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
[Objectives]The paper was to investigate the garden greenbelt in 30 sample plots such as parks,roads,communities,etc.in Shijiazhuang City.[Methods]The species,abundance and frequency of weeds in the greenbelt of publi...[Objectives]The paper was to investigate the garden greenbelt in 30 sample plots such as parks,roads,communities,etc.in Shijiazhuang City.[Methods]The species,abundance and frequency of weeds in the greenbelt of public gardens were recorded through point-line-surface investigation,and typical plants were sampled.[Results]There were 56 species of alien invasive plants in garden greenbelts of Shijiazhuang City,belonging to 44 genera and 20 families.In terms of life form,herbaceous plants were absolutely dominant,accounting for 92.8%of the total.The most alien invasive plants were native to America,accounting for 66.1%of the total.In terms of introduction path,the plants introduced artificially and unintentionally accounted for almost half.The species and quantity of alien invasive plants were related to the size of greenbelt area,the length of the build time of the surveyed plot,the composition structure of greenbelt and the level of green management and protection.There was larger distribution of alien invasive plants in the sample plots with large greenbelt area,long build time,herbaceous-dominated greenbelt and low level of green management and protection.Among the 56 alien invasive plants,3 plants were toxic.From the perspective of invasiveness,the alien invasive plants in the garden greenbelt of Shijiazhuang City could be divided into 5 levels:invasive alien species of malignant consequences,invasive alien species of severe consequences,invasive alien species of partial consequences,invasive alien species of average consequences,and invasive alien species to be observed.[Conclusions]This study will provide a reference for the prevention and control of alien plant invasion,and lay a foundation for the prevention and control of existing invasive plants.展开更多
In this paper,based on the process data of evaluating the benchmark land prices of collective construction land and agricultural land,the score of influencing factors is calculated,and a regression model between value...In this paper,based on the process data of evaluating the benchmark land prices of collective construction land and agricultural land,the score of influencing factors is calculated,and a regression model between value-added benefits and influencing factors is established.According to the contribution of the government and collectives to value-added benefits,the distribution proportions of different purposes and levels are calculated.The research results show that there are significant differences in the distribution proportion of value-added income among different levels.The government distribution proportion decreases with the decrease of level,while the collective distribution proportion increases with the decrease of level.For each level of decrease in commercial service industry land and industrial and mining warehousing industry land,the government distribution proportion decreases by an average of 2.66%and 2.34%,while the collective distribution proportion increases by an average of 2.66%and 2.34%,respectively.The average distribution proportion of the government in the value-added income of commercial service industry land is 31.58%,which is much higher than the average income of 23.68%in the value-added income of industrial and mining warehousing industry land.展开更多
In addition to the quality and quantity of farmland, the health of farmland has also become an important research direction in the field of farmland protection. In order to comprehensively evaluate the relationship an...In addition to the quality and quantity of farmland, the health of farmland has also become an important research direction in the field of farmland protection. In order to comprehensively evaluate the relationship and distribution of health and farmland production capacity, the depression area behind the Yellow River in Henan Province is taken as the research object. Using production capacity evaluation data and system health evaluation results, the health status and production capacity of farmland in the region are coupled. The results show that high productivity farmland is most distributed in areas with moderate health risks, while low productivity farmland is more distributed in areas with low health risks. Based on their coupling characteristics, the depression area behind the Yellow River can be divided into five types, and management and protection strategies can be formulated separately.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 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 chan...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
The diurnal and seasonal dynamics of soil respiration in the A. ordosica shrubland on Ordos Plateau were investigated in the growing season (May-October) of 2006 and their environmental driving factors were also ana...The diurnal and seasonal dynamics of soil respiration in the A. ordosica shrubland on Ordos Plateau were investigated in the growing season (May-October) of 2006 and their environmental driving factors were also analyzed, Results indicated that diurnal dynamics of soil respiration rate and its temperature dependence showed some discrepancy in two different growth stages (the vegetative growth stage and the reproductive growth stage). During the vegetative growth stage, the diurnal variation of soil respiration was slight and not correlated with the daily temperature change, but during the reproductive growth stage, the daily respiration variation was relatively large and significantly correlated with the diurnal variation of air and soil temperature. In the growing season, the peak value of soil respiration occurred at July and August because of the better soil water-heat conditions and their optimal deployment in this period. In the shrubland ecosystem, precipitation was the switch of soil respiration pulses and can greatly increase soil respiration rates after soil rewetting. Moreover, the soil respiration rates in the growing season and the air temperature and soil surface water content were closely correlated (p〈0.05) each other. The stepwise regression model indicated that the variation of soil surface moisture accounted for 41.9% of the variation in soil respiration (p〈0.05).展开更多
Topsoil soil organic carbon (SOC) that plays an important role in mitigating atmospheric carbon dioxide (CO_2) buildup is greatly affected by human activities.To evaluate the influence of land-use changes on SOC stock...Topsoil soil organic carbon (SOC) that plays an important role in mitigating atmospheric carbon dioxide (CO_2) buildup is greatly affected by human activities.To evaluate the influence of land-use changes on SOC stocks in paddy soils,a new algorithm was developed by integrating MODIS (moderate resolution imaging spectral-radiometer) and TM/ETM data for timely monitoring the land-use change in Wujiang County.Thereafter,the land-use class-maps derived from MODIS and TM/ETM analyses were further used to estima...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-pum...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 over- exploitation, 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 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
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
In order to understand the similarity or difference of inorganic As species uptake and transport related to phosphorus in Ashyperaccumulator, uptake and transport of arsenate (As(V)) and arsenite (As(Ⅲ)) were...In order to understand the similarity or difference of inorganic As species uptake and transport related to phosphorus in Ashyperaccumulator, uptake and transport of arsenate (As(V)) and arsenite (As(Ⅲ)) were studied using Pteris vittata L. under sand culture. 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. Moderate increases, 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 high concentrations of phosphate (≥1.0 mmol/L). Phosphate apparently reduced As transport and the proportion of As accumulated in fronds of P. vittata when As was supplied as As(Ⅴ). It may in part be due to competition between phosphorus and As(Ⅴ) during transport. In contrast, phosphate had a much smaller effect on As transport when the As was supplied as As(Ⅲ). Therefore, the results from present experiments indicates that a higher concentration of phosphate suppressed As accumulation and transport in P. vittata, especially in the fronds, when exposed to As(Ⅴ), but the suppression of phosphate to As transport may be insignificant when P. vittata exposed to As(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
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
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
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
Soil respiration is a key component of the global terrestrial ecosystem carbon cycle. The static opaque chamber method was used to measure the CO2 effiuxes 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 effiuxes 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 effiuxes 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 effiux 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 g Cm^-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
The water conservation capacities of main forests in Beijing,China were estimated through the quantitative analysis.Various methods developed in published papers on forest hydrology were employed.The forests in Huairo...The water conservation capacities of main forests in Beijing,China were estimated through the quantitative analysis.Various methods developed in published papers on forest hydrology were employed.The forests in Huairou,Yanqing,Miyun,Mentougou and Fangshan districts are the main contributors to water conservation(the cumulative ratio reaches 65%),and the forests in Tongzhou,Chaoyang,Shunyi and Daxing districts have the highest water conservation capacity(3000 m3/ha).Altitude and slope are the key factors to affect the water conservation capacity.The forests located in Plain Area,Hilly Area,Low Mountain,and Middle Mountain contributes 27%,28%,24% and 21% of the conserved water,respectively.The water conservation capacity of forests in Plain Area(2 948 m3/ha),is superior to the forests in other regions.And the forests situated on Flat Slope,Moderate Slope and Gentle Slope constitute the largest proportion(nearly 93%) of water conservation,while the forests on Flat Slope has the highest water conservation capacity(2 797 m3/ha),and the forest on Steep slope has the lowest water conservation capacity(948 m3/ha).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
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 the removal efficiency of pollutants is relatively low. Enhancing the treatment efficiency 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 common reed Phragraites Typhia are planted, respectively; each stage has a dimension of 4 m^2 (2 m × 2 m). Wastewater from facultative pond was fed into the system intermittently at a flow rate of 0.4 m^3/d. Recirculation rates of 0, 25%, 50%, 100% and 150% were adopted to evaluate the effect of the recirculation rate on pollutants removal. It shows that with effluent recirculation the average removal efficiencies of NH4-N, biological oxygen demand (BOD5) and suspended solids(SS) obviously 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 improvement 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 outflow reveal that the adoption of effluent recirculation is benefi- cial to the formation of oxide environment in wetland. The exponential relationships with excellent 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 the outflow decreases as the alkalinity is consumed by gradually enhanced nitrification process. When recirculation rate is kept constant 100%, the ambient temperature appears to affect NH4-N removal, but does not have significant influence on BOD5 removal.展开更多
Daba Mountain area is one of the two endemic selenosis areas in China,which may relate with the environmental behaviors of selenium (Se) in soil.This study focuses on the concentraion and distribution of Se and its re...Daba Mountain area is one of the two endemic selenosis areas in China,which may relate with the environmental behaviors of selenium (Se) in soil.This study focuses on the concentraion and distribution of Se and its relationships with some other elements in natural soil in the area.The average concentration of Se in Daba Mountain soils was 14.3 times higher than the value cited for natural soil background worldwide,suggesting that soils in the region were contaminated by the element.The finding was confirmed...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Supported by National Key R&D Program(2020YFF0305905-06)Science and Technology Project of Hebei Academy of Sciences(22112)Key Discipline Project of Hebei Academy of Sciences(491-0401-YBN-DDH4).
文摘[Objectives]The paper was to investigate the garden greenbelt in 30 sample plots such as parks,roads,communities,etc.in Shijiazhuang City.[Methods]The species,abundance and frequency of weeds in the greenbelt of public gardens were recorded through point-line-surface investigation,and typical plants were sampled.[Results]There were 56 species of alien invasive plants in garden greenbelts of Shijiazhuang City,belonging to 44 genera and 20 families.In terms of life form,herbaceous plants were absolutely dominant,accounting for 92.8%of the total.The most alien invasive plants were native to America,accounting for 66.1%of the total.In terms of introduction path,the plants introduced artificially and unintentionally accounted for almost half.The species and quantity of alien invasive plants were related to the size of greenbelt area,the length of the build time of the surveyed plot,the composition structure of greenbelt and the level of green management and protection.There was larger distribution of alien invasive plants in the sample plots with large greenbelt area,long build time,herbaceous-dominated greenbelt and low level of green management and protection.Among the 56 alien invasive plants,3 plants were toxic.From the perspective of invasiveness,the alien invasive plants in the garden greenbelt of Shijiazhuang City could be divided into 5 levels:invasive alien species of malignant consequences,invasive alien species of severe consequences,invasive alien species of partial consequences,invasive alien species of average consequences,and invasive alien species to be observed.[Conclusions]This study will provide a reference for the prevention and control of alien plant invasion,and lay a foundation for the prevention and control of existing invasive plants.
文摘In this paper,based on the process data of evaluating the benchmark land prices of collective construction land and agricultural land,the score of influencing factors is calculated,and a regression model between value-added benefits and influencing factors is established.According to the contribution of the government and collectives to value-added benefits,the distribution proportions of different purposes and levels are calculated.The research results show that there are significant differences in the distribution proportion of value-added income among different levels.The government distribution proportion decreases with the decrease of level,while the collective distribution proportion increases with the decrease of level.For each level of decrease in commercial service industry land and industrial and mining warehousing industry land,the government distribution proportion decreases by an average of 2.66%and 2.34%,while the collective distribution proportion increases by an average of 2.66%and 2.34%,respectively.The average distribution proportion of the government in the value-added income of commercial service industry land is 31.58%,which is much higher than the average income of 23.68%in the value-added income of industrial and mining warehousing industry land.
基金Supported by Henan Provincial Natural Science Foundation Project(212300410168)Basic Research Business Fee Project of Henan Academy of Sciences(220601065).
文摘In addition to the quality and quantity of farmland, the health of farmland has also become an important research direction in the field of farmland protection. In order to comprehensively evaluate the relationship and distribution of health and farmland production capacity, the depression area behind the Yellow River in Henan Province is taken as the research object. Using production capacity evaluation data and system health evaluation results, the health status and production capacity of farmland in the region are coupled. The results show that high productivity farmland is most distributed in areas with moderate health risks, while low productivity farmland is more distributed in areas with low health risks. Based on their coupling characteristics, the depression area behind the Yellow River can be divided into five types, and management and protection strategies can be formulated separately.
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"
文摘The diurnal and seasonal dynamics of soil respiration in the A. ordosica shrubland on Ordos Plateau were investigated in the growing season (May-October) of 2006 and their environmental driving factors were also analyzed, Results indicated that diurnal dynamics of soil respiration rate and its temperature dependence showed some discrepancy in two different growth stages (the vegetative growth stage and the reproductive growth stage). During the vegetative growth stage, the diurnal variation of soil respiration was slight and not correlated with the daily temperature change, but during the reproductive growth stage, the daily respiration variation was relatively large and significantly correlated with the diurnal variation of air and soil temperature. In the growing season, the peak value of soil respiration occurred at July and August because of the better soil water-heat conditions and their optimal deployment in this period. In the shrubland ecosystem, precipitation was the switch of soil respiration pulses and can greatly increase soil respiration rates after soil rewetting. Moreover, the soil respiration rates in the growing season and the air temperature and soil surface water content were closely correlated (p〈0.05) each other. The stepwise regression model indicated that the variation of soil surface moisture accounted for 41.9% of the variation in soil respiration (p〈0.05).
文摘Topsoil soil organic carbon (SOC) that plays an important role in mitigating atmospheric carbon dioxide (CO_2) buildup is greatly affected by human activities.To evaluate the influence of land-use changes on SOC stocks in paddy soils,a new algorithm was developed by integrating MODIS (moderate resolution imaging spectral-radiometer) and TM/ETM data for timely monitoring the land-use change in Wujiang County.Thereafter,the land-use class-maps derived from MODIS and TM/ETM analyses were further used to estima...
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 over- exploitation, 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 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 Ashyperaccumulator, uptake and transport of arsenate (As(V)) and arsenite (As(Ⅲ)) were studied using Pteris vittata L. under sand culture. 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. Moderate increases, 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 high concentrations of phosphate (≥1.0 mmol/L). Phosphate apparently reduced As transport and the proportion of As accumulated in fronds of P. vittata when As was supplied as As(Ⅴ). It may in part be due to competition between phosphorus and As(Ⅴ) during transport. In contrast, phosphate had a much smaller effect on As transport when the As was supplied as As(Ⅲ). Therefore, the results from present experiments indicates that a higher concentration of phosphate suppressed As accumulation and transport in P. vittata, especially in the fronds, when exposed to As(Ⅴ), but the suppression of phosphate to As transport may be insignificant when P. vittata exposed to As(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 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 effiuxes 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 effiuxes 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 effiux 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 g Cm^-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.
基金supported by the Major State Basic Research Development Program of China (973 Program) (2009CB421106)Self-deployment & Innovation Project of IGSNRR (200905010)
文摘The water conservation capacities of main forests in Beijing,China were estimated through the quantitative analysis.Various methods developed in published papers on forest hydrology were employed.The forests in Huairou,Yanqing,Miyun,Mentougou and Fangshan districts are the main contributors to water conservation(the cumulative ratio reaches 65%),and the forests in Tongzhou,Chaoyang,Shunyi and Daxing districts have the highest water conservation capacity(3000 m3/ha).Altitude and slope are the key factors to affect the water conservation capacity.The forests located in Plain Area,Hilly Area,Low Mountain,and Middle Mountain contributes 27%,28%,24% and 21% of the conserved water,respectively.The water conservation capacity of forests in Plain Area(2 948 m3/ha),is superior to the forests in other regions.And the forests situated on Flat Slope,Moderate Slope and Gentle Slope constitute the largest proportion(nearly 93%) of water conservation,while the forests on Flat Slope has the highest water conservation capacity(2 797 m3/ha),and the forest on Steep slope has the lowest water conservation capacity(948 m3/ha).
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.
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 the removal efficiency of pollutants is relatively low. Enhancing the treatment efficiency 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 common reed Phragraites Typhia are planted, respectively; each stage has a dimension of 4 m^2 (2 m × 2 m). Wastewater from facultative pond was fed into the system intermittently at a flow rate of 0.4 m^3/d. Recirculation rates of 0, 25%, 50%, 100% and 150% were adopted to evaluate the effect of the recirculation rate on pollutants removal. It shows that with effluent recirculation the average removal efficiencies of NH4-N, biological oxygen demand (BOD5) and suspended solids(SS) obviously 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 improvement 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 outflow reveal that the adoption of effluent recirculation is benefi- cial to the formation of oxide environment in wetland. The exponential relationships with excellent 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 the outflow decreases as the alkalinity is consumed by gradually enhanced nitrification process. When recirculation rate is kept constant 100%, the ambient temperature appears to affect NH4-N removal, but does not have significant influence on BOD5 removal.
文摘Daba Mountain area is one of the two endemic selenosis areas in China,which may relate with the environmental behaviors of selenium (Se) in soil.This study focuses on the concentraion and distribution of Se and its relationships with some other elements in natural soil in the area.The average concentration of Se in Daba Mountain soils was 14.3 times higher than the value cited for natural soil background worldwide,suggesting that soils in the region were contaminated by the element.The finding was confirmed...