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THE spatial distribution AND MOMENTS OF CIRCULAR FREELY JOINTED CHAIN

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Chinese Journal of Polymer Science 1991年第2期9卷 101-107页

作者：郝鸣鸿 Institute of Molecular Science Shanxi University Taiyuan Shanxi

The spatial distribution function and second moments of circular freely jointed chain are derived based on an analytical method. The circular Gauss chain, which is simple for long chains, is compared with the circular freely jointed chain, which is exact for short chains. It is shown that the Gauss chain model predicts a more compact configurational distribution than the exact freely jointed chain. The two chain models, however, become closer to each other when the chain length increases. It is found that the difference of the mean square radius of gyration calculated with these two chain models is a constant, independent of the chain length.

关键词： Freely Jointed Chain Gauss Chain spatial distribution

spatial distribution of phosphorus forms in sediments with different distances to the estuary of the Dianchi Lake,China

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Frontiers of Environmental Science & Engineering 2010年第3期4卷 295-300页

作者： Shaoyong LU Xiangcan JIN Fengchang WU Jianning GUO Jing SI Research Center of Lake Eco-environment Chinese Research Academy of Environmental SciencesBeijing 100012China Department of Environmental Engineering Jilin Architectural and Civil Engineering InstituteChangchun 130021China

Effects of human activity on the distribution of phosphorus(P)forms were investigated for the sediments and porewaters in Daqinghe Estuary of Dianchi Lake,China.The concentrations of total P(TP),inorganic-P(IP),and organic-P(Org-P),and the ratio of iron-bound P(Fe-P)/calcium-bound P(Ca-P)in the sediments decreased with the increasing distance from the sampling site to the estuary.This is probably due to the flocculant materials,e.g.,ferric and aluminous salts,usually being added in the wastewater treatment processes.The concentration of ammonia in the sediment porewaters significantly decreased with the increasing distance from the sampling site to the estuary.Both concentrations of total nitrogen and nitrogen in the sediment porewaters decreased to some content with the increasing distance from the sampling site to the estuary.However,the concentrations of nitrate,dissolved total P(DTP),and TP did not have strong relationship with the distances from the sampling sites to the estuary.Pollution load and water quantity also had an important influence on the concentrations of P in sediments and its interstitial water in estuary sedimentary area.

关键词： estuary sedimentary area phosphorus(P) spatial distribution human activity the Dianchi Lake

spatial distribution of water and wind erosion and their influence on the soil quality at the agropastoral ecotone of North China

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International Soil and Water Conservation Research 2020年第3期8卷 253-265页

作者： Yanzai Wang Yifan Dong Zhengan Su Simon M.Mudd Qiuhong Zheng Gang Hu Dong Yan Institute of International Rivers and Eco-Security Yunnan UniversityKunming650091PR China Key Laboratory of Mountain Hazards&Surface Process Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu610041PR China College of Geography and Tourism Chongqing Normal UniversityChongqing401331PR China School of GeoSciences University of EdinburghEdinburghEH89XPUK China Meteorological Administration Training Center CMABeijing100081PR China School of Tourism and Geography Sciences Qingdao266071ShandongPR China National Institute for Radiological Protection Chinese Center for Disease Control and PreventionBeijing100088PR China

In semiarid regions,wind and water erosion are serious environmental and ecological problems around world.They have different impacts on soil quality over a range of spatial scales.Analyzing the spatial distribution of soil erosion and understanding the impacts of wind and water erosion on soil quality at the regional scale is vital for mitigating soil erosion risk.In this study we explore the spatial distributions of water and wind erosion around Zhangjiakou city which suffers both water and wind erosion contemporaneously,and detect the influence of soil erosion on soil quality.We find that annual wind erosion intensities range 4.99-10.05 t ha-1 yr-1,and annual water erosion intensities range 2.92-4.14 t ha-1 yr-1.Areas with higher potential wind and total erosion risk occur mainly in northwest and southeast Zhangjiakou city,whereas potential water erosion risk is highest in the southwest and central regions.The highest erosion rates are concentrated in gentle parts of the landscape,where agriculture has led to low vegetation cover.Steeper portions of the landscape,which remain forested,have lower erosion rates.These spatial patterns are dominated by higher wind erosion,which correlates with sur-face soil coarsening and higher water infiltration,whereas the soil water holding capacity decreases with increasing wind erosion rates.In regions with high water infiltration rates,we find the intensity of water erosion weakened.To mitigate risks of soil degradation,suitable erosion measures should be imple-mented according to the dominant erosion type,which varies in space.

关键词： Soil erosion Soil quality spatial distribution Agropastoral ecotone

spatial distribution of Soil Organic Matter and Nutrients in the Pear Orchard Under Clean and Sod Cultivation Models

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Journal of Integrative Agriculture 2013年第2期12卷 344-351页

作者： XU Ling-fei ZHOU Peng HAN Qing-fang LI Zhi-hui YANG Bao-ping NIE Jun-feng College of Horticulture Northwest A&F University Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in Northwest China Ministry of Agriculture Key Laboratory of Crop Production and Ecology Minister of Agriculture

The soil organic matter and nutrients are fundamental for the sustainability of pear production, but little is known about the spatial distribution of soil organic matter and nutrients in a pear orchard. With the soil of the pear （cv. Dangshansu on P.betulifolia Bunge. rootstock） orchard under clean and sod cultivation models as test materials, the experiment was conducted to evaluate spatial variability of soil organic matter （SOM）, total nitrogen （STN）, total phosphorus （STP）, total potassium （STK）, available nitrogen （SAN）, and available potassium （SAK） in and between rows at different soil depths （0-60 cm）. The SOM, STN, STP, STK, SAN and SAK of the different soil layers under the two tillage models were different in the vertical direction. The SOM, STN, STP and SAN in the 0-20 cm soil layer were higher than those in the 20-40 and 40- 60 cm soil layers. The STK of 40-60 cm soil layer was higher than that in the 0-20 and 20-40 cm soil layers. The STK increased with the depth of soil in the vertical direction in the clean cultivated pear orchard. Variability of the SOM, STN, STP, STK, SAN and SAK of sample sites in between rows of the same soil layer was found in the pear orchard soil in the horizontal direction under clean and sod cultivation management systems, except that STK of all sites did not show the difference in identical soil layers in the pear orchard under clean cultivation. The sod cultivation model improved the SOM, STN, and STK in the 0-20 cm soil layer in the pear orchard, and the three components increased by 12.8, 12.7 and 7.3% compared to clean cultivation, respectively. The results can be applicable to plan collection of orchard soil samples, assess orchard soil quality, and improve orchard soil management practices.

关键词： spatial distribution soil organic matter soil nutrients clean cultivation sod cover pear orchard

Migration and distribution characteristics of soil heavy metal(loid)s at a lead smelting site

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Journal of Environmental Sciences 2024年第1期135卷 600-609页

作者： Chuxuan Li Mu Li Jiaqing Zeng Shanxin Yuan Xinghua Luo Chuan Wu Shengguo Xue School of Metallurgy and Environment Central South UniversityChangsha 410083China Chinese National Engineering Research Center for Control and Treatment of Heavy Metal Pollution Central South UniversityChangsha 410083China

Heavy metal(loid)s contamination is a constant issue at smelting sites.It is essential to investigate the spatial distribution and migration characteristics of heavy metal(loid)s in the soil for environmental management and remediation strategies of non-ferrous smelting sites.In this study,203 soil samples from 57 sites were collected in a typical lead smelting site.The findings demonstrated that there were significant Pb,Zn,Cd,and As contamination in soil samples.The spatial distribution of heavy metal(loid)s showed strong spatial heterogeneity,the contaminated soil areas of Pb,As,Cd,and Zn were 99.5%,98.9%,85.3%,and 72.4%,respectively.Pb,Cd,and As contamination of the soil reached a depth of 5 m,which migrated from the surface to deep soil layers.The leaching contents of Zn,Pb,and As decreased obviously in 3-4 m soil layer,but the leaching content of Cd was still high,which indicated the high migration of Cd.With the increase of depth,the proportion of acid soluble fraction of heavy metal(loid)s decreased,and the residual fraction increased.The acid soluble fraction of Cd accounted for a higher proportion,and As mainly existed in reducible and residual fractions in soil.According to the calculation of the migration factor,the migration of heavy metal(loid)s in soils were ordered as Cd>Zn>Pb>As.The outcomes are advantageous for risk reduction and site remediation for non-ferrous metal smelting sites.

关键词： Smelting sites Heavy metal(loid)s spatial distribution Chemical speciation Migration characteristics

spatial distribution Characteristics and Influencing Factors of Traditional Villages in Guizhou Province

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Journal of Landscape Research 2022年第1期14卷 37-46页

作者： ZHANG Yihong MIN Tingdong BAI Bin YANG Qing School of Economics and Management Tongren UniversityTongrenGuizhou554300 China Guizhou University of Finance and Economics GuiyangGuizhou550025China

Traditional villages have high historical,cultural,scientific,artistic,social and economic value.They reflect the harmony and balance among long-term production,human life and natural environment.They are a community of tangible and intangible cultural heritages,and have received extensive attention from political circles,academic circles and the public.Through the Arc GIS10.3 geographic information system,724 traditional villages in Guizhou Province,China are visualized,and the nearest neighbor index,geographic concentration index,imbalance index,kernel density estimation and other methods are employed to analyze the spatial distribution type,distribution balance,spatial agglomeration characteristics and influencing factors.Studies have shown that the traditional villages in Guizhou Province tend to be concentrated and distributed,spatially forming high-density areas in southeastern Guizhou,second high-density areas in Anshun,moderate-density areas in Tongren,and low-density areas in Zunyi.From the city (prefecture) scale,traditional villages in Guizhou Province are relatively concentrated in Qiandongnan Prefecture,Tongren City,Anshun City and Qiannan Prefecture.From a regional perspective,the distribution of traditional villages in Guizhou Province is uneven,mainly distributed in Qiannan,Qiandong and Qianzhong.Their spatial distribution is affected by factors such as natural environment,traffic accessibility,ethnic culture,and economic development.It reveals the spatial distribution characteristics and influencing factors of traditional villages in Guizhou Province,and provides relevant realistic and theoretical foundations for the protection,inheritance and innovative development of traditional villages.In addition,the formation mechanism of traditional villages needs to be further analyzed based on information reflecting the attributes of traditional villages such as village history,village types,site selection patterns,characteristic buildings,production and life.It is also necessary to improve the tradition

关键词： Traditional villages Geographic information system spatial distribution Influencing factors

spatial distribution and Inscribed Criteria of Cultural Landscape World Heritage Sites

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Journal of Landscape Research 2023年第1期15卷 63-67,72页

作者： XIAO Xiangyun YANG Xiaoshuang XIAO Shizhen MU Dijin School of Karst Science Guizhou Normal University/State Engineering Technology Institute for Karst Desertifi cation ControlGuiyangGuizhou 550001China

As an important type of world heritage sites,cultural landscape has always been an important research subject.In order to explore the spatial distribution and evolution mode of cultural landscape all over the world,the paper systematically elaborated the historical context of cultural landscape.The distribution characteristics were analyzed by statistical methods,and the connotation and evolution law represented by cultural landscape in different regions were expounded.The word frequency of regional heritage criteria was analyzed,and the local characteristics of each case were discussed.The research shows that the spatial distribution of global cultural landscape is unbalanced,mainly concentrated in Europe,and the spatial distribution characteristics are closely related to geographical environment,social history,economic development level and many other factors.In terms of inscribed criteria for world heritage sites,most cultural landscapes are mainly based on cultural criteria,but also involve natural criteria.The recognition and protection of cultural landscapes that simultaneously meet multiple criteria will become the focus in the future.

关键词： Cultural landscape World heritage site spatial distribution Inscribed criteria

spatial distribution and Ages of Alkaline Intrusive Rocks in China and Related Tectonics

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Acta Geologica Sinica(English Edition) 1998年第4期72卷 363-381页

作者： YUAN Zhongxin BAI Ge Institute of Mineral Deposits Chinese Academy of Geological Sciences 26 Baiwanzhuang Beijing 100037

On the basis of the geological data from 220 intrusions and isotope ages of 115 rock bodies, the paper discusses the distribution of 18 alkaline intrusive rock belts along deep faults and their relations to the plate tectonic activity. In view of the presence of a large amount of Variscan alkaline rocks of deep-source character, it is inferred that mantle diapirism was very strong in China during the Variscan. Besides anorogenic and postorogenic alkaline granites, there also occur alkaline granites formed in the terminal orogenic stage when the regional tectonic activity was of compressional nature. Finally, the paper discusses the tectonic environment of the Maoniuping nordmarkite in Mianning county, Sichuan province, and the authors consider it to be a compressional environment originating after rift closing.

关键词： alkaline intrusive rock spatial distribution age tectonic China

spatial distribution Characteristics of Organic Acids in Two Late-blooming Rhododendron Species

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Asian Agricultural Research 2022年第2期14卷 50-53,65页

作者： Jiangtao HAO Yuan JING Chaochan LI Guizhou Provincial Key Laboratory of Mountainous Environmental Protection Guizhou Normal University Guiyang 550001 China

[Objectives]The spatial distribution characteristics of organic acids in two late-blooming Rhododendron species(Rhododendron decorum and Rhododendron stamineum)in Guizhou Baili Rhododendron National Forest Park were explored,in order to provide reference for exploring the plant-soil relationship of subtropical forest.[Methods]The fresh leaf,stem,root,litter,humus and soil samples of R.decorum and R.stamineum were collected.The contents of eight low molecular weight organic acids including oxalic acid,tartaric acid,malic acid,citric acid,acetic acid,lactic acid,succinic acid and formic acid were determined by high performance liquid chromatography(HPLC).[Results]Oxalic acid is the main organic acid in the two species of Rhododendron.Among different samples,the content of organic acids was in the following order:root>fresh leaf>humus>litter>stem>soil.[Conclusions]The content of organic acids in the root was significantly higher than that in other parts.The types of organic acids in stems were the least.

关键词： Subtropical forest Low molecular weight organic acids spatial distribution