 MODIS products and 2006, 2012, 2015 coastline which were extracted from MODIS images. Change area, SCE (Shoreline Change Envelope) and NSM (Net Shoreline Movement) were applied to analyze the variation of the ice shelf front. The results shows that, the ice front of Amery ice shelf has advanced since 1997 and the total outward extension distance of the ice front was about 20 to 25 km while the advance area reached 3.03×10³ km². Ross ice shelf and Filchner-Ronne ice shelf continued to advance after ice calving events under the driver action of glacier. However, the advance area was less than the retreat area and the net change area is respectively -9.39×10³ km² and -5.86×10³ km². The retreat distance of the collapse area were up to 53 km and 39 km in the two biggest ice shelves.  相似文献   

Mechanical characteristics of dip basement effects on dump stability in the Shengli open pit mine in Inner Mongolia,China     

Liu Han  Jisen Shu  Qingxiang Cai  Hongwen Jing  Hua Tian 《Arabian Journal of Geosciences》2016,9(20):750

For waste dump slopes that form basements, landslides can be prevented by determining a stability evolving law of dynamic development. Keeping this issue in mind, the relationship between the mechanical structure and stability of waste dumps with basements is studied. Three key factors that influence waste dump stability are presented, and judgment criteria for self-locking and unlocking states of dump basements are provided. From the friction coefficient of waste dump basement stability analyses of the Shengli open pit mine, the results indicate that waste dump basements on the right side of fault F8 and on the left side of fault F61 are subjected to self-locking. However, between faults F61 and F8, the basement is subjected to unlocking. Regarding the residual thrusting of unlocking areas, structure and stability optimization schemes for waste dumps in the Shengli open pit mine are provided through a mechanics analysis. Reducing the slopes and basement angles of waste dumps can enhance their stability by increasing basement roughness levels.  相似文献   

南极低温降解菌Shewanella sp. NJ49羟化酶分离纯化及最适产酶条件研究     

刘芳明  王以斌  曲长凤  梁强  郑洲  缪锦来  肖天 《海洋科学》2016,40(5):1-8

羟化酶是细菌降解烷烃的关键酶,本文以南极低温降解菌Shewanella sp.NJ49为研究对象,通过硫酸铵沉淀、超滤浓缩及葡聚糖凝胶Sephadex G-75柱层析方法,分离纯化NJ49的羟化酶,获得了单一羟化酶组分,研究了温度、p H、表面活性剂和盐度等环境因素对NJ49羟化酶酶活活性影响。结果表明,羟化酶组分由α、β、γ三个亚基组成,分子质量分别为56,45和36 k D。NJ49最适产酶条件为:温度15℃、p H7.2、盐度55;不同类型表面活性剂对酶的活性影响效应不一,两性离子表面活性剂、阳离子表面活性剂、非离子表面活性剂对酶活没有作用,阴离子表面活性剂+非离子表面活性剂混和剂和阳离子表面活性剂+非离子表面活性剂混和剂能提高羟化酶的活性。  相似文献   

Factors driving riverbed scouring and sedimentation in the Bayangaole to Toudaoguai reaches of the Upper Yellow River     

Suzhen Hou  Ping Wang  Yan Guo  Tian Hu 《地理学报(英文版)》2016,26(9):1305-1320

The Inner Mongolia reaches of the Yellow River face problems of severe sedimentation caused by a variety of complex factors. The sedimentation process in those reaches has been characterized using the sediment balance method, and the key factors affecting the process have been analyzed using the correlation analysis method. The results show that during the period 1952–2012 the Bayangaole (Bayan Gol) to Toudaoguai reaches in Inner Mongolia have undergone successive processes of accumulative sedimentation, then relative balance, and then accumulative sedimentation once again. The total annual sedimentation is 12.0341×10⁸ m³, of which accumulations from July to October account for 95.1% and the reaches from Sanhuhekou to Toudaoguai account for 98.5%. The main factor affecting scouring and sedimentation of the Bayangaole to Sanhuhekou reaches is the combined water and sediment condition. The critical conditions for equilibrium are an incoming sediment coefficient < 0.007 kg·s·m^–6 and a flow discharge > 700 m³·s^–1. The main factor affecting scouring and sedimentation of the Sanhuhekou to Toudaoguai reaches is the incoming sediment from the tributaries on the south bank and the combined water and sediment condition of the main stream. The critical conditions of the main stream for maintaining equilibrium status are a flow discharge of the main stream exceeding 800 m³·s^–1 and a comprehensive incoming sediment coefficient < 0.005 kg·s·m^–6. The incoming sediment from the tributaries has little impact on the main stream when the annual sediment load is less than 0.1×10⁸ t. The incoming sediment coefficient of the main stream and the incoming sediment from the tributaries both play vital roles in the riverbed evolution of the Inner Mongolia reaches, but the latter contributes the most.  相似文献   

基于多光谱遥感的扎龙湿地湖泡水深反演研究     

张艳红  李丽丽  郭花利  吴梦红  邢立新 《湿地科学》2016,(4):477-483

以扎龙湿地龙泡子为研究对象,利用58个实测水深数据和季相最接近的Quick Bird数据,建立湖泊水深的反演模型。探索性地建立了单波段和多波段组合的线性(多元)回归模型、指数模型、二次多项式模型、微分模型和对数模型等;通过对比模型的决定系数R2,比较模型精度;线性模型、对数模型、指数模型和幂指数模型的R2小于0.5,而二次多项式模型和多元线性回归模型的R2大于0.5,精度相对较高;筛选出拟合度较高的模型,用20个实测验证样本,采用相对误差和均方根误差进行模型精度评价;最后,利用精度较高的模型,进行龙泡子水深反演计算。水深反演结果表明,用选出的模型反演得到的龙泡子水深基本一致,为170~200 cm,即使有稀疏的水草覆盖,依然可以表现出水深渐变的趋势。以蓝、绿、红和近红外波段多光谱遥感反射率为自变量,建立的线性湖泡水深反演模型y=123.990-3.332B1+183.859B2-237.133B3-37.143B4(y为水深;B1、B2、B3和B4分别为蓝、绿、红和近红外波段的水体反射率),能较好地反演扎龙湿地湖泡的水深。  相似文献   

Mass-front velocity of dry granular flows influenced by the angle of the slope to the runout plane and particle size gradation   总被引：2，自引：0，他引：2  

Xiao-yi Fan  Shu-jun Tian  You-yi Zhang 《山地科学学报》2016,13(2):234-245

The mass-front velocities of granular flows results from the joint action of particle size gradations and the underlying surfaces.However,because of the complexity of friction during flow movement,details such as the slope-toe impedance effects and momentum-transfer mechanisms have not been completely explained by theoretical analyses,numerical simulations,or field investigations.To study the mass-front velocity of dry granular flows influenced by the angle of the slope to the runout plane and particle size gradations we conducted model experiments that recorded the motion of rapid and long-runout rockslides or avalanches.Flume tests were conducted using slope angles of 25°,35°,45°,and 55° and three particle size gradations.The resulting mass-front motions consisted of three stages:acceleration,velocity maintenance,and deceleration.The existing methods of velocity prediction could not explain the slowing effect of the slope toe or the momentum-transfer steady velocity stage.When the slope angle increased from 25° to 55°,the mass-front velocities dropped significantly to between 44.4% and59.6% of the peak velocities and energy lossesincreased from 69.1% to 83.7% of the initial,respectively.The velocity maintenance stages occurred after the slope-toe and mass-front velocity fluctuations.During this stage,travel distances increased as the angles increased,but the average velocity was greatest at 45°.At a slope angle of 45°,as the median particle size increased,energy loss around the slope toe decreased,the efficiency of momentum transfer increased,and the distance of the velocity maintenance stage increased.We presented an improved average velocity formula for granular flow and a geometrical model of the energy along the flow line.  相似文献   

Livelihood changes and evolution of upland ethnic communities driven by tourism: a case study in Guizhou Province,southwest China     

Ya-juan Li  Hu Yu  Tian Chen  Jing Hu  Hai-yang Cui 《山地科学学报》2016,13(7):1313-1332

As an effective livelihood approach to alleviate poverty without rural population migration, ethnic tourism has become the primary choice of economic development in ethnic areas worldwide in addition to traditional livelihood approaches. This article applies the theories of livelihood to study the community evolution driven by tourism livelihood and examine three mountainous tourism communities in different stages of tourist area life cycle. Drawing on the methods of GIS spatial analysis, semi-structured interviews and questionnaires, this article proposes a sustainable livelihood framework for ethnic tourism to explore the evolution of ethnic tourism communities by identifying changes in livelihood assets (natural, financial, social, cultural and human capitals) in the process of tourism development. The results show that the development of ethnic tourism has led to changes in the increase of building land, and the diversification of land use functions with a trend of shifting from meeting local villagers' living needs to satisfying tourists, income composition and uneven distribution of tourism income spatially. Ethnic tourism also led to the deterioration of traditional social management structure, collapse of neighboring relationship, the over- commercialization and staged authenticity of ethnic culture, as well as the gradual vanish of agricultural knowledge with a trend of increasing modern business knowledge and higher education. In addition, these changes, involving livelihood assets from natural, economic, human, social and cultural aspects are interrelated and interactive, which form new evolution characters of ethnic community. This study reveals the conflicts over livelihood approaches which have formed new vulnerabilities to impact on sustainable evolution of ethnic communities. This research provides implications for achieving the sustainable development of ethnic communities with the driving force of tourism livelihood.  相似文献   

The modeled atmospheric and oceanic response to the South China Sea SST anomaly     

Xiande Zhu  Lixin Wu  Jun Zhou  Jianjun Gao 《中国海洋大学学报(英文版)》2016,15(5):741-750

The sensitivity of the global atmospheric and oceanic response to sea surface temperature anomaly (SSTA) throughout the South China Sea (SCS) is investigated using the Fast Ocean-Atmosphere Model (FOAM). Forced by a warming SST, the experiment explicitly demonstrates that the responses of surface air temperature (SAT) and SST exhibit positive anomalous center over SCS and negative anomalous center over the Northern Pacific Ocean (NPO). The atmospheric response to the warm SST anomalies is characterized by a barotropical anomaly in middle-latitude, leading to a weak subtropical high in summer and a weak Aleutian low in winter. Accordingly, Indian monsoon and eastern Asian monsoon strengthen in summer but weaken in winter as a result of wind convergence owing to the warm SST. It is worth noting that the abnormal signals propagate poleward and eastward away in the form of Rossby Waves from the forcing region, which induces high pressure anomaly. Owing to action of the wind-driven circulation, an anomalous anti-cyclonic circulation is induced with a primary southward current in the upper ocean. An obvious cooling appears over the North Pacific, which can be explained by anomalous meridional cold advection and mixing as shown in the analysises of heat budget and other factors that affect SST.  相似文献   

Study on the adsorption behavior of modified persimmon powder biosorbent on Pt(IV)     

Q. Q. Gong  X. Y. Guo  S. Liang  C. Wang  Q. H. Tian 《International Journal of Environmental Science and Technology》2016,13(1):47-54

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Impacts of mineralogical compositions on different trapping mechanisms during long-term CO<Subscript>2</Subscript> storage in deep saline aquifers     

Kairan Wang  Tianfu Xu  Hailong Tian  Fugang Wang 《Acta Geotechnica》2016,11(5):1167-1188

Deep saline aquifers in sedimentary basins are considered to have the greatest potential for CO₂ geological storage in order to reduce carbon emissions. CO₂ injected into a saline sandstone aquifer tends to migrate upwards toward the caprock because the density of the supercritical CO₂ phase is lower than that of formation water. The accumulated CO₂ in the upper portions of the reservoir gradually dissolves into brine, lowers pH and changes the aqueous complexation, whereby induces mineral alteration. In turn, the mineralogical composition could impose significant effects on the evolution of solution, further on the mineralized CO₂. The high density of aqueous phase will then move downward due to gravity, give rise to “convective mixing,” which facilitate the transformation of CO₂ from the supercritical phase to the aqueous phase and then to the solid phase. In order to determine the impacts of mineralogical compositions on trapping amounts in different mechanisms for CO₂ geological storage, a 2D radial model was developed. The mineralogical composition for the base case was taken from a deep saline formation of the Ordos Basin, China. Three additional models with varying mineralogical compositions were carried out. Results indicate that the mineralogical composition had very obvious effects on different CO₂ trapping mechanisms. Specific to our cases, the dissolution of chlorite provided Mg²⁺ and Fe²⁺ for the formation of secondary carbonate minerals (ankerite, siderite and magnesite). When chlorite was absent in the saline aquifer, the dominant secondary carbon sequestration mineral was dawsonite, and the amount of CO₂ mineral trapping increased with an increase in the concentration of chlorite. After 3000 years, 69.08, 76.93, 83.52 and 87.24 % of the injected CO₂ can be trapped in the solid (mineral) phase, 16.05, 11.86, 8.82 and 6.99 % in the aqueous phase, and 14.87, 11.21, 7.66 and 5.77 % in the gas phase for Case 1 through 4, respectively.  相似文献