Sand/dust storms are some of the main hazards in arid and semi-arid zones. These storms also influence global environmental changes. By field observations, empirical statistics, and numerical simulations, pioneer rese...Sand/dust storms are some of the main hazards in arid and semi-arid zones. These storms also influence global environmental changes. By field observations, empirical statistics, and numerical simulations, pioneer researchers on these natural events have concluded the existence of a positive relationship between thermodynamic effects and sand/dust storms. Thermodynamic effects induce an unsteady stratified atmosphere to influence the process of these storms. However, studies on the relationship of thermodynamic effects with particles (i.e., sand and dust) are limited. In this article, wind tunnel with heating was used to simulate the quantitative relationship between thermodynamic effects and particle movement on different surfaces. Compared with the cold state, the threshold wind velocity of particles is found to be significantly decrease under the hot state. The largest decrease percentage exceedes 9% on fine and coarse sand surfaces. The wind velocity also has a three-power function in the sand transport rate under the hot state with increased sand transport. Thermodynamic effects are stronger on loose surfaces and fine particles, but weaker on compacted surfaces and coarse particles.展开更多
Weathered clastic crust can be subdivided into weathered clay and leached zone in terms of variable weathering of different minerals and mobility of weathered products.On the basis of clastic outcrops and well cores i...Weathered clastic crust can be subdivided into weathered clay and leached zone in terms of variable weathering of different minerals and mobility of weathered products.On the basis of clastic outcrops and well cores in the Junggar Basin,the dark red Fe-rich weathered clay is formed in an arid environment,whereas the light blue Al-rich weathered clay under humid conditions.According to the geochemical analysis,a new weathering index for weathered clastic crust is built mainly on Fe and Al contents,accurately indicating the weathered clay,sandy leached zone,and muddy leached zone in the Junggar Basin.The breaking pressure of weathered clay is rather large,the same as that of normal muddy cap,effectively to seal oil or gas.The porosity of underlying leached zone is greatly enhanced by weathering and leaching,but its permeability is a function of clay mineral content,i.e.,the higher the clay content,the worse the permeability.Weathered crust provides effective sealing conditions for both top and bottom layers of a petroleum reservoir,and is important in the clastic hydrocarbon exploration.展开更多
Understanding the factors affecting the CO 2 emission from agricultural practices is crucial for global warming.A study was performed in an apricot orchard field in the experimental farm of the Harran University,South...Understanding the factors affecting the CO 2 emission from agricultural practices is crucial for global warming.A study was performed in an apricot orchard field in the experimental farm of the Harran University,Southeast Turkey,to i) quantify weekly and seasonal variations of the CO 2 emissions from a Vertisol under apricot orchard;ii) evaluate the difference in CO 2 emission between the area under trees and rows;and iii) assess the relationships between the amounts of CO 2 emissions and environmental parameters for better use and management of the soils from the view point of carbon balance and flux in a semi-arid environment under drip irrigation.Soil CO 2 emission measurements were performed during May 2008 and May 2010,from both under tree crowns (CO 2-UC) and between tree rows (CO 2-BR),on a weekly basis in southeast Turkey with a semi-arid climate.CO 2 emissions were statistically correlated with weather and soil parameters such as air temperature,relative humidity,rainfall,soil water content,and soil temperature at various depths from 5 to 100 cm.The weekly emissions ranged from 82 to 1 110 kg CO 2 ha 1 week 1 and from 96 to 782 kg CO 2 ha 1 week 1 in CO 2-UC and CO 2-BR,respectively.Increase in CO 2 emission in the second year was due to increases in mean air and soil temperatures.The weekly and monthly cumulative CO 2 emissions were positively correlated with the air and soil temperatures.Multiple linear regression analysis explained 35% and 83% variations in average weekly and monthly CO 2 emissions,by using meteorological data.Including the interaction effects of meteorological parameters in regression equations nearly doubled the variance explained by the regression models.According to stepwise regression analysis,soil and air temperatures were found to have the most significant impact on the temporal variability of the soil CO 2 emission.展开更多
基金Under the auspices of National Natural Science Foundation of China (No. 40930741, 41071009, 41001005)Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-329)
文摘Sand/dust storms are some of the main hazards in arid and semi-arid zones. These storms also influence global environmental changes. By field observations, empirical statistics, and numerical simulations, pioneer researchers on these natural events have concluded the existence of a positive relationship between thermodynamic effects and sand/dust storms. Thermodynamic effects induce an unsteady stratified atmosphere to influence the process of these storms. However, studies on the relationship of thermodynamic effects with particles (i.e., sand and dust) are limited. In this article, wind tunnel with heating was used to simulate the quantitative relationship between thermodynamic effects and particle movement on different surfaces. Compared with the cold state, the threshold wind velocity of particles is found to be significantly decrease under the hot state. The largest decrease percentage exceedes 9% on fine and coarse sand surfaces. The wind velocity also has a three-power function in the sand transport rate under the hot state with increased sand transport. Thermodynamic effects are stronger on loose surfaces and fine particles, but weaker on compacted surfaces and coarse particles.
基金supported by National Science and Technology Major Projects(Grant No.2011ZX05001-003)
文摘Weathered clastic crust can be subdivided into weathered clay and leached zone in terms of variable weathering of different minerals and mobility of weathered products.On the basis of clastic outcrops and well cores in the Junggar Basin,the dark red Fe-rich weathered clay is formed in an arid environment,whereas the light blue Al-rich weathered clay under humid conditions.According to the geochemical analysis,a new weathering index for weathered clastic crust is built mainly on Fe and Al contents,accurately indicating the weathered clay,sandy leached zone,and muddy leached zone in the Junggar Basin.The breaking pressure of weathered clay is rather large,the same as that of normal muddy cap,effectively to seal oil or gas.The porosity of underlying leached zone is greatly enhanced by weathering and leaching,but its permeability is a function of clay mineral content,i.e.,the higher the clay content,the worse the permeability.Weathered crust provides effective sealing conditions for both top and bottom layers of a petroleum reservoir,and is important in the clastic hydrocarbon exploration.
基金Supported by the Harran Universitesi Bilimsel Ara stirma Projeleri Komisyonu (HBAK),Turkey (No. 799)
文摘Understanding the factors affecting the CO 2 emission from agricultural practices is crucial for global warming.A study was performed in an apricot orchard field in the experimental farm of the Harran University,Southeast Turkey,to i) quantify weekly and seasonal variations of the CO 2 emissions from a Vertisol under apricot orchard;ii) evaluate the difference in CO 2 emission between the area under trees and rows;and iii) assess the relationships between the amounts of CO 2 emissions and environmental parameters for better use and management of the soils from the view point of carbon balance and flux in a semi-arid environment under drip irrigation.Soil CO 2 emission measurements were performed during May 2008 and May 2010,from both under tree crowns (CO 2-UC) and between tree rows (CO 2-BR),on a weekly basis in southeast Turkey with a semi-arid climate.CO 2 emissions were statistically correlated with weather and soil parameters such as air temperature,relative humidity,rainfall,soil water content,and soil temperature at various depths from 5 to 100 cm.The weekly emissions ranged from 82 to 1 110 kg CO 2 ha 1 week 1 and from 96 to 782 kg CO 2 ha 1 week 1 in CO 2-UC and CO 2-BR,respectively.Increase in CO 2 emission in the second year was due to increases in mean air and soil temperatures.The weekly and monthly cumulative CO 2 emissions were positively correlated with the air and soil temperatures.Multiple linear regression analysis explained 35% and 83% variations in average weekly and monthly CO 2 emissions,by using meteorological data.Including the interaction effects of meteorological parameters in regression equations nearly doubled the variance explained by the regression models.According to stepwise regression analysis,soil and air temperatures were found to have the most significant impact on the temporal variability of the soil CO 2 emission.
