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Wind tunnel simulation of the effects of freeze–thaw cycles on soil erosion in the Qinghai–Tibet Plateau

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Research in Cold and Arid Regions 2016年第3期8卷 187-195页

作者： ShengBo Xie jianjun qu Tao Wang Key Laboratory of Desert and Desertification/Dunhuang Gobi and Desert Research Station State Key Laboratory of Frozen Soil EngineeringCold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of SciencesLanzhouGansu 730000China

Intense freezing and thawing actions occur in the Qinghai-Tibet Plateau because of its high elevation and cold temperature. The plateau＇s unique environment makes it easy to generate wind erosion under dry, windy weather conditions, resulting in the emergence ofdesertification. As a major form of freeze-thaw erosion, freeze-thaw and wind erosion is displayed prominently on the Qinghai-Tibet Plateau. Therefore, in this study, soil samples were collected from the surface of the plateau to undergo freeze-thaw and wind erosion simulation experiments. Results show that wind erosion strength increases with an increasing number of freeze-thaw cycles, water content in the freezing-thawing process, and the difference in freeze-thaw temperatures. Therefore, in the conditions of water participation, the main reason for the freeze-thaw and wind erosion in the Qinghai-Tibet Plateau is the damage to the soil structure by repeated, fierce freeze-thaw actions, and the sand-bearing wind is the main driving force for this process. The research results have theoretical significance for exploring the formation mechanism of freeze-thaw and wind erosion in the Qinghai-Tibet Plateau, and provide a scientific basis for freeze-thaw desertification control in the plateau.

关键词： freeze-thaw cycles wind erosion strength wind tunnel simulation Qinghai-Tibet Plateau

New discoveries on the effects of desertification on the ground temperature of permafrost and its significance to the Qinghai-Tibet Plateau

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Chinese Science Bulletin 2012年第8期57卷 838-842页

作者： XIE ShengBo qu jianjun ZU RuiPing ZHANG KeCun HAN QingJie Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy ofSciencesLanzhou 730000China Dunhuang Gobi and Desert Research Station Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy ofSciencesDunhuang 736200China Gansu Center for Sand Hazard Reduction Engineering and Technology Lanzhou 730000China

The desert and permafrost conditions of the Qinghai-Tibet Plateau are ***,the effects of desertification on the ground temperature of permafrost are currently ***,understanding this problem has become more urgent because of increasing desertification on the *** this reason,an observational field experiment was undertaken by the authors at Honglianghe on the Qinghai-Tibet *** ground temperature probes were used,and synchronized contrasting observations were made in an open *** of the ground temperature of permafrost below sand layers with a range of thicknesses were made from May 2010 to April *** sand layers were found to play a key role in the protection of the underlying *** ground temperature below a permafrost table overlain by a thick sand layer was lower than that of the average annual temperature for the natural ground surface,and the temperature drop was roughly constant at 0.2°*** the warmer part of the year (May to September),the maximum temperature drops over the five months were 3.40,3.72,4.85,3.16,and 1.88°C,*** ground temperature near a permafrost table overlain by a thin sand layer was also lower than that of the average annual temperature for the natural ground ***,in this case the average of the annual maximum temperature drop was significantly less,0.71°*** scientific significance of our preliminary conclusions is not only to present an exploration of the interaction between desertification and permafrost,but also to provide new engineering ideas for protecting the permafrost in regions where construction is required on the Qinghai-Tibet Plateau.

关键词：多年冻土地区青藏高原地温观测荒漠化地面温度田间试验热敏电阻最高温度

Bacterial diversity in the sediment of Crescent Moon Spring,Kumtag Desert,Northwest China

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Journal of Arid Land 2017年第2期9卷 278-286页

作者： ZHANG Wei ZHANG Gaosen WU Xiukun LIU Guangxiu DONG Zhibao qu jianjun WANG Yun CHEN Tuo Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Gansu Key Laboratory of Extreme Environmental Microbial Resources and Engineering Lanzhou 730000China Dunhuang Gobi and Desert Ecology and Environment Research Station Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesDunhuang 736200China

Desert lake, a unique oasis in desert ecosystems, harbours different bacterial communities. Thus, it is considered as a hub of bacterial diversity. In this study, bacterial diversity in the sediment of Crescent Moon Spring, Kumtag Desert, Northwest China was analyzed using high-throughput amplicon pyrosequencing analysis. The sequences of the most abundant OUTs （Operational Taxonomic Units） in the sediment of Crescent Moon Spring were compared with the sequences of those most abundant OUTs of various origins from NCBI GenBank database to detect the origins of bacteria in the sediment of Crescent Moon Spring. Also, bacterial compositions between sediment of Crescent Moon Spring and other desert and lake ecosystems （including desert lakes） worldwide were compared using cluster analysis to determine the possible factors affecting bacterial compositions. In total, 11,855 sequences were obtained and 30 phyla were identified. At the phylum level, the dominant phylum was Proteobacteria with α-Proteobacteria being the first dominant class and the second dominant phylum was Planctomycetes. Our finding that α-Proteobacteria being the first dominant class of Proteobacteria and Planctomycetes being the second dominant phyla are somewhat contradictory with reports from other desert lake sediments. This difference could be resulted from water hydration and conductivity, as well as oligotrophic conditions of Crescent Moon Spring. At the genus level, Rhodobacter, Caldilinea, Planctomyces, and Porphyrobacterwere the dominant genera in the sediment of Crescent Moon Spring. Comparisons on sequences of the most abundant OUTs （including OTU3615, OTU6535, and OTU6646） between sediment of Crescent Moon Spring and various origins from NCBI GenBank database indicate that the origins of bacteria in the sediment of Crescent Moon Spring are likely from the underground water. Furthermore, cluster analysis on comparisons of bacteria compositions between sediment of Crescent Moon Spring and other

关键词： bacterial diversity pyrosequencing analysis desert lake desert and lake ecosystems Crescent Moon Spring

Climate change inferred from aeolian sediments in a lake shore environment in the central Tibetan Plateau during recent centuries

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Research in Cold and Arid Regions 2018年第2期10卷 134-144页

作者： BenLi Liu jianjun qu ShiChang Kang Bing Liu Dunhuang Gobi Desert Ecological and Engineering Research Station/Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences State Key Laboratory of Cryospheric Sciences Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences

Studies of the past climate variation on the Tibetan Plateau(TP) are currently limited in number and low in density and temporal resolution. We investigated the climate condition from about 400 years before present(B.P.) in the central TP at the shore of Co(means "lake") Nag using aeolian sediments. A 2.7-m sand profile with 57 sediment samples and six optically stimulated luminescence(OSL) samples were studied through grain-size analysis, geochemical elements and parameters, and depositional rate estimation. A previous assumption was verified that sand deposition at the shore of Lake Co Nag originated from hills to the east. Two significant wet periods between 90–140 and about 380 years B.P. were indicated by the variation of element profiles and sediment depositional rates. Aeolian activity is sensitive to variations from different seasonal changing patterns of climate factors in the study area, and aeolian sediments respond differently to climate conditions during the cold little ice age(LIA) and the warm 20 th century. Present day dry seasons of winter and spring might be much warmer and drier compared to seasons of 400 years ago although summer precipitation has increased, resulting in significantly more aeolian activity and higher depositional rate(about 6 times compared to 380–240 years ago) of sandy sediments. Aeolian problems like blown-sand deposition and desertification may be worse in a projected warming future in the central TP as well as other cold and high altitude regions. Our results suggest an agreement with environmental evolution during the little ice age and the 20 th century in a broader scale on the TP.

关键词： Tibetan Plateau aeolian sediments geochemical element OSL dating

A method to obtain soil-moisture estimates over bare agricultural fields in arid areas by using multi-angle RADARSAT-2 data

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Research in Cold and Arid Regions 2018年第2期10卷 145-150页

作者： JunZhan Wang jianjun qu LiHai Tan KeCun Zhang Dunhuang Gobi and Desert Ecology and Environment Research Station Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences

Soil moisture is an important parameter for agriculture, meteorological, and hydrological studies. This paper focuses on soil-moisture estimation methodology based on the multi-angle high-and low-incidence-angle mode RADARSAT-2 data obtained over bare agricultural fields in an arid area. Backscattering of the high-and low-incidence angles is simulated by using AIEM(advanced integral equation model), with the surface-roughness estimation model built based on the simulated data. Combining the surface-roughness estimation model with the backscattering model of the low-incidence-angle mode, a soil-moisture estimation method is put forward. First, the natural logarithm(ln) of soil moisture was obtained and then the soil moisture calculated. Soil moisture of the study area in Dunhuang, Gansu Province, was obtained based on this method; a good agreement was observed between the estimated and measured soil moisture. The coefficient of determination was 0.85, and the estimation precision reached 4.02% in root mean square error(RMSE). The results illustrate the high potential of the approach developed and RADARSAT-2 data to monitor soil moisture.

关键词： RADARSAT-2 bare soil soil moisture

Classification of full-polarization ALOS-PALSAR imagery using SVM in arid area of Dunhuang

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Research in Cold and Arid Regions 2016年第3期8卷 263-267页

作者： JunZhan Wang jianjun qu WeiMin Zhang KeCun Zhang Dunhuang Gobi and Desert Ecology and Environment Research Station Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences

Classification is an important process in interpretation of synthetic aperture radar （SAR） imagery. As an advanced instrument for remote sensing, the polarimetric SAR has been applied widely in many fields. The main aim of this paper is to explore the ability of the full-polarization SAR data in classification. The study area is a part of Dunhuang, Gansu Province, China. An L-band full-polarization image of Dunhuang which includes quad-polarization modes was acquired by the ALOS-PALSAR （Advanced Land Observing Satellite-the Phased Array type L-band Synthetic Aperture Radar）. Firstly, new characteristic information was extracted by the difference operation, ratio operation, and principal component transform based on the full-polarization （HH, HV or VH, VV） modes SAR data. Then the single-, dual-, full-polarization SAR data and new SAR characteristic information were used to analyze quantitatively the classification accuracy based on the Support Vector Machines （SVM）. The results show that classification overall accuracy of single-polarization SAR data is poor, and the highest is 56.53% of VV polarization. The classification overall accuracy of dual-polarization SAR is much better than single-polarization, the highest is 74.77% ofHV ＆ VV polarization data. The classification overall accuracy of full-polarization SAR is 80.21%, adding the difference characteristic information, ratio characteristic information and the first principal component （PC1） respectively, the overall accuracy increased by 3.09%, 3.38%, 4.14% respectively. When the full-polarization SAR data in combination with the all characteristic information, the classification overall accuracy reached to 91.01%. The full-polarization SAR data in combination with the band math characteristic information or the PC1 can greatly improve classification accuracy.

关键词： full-polarization PALSAR classification the Support Vector Machines (SVM)

Large scale sand saltation over hard surface:a controlled experiment in still air

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Journal of Arid Land 2021年第6期13卷 599-611页

作者： LIU Benli WANG Zhaoyun NIU Baicheng qu jianjun Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Research Station of Gobi Desert Ecology and Environment in Dunhuang of Gansu Province Lanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China Qinghai Normal University Xining 810004China

Saltation is the major particle movement type in wind erosion *** sand grains can rebound up to tens of times larger in length and height over hard surface(such as gravel surface)than over loose sand *** usually have different faces,causing distinct response of the impacting grains,but the effects of the grain and gravel-surface contact angle on grain rebound are not yet well *** performed full-range controlled experiments of grain saltation using different contact angles,grain sizes and impact speeds in still air,to show that contact angle increases the height of representative saltation path but decreases particle travel *** results were compared with outputs from the COMprehensive numerical model of SALTation(COMSALT).Large saltation height of 4.8 m and length of 9.0 m were *** maximum and representative saltation height over the gravel surface were found to be about 4.9 times and 12.8 times those over the loose sandy surface,*** maximum saltation length may be reduced by 58%and the representative saltation height may be increased by 77%as contact angle increases from 20°to 40°.We further showed that the collision inertia contributes 60%of the saltation length,and wind contributes to the other 40%.These quantitative findings have important implications for modeling saltation trajectory over gravel surface.

关键词： sand saltation trajectory gravel surface contact angle full-scale experiment

Succession of soil bacterial and fungal communities of Caragana korshinskii plantation in a typical agro-pastoral ecotone in northern China over a 50-a period

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Journal of Arid Land 2021年第10期13卷 1071-1086页

作者： MA Gailing GOU Qianqian WANG Guohua qu jianjun College of Geographical Sciences Shanxi Normal UniversityLinfen 041004China Northwest Institute of Eco-Environment and Resources Chinese of Academy of SciencesLanzhou 730000China

Bacterial and fungal communities play critical roles in reestablishing vegetation structure,function and biodiversity in ecosystem restoration in arid and semi-arid ***,the long-term successional changes in bacterial and fungal communities that occur with artificial vegetation development are not fully *** this study,we investigated the successional changes in bacterial and fungal communities in Caragana korshinskii *** over a period of 50 a(6,12,18,40 and 50 a)and their relationships with key soil environmental factors in a typical agro-pastoral ecotone,northern *** results showed that bacterial and fungal diversities(α-andβ-diversity)were significantly affected by plantation age;moreover,the change in fungal community was more evident than that in bacterial *** samples from 12 a plantation had the highest(P<0.05)bacterial and fungalα-diversity(i.e.,abundance-based coverage estimator(ACE)and Chao1 index)at 0-10 cm depth compared with other ***,soil samples from plantation at the late recovery stage(40-50 a)had the highestα-diversity at 10-20 cm *** bacterial community was not significantly affected by plantation age at the genus level;but,soil fungal community was significantly affected at the genus ***,Mortierella and Chaetomium were the dominant genera at natural recovery stage(0 a);Inocybe was the dominant genus at the early recovery stage(6-12 a);Inocybe and Mortierella were the dominant genera at the mid-recovery stage(12-40 a);And Mortierella,Cladosporium and Humicola were the dominant genera at the late recovery stage(40-50 a).Redundancy analysis(RDA)showed thatβ-glucosidase activity,total nitrogen and soil organic carbon were closely associated with bacterial community composition,while alkaline phosphatase,urease activity and total nitrogen were associated with fungal community composition,indicating that changes in enzyme activity and soil nutrients were the most important determ

关键词： bacteria fungi diversity dominant genus ecological pattern Caragana korshinskii

Wind tunnel simulation experiment and investigation on the electrification of sandstorms

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Science China Earth Sciences 2004年第6期47卷 529-539页

作者： qu jianjun YAN Muhong DONG Guangrong ZHANG Hongfa ZU Ruiping TUO Wanquan ZHAO Aiguo XIAO Zhenghua LI Fang YANG Bao Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute and Shapotou Desert Research and Experiment Station Chinese Academy of Sciences Lanzhou 730000 China

Electric discharge phenomenon is often observed during the passage of sandstorms over desert regions and sometimes does great damage to human beings. Based on previous researches on the electrification of sandstorms by the scholars both at home and aboard,the authors conducted the simulation experiments on the electric fields of sandstorm-triggered creeping-saltating sand, suspending sand and watered suspending sand in the large-scale wind tunnel. According to the experimental results the electric field structure and its formation mechanism were analysed and discussed, the quantity of electric charges and electric field strengthwere measured and calculated, and finally several conclusions were drawn.

关键词： sand drift structure electrification mechanism wind tunnel simulation