检索结果-南通市图书馆

Changes in hair arsenic concentration in a population exposed to heavy pollution:Follow-up investigation in Chenzhou City,Hunan Province,Southern china

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental sciences 2010年第2期22卷 283-289页

作者： Bin Wu,Tongbin Chen Center for Environmental Remediation,institute of geographic sciences and natural resources {5.,chinese academy of sciences,beijing 100101,china. [a] Center for Environmental Remediation Institute of Geographic Sciences natural resources research Chinese Academy of Sciences Beijing 100101 China

Follow-up investigation on hair arsenic concentration was conducted in an arsenic heavily polluted area of southern china in 2002 and 2006. The results showed that the geometric mean of hair arsenic concentration decreased from 2.95.mg/kg in 2002 to 1.78 mg/kg in 2006, when the percentage of the population with levels over 1 mg/kg only decreased from 93.4% in 2002 to 80.5. in 2006. Over this four-year period, the population with high arsenic concentrations decreased significantly while there was no obvious change in hair arsenic concentration for people who had relatively low concentrations. In terms of age distribution, young and old people had higher hair arsenic concentrations than the middle-aged. All of these results showed that it is difficult to reverse the negative impact of arsenic pollution on human health. Arsenic pollution has a long-term continuous influence on the health of local residents.

关键词： arsenic human health soil contamination hair arsenic

Rocky Land Desertification and its Driving Forces in the Karst Areas of Rural Guangxi,Southwest china

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2008年第4期5卷 350-357页

作者： LIU Yansui WANG Jieyong DENG Xiangzheng institute of geographic sciences and natural resources {5. Chinese Academy of Science Beijing 100101 China institute of geographic sciences and natural resources {5. Chinese Academy of Science Beijing loolo~ ChinaGraduate University of Chinese Academy of Sciences Beijing 100039 China

With a subtropical climate,Guangxi Zhuang Autonomous Region has a typical karst *** desertification has become a serious environmental issue due to its high vulnerability caused by the joint effect of natural settings and human activities,because of which its eco-environment has been deteriorated in recent years,and farmland has been disappearing sharply at the same ***,in turn,has exacerbated the poverty level in the rural areas of the *** this study,we monitored the spatial distribution of rocky land desertification and its temporal evolution using Landsat TM/ETM images of 1985.1995.2000 and *** also analyzed the driving forces of the desertification and its *** constructing regression models by using all the relevant variables and considering the lagged effects as well as fixed effects,we quantified the exact role of different factors causing rocky land desertification in the study area with some new *** new findings in this study are greatly helpful for preserving,restoring and reconstructing the degraded mountain environment in Guangxi and other karst areas in Southwest china,and also for alleviating poverty in the rural areas in the future.

关键词： Rocky land desertification karstmountain area rural poverty driving force Guangxi Southwest china

STUDY ON DEVELOPMENT STRATEGY OF SHIPPING CENTERS AND TRANSPORTATION NETWORKS IN THE YELLOW SEA RIM

在线全文

学校读者我要写书评

暂无评论

chinese geographical Science 2003年第2期13卷 97-103页

作者： JIN Feng-jun (institute of geographic sciences and natural resources {5., chinese Acad emy of sciences, beijing 100101, P.R. china) institute of geographic sciences and natural resources {5. Chinese Academy of Sciences Beijing 100101 P. R. China

It is very important to establish cooperative mechanism to guarantee allmembers to develop their e-conomies in the Yellow Sea Rim. In this paper, the development strategiesof shipping centers and transportation network are discussed based on economic globalizationtendency. The results argue that a united transportation network should be built in order to promotethe economic competition of Northeast Asia in the world. As a key component of the economiccooperation, a hierarchical shipping centers network should be established with Hong Kong, Shanghai,Pusan, Kobe, and Tokyo as cores. The authorities of china, Japan, R. 0. Korea and D. P. R. Koreashould make more efforts to build a set of cooperation institutions based on raising thetransportation efficiency.

关键词： the yellow sea rim shipping center transportation network hub-and-spoke system

ANALYSIS OF DRIVING FORCES ON THE CHANGE OF HISTORICAL FARMLAND USE IN SHANDONG PROVINCE DURING THE QING DYNASTY (1644-1911)

在线全文

学校读者我要写书评

暂无评论

chinese geographical Science 2003年第3期13卷 207-215页

作者： ZHANG Xue-in, GE Quan-heng, ZHENG Jing-un(institute of geographic sciences and natural resources {5., chinese academy of sciences, beijing 100101, P. R. china) institute of geographic sciences and natural resources {5. Chinese Academy of Sciences Beijing P. R. China

How land-cover has been changed by human use over the last 300 years is oneof the five overarching questions guiding the Land-use/Cover Change (LUCC) Science/research *** has variety of historical documents providing unique data superiority. So the characteristicsof farmland area in Shandong Province during the Qing Dynasty (1644-1911) are summarized firstly: 1)the rising trend of farmland area was striking; 2) farmland area had remarkable fluctuation; 3)farmland area per capita decreased dramatically; 4) wasteland reclamation index increased ***, the driving forces of farmland area change are analyzed. It is concluded that natural andhuman factors are jointly influential. Among the driving forces, human dimensions are the mainfactors of farmland area change, which direct the general tendency of the changes mentioned *** the natural factors influence the stability of farmland area as well. Variation of the naturalfactors would act as the major contributory factor to farmland area change during years or periodsof abrupt climatic changes, or during the intensive occurring periods of natural hazards. Besides,the passive aspects of human factors, such as war chaos also influenced the fluctuation of thefarmland area. This research indicates that it is feasible to study the land-use/cover change bychinese historical literatures, which has huge potential to provide a comprehensive picture of thegrowing dominance of human land-use and land-cover patterns that can be used in many global changeresearch projects.

关键词： farmland driving forces shandong province qing dynasty

CH_4 uptake flux of Leymus chinensis steppe during rapid growth season in Inner Mongolia,china

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2010年第7期53卷 977-983页

作者： GENG YuanBo1, LUO GuangQiang1,2 & YUAN GuoFu1 1 institute of geographic sciences and natural resources {5., chinese academy of sciences, beijing 100101, china 2 Graduate University of chinese academy of sciences, beijing 100049, china 1. institute of geographic sciences and natural resources {5. Chinese Academy of Sciences Beijing 100101 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

The influence of near ground atmosphere CH4 concentration, soil water content, soil Eh, plants, soil temperature, and pH on CH4 uptake flux of Leymus chinensis steppe during rapid growth season was studied using field in-situ measurement in Xilin River basin of Inner Mongolia, china. The results showed that CH4 uptake flux was positively correlated with near ground atmosphere CH4 concentration and soil Eh but negatively correlated with soil water content. Precipitation may decrease the CH4 flux by increasing the soil water content. The average fluxes of three treatments during the observation period were 1.5. (natural conditions, 1.5. (aboveground plants were excluded), and 2.00 mg m?2 d?1 (all plants were removed), respectively. The difference between the CH4 flux of natural condition treatment and that of removing aboveground plants treatment is small, whereas the flux of removing all plants treatment is larger than the other two treatments. This means that the contribution of aboveground plants to CH4 uptake flux is smaller than that of roots or roots-removing process. CH4 uptake flux is not sensitive to soil temperature and the narrow-ranged soil pH (6.36–7.86). The Leymus chinensis steppe acts as a sink for CH4, and thus more studies should be focused on its affecting factors and related mechanisms.

关键词： CH4 uptake flux Leymus chinensis steppe affecting factors static opaque chamber/gas chromatography method

Relationship between erosion and sediment yield in drainage basins of loess gully-hilly areas

在线全文

学校读者我要写书评

暂无评论

Journal of geographical sciences 2001年第1期11卷 71-79页

作者： CHEN Hao (institute of geographic sciences and natural resources {5., CAS, beijing 100101, china) institute of geographic sciences and natural resources {5. CAS Beijing China

From a long-term point of view, the balance between erosion and sediment yield in a drainage system can basically realize, i.e., the delivery ratio can be close to 1. However, substantial variations among individual rainfall events or between annual delivery ratio exist, causing frequent sediment retaining or re-erosion and re-delivery of the retained sediments in a short period of time. Thus the delivery ratio will be 1. The sediment delivery ratio is closely related to the spatial distribution of rainfall and magnitude of rise and fall of peak flood and that of runoff depth in the drainage system. Delivery ratio of single event in a drainage system and changes of delivery capacity of silt-laden runoff in various classes of gullies can be expressed by transformation mechanism of shear force of a single rainstorm event with flood resulting from increase and decrease of peak flood per unit area.

关键词： delivery ratio interaction flood and geomorphology dynamic mechanism rainstorm flood

Thresholds of geographic environmental elements in sediment yield of drainage basins

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2005年第2期48卷 230-240页

作者： CHEN Hao, ZHOU Jinxing, CAI Qiangguo, LU Zhongchen & LI Zhongyan institute of geographic sciences and natural resources {5., chinese academy of sciences, beijing 100101, china institute of Forestry Science, chinese academy of Forestry Science, beijing 100091, china {5. Center for Eco-Environment sciences, chinese academy of sciences, beijing 100085. china Computing institute of Science and Engineering, North china Electric Power University, beijing 102206, china 1. institute of geographic sciences and natural resources {5. Chinese Academy of Sciences 100101 Beijing China 2. institute of Forestry Science Chinese Academy of Forestry Science 100091 Beijing China 3. research Center for Eco-Environment sciences Chinese Academy of Sciences 100085 Beijing China 4. Computing institute of Science and Engineering North China Electric Power University 102206 Beijing China

Threshold of environmental elements in drainage basin sediment yield refers to, under effect of climate, underlying surface and human activity, a turning point of abrupt changes in drainage sediment yield related to environmental element characteristics. Previous studies on threshold of sediment yield of relevant drainage basins were mainly concentrated on impact of natural zones with a few researches on impact of other environmental elements. Particularly studies on compound environmental element threshold in drainage basin sediment yield remain blank today. Studies indicate that sediment yield in drainage basins is affected by compound interactions and complex actions. Based on single element analysis, the present paper gives quantitatively compound threshold of environmental elements affecting sediment yield of the drainage basin between Hekouzhen and Tongguan in the middle Yellow River by the method of multi-variant, polynomial formula regression analysis.

关键词： middle Yellow River, environmental element, sediment, sediment delivery mudule, threshold.

PLS path model building:A multivariate approach to land price studies-A case study in beijing

在线全文

学校读者我要写书评

暂无评论

Progress in natural Science:Materials International 2009年第11期19卷 1643-1649页

作者： Wenjie Wu~(a,b),Wenzhong Zhang~(a,*) a institute of geographic sciences and natural resources {5.,CAS,beijing 100101,china b Graduate University of chinese academy of sciences,beijing 100049,china institute of geographic sciences and natural resources {5. CAS Beijing 100101 China Graduate University of chinese academy of sciences Beijing 100049 China

Previous studies have revealed that statistical methods can be used to analyze land-leasing parcel ***,the conventional statistical methods used in land analysis have some limitations,especially in cases of limited observational *** this paper,with the help of geographic information system(GIS) techniques,a partial least squares(PLS) path model is applied to study the relationship between residential land prices and various determinants through a case study of beijing in *** a preliminary analysis,four latent variables are selected:accessibility of the workplace center,livability,traffic,and environment *** results show that the observation variables have a strong explanatory power for their corresponding latent variables,and the four latent variables have varying impacts on residential land *** the latent variables,accessibility to the workplace center has the strongest impact on the residential land price.

关键词： Land PLS path model GIS beijing

Continuous wavelet transform and discrete multi-resolution analysis of surface fluxes and atmospheric stability

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in natural Science:Materials International 2006年第4期16卷 403-409页

作者： JIANG Zhaoyang, YU Qiang, WANG Tianduo, SUN Xiaomin and ZHANG Renhua Shanghai institute of Plant Physiology and Ecology, chinese academy of sciences, Shanghai 200032, china institute of geographic {5. and natural resources research, chinese academy of sciences, beijing 100101, china [a]Shanghai institute of Plant Physiology and Ecology Chinese Academy of Sciences Shanghai China [b]institute of Geograhpic sciences and natural resources research Chinese Academy of Sciences Beijing China

Variations of land surface fluxes of sensible heat (H), latent heat (LE), and CO2(F-CO2) obtained from the eddy-co-variance measurements above a winter wheat field from March 30 to April 24, 2001 have been studied at scales ranging from 10 minutes to days. Wavelet transform is used in the analysis of land surface fluxes and atmospheric stability (ξ) calculated from the measurements to reveal the changes in land surface fluxes in hours to days scales. The main results are: (1) Concise and compact information about the fluxes, net radiation (Rn), temperature ( T) and ξ in the scale-time domain are extracted from the data by continuous wavelet analysis, and 1 day, 0.5.day and short-period (shorter than 0.5.day) components are revealed. Continuous wavelet coefficients can be used to characterize periodic components of changes in fluxes and ξ. (2) Discrete-time multi-resolution analysis can be used to concentrate total energy variance of time series of the measurements to a small number of coefficients, plotting the relative energy distribution to get several meaningful characteristics of the data. (3) Under neutral atmospheric conditions, the relative energy distributions of the Haar multi-resolution analysis of the three non-dimensional coefficients ( T/T* , q/q * and c/c * ) display clear similarities.

关键词： atmospheric stability flux continuous wavelet transform multi-resolution wavelet analysis.