Accessibility and capacity of medical resources are key for the health care and emergency response, while the efficiency of the medical resources is very much limited by hypoxia in Tibet, China.Through introducing exe...Accessibility and capacity of medical resources are key for the health care and emergency response, while the efficiency of the medical resources is very much limited by hypoxia in Tibet, China.Through introducing exercise efficiency, this study explores the accessibility of township residence to county-ship medical resources in Tibet using weighted mean travel time(WMT), and evaluates the medical capacity accordingly.The results show that: 1) the average travel time of township residence to county-level hospital is around2 h by motor vehicle in Tibet.More than half of the population can not reach the county-ship hospital within 1 h, 33.24% of the population can not reach within 2 h, and 3.75% of the population can not reach within 6 h.2) When considering the catchment of the medical resources and the population size, the WMT of the county-ship medical resources ranges from 0.25 h to 10.92 h.3) After adjusted by travel time and exercise efficiency, the county-ship medical capacity became more unequal, with 38 out of 74 counties could not meet the national guideline of 1.8 medical beds per 1000.4) In total, there are 17 counties with good WMT and sufficient medical resources,while 13 counties having very high WMT and low capacity of medical resources in Tibet.In the end, suggestions on medical resources relocation and to improve the capacity are provided.This study provides a method to incorporate exercise efficiency to access the accessibility and evaluate medical capacity that can be applied in high altitude ranges.展开更多
The shrinking and drying up of wetlands in arid and semiarid areas of China have been widely observed in the recent years,but there has been no consensus on whether the aggravation is caused by human activities or by ...The shrinking and drying up of wetlands in arid and semiarid areas of China have been widely observed in the recent years,but there has been no consensus on whether the aggravation is caused by human activities or by global climate warming.For a better understanding of the cause,this study investigates the dynamic changes of Baiyangdian Lake wetland over the last 40 years.It is shown that since the 1980s,Baiyangdian Lake has suffered from an insufficient water input and shrunk considerably.By using SPSS11.0,this study undertakes a detailed analysis on the significance of the effects of the possible driving factors for the degradation.It is identified that the North China Plain has been warming up significantly in recent years,which causes a significant reduction in the precipitation and inflow to the lake.Although human disturbances such as the irrigation and storage of water in reservoirs do not play a decisive role,they accelerate the degradation and their effects should be minimized.展开更多
Glacier is one kind of the most beautiful geological sightseeing in the world as well as a special kind of tourism resources.The characters of glacier tourism include scarcity,frangibility,localization of tourist acti...Glacier is one kind of the most beautiful geological sightseeing in the world as well as a special kind of tourism resources.The characters of glacier tourism include scarcity,frangibility,localization of tourist activity,scien-tific connotation,and integrated function and value.The paper summarizes the latest researches in developing glacier tourism resources.Regarding the Bogda Glacier Park as an example,the authors analyze the characteristics of glacier tourism resources in detail and the conditions and potential threats of glacier tourism development.Suggestions on glacier tourism development and protection are given as follows:1) to plan function subarea scientifically and rea-sonably;2) to combine tourism,scientific research with ecological education;3) to take countermeasures of environ-mental protection;4) to integrate tourism resources and strengthening regional cooperation.Finally,emphases are put forward on resources conformity along the tourism line and cooperation of tourism management.The paper aims to seek after the coordination path in exploitation and protection of glacier tourism resources to guide the exploitation of other glacier tourism destinations.展开更多
The Fluorine release rate of coal, clay of different Fluorine content, and coalmixed with clay used by resident households were studied by using the ion selective electrode(ISE) and solidoid balance methods, and the d...The Fluorine release rate of coal, clay of different Fluorine content, and coalmixed with clay used by resident households were studied by using the ion selective electrode(ISE) and solidoid balance methods, and the degree of influence on Fluorine pollutiongenerated by coal and clay was analyzed according to the proportion characteristicsof coal used by resident households.The results show that the Fluorine release rate ofcoal is more than 95% during combustion; The Fluorine release rate of clay is more than99%; The Fluorine release rate of coal mixed with clay is between 56.44% and 96.64%,and the average value is 76.68%.The clay as a binder for fine coal is one importantsource of Fluorine pollution caused by coal-combustion in Zhaotong, Yunnan Province.When the Fluorine content of coal is less than 80 mg/kg, the Fluorine amount releasedfrom clay (in which Fluorine content is more than 530 mg/kg) is more than 50% of the totalFluorine amount released from coal and clay during coal-combustion.The Fluorineamount released from clay (in which Fluorine content is more than 1 000 mg/kg) is morethan 70% of total Fluorine amount released from coal and clay during coal-combustion.展开更多
The peri-urbanization area as a kind of rural-urban interface is changing rapidly, in physical, economic, and social terms. The land use pattern in such area is shifting away from the assumptions of mainstream paradig...The peri-urbanization area as a kind of rural-urban interface is changing rapidly, in physical, economic, and social terms. The land use pattern in such area is shifting away from the assumptions of mainstream paradigms to new conceptual landscapes, which leads to a series of problems on economic development and social stabilization. There are many researches on non-agricultural land-use in peri-urbanization area. In this paper both international and domestic research literature is reviewed by dividing six parts. The first part introduces the conception of peri-ur-banization area and its driver factors. Then In the second and the third part, the paper expatiates on the progress in the non-agricultural land-use in peri-urban area on land-use pattern, evolution, characteristics, problems, etc. The forth part focuses on the reasons that cause the land-use problems in the research area, while the fifth part reviews the integrating ways of non-agricultural land-use. Finally, recommendations for further study are draw with specific reference to the current and future position of non-agricultural land-use study in peri-urban area.展开更多
The purpose of this paper is to document the likely impacts of climate change on China’s agriculture and the current adaptation efforts made by government and farmers.The review of literature shows that climate chang...The purpose of this paper is to document the likely impacts of climate change on China’s agriculture and the current adaptation efforts made by government and farmers.The review of literature shows that climate change will have a significant impact on agriculture,primarily through its effect on crop yields.The extent of predicted impacts highly depends on the crop,the CO2 fertilization effect assumption and adaptation abilities.Market response to the production shocks resulting from climate change will lessen the impacts on agricultural production predicted by natural scientists.On adaptation,the government’s major efforts have been in the developing new technologies,reforming extension system and enhancing institutional capacity.Farmers do adapt to climate change,but their adaptation measures cannot fully offset the negative impacts of climate change.The paper concludes and makes implications for future studies.展开更多
Quantitative assessment of development sustainability could be a challenge to regional management and planning,especially for areas facing great risks of water shortage.Surface-water decline and groundwater over-pumpi...Quantitative assessment of development sustainability could be a challenge to regional management and planning,especially for areas facing great risks of water shortage.Surface-water decline and groundwater over-pumping have caused serious environmental problems and limited economic development in many regions all around the world.In this paper,a framework for quantitatively evaluating development sustainability was established with water-related eco-environmental carrying capacity(EECC) as the core measure.As a case study,the developed approach was applied to data of the Haihe River Basin,China,during 1998 through 2007.The overall sustainable development degree(SDD) is determined to be 0.39,suggesting that this rate of development is not sustainable.Results of scenario analysis revealed that overshoot,or resource overexploitation,of the Basin's EECC is about 20% for both population and economy.Based on conditions in the study area in 2007,in order to achieve sustainable development,i.e.,SDD>0.70 in this study,the EECC could support a population of 108 million and gross domestic product(GDP) of 2.72 trillion CNY.The newly developed approach in quantifying ecoenvironmental carrying capacity is anticipated to facilitate sustainable development oriented resource management in waterdeficient areas.展开更多
The overall goal of this paper is to examine impacts of climate change on water supply and demand balance and their consequences on agricultural production in ten river basins in China. To realize this goal, China Wat...The overall goal of this paper is to examine impacts of climate change on water supply and demand balance and their consequences on agricultural production in ten river basins in China. To realize this goal, China Water Simulation Model (CWSM) is used to analyze three alternative climate scenarios (A1B, A2 and B2). The results show that the impacts of climate change on water supply and demand balance differ largely among alternative scenarios. While significant impacts of climate change on water balance will occur under the A1B scenario, the impacts of climate change under the A2 and B2 scenarios will be marginal. Under the A1B scenario, the water shortage in the river basins located in the northern China will become more serious, particularly in Liaohe and Haihe river basins, but the other river basins in the southern China will improve their water balance situations. Despite larger impacts of climate change on water balance in the northern China, its impacts on total crops' production will be moderate if farmers would be able to reallocate water among crops and adjust irrigated and rainfed land. The paper concludes with some policy implications.展开更多
The population growth and demand for high living standard not only increase food demand but also cause more loss of the limited cultivated land resources.Cultivated land loss caused by disasters and the implementation...The population growth and demand for high living standard not only increase food demand but also cause more loss of the limited cultivated land resources.Cultivated land loss caused by disasters and the implementation of the “Conversion of Cropland to Forest or Grassland” project make this situation even worse in China.Thus,there is a problem to be solved imminently that to what extent the cultivated land can guarantee food security of China.Based on time-series data on food production and cultivated land area from 1989 to 2003 and other research results,this paper constructs quality index of cultivated land according to different land quality.Regression models are adopted to predicate changes of main factors from 2004 to 2030,which have great effect on cultivated land area or grain productivity,and verify accuracy with coefficient of determination(R2).Nine results were got according to three scenarios of decreasing rate of population growth rate and three cases of urban and rural built-up area per capita.There results show that China’s food supply can only be maintained at a low to middle level of 370-410kg per capita,that is,China has enough land productivity to meet primary demand of food independently.However,it cannot reach the safe target of 500kg per capita if there is no breakthrough in breeding or no remarkable improvement of irrigation works,when the grain self-sufficiency maintains no less than 80%.To breed productive crops and to improve land productivity by meliorating low quality cultivated land are appropriate measures to shrink the gap between food demand and supply.The results may offer helpful information for the formulation of policies on population growth,land use,protection of cultivated land.展开更多
The most serious erosion on the Loess Plateau of China exists in the wind-water erosion crisscross region where the annual precipitation is about 400 mm,the ecological environment is very fragile,and water is the key ...The most serious erosion on the Loess Plateau of China exists in the wind-water erosion crisscross region where the annual precipitation is about 400 mm,the ecological environment is very fragile,and water is the key limiting factor for improving the environment. In this study,changes of soil moisture content for Caragana korshinskii Kom. shrubland in the gully bank of the Loess Plateau were studied using the methods of soil sampling and neutron probe. A typical gully(75 m long,28 m wide,and 10 m deep) was selected,and six neutron probe access tubes(6 m long) were installed at points 50,100,200,300,400,and 500 cm from the gully border for obtaining soil moisture data from July to October 2004 at approximately 10 d intervals. Soil samplings were simultaneously carried out for moisture determination at the six points. Results showed that the soil moisture of the shrubland in the gully bank significantly varied between 300 and 400 cm in the horizontal direction and up to 600 cm in vertical direction of the gully. Seasonal changes in soil moisture revealed a curve with a single peak that occurred at the end of August or early September. A linear regression equation was fit for soil water storage and the distance from the gully border,with coefficients depending on rainfall characteristics,sampling point,and time of measurement.展开更多
The seasonal mean atmospheric precipitable water and water vapor transport over the Haihe River Basin (HRB) inNorth China with a focus on their interannual to interdecadal variability, and then the relationships of th...The seasonal mean atmospheric precipitable water and water vapor transport over the Haihe River Basin (HRB) inNorth China with a focus on their interannual to interdecadal variability, and then the relationships of the interannual andinterdecadal variability of the water cycle over the HRB to the Pacific Decadal Oscillation (PDO) and El Nino-SouthernOscillation (ENSO) phenomena were investigated using the observational and National Centers for Environmental Pre-diction (NCEP) reanalysis data. There was a strong interdecadal variability for the water cycle (such as precipitationand water vapor transport) over the region, with an abrupt change occurring mostly in the mid 1970s. The intensity ofthe East Asian summer monsoon largely affected the atmospheric water vapor transport. Generally, the net meridionalconvergence of the water vapor flux over the region was relatively large before 1965, and it declined gradually from thenon with a further notable decrease since mid 1970s. Zonal water vapor transport was similar to meridional, but with amuch smaller magnitude and no noteworthy turning in the mid 1970s. Results also suggested that the wind field playedan important role in the water vapor transport over the HRB before the mid 1960s, and the interdecadal variability ofthe water cycle (precipitation, water vapor transport, etc.) in the summer was related to the PDO; however, interannualvariation of the water vapor transport could also be related to the ENSO phenomena.展开更多
Elemental composition and geochemical characteristics of iron-manganese nodules from nine main soils in China were studied by chemical and multivariate statistical analyses to better understand the reactions and funct...Elemental composition and geochemical characteristics of iron-manganese nodules from nine main soils in China were studied by chemical and multivariate statistical analyses to better understand the reactions and functions of iron-manganese nodules in soils and sediment. Compared to the corresponding soils, Mn, Ba, Cd, Co and Pb had strong accumulation, Ni had moderate accumulation, while Ca, Cu, Fe, Na, P, Sr and Zn accumulated to a minor degree in the iron-manganese nodules. In contrast, Si, Al, K, Mg and Ti were reduced in the iron-manganese nodules. The contents of Ba, Cd, Co, Cu, Ni, Pb and Zn were positively and significantly correlated with that of MnO2 in the iron-manganese nodules, while the contents of Cr, Cu, Ni, Pb and Zn were positively and significantly correlated with that of Fe2O3 in soils. Based on a principle component analysis, the elements of iron-manganese nodules were divided into four groups: 1) Mn, Ba, Cd, Co, Cu, Li, Ni, Pb and Zn that were associated with Mn oxides, 2) Fe, Cr and P that were associated with Fe oxides, 3) Si, K, and Mg that were included in the elemental composition of phyllosilicate, and 4) Ca, Na, Al and Ti that existed in todorokite, birnessite, lithiophorite and phyllosilicate. It was suggested that accumulation, mineralization and specific adsorption were involved in the formation processes of soil iron-manganese nodules.展开更多
In order to understand the similarity or difference of inorganic As species uptake and transport related to phosphorus in As-hyperaccumulator,uptake and transport of arsenate(As(V))and arsenite(As(III))were studied us...In order to understand the similarity or difference of inorganic As species uptake and transport related to phosphorus in As-hyperaccumulator,uptake and transport of arsenate(As(V))and arsenite(As(III))were studied using Pteris vittata L.under sandculture.Higher concentrations of phosphate were found to inhibit accumulation of arsenate and arsenite in the fronds of P.vittata.The reduction in As accumulation was greater in old fronds than in young fronds,and relatively weak in root and rhizome.Moderateincreases,from 0.05 to 0.3 mmol/L,in phosphate reduced uptake of As(III)more than As(V),while the reverse was observed at highconcentrations of phosphate(1.0 mmol/L).Phosphate apparently reduced As transport and the proportion of As accumulated in frondsof P.vittata when As was supplied as As(V).It may in part be due to competition between phosphorus and As(V)during transport.Incontrast,phosphate had a much smaller effect on As transport when the As was supplied as As(III).Therefore,the results from presentexperiments indicates that a higher concentration of phosphate suppressed As accumulation and transport in P.vittata,especially inthe fronds,when exposed to As(V);but the suppression of phosphate to As transport may be insignificant when P.vittata exposed toAs(III)under sand culture conditions.The finding will help to understand the interaction of P and As during their uptake process in P.vittata.展开更多
This paper addresses the emergence of water security problems in North China with the aim of highlighting key waterresources management and water security issues for the long-term development of North China. Three key...This paper addresses the emergence of water security problems in North China with the aim of highlighting key waterresources management and water security issues for the long-term development of North China. Three key problemsrelated to water resources and security issues in North China in the 21st century are addressed, namely 1) the watercycle under environmental change, 2) agricultural water saving, and 3) water security. Development of internationalresearch related to these issues is also reviewed. The research plan developed recently by the Chinese Academy of Sciences(CAS) is discussed and suggestions on research and development of water resources science in North China are presented.Thanks to focus on experimental catchments and dedicated research stations, a detailed knowledge of the water cycle onNorth China farmland has been compiled. A range of techniques that include isotope tracers has been used to acquirehydrologic data. Much research has been devoted to developing distributed hydrological models at different scales. In thewell irrigation district, five different water saving irrigation regimes have been investigated, and these regimes have hadwidespread application, and reduced water use 60-150 mm while they increased water use efficiency (WUE) by 20%-30%.Furthermore, preventing water pollution is the most essential step to ensure North China’s water security.展开更多
Precipitation is the major driver of ecosystem functions and processes in semiarid and arid regions. In such water- limited ecosystems, pulsed water inputs directly control the belowground processes through a series o...Precipitation is the major driver of ecosystem functions and processes in semiarid and arid regions. In such water- limited ecosystems, pulsed water inputs directly control the belowground processes through a series of soil drying and rewetting cycles. To investigate the effects of sporadic addition of water on soil CO 2 efflux, an artificial precipitation event (3 mm) was applied to a desert shrub ecosystem in the Mu Us Sand Land of the Ordos Plateau in China. Soil respiration rate increased 2.8-4.1 times immediately after adding water in the field, and then it returned to background level within 48 h. During the experiment, soil CO 2 production was between 2 047.0 and 7 383.0 mg m -2 . In the shrubland, soil respiration responses showed spatial variations, having stronger pulse effects beneath the shrubs than in the interplant spaces. The spatial variation of the soil respiration responses was closely related with the heterogeneity of soil substrate availability. Apart from precipitation, soil organic carbon and total nitrogen pool were also identified as determinants of soil CO2 loss in desert ecosystems.展开更多
Soil respiration is a key component of the global terrestrial ecosystem carbon cycle. The static opaque chamber method was used to measure the CO2 effluxes from soil of a semiarid Aneurolepidium chinense steppe and a ...Soil respiration is a key component of the global terrestrial ecosystem carbon cycle. The static opaque chamber method was used to measure the CO2 effluxes from soil of a semiarid Aneurolepidium chinense steppe and a Stipa krylovii steppe in the Xilin River Basin of Inner Mongolia, China from March 2002 to December 2004. The results indicated that the soil respiration rates of the semiarid Aneurolepidium chinense steppe and the Stipa krylovii steppe were both relatively high from mid-May to mid-September of each year and remained low during the rest of the year. The minimum value of soil respiration occurred in December or January and negative effluxes of CO2 appeared for several days during the non-growing season of individual years at the two sampling sites. A high annual variation was found in the two steppes with the coefficients of variance (CV) being over 94%, even high to 131%. The annual sums of soil CO2 efflux of the Aneurolepidium chinense steppe varied between 356.4 gC m-2 yr-1 and 408.8 gC m-2 yr-1, while those of the Stipa krylovii steppe in the three years were in the range of 110.6 gC m-2 yr-1 to 148.6 gC m-2 yr-1. The mean respiration rates of the Aneurolepidium chinense steppe were significantly higher than those of the Stipa krylovii steppe in different statistical periods with the exception of the non-growing season. About 59.9% and 80.6% of the soil respiration variations in both steppes for the whole sampling period were caused by the changes of temperature and soil water content. In the Aneurolepidium chinense steppe, the soil respiration rate has significant or extremely significant positive correlation (r = 0.58-0.85, p < 0.05 or p < 0.01) with air temperature and ground temperature of the topsoil except in 2002; the unique contributions of temperature change to the soil respiration variation of the three years were 53.3%, 81.0% and 58.6%, respectively. But, for the Stipa krylovii steppe in the same time interval, the soil water content (especially that of the 10-20 cm layer) has a greater effect on the change of soil respiration, and the unique contributions of the change of the 10-20 cm soil water content to the variations of soil respiration in 2002 and 2003 were 60.0% and 54.3%, respectively. In 2004, in spite of the higher contribution of temperature than soil water content, the contribution of ground temperature at a depth of 10 cm was only 46.2%, much weaker than that of any single year in the Aneurolepidium chinense steppe.展开更多
Livestock wastewater has been a major contributor to Chinese cultural eutrophication of surface waters. Constructed wetlands are under study as a best management practice to treat wastewater from dairy and swine opera...Livestock wastewater has been a major contributor to Chinese cultural eutrophication of surface waters. Constructed wetlands are under study as a best management practice to treat wastewater from dairy and swine operations, but th e removal efficiency of pollutants is relatively low. Enhancing the treatment ef ficiency of livestock wastewater by effluent recirculation was investigated in a pilot-scale vertical-flow constructed wetland. The wetland system was composed of downflow and upflow stages, on which narrow-leaf Phragmites communis and comm on reed Phragmites Typhia are planted, respectively; each stage has a dimension of 4 m2 (2 m×2 m). Wastewater from facultative pond was fed into the system int ermittently at a flow rate of 0.4 m3/d. Recirculation rates of 0, 25%, 50%, 100% and 150% were adopted to evaluate the effect of the recirculation rate on pollu tants removal. It shows that with effluent recirculation the average removal eff iciencies of NH4-N, biological oxygen demand(BOD5) and suspended solids(SS) obvi ously increase to 61.7%, 81.3%, and 77.1%, respectively, in comparison with the values of 35.6%, 50.2%, and 49.3% without effluent recirculation. But the improv ement of TP removal is slight, only from 42.3% to 48.9%. The variations of NH4-N , dissolved oxygen(DO) and oxidation-reduction potential(ORP) of inflow and outf low reveal that the adoption of effluent recirculation is benefi- cial to the fo rmation of oxide environment in wetland. The exponential relationships with exce llent correlation coefficients(R2 >0.93) are found between the removal rates of NH4-N and BOD5 and the recirculation rates. With recirculation the pH value of t he outflow decreases as the alkalinity is consumed by gradually enhanced nitrifi cation process. When recirculation rate is kept constant 100%, the ambient tempe rature appears to affect NH4-N removal, but does not have significant influence on BOD5 removal.展开更多
基金Under the auspices of the Second Tibetan Plateau Scientific Expedition and Research Program (STEP)(No.2019QZKK0607)。
文摘Accessibility and capacity of medical resources are key for the health care and emergency response, while the efficiency of the medical resources is very much limited by hypoxia in Tibet, China.Through introducing exercise efficiency, this study explores the accessibility of township residence to county-ship medical resources in Tibet using weighted mean travel time(WMT), and evaluates the medical capacity accordingly.The results show that: 1) the average travel time of township residence to county-level hospital is around2 h by motor vehicle in Tibet.More than half of the population can not reach the county-ship hospital within 1 h, 33.24% of the population can not reach within 2 h, and 3.75% of the population can not reach within 6 h.2) When considering the catchment of the medical resources and the population size, the WMT of the county-ship medical resources ranges from 0.25 h to 10.92 h.3) After adjusted by travel time and exercise efficiency, the county-ship medical capacity became more unequal, with 38 out of 74 counties could not meet the national guideline of 1.8 medical beds per 1000.4) In total, there are 17 counties with good WMT and sufficient medical resources,while 13 counties having very high WMT and low capacity of medical resources in Tibet.In the end, suggestions on medical resources relocation and to improve the capacity are provided.This study provides a method to incorporate exercise efficiency to access the accessibility and evaluate medical capacity that can be applied in high altitude ranges.
基金Under the auspices of the National Natural Science Foundation of China (No. 30570303)
文摘The shrinking and drying up of wetlands in arid and semiarid areas of China have been widely observed in the recent years,but there has been no consensus on whether the aggravation is caused by human activities or by global climate warming.For a better understanding of the cause,this study investigates the dynamic changes of Baiyangdian Lake wetland over the last 40 years.It is shown that since the 1980s,Baiyangdian Lake has suffered from an insufficient water input and shrunk considerably.By using SPSS11.0,this study undertakes a detailed analysis on the significance of the effects of the possible driving factors for the degradation.It is identified that the North China Plain has been warming up significantly in recent years,which causes a significant reduction in the precipitation and inflow to the lake.Although human disturbances such as the irrigation and storage of water in reservoirs do not play a decisive role,they accelerate the degradation and their effects should be minimized.
基金Under the auspices of the Western Bright Project (No. 20025023)
文摘Glacier is one kind of the most beautiful geological sightseeing in the world as well as a special kind of tourism resources.The characters of glacier tourism include scarcity,frangibility,localization of tourist activity,scien-tific connotation,and integrated function and value.The paper summarizes the latest researches in developing glacier tourism resources.Regarding the Bogda Glacier Park as an example,the authors analyze the characteristics of glacier tourism resources in detail and the conditions and potential threats of glacier tourism development.Suggestions on glacier tourism development and protection are given as follows:1) to plan function subarea scientifically and rea-sonably;2) to combine tourism,scientific research with ecological education;3) to take countermeasures of environ-mental protection;4) to integrate tourism resources and strengthening regional cooperation.Finally,emphases are put forward on resources conformity along the tourism line and cooperation of tourism management.The paper aims to seek after the coordination path in exploitation and protection of glacier tourism resources to guide the exploitation of other glacier tourism destinations.
基金Acknowledgment This work was supported by the State＇s Key Project of Research and Development Plan （2010CB428404） and the Natural Science Foundation of China （41471026）.
文摘气候变化在北方中国平原(NCP ) 上为农业生产在水资源的可获得性上正在有可观的影响，在自从 1950 年代，水的缺乏当前关于弄干的趋势正在扰乱农业生产的稳定性和可持续性的地方。然而，尽管潜在的土壤水分蒸发蒸腾损失总量(et ) 在气候变化下面显示出一个减少的趋势，实际 et 稍微在水文学骑车与加速增加了。全球气候模型(GCM ) 整体设计由源于全球温暖的 2050 年代，增加的庄稼水需求和加强的 et 预言那将关于 4%-24% 减少水资源剩余(降水 et ) 并且显著地在庄稼生长时期增加灌溉水需求。这研究为创新农业可持续性估计可能的缓解和改编措施。它被表明那减少在水有限盆的冬季小麦(3.0%-15.9%) 的播种区域，和在庄稼水使用的改进，效率将有效地减轻水缺乏并且加强农业系统的跳回到气候变化。
基金Acknowledgment This study was supported by the National Key Basic Research Development Program Project （2010CB428400） and the Natural Science Foundation of China （51279140）.
基金Supported by the National High-Tech Research and Development Program of China(2006AA06Z380)the National Natural Science Fundation of China(40872210)Western Key Fund(90202017)
文摘The Fluorine release rate of coal, clay of different Fluorine content, and coalmixed with clay used by resident households were studied by using the ion selective electrode(ISE) and solidoid balance methods, and the degree of influence on Fluorine pollutiongenerated by coal and clay was analyzed according to the proportion characteristicsof coal used by resident households.The results show that the Fluorine release rate ofcoal is more than 95% during combustion; The Fluorine release rate of clay is more than99%; The Fluorine release rate of coal mixed with clay is between 56.44% and 96.64%,and the average value is 76.68%.The clay as a binder for fine coal is one importantsource of Fluorine pollution caused by coal-combustion in Zhaotong, Yunnan Province.When the Fluorine content of coal is less than 80 mg/kg, the Fluorine amount releasedfrom clay (in which Fluorine content is more than 530 mg/kg) is more than 50% of the totalFluorine amount released from coal and clay during coal-combustion.The Fluorineamount released from clay (in which Fluorine content is more than 1 000 mg/kg) is morethan 70% of total Fluorine amount released from coal and clay during coal-combustion.
文摘The peri-urbanization area as a kind of rural-urban interface is changing rapidly, in physical, economic, and social terms. The land use pattern in such area is shifting away from the assumptions of mainstream paradigms to new conceptual landscapes, which leads to a series of problems on economic development and social stabilization. There are many researches on non-agricultural land-use in peri-urbanization area. In this paper both international and domestic research literature is reviewed by dividing six parts. The first part introduces the conception of peri-ur-banization area and its driver factors. Then In the second and the third part, the paper expatiates on the progress in the non-agricultural land-use in peri-urban area on land-use pattern, evolution, characteristics, problems, etc. The forth part focuses on the reasons that cause the land-use problems in the research area, while the fifth part reviews the integrating ways of non-agricultural land-use. Finally, recommendations for further study are draw with specific reference to the current and future position of non-agricultural land-use study in peri-urban area.
基金the financial support of Ministry of Science and Technology of China (2012CB955700, 2010CB428406)the National Natural Sciences Foundation of China (70925001 and 71161140351)+1 种基金International Development Research Center (107093-001)World Bank, and the CAS (Chinese Academy of Sciences) Strategic Priority Research Program (XDA01020304)
文摘The purpose of this paper is to document the likely impacts of climate change on China’s agriculture and the current adaptation efforts made by government and farmers.The review of literature shows that climate change will have a significant impact on agriculture,primarily through its effect on crop yields.The extent of predicted impacts highly depends on the crop,the CO2 fertilization effect assumption and adaptation abilities.Market response to the production shocks resulting from climate change will lessen the impacts on agricultural production predicted by natural scientists.On adaptation,the government’s major efforts have been in the developing new technologies,reforming extension system and enhancing institutional capacity.Farmers do adapt to climate change,but their adaptation measures cannot fully offset the negative impacts of climate change.The paper concludes and makes implications for future studies.
基金funding support from the Key Knowledge Innovation Project of the Chinese Academy of Sciences(Kzcx2-yw-126)the Key Technology R&D Program of China(2006BAB14B07)the National Natural Sciences Foundation of China(40730632,40701027)
文摘Quantitative assessment of development sustainability could be a challenge to regional management and planning,especially for areas facing great risks of water shortage.Surface-water decline and groundwater over-pumping have caused serious environmental problems and limited economic development in many regions all around the world.In this paper,a framework for quantitatively evaluating development sustainability was established with water-related eco-environmental carrying capacity(EECC) as the core measure.As a case study,the developed approach was applied to data of the Haihe River Basin,China,during 1998 through 2007.The overall sustainable development degree(SDD) is determined to be 0.39,suggesting that this rate of development is not sustainable.Results of scenario analysis revealed that overshoot,or resource overexploitation,of the Basin's EECC is about 20% for both population and economy.Based on conditions in the study area in 2007,in order to achieve sustainable development,i.e.,SDD>0.70 in this study,the EECC could support a population of 108 million and gross domestic product(GDP) of 2.72 trillion CNY.The newly developed approach in quantifying ecoenvironmental carrying capacity is anticipated to facilitate sustainable development oriented resource management in waterdeficient areas.
基金the financial support of Ministry of Science and Technology of China (2012CB955700,2010CB428406)the National Natural Sciences Foundation of China (70925001, 71161140351)+2 种基金the International Development Research Center (107093-001)the Australian Center for International Agriculture (ADP/2010/070)World Bank, and the CAS Strategic Priority Research Program(XDA01020304)
文摘The overall goal of this paper is to examine impacts of climate change on water supply and demand balance and their consequences on agricultural production in ten river basins in China. To realize this goal, China Water Simulation Model (CWSM) is used to analyze three alternative climate scenarios (A1B, A2 and B2). The results show that the impacts of climate change on water supply and demand balance differ largely among alternative scenarios. While significant impacts of climate change on water balance will occur under the A1B scenario, the impacts of climate change under the A2 and B2 scenarios will be marginal. Under the A1B scenario, the water shortage in the river basins located in the northern China will become more serious, particularly in Liaohe and Haihe river basins, but the other river basins in the southern China will improve their water balance situations. Despite larger impacts of climate change on water balance in the northern China, its impacts on total crops' production will be moderate if farmers would be able to reallocate water among crops and adjust irrigated and rainfed land. The paper concludes with some policy implications.
基金Under the auspices of the National Natural Science Foundation of China (No. 40671007), Innovation Project of Institute of Geographical Sciences and Natural Resources Research, CAS
文摘The population growth and demand for high living standard not only increase food demand but also cause more loss of the limited cultivated land resources.Cultivated land loss caused by disasters and the implementation of the “Conversion of Cropland to Forest or Grassland” project make this situation even worse in China.Thus,there is a problem to be solved imminently that to what extent the cultivated land can guarantee food security of China.Based on time-series data on food production and cultivated land area from 1989 to 2003 and other research results,this paper constructs quality index of cultivated land according to different land quality.Regression models are adopted to predicate changes of main factors from 2004 to 2030,which have great effect on cultivated land area or grain productivity,and verify accuracy with coefficient of determination(R2).Nine results were got according to three scenarios of decreasing rate of population growth rate and three cases of urban and rural built-up area per capita.There results show that China’s food supply can only be maintained at a low to middle level of 370-410kg per capita,that is,China has enough land productivity to meet primary demand of food independently.However,it cannot reach the safe target of 500kg per capita if there is no breakthrough in breeding or no remarkable improvement of irrigation works,when the grain self-sufficiency maintains no less than 80%.To breed productive crops and to improve land productivity by meliorating low quality cultivated land are appropriate measures to shrink the gap between food demand and supply.The results may offer helpful information for the formulation of policies on population growth,land use,protection of cultivated land.
基金National Natural Sciences Foundation of China (Nos.40501072 and 40673067)the Major State Basic Research Develop-ment Program of China (No.2002CB 412503)the Knowledge Inno-vation Program of the Institute of Geographic Sciences and Natural Re-sources Research,CAS "The effect of human activities on regional envi-ronmental quality,the health risk and the environmental remediation"
基金the National Science Found for Distinguished Young Scholars of China (No.40025106)the National Natural Science Foundation of China (Nos.90102012 and 40371074).
文摘The most serious erosion on the Loess Plateau of China exists in the wind-water erosion crisscross region where the annual precipitation is about 400 mm,the ecological environment is very fragile,and water is the key limiting factor for improving the environment. In this study,changes of soil moisture content for Caragana korshinskii Kom. shrubland in the gully bank of the Loess Plateau were studied using the methods of soil sampling and neutron probe. A typical gully(75 m long,28 m wide,and 10 m deep) was selected,and six neutron probe access tubes(6 m long) were installed at points 50,100,200,300,400,and 500 cm from the gully border for obtaining soil moisture data from July to October 2004 at approximately 10 d intervals. Soil samplings were simultaneously carried out for moisture determination at the six points. Results showed that the soil moisture of the shrubland in the gully bank significantly varied between 300 and 400 cm in the horizontal direction and up to 600 cm in vertical direction of the gully. Seasonal changes in soil moisture revealed a curve with a single peak that occurred at the end of August or early September. A linear regression equation was fit for soil water storage and the distance from the gully border,with coefficients depending on rainfall characteristics,sampling point,and time of measurement.
基金the Key Knowledge Innovation Project of the Chinese Academy of Sciences (Nos. KZCX2-SW-317and KZCX3-SW-226).
文摘The seasonal mean atmospheric precipitable water and water vapor transport over the Haihe River Basin (HRB) inNorth China with a focus on their interannual to interdecadal variability, and then the relationships of the interannual andinterdecadal variability of the water cycle over the HRB to the Pacific Decadal Oscillation (PDO) and El Nino-SouthernOscillation (ENSO) phenomena were investigated using the observational and National Centers for Environmental Pre-diction (NCEP) reanalysis data. There was a strong interdecadal variability for the water cycle (such as precipitationand water vapor transport) over the region, with an abrupt change occurring mostly in the mid 1970s. The intensity ofthe East Asian summer monsoon largely affected the atmospheric water vapor transport. Generally, the net meridionalconvergence of the water vapor flux over the region was relatively large before 1965, and it declined gradually from thenon with a further notable decrease since mid 1970s. Zonal water vapor transport was similar to meridional, but with amuch smaller magnitude and no noteworthy turning in the mid 1970s. Results also suggested that the wind field playedan important role in the water vapor transport over the HRB before the mid 1960s, and the interdecadal variability ofthe water cycle (precipitation, water vapor transport, etc.) in the summer was related to the PDO; however, interannualvariation of the water vapor transport could also be related to the ENSO phenomena.
基金Project supported by the National Natural Science Foundation of China (No. 40101017)the Doctor Foundation of the Ministry of Education of China (No. 2002050411).
文摘Elemental composition and geochemical characteristics of iron-manganese nodules from nine main soils in China were studied by chemical and multivariate statistical analyses to better understand the reactions and functions of iron-manganese nodules in soils and sediment. Compared to the corresponding soils, Mn, Ba, Cd, Co and Pb had strong accumulation, Ni had moderate accumulation, while Ca, Cu, Fe, Na, P, Sr and Zn accumulated to a minor degree in the iron-manganese nodules. In contrast, Si, Al, K, Mg and Ti were reduced in the iron-manganese nodules. The contents of Ba, Cd, Co, Cu, Ni, Pb and Zn were positively and significantly correlated with that of MnO2 in the iron-manganese nodules, while the contents of Cr, Cu, Ni, Pb and Zn were positively and significantly correlated with that of Fe2O3 in soils. Based on a principle component analysis, the elements of iron-manganese nodules were divided into four groups: 1) Mn, Ba, Cd, Co, Cu, Li, Ni, Pb and Zn that were associated with Mn oxides, 2) Fe, Cr and P that were associated with Fe oxides, 3) Si, K, and Mg that were included in the elemental composition of phyllosilicate, and 4) Ca, Na, Al and Ti that existed in todorokite, birnessite, lithiophorite and phyllosilicate. It was suggested that accumulation, mineralization and specific adsorption were involved in the formation processes of soil iron-manganese nodules.
基金Project supported by the National Foundation for Distinguished Youthof China(No.40325003)the National Natural Science Foun-dation of China(No.40232022).
文摘In order to understand the similarity or difference of inorganic As species uptake and transport related to phosphorus in As-hyperaccumulator,uptake and transport of arsenate(As(V))and arsenite(As(III))were studied using Pteris vittata L.under sandculture.Higher concentrations of phosphate were found to inhibit accumulation of arsenate and arsenite in the fronds of P.vittata.The reduction in As accumulation was greater in old fronds than in young fronds,and relatively weak in root and rhizome.Moderateincreases,from 0.05 to 0.3 mmol/L,in phosphate reduced uptake of As(III)more than As(V),while the reverse was observed at highconcentrations of phosphate(1.0 mmol/L).Phosphate apparently reduced As transport and the proportion of As accumulated in frondsof P.vittata when As was supplied as As(V).It may in part be due to competition between phosphorus and As(V)during transport.Incontrast,phosphate had a much smaller effect on As transport when the As was supplied as As(III).Therefore,the results from presentexperiments indicates that a higher concentration of phosphate suppressed As accumulation and transport in P.vittata,especially inthe fronds,when exposed to As(V);but the suppression of phosphate to As transport may be insignificant when P.vittata exposed toAs(III)under sand culture conditions.The finding will help to understand the interaction of P and As during their uptake process in P.vittata.
基金the Knowledge Innovation Key Project of the Chinese Academy of Sciences (Nos. KZCX2-SW-317/CX10G-E01-08 and KZCX1-09-02) and the National Natural Science Foundation of China (No. 50279049).
文摘This paper addresses the emergence of water security problems in North China with the aim of highlighting key waterresources management and water security issues for the long-term development of North China. Three key problemsrelated to water resources and security issues in North China in the 21st century are addressed, namely 1) the watercycle under environmental change, 2) agricultural water saving, and 3) water security. Development of internationalresearch related to these issues is also reviewed. The research plan developed recently by the Chinese Academy of Sciences(CAS) is discussed and suggestions on research and development of water resources science in North China are presented.Thanks to focus on experimental catchments and dedicated research stations, a detailed knowledge of the water cycle onNorth China farmland has been compiled. A range of techniques that include isotope tracers has been used to acquirehydrologic data. Much research has been devoted to developing distributed hydrological models at different scales. In thewell irrigation district, five different water saving irrigation regimes have been investigated, and these regimes have hadwidespread application, and reduced water use 60-150 mm while they increased water use efficiency (WUE) by 20%-30%.Furthermore, preventing water pollution is the most essential step to ensure North China’s water security.
基金Project supported by the National Natural Science Foundation of China (Nos. 40730105, 40501072 and 40673067)the National Key Basic Research Program (973 Program) of China (No. 2002CB412503)the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KZCX2-YW-149)
文摘Precipitation is the major driver of ecosystem functions and processes in semiarid and arid regions. In such water- limited ecosystems, pulsed water inputs directly control the belowground processes through a series of soil drying and rewetting cycles. To investigate the effects of sporadic addition of water on soil CO 2 efflux, an artificial precipitation event (3 mm) was applied to a desert shrub ecosystem in the Mu Us Sand Land of the Ordos Plateau in China. Soil respiration rate increased 2.8-4.1 times immediately after adding water in the field, and then it returned to background level within 48 h. During the experiment, soil CO 2 production was between 2 047.0 and 7 383.0 mg m -2 . In the shrubland, soil respiration responses showed spatial variations, having stronger pulse effects beneath the shrubs than in the interplant spaces. The spatial variation of the soil respiration responses was closely related with the heterogeneity of soil substrate availability. Apart from precipitation, soil organic carbon and total nitrogen pool were also identified as determinants of soil CO2 loss in desert ecosystems.
基金This work was jointly supported by the Knowledge Innovation Program of the Chinese Academy of Sciences （Grant No. KZCX1-SW-01-04） the National Natural Science Foundation of China （Grant No. 40501072） the project on the Carbon Cycle and Driving Mechanisms in the Chinese Terrestrial Ecosystem （Grant No. 2002CB412503）.
文摘Soil respiration is a key component of the global terrestrial ecosystem carbon cycle. The static opaque chamber method was used to measure the CO2 effluxes from soil of a semiarid Aneurolepidium chinense steppe and a Stipa krylovii steppe in the Xilin River Basin of Inner Mongolia, China from March 2002 to December 2004. The results indicated that the soil respiration rates of the semiarid Aneurolepidium chinense steppe and the Stipa krylovii steppe were both relatively high from mid-May to mid-September of each year and remained low during the rest of the year. The minimum value of soil respiration occurred in December or January and negative effluxes of CO2 appeared for several days during the non-growing season of individual years at the two sampling sites. A high annual variation was found in the two steppes with the coefficients of variance (CV) being over 94%, even high to 131%. The annual sums of soil CO2 efflux of the Aneurolepidium chinense steppe varied between 356.4 gC m-2 yr-1 and 408.8 gC m-2 yr-1, while those of the Stipa krylovii steppe in the three years were in the range of 110.6 gC m-2 yr-1 to 148.6 gC m-2 yr-1. The mean respiration rates of the Aneurolepidium chinense steppe were significantly higher than those of the Stipa krylovii steppe in different statistical periods with the exception of the non-growing season. About 59.9% and 80.6% of the soil respiration variations in both steppes for the whole sampling period were caused by the changes of temperature and soil water content. In the Aneurolepidium chinense steppe, the soil respiration rate has significant or extremely significant positive correlation (r = 0.58-0.85, p < 0.05 or p < 0.01) with air temperature and ground temperature of the topsoil except in 2002; the unique contributions of temperature change to the soil respiration variation of the three years were 53.3%, 81.0% and 58.6%, respectively. But, for the Stipa krylovii steppe in the same time interval, the soil water content (especially that of the 10-20 cm layer) has a greater effect on the change of soil respiration, and the unique contributions of the change of the 10-20 cm soil water content to the variations of soil respiration in 2002 and 2003 were 60.0% and 54.3%, respectively. In 2004, in spite of the higher contribution of temperature than soil water content, the contribution of ground temperature at a depth of 10 cm was only 46.2%, much weaker than that of any single year in the Aneurolepidium chinense steppe.
文摘Livestock wastewater has been a major contributor to Chinese cultural eutrophication of surface waters. Constructed wetlands are under study as a best management practice to treat wastewater from dairy and swine operations, but th e removal efficiency of pollutants is relatively low. Enhancing the treatment ef ficiency of livestock wastewater by effluent recirculation was investigated in a pilot-scale vertical-flow constructed wetland. The wetland system was composed of downflow and upflow stages, on which narrow-leaf Phragmites communis and comm on reed Phragmites Typhia are planted, respectively; each stage has a dimension of 4 m2 (2 m×2 m). Wastewater from facultative pond was fed into the system int ermittently at a flow rate of 0.4 m3/d. Recirculation rates of 0, 25%, 50%, 100% and 150% were adopted to evaluate the effect of the recirculation rate on pollu tants removal. It shows that with effluent recirculation the average removal eff iciencies of NH4-N, biological oxygen demand(BOD5) and suspended solids(SS) obvi ously increase to 61.7%, 81.3%, and 77.1%, respectively, in comparison with the values of 35.6%, 50.2%, and 49.3% without effluent recirculation. But the improv ement of TP removal is slight, only from 42.3% to 48.9%. The variations of NH4-N , dissolved oxygen(DO) and oxidation-reduction potential(ORP) of inflow and outf low reveal that the adoption of effluent recirculation is benefi- cial to the fo rmation of oxide environment in wetland. The exponential relationships with exce llent correlation coefficients(R2 >0.93) are found between the removal rates of NH4-N and BOD5 and the recirculation rates. With recirculation the pH value of t he outflow decreases as the alkalinity is consumed by gradually enhanced nitrifi cation process. When recirculation rate is kept constant 100%, the ambient tempe rature appears to affect NH4-N removal, but does not have significant influence on BOD5 removal.
