Since the reform and opening-up program started in 1978,the level of urbanization has increased rapidly in China.Rapid urban expansion and restructuring have had significant impacts on the ecological environment espec...Since the reform and opening-up program started in 1978,the level of urbanization has increased rapidly in China.Rapid urban expansion and restructuring have had significant impacts on the ecological environment especially within built-up areas.In this study,ArcGIS 10,ENVI 4.5,and Visual FoxPro 6.0 were used to analyze the human impacts on vegetation in the built-up areas of 656Chinese cities from 1992 to 2010.Firstly,an existing algorithm was refined to extract the boundaries of the built-up areas based on the Defense Meteorological Satellite Program Operational Linescan System(DMSP_OLS)nighttime light data.This improved algorithm has the advantages of high accuracy and speed.Secondly,a mathematical model(Human impacts(HI))was constructed to measure the impacts of human factors on vegetation during rapid urbanization based on Advanced Very High Resolution Radiometer(AVHRR)Normalized Difference Vegetation Index(NDVI)and Moderate Resolution Imaging Spectroradiometer(MODIS)NDVI.HI values greater than zero indicate relatively beneficial effects while values less than zero indicate proportionally adverse effects.The results were analyzed from four aspects:the size of cities(metropolises,large cities,medium-sized cities,and small cities),large regions(the eastern,central,western,and northeastern China),administrative divisions of China(provinces,autonomous regions,and municipalities)and vegetation zones(humid and semi-humid forest zone,semi-arid steppe zone,and arid desert zone).Finally,we discussed how human factors impacted on vegetation changes in the built-up areas.We found that urban planning policies and developmental stages impacted on vegetation changes in the built-up areas.The negative human impacts followed an inverted′U′shape,first rising and then falling with increase of urban scales.China′s national policies,social and economic development affected vegetation changes in the built-up areas.The findings can provide a scientific basis for municipal planning departments,a decision-making reference for government,and scientific guidance for sustainable development in China.展开更多
The Pursuit of Happyness has always been a well-received film ever since its release in 2006. This film mainly describes how a black American worms his way from the bottom of the society to success. This paper intends...The Pursuit of Happyness has always been a well-received film ever since its release in 2006. This film mainly describes how a black American worms his way from the bottom of the society to success. This paper intends to make a detailed description of the life experience of the main character, including his life obstacles and fighting. It also expounds on the image of the main character. Moreover, through the analysis of the reasons why Chris, an average American with his unyielding spirits, succeeds in seizing his happiness through sorrow and pain in life, the practical significance with regard to individual and social development is put into the limelight.展开更多
The Sinian Dengying Formation in China hosts one of the oldest gas-bearing reservoirs in the world.With a long geological history,it has developed into the reservoir rocks,whose quality depends on chemical dissolution...The Sinian Dengying Formation in China hosts one of the oldest gas-bearing reservoirs in the world.With a long geological history,it has developed into the reservoir rocks,whose quality depends on chemical dissolution and cementation.Despite presence of cavities and pores in the algal dolomites of the Dengying Formation,they were mostly filled with various forms of dolomite cements.Therefore,the investigation of these dolomites and their evolution is significant for analyzing the mechanism of pore space preservation.There are five types of cements in the Dengying Formation,which were well sampled for lab measurements such as thin section,cathodeluminescence,minor elements,isotope analysis of carbon,oxygen and strontium,in attempt to explore the fillers' geochemical characteristics and the diagenetic fluids.They are characterized as follows:firstly,fibrous rim dolomite cement is a typical product formed at sea bottom,and geochemically very similar to the matrix(micrite and microcrystalline dolomite),which could be a reflection of the geochemical characteristics of water at that time;secondly,the diagenetic fluids of the foliated dolomite cements tend to be inheriting,derived from the shallow burial "imprisoned" seawater;thirdly,fine-to medium-grained dolomite cements with fairly high strontium isotopes and low carbon and oxygen isotopes were precipitated chiefly in freshwater during the period of uplifting caused by Tongwan tectonic movement;fourthly,coarse-grained dolomite cements bear a relatively high percentage of Mn element,but low in Fe and Sr,with carbon and oxygen isotopes remarkably shifted to negative values,which all show that they are related to hydrocarbon maturation and migration,and corresponding Thermochemical Sulfate Reduction;lastly,saddle-shaped dolomite cements are hydrothermally associated,and they were formed in high-temperature brine,which had passed through the areas rich in radioactive strontium isotopes.展开更多
Carbon isotope, sulfur isotope, and trace element(including Rare Earth Elements, REE) analyses were conducted on the carbonates of the Dengying Formation at Lianghekou section in southern Shaanxi to reconstruct the te...Carbon isotope, sulfur isotope, and trace element(including Rare Earth Elements, REE) analyses were conducted on the carbonates of the Dengying Formation at Lianghekou section in southern Shaanxi to reconstruct the terminal Ediacaran shallow-water environment on the northwestern margin of the Yangtze Platform. At Lianghekou section, samples in the middle 50-m of the Beiwan Member show characteristics of low ΣREE concentrations, no MREE-enriched REE distribution patterns, high Ce/Ce* values close to 1, and enriched redox-sensitive elements, whereas samples in the lower 30-m and upper 10-m show opposite characteristics of high ∑REE concentrations, MREE-enriched REE distribution patterns, low Ce/Ce* values around 0.6, and no redox-sensitive elements enriched, indicating that oxygenation did occur in the shallow water on the northwestern margin of the Yangtze Platform and redox conditions of the shallow water fluctuated from relatively oxygenated to anoxic and then back to oxygenated again. We propose that the anoxia appeared in middle of the Beiwan time may associate with the anoxic upwelled water. On one hand, abundant nutrients were brought in by this upwelling event, which stimulated the photosynthetic carbon fixation and increased the organic carbon burial under this anoxic condition, causing a peak of 3.6‰ in δ 13 C. On the other hand, because the anoxic upwelled water replaced the oxic shallow water, together with the increasing organic matter in the water column, bacterial sulfate reduction was enhanced and therefore quickly reduced the sulfate concentration, which eventually caused δ 34 S increasing to 50‰. However, as the upwelling gradually disappeared, δ 13 C and δ 34 SCAS values decreased as well in the late Beiwan time, indicating the shallow water went back to suboxic or oxic again.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41171143,40771064)Program for New Century Excellent Talents in University(No.NCET-07-0398)Fundamental Research Funds for the Central Universities(No.lzu-jbky-2012-k35)
文摘Since the reform and opening-up program started in 1978,the level of urbanization has increased rapidly in China.Rapid urban expansion and restructuring have had significant impacts on the ecological environment especially within built-up areas.In this study,ArcGIS 10,ENVI 4.5,and Visual FoxPro 6.0 were used to analyze the human impacts on vegetation in the built-up areas of 656Chinese cities from 1992 to 2010.Firstly,an existing algorithm was refined to extract the boundaries of the built-up areas based on the Defense Meteorological Satellite Program Operational Linescan System(DMSP_OLS)nighttime light data.This improved algorithm has the advantages of high accuracy and speed.Secondly,a mathematical model(Human impacts(HI))was constructed to measure the impacts of human factors on vegetation during rapid urbanization based on Advanced Very High Resolution Radiometer(AVHRR)Normalized Difference Vegetation Index(NDVI)and Moderate Resolution Imaging Spectroradiometer(MODIS)NDVI.HI values greater than zero indicate relatively beneficial effects while values less than zero indicate proportionally adverse effects.The results were analyzed from four aspects:the size of cities(metropolises,large cities,medium-sized cities,and small cities),large regions(the eastern,central,western,and northeastern China),administrative divisions of China(provinces,autonomous regions,and municipalities)and vegetation zones(humid and semi-humid forest zone,semi-arid steppe zone,and arid desert zone).Finally,we discussed how human factors impacted on vegetation changes in the built-up areas.We found that urban planning policies and developmental stages impacted on vegetation changes in the built-up areas.The negative human impacts followed an inverted′U′shape,first rising and then falling with increase of urban scales.China′s national policies,social and economic development affected vegetation changes in the built-up areas.The findings can provide a scientific basis for municipal planning departments,a decision-making reference for government,and scientific guidance for sustainable development in China.
文摘The Pursuit of Happyness has always been a well-received film ever since its release in 2006. This film mainly describes how a black American worms his way from the bottom of the society to success. This paper intends to make a detailed description of the life experience of the main character, including his life obstacles and fighting. It also expounds on the image of the main character. Moreover, through the analysis of the reasons why Chris, an average American with his unyielding spirits, succeeds in seizing his happiness through sorrow and pain in life, the practical significance with regard to individual and social development is put into the limelight.
基金supported by National Natural Science Foundation of China (Grant No. 40739903)
文摘The Sinian Dengying Formation in China hosts one of the oldest gas-bearing reservoirs in the world.With a long geological history,it has developed into the reservoir rocks,whose quality depends on chemical dissolution and cementation.Despite presence of cavities and pores in the algal dolomites of the Dengying Formation,they were mostly filled with various forms of dolomite cements.Therefore,the investigation of these dolomites and their evolution is significant for analyzing the mechanism of pore space preservation.There are five types of cements in the Dengying Formation,which were well sampled for lab measurements such as thin section,cathodeluminescence,minor elements,isotope analysis of carbon,oxygen and strontium,in attempt to explore the fillers' geochemical characteristics and the diagenetic fluids.They are characterized as follows:firstly,fibrous rim dolomite cement is a typical product formed at sea bottom,and geochemically very similar to the matrix(micrite and microcrystalline dolomite),which could be a reflection of the geochemical characteristics of water at that time;secondly,the diagenetic fluids of the foliated dolomite cements tend to be inheriting,derived from the shallow burial "imprisoned" seawater;thirdly,fine-to medium-grained dolomite cements with fairly high strontium isotopes and low carbon and oxygen isotopes were precipitated chiefly in freshwater during the period of uplifting caused by Tongwan tectonic movement;fourthly,coarse-grained dolomite cements bear a relatively high percentage of Mn element,but low in Fe and Sr,with carbon and oxygen isotopes remarkably shifted to negative values,which all show that they are related to hydrocarbon maturation and migration,and corresponding Thermochemical Sulfate Reduction;lastly,saddle-shaped dolomite cements are hydrothermally associated,and they were formed in high-temperature brine,which had passed through the areas rich in radioactive strontium isotopes.
基金supported by the National Basic Research Program of China(Grant No.2011CB808805)MOST Special Fund from the State Key Laboratory of Continental Dynamics,Northwest University,and National Natural Science Foundation of China(Grant No.41172029)
文摘Carbon isotope, sulfur isotope, and trace element(including Rare Earth Elements, REE) analyses were conducted on the carbonates of the Dengying Formation at Lianghekou section in southern Shaanxi to reconstruct the terminal Ediacaran shallow-water environment on the northwestern margin of the Yangtze Platform. At Lianghekou section, samples in the middle 50-m of the Beiwan Member show characteristics of low ΣREE concentrations, no MREE-enriched REE distribution patterns, high Ce/Ce* values close to 1, and enriched redox-sensitive elements, whereas samples in the lower 30-m and upper 10-m show opposite characteristics of high ∑REE concentrations, MREE-enriched REE distribution patterns, low Ce/Ce* values around 0.6, and no redox-sensitive elements enriched, indicating that oxygenation did occur in the shallow water on the northwestern margin of the Yangtze Platform and redox conditions of the shallow water fluctuated from relatively oxygenated to anoxic and then back to oxygenated again. We propose that the anoxia appeared in middle of the Beiwan time may associate with the anoxic upwelled water. On one hand, abundant nutrients were brought in by this upwelling event, which stimulated the photosynthetic carbon fixation and increased the organic carbon burial under this anoxic condition, causing a peak of 3.6‰ in δ 13 C. On the other hand, because the anoxic upwelled water replaced the oxic shallow water, together with the increasing organic matter in the water column, bacterial sulfate reduction was enhanced and therefore quickly reduced the sulfate concentration, which eventually caused δ 34 S increasing to 50‰. However, as the upwelling gradually disappeared, δ 13 C and δ 34 SCAS values decreased as well in the late Beiwan time, indicating the shallow water went back to suboxic or oxic again.
