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Study of spatial distribution of sandy desertification in North China in recent 10 years

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Science China Earth Sciences 2004年第Z1期47卷 78-88页

作者： WANG Tao, WU Wei, XUE Xian, SUN Qingwei & CHEN GuangtingKey Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China Department of Environment Engineering, Peking University, Beijing 100871, China Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China Department of Environment Engineering Peking University Beijing China

Sandy desertification is a land degradation characterized by wind erosion, mainly resulted from the excessive human activities in arid, semiarid and part of sub-humid regions in North China. It is one of main kinds of desertification/land degradation as well as water-soil erosion and salinization in China. Rapid and continuous spread of sandy desertification during last 50 years has created a major environmental and socio-economic problem in North China. Remote sensing monitored results in 2000 showed that the sandy desertified land area has been 38.57×104 km2. The area of potential to slightly sandy desertified land is 13.93×104 km2, moderately land 9.977×104 km2, severely land 7.909×104 km2 and very severely land 6.756×104km2. Sandy desertification mainly occurs in the semi-arid mixed farming-grazing zone and its northern rangeland zone, semi-arid dryland rainfed cropping zone and arid oasis-desert margin zone. The average annually developmental rate of sandy desertified land increased from 2,100tion in North China is "overall deterioration, while local rehabilitation". Already achieved rehabilitation results and monitoring assessment show that about 60% of desertified land in North China can be restored under the conditions of rational land-use ways and intensity.

关键词： sandy desertified land, spatial distribution, remote sensing monitoring, last 10 years, North China.

Reanalysis of the 3D quasi-stationary grain size distribution based on Hillert's grain growth rate equation

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Science China(Technological Sciences) 2004年第1期47卷 112-120页

作者： WANG Chao LIU Guoquan School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Based on Hillert's 3D grain growth rate equation, the grain growth continuity equation was solved. The results show that there are an infinite number of 3D quasi-stationary grain size distributions. This conclusion ha... 详细信息

关键词： Hillert's grain growth equation, continuity equation, quasi-stationary state, grain size distribution, analytical distribution.

Prediction of permafrost distribution on the Qinghai-Tibet Plateau in the next 50 and 100 years

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Science China Earth Sciences 2005年第6期48卷 797-804页

作者： NAN Zhuotong LI Shuxun CHENG Guodong State Key Laboratory of Frozen Soil Engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China State Key Laboratory of Frozen Soil Engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China State Key Laboratory of Frozen Soil Engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

Intergovernmental Panel on Climate Change (IPCC) in 2001 reported that the Earth air temperature would rise by 1.4-5.8℃ and 2.5℃ on average by the year 2100. China re-gional climate model results also showed that the air temperature on the Qinghai-Tibet Plateau (QTP) would increase by 2.2-2.6℃ in the next 50 years. A numerical permafrost model was developed to predict the changes of permafrost distribution on the QTP over the next 50 and 100 years under the two climatic warming scenarios, i.e. 0.02℃/a, the lower value of IPCC’s estima-tion, and 0.052℃/a, the higher value predicted by Qin et al. Simulation results show that ( i ) in the case of 0.02℃/a air-temperature rise, permafrost area on the QTP will shrink about 8.8% in the next 50 years, and high temperature permafrost with mean annual ground temperature (MAGT) higher than ?0.11℃ may turn into seasonal frozen soils. In the next 100 years, perma-frost with MAGT higher than ?0.5℃ will disappear and the permafrost area will shrink up to 13.4%. (ii) In the case of 0.052℃/a air-temperature rise, permafrost area on the QTP will reduce about 13.5% after 50 years. More remarkable degradation will take place after 100 years, and permafrost area will reduce about 46%. Permafrost with MAGT higher than ?2℃ will turn into seasonal frozen soils and even unfrozen soils.

关键词： permafrost distribution, scenario prediction, the Qinghai-Tibet Plateau (QTP), numerical methods, Geo-graphical Information System (GIS).

Modeling diameter distribution of the broadleaved-Korean pine mixed forest on Changbai Mountains of China

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Science China(Technological Sciences) 2006年第Z1期49卷 177-188页

作者： WANG Shunzhong, DAI Limin, LIU Guohua, YUAN Jianqiong, ZHANG Hengmin & WANG Qingli Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China Graduate University of Chinese Academy of Sciences, Beijing 100039, China State Key Lab of Systems Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China Institute of Applied Ecology Chinese Academy of Sciences Shenyang China Graduate University of Chinese Academy of Sciences Beijing China State Key Lab of Systems Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing China

The broadleaved-Korean pine mixed forest is a native vegetation in the Changbai Mountains, northeast China. The probability density functions including the normal, negative exponential, Weibull and finite mixture distribution, were used to describe the diameter distributions of the species groups and entire forest stand. There is a strong correlation between parameters and mean DBH except the shape parameters in the mixture distribution. The diameter classes of species and entire forest stand showed not negative exponential but normal and "S" distribution. The mixture function was better than normal and Weibull to describe the model distribution. The location parameter had an effect on the estimated frequency in the first diameter class, when the estimated location parameter was bigger than the lower limit of the first diameter class.

关键词： broadleaved-Korean pine mixed forest, diameter distribution, finite mixture distribution.

Adsorption of surfactants onto acrylic ester resins with different pore size distribution

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Science China Chemistry 2006年第5期49卷 445-453页

作者： YANG Weiben1,2,3,LI Aimin1,3,CAI Jianguo1,3,MENG Guanhua1,3 & ZHANG Quanxing1,3 1. State Key Laboratory of Pollution Control and Resource Reuse,School of the Environment,Nanjing University,Nanjing 210093,China 2. Nanjing College of Chemical Technology,Nanjing 210048,China 3. Jiangsu Engineering & Technology Research Center for Organic Toxicant Control and Resource Reuse,Nanjing 210038,China State Key Laboratory of Pollution Control and Resource Reuse School of the Environment Nanjing University Nanjing China Nanjing College of Chemical Technology Nanjing China Jiangsu Engineering & Technology Research Center for Organic Toxicant Control and Resource Reuse Nanjing China

In this study, a series of acrylic ester resins with different pore size distribution were prepared successfully by varying the type and the amount of pore-forming agents. In order to inves-tigate the adsorption behavior and mechanism of surfactants on acrylic ester resins, three kinds of surfactants were utilized as adsorbates that were sodium 6-dodecyl benzenesulfonate (6-NaDBS), sodium 1-dodecyl benzene sulfonate (1-NaDBS) and sodium 1-dodecyl sulfonate, respectively. It was observed that the surface area was available in a particular pore size and an appropriate pore size of resins appeared to be more important for the adsorption of surfactants. As compared to commercial acrylic ester resins XAD-7 and HP2MG, 50# and 38# resins exhibited more excellent adsorption properties toward 1-NaDBS and 6-NaDBS. The experimental equilibrium data were fitted to the Langmuir, and double-Langmuir models. Two models provided very good fittings for all resins over the temperature range studied. The investigation indicated that electrostatic attraction and hydrogen bond between resins and surfactants were the main forces and had an obvious effect on adsorption proc-ess.

关键词： acrylic ester resin, surfactant, adsorption, pore size distribution, isotherm.

Consecutive reversible ionization-recombination reactions and ionic charge state distribution of Au plasma

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Science China(Physics,Mechanics & Astronomy) 2005年第5期48卷 575-584页

作者： ZHU Zhiyan1, ZHU Zhenghe1, TANG Changhuan1, TANG Yongjian2 & GAO Tao1 1. Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China 2. China Academy of Engineering Physics, Mianyang 621900, China Institute of Atomic and Molecular Physics Sichuan University Chengdu China China Academy of Engineering Physics Mianyang China

The present work proposes kinetics of ionization-recombination to study the charge state distribution of Au plasma. The first step is to calculate the average lifetime, energy level structure, degeneracy and partition function of Au48+―Au52+ by relativistic quantum mechanics, and next to compute the equilibrium constant and the second-order recombination rate constant by statistical thermodynamics. Based on these data, the differential equations of consecutive reversible ionization-recombination reactions are solved from which the charge state distribution and its average charge are derived. Finally, the influence of electron temperature and density on average charge is given in this paper. It is called the first-principle theory, for no experimental data are needed.

关键词： Au plasma, ionization-recombination dynamics, ionic charge state distribution, average charge.

Characteristics of vertical ozone distribution in the lower troposphere in the Yangtze River Delta at Lin'an in the spring of 2001

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Science China Earth Sciences 2005年第9期48卷 1519-1528页

作者： ZHENG Xiangdong1, CHAN Chuenyu2, CUI Hong2, QIN Yu3, CHAN Loyan2, ZHENG Yongguang3 & LEE Yusiang2 1. Chinese Academy of Meteorological Sciences, Beijing 100081, China 2. Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong, China 3. Department of Atmospheric Sciences, Peking University, Beijing 100871, China Chinese Academy of Meteorological Sciences Beijing China Department of Civil and Structural Engineering Hong Kong Polytechnic University Hung Hom Hong Kong China Department of Atmospheric Sciences Peking University Beijing China

We analyzed vertical distributions of ozone (O3) in the lower troposphere (< 5 km above ground) at Lin’an (119.75°E, 30.30°N), Zhejiang Province using electrochemical concen- tration cell (ECC) ozonesonde data obta... 详细信息

We analyzed vertical distributions of ozone (O3) in the lower troposphere (distributions are controlled by metrological conditions and the char- acteristics of O3 profiles are related to those of wet bulb potential temperature and wind field. O3 below 2 km showed that the strongest variability and enhanced O3 mixing ratios were associated with easterly winds that blow pollutants from the upwind source region of the Yangtze River Delta (YRD) region. Vertical O3 profiles below 5 km can be grouped into 5 categories: (1) peak mixing ratio type, (2) well-mixed type, (3) layered-structure type, (4) episodic pollution type and (5) alti- tudinal increasing type. Vertical distributions of O3 affected by regional transport of polluted air masses were investigated. Transport of polluted air from high latitudes of northern China, ac- companying subsiding motion of air and stagnant atmospheric conditions are important factors that lead to high mixing ratios of O3 at Lin’an. The stagnant atmospheric conditions associated with a continental high pressure system and pollution plume transported from the YRD and cen- tral-eastern China also lead to regional accumulation of O3 and high O3 mixing ratio at Lin’an. Long-range transport of O3 and pollutants from the Pearl River Delta in South China and in-situ O3 formation also resulted in elevated O3 mixing ratios at around 1 km altitudes and layered O3 distribution in the lower troposphere.

关键词： vertical ozone distribution, lower troposphere, Yangtze River Delta, Lin'an.

Correlation of fractal pore-size distribution of activated carbon fiber with its adsorption for low concentration benzene vapor

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Science China Chemistry 2002年第5期45卷 475-480页

作者：黄正宏杨骏兵康飞宇梁开明 Department of Materials Science and Engineering Tsinghua University Beijing China

Fractal pore-size distribution K(x) is given based on J(x) function proposed by Jaronic. Activated carbon fibers (ACF) with different surface areas are characterized by using two functions mentioned above. The present work studies the fractal pore-size distribution of ACF and adsorption isotherms of nonpolar benzene vapor on ACF, and thereby reveals the correlation between them.

关键词： activated carbon fiber (ACF), fractal, pore-size distribution, gas adsorption.

Theory and practice of runoff space-time distribution

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Science China(Technological Sciences) 2004年第Z1期47卷 90-105页

作者： Thomas M. Over Department of Geology/Geography Eastern Illinois University Charleston IL 61920 USA

Based on the domestic and foreign concerning researches, this paper submits the runoff space-time distribution theory which shows evident scientific significances and powerful practical functions. On the basis of digital basin unit cell deriving from the digital elevation model (DEM) and assumption of linear confluence, this theory has been applied successfully to the runoff correlation researches in humid regions. In order to prove the adaptability of the theory in arid and semi-drought regions, this paper is used to the runoff correlation analysis in Wuding River basin——a tributary of Yellow River Basin, and has gained preliminary effective verification.

关键词： runoff space-time distribution, theory, the Wuding River, correlation coefficient, practice.