To predict the soil-water characteristic curve(i.e.SWCC)of natural and remoulded Malan loess from soil physical properties,one-point methods for determining the SWCC that are much simpler than experimental methods are...To predict the soil-water characteristic curve(i.e.SWCC)of natural and remoulded Malan loess from soil physical properties,one-point methods for determining the SWCC that are much simpler than experimental methods are proposed.The predicted SWCC is presented in the form of the BRUTSAERT equation,in which the four model parameters can be estimated from soil physical properties using the best correlations obtained in the present study along with one measured data point.The proposed one-point methods are validated using the measured SWCC data reported in the literature.The results of validation studies suggest that the proposed one-point methods can provide reasonable prediction of the SWCC for natural and remoulded Malan loess.The measured data point should be within the transition zone;the measured suction is suggested between25to100kPa for natural loess,while between100to500kPa for remoulded loess.展开更多
The platforms on both sides of the Malangou River （a lateral ditch of the Qingshui River that is a tributary of the Yongding River） where Malan Village in Zhaitang Town of Mentougou District of Beijing is located ar...The platforms on both sides of the Malangou River （a lateral ditch of the Qingshui River that is a tributary of the Yongding River） where Malan Village in Zhaitang Town of Mentougou District of Beijing is located are the place of China＇s typical section of the Quaternary Malan loess. During the investigation in the eastern suburbs of Beijing City, the authors not only clarified 5 grades of terraces on the Pinggu piedmont plain, but also found a clayey silt section mixed with a small amount of alluvial-diluvial gravel layers at a height of 15-25 m above the river level near a Fishpond in Xinli Village of Nandule Town. Results of the study of grain size of the section document that the loess mostly is silty soil （0.05--0.005 mm）, and that the grain size probability cumulative curves of the section are dominated by single-peak, coarse-grained segment I and coarse-grained segment II types, reflecting that its depositional environment is similar to eolian phase. Identification results of heavy minerals from the section show that their contents account for 0.01%-0.11%, averaging 0.04%. There are 24 kinds of heavy minerals, most of which are stable heavy minerals, and the clay minerals mostly are illite, which is consistent with the Malan loess on the Loess Plateau. The chemical composition data reflect that the source area of the loess is relatively arid. The six grade classification of sporopollen in the section further shows the subdivision of the history of alternating warm and humid phases in this geological period. The thermoluminescence dating results range from 21.0 ka to 59.2 ka, convincingly demonstrating that the section indeed consists of Malan loess. The above studies provide a new basis for overall understanding of the distribution of the Malan loess at the northeast margin of the North China Plain and its environment change in the Late Pleistocene.展开更多
Loess has unique compositions and structural characteristics and can be used for environmental protection.Differences between the surface characteristics of the Malan loess from the suburbs of Taiyuan,Shanxi Province ...Loess has unique compositions and structural characteristics and can be used for environmental protection.Differences between the surface characteristics of the Malan loess from the suburbs of Taiyuan,Shanxi Province before and after reaction with Cr(Ⅲ) solution were studied by SEM/EDS,IR and XRD.The results showed that the Malan loess has a strong ability to remove Cr(Ⅲ) from the solution.The surface characteristics of loess include an effect on Cr(Ⅲ) in solution,as supported by the strong test evidence including the disappearance of Cr peak in the EDS spectrum,the disappearance of carbonate characteristic peaks in the infrared spectrogram,and the positive correlation between Fe and Cr peaks.展开更多
In this paper, climatic and environmental changes were reconstructed since 1129A.D. based on the Malan ice core from Hol Xil, the northern Tibetan Plateau. The record of δ 18O in the Malan ice core indicated that the...In this paper, climatic and environmental changes were reconstructed since 1129A.D. based on the Malan ice core from Hol Xil, the northern Tibetan Plateau. The record of δ 18O in the Malan ice core indicated that the warm-season air temperature variations displayed a general increase trend, the 20th-century warming was within the range of natural climate variability, and the warmest century was the 17th century while the warmest decade was the 1610s, over the entire study period. The “Medieval Warm Epoch” and “Little Ice Age” were also reflected by the ice core record. The dust ratio in the Malan ice core is a good proxy for dust event frequency. The 870-year record of the dust ratio showed that dust events occurred much frequently in the 19th century. Comparing the variations of δ 18O and the dust ratio, it is found that there was a strong negative correlation between them on the time scales of 101―102 years. By analyses of all the climatic records of ice cores and tree rings from the northern Tibetan Plateau, it was revealed that dust events were more frequent in the cold and dry periods than in the warm and wet periods.展开更多
A preliminary study of the Malan loess on the eastern margin of the Qinghai-Xizang(Tibetan)Plateau and its adjacent area shows that along the boundary of Kunlun Mts.-Buqing Mts.-A’nymaqnMts.-South Qinling(Motianling)...A preliminary study of the Malan loess on the eastern margin of the Qinghai-Xizang(Tibetan)Plateau and its adjacent area shows that along the boundary of Kunlun Mts.-Buqing Mts.-A’nymaqnMts.-South Qinling(Motianling),the Malun loess falls roughly into two main depositional regions:to itsnorth,a hot loess region in which dusts come mainly from the Asian inland arid area;to its south,a coldloess region in which dusts come chiefly from the Qinghai-Xizang Plateau.The possible causative fac-tors and processes for the loess difference are the uplift of the Plateau and the effects of its resultant particuolar landform,the interactions of its induced Asian monsoon,by-flowing westlies and plateau monsoon,and thedifference of sediments of source areas.展开更多
Loess of China, especially the Malan loess distributed along the middle reaches of the Huanghe River, has attracted great attention of many geologists throughout the world because of its extensive occurrence and close...Loess of China, especially the Malan loess distributed along the middle reaches of the Huanghe River, has attracted great attention of many geologists throughout the world because of its extensive occurrence and close relation with the living environment of mankind. As the Malan loess was formed relatively late, and thus has not been affected by hysterogenic diagenesis, it has well preserved the primary characteristics at the time of展开更多
The Quaternary loess deposits in the arid-semiarid area in northwestern China are composed of eolian sedimemts which are continuous in terms of sedimentation and have undergone little alternation after deposition.They...The Quaternary loess deposits in the arid-semiarid area in northwestern China are composed of eolian sedimemts which are continuous in terms of sedimentation and have undergone little alternation after deposition.They provide an ideal place for the preservation of the extraterrestrial falls on the earth.The Late Pleistocene Malan loess is chosedn for our study of the preserved cosmic dusts.展开更多
By comprehensive analyses, it was found that the variations in d 18O recorded in Malan ice core from theKekexili Region on the Tibetan Plateau could represent thechanges in air temperature during the summer half year ...By comprehensive analyses, it was found that the variations in d 18O recorded in Malan ice core from theKekexili Region on the Tibetan Plateau could represent thechanges in air temperature during the summer half year (from May to October) over the Kekexili Region and the northern margin of the Tibetan Plateau. The general increase trend in d18O in this ice core during the past century indicated climate warming, and it was estimated that air temperature during the summer half-year rose about 1.2C over there then. However, this ice core record documented that the study area has been cooling while most of the world has been dramatically warming since the late 1970s. A teleconnection was foundbetween the variations in d 18O in the Malan ice core and the North Atlantic Oscillation. Moreover, the variations in d 18O in this ice core were similar to that in the summer half-year air temperature over the southern Tibetan Plateau on thecenturial time scale, but opposite on the multidecadal timescale.展开更多
In order to understand the relationship be- tween the community structure of bacteria in ice core and the past climate and environment, we initiated the study on the microorganisms in the three selected ice samples fr...In order to understand the relationship be- tween the community structure of bacteria in ice core and the past climate and environment, we initiated the study on the microorganisms in the three selected ice samples from the Malan ice core drilled from the Tibetan Plateau. The 16S ribosomal DNA (rDNA) molecules were directly amplified from the melt water samples, and three 16S rDNA clone li- braries were established. Among 94 positive clones, eleven clones with unique restriction pattern were used for partial sequence and compared with eight reported sequences from the same ice core. The phylotypes were divided into 5 groups: alpha, beta, gamma proteobacteria; CFB, and other eubac- teria group. Among them, there were many “typical Malan glacial bacteria” pertaining to psychrophilies and new bacte- ria found in the ice core. At a longer time scale, the concen- tration distribution of “typical Malan glacial bacteria” with depth showed negative correlation with temperature varia- tions and was coincident with dirty layer. It implied the in- fluence of temperature on the microbial record through im- pact on the concentrations of the “typical Malan glacial bac- teria”. In addition, the nutrition contained in ice was another important factor controlling the distribution of microbial population in ice core section. Moreover, the result displayed an apparent layer distribution of bacterial community in the ice core section, which reflected the microbial response to the past climatic and environmental conditions at the time of deposition.展开更多
By analyses of the dust layers in the Malan ice core from the northern Tibetan Plateau, it was found that dirty ratio in this core might be a good proxy for dust event frequency. The variations in the dirty ratio disp...By analyses of the dust layers in the Malan ice core from the northern Tibetan Plateau, it was found that dirty ratio in this core might be a good proxy for dust event frequency. The variations in the dirty ratio displayed a de- crease trend over the past 200 years, which implies that dust events became less frequent during the study period. The decrease trend in the variations in dust event frequency might be caused mostly by the natural processes, including increasing precipitation and weakening westerly which might be related with global warming. Furthermore, significant negative correlation was found between the dirty ratio and δ 18O in the Malan ice core. This is highly important for studying the effect of atmospheric dust on climate change.展开更多
应用L ev ins、Shannon-W iener生态位宽度公式和P ianka生态位重叠公式,定量研究了黄土高原马栏林区主要植物种的生态位宽度和生态位重叠特征,同时对主要种在演替系列上的生态位变化规律进行了分析.结果表明,在该地区森林群落演替系列...应用L ev ins、Shannon-W iener生态位宽度公式和P ianka生态位重叠公式,定量研究了黄土高原马栏林区主要植物种的生态位宽度和生态位重叠特征,同时对主要种在演替系列上的生态位变化规律进行了分析.结果表明,在该地区森林群落演替系列中,乔木种生态位宽度的平均水平小于灌木种,建群种的生态位宽度小于主要伴生种;生态位宽度较大的种与其它各物种间生态位重叠的平均值较大,生态位宽度较小的种则相反,甚至没有重叠.由于物种生物生态学特性的不同和环境的异质性,具较宽生态位的物种间的生态位重叠也可能较小,生态位宽度较窄的物种间也可能有较大的生态位重叠,同属植物种对间也存在生态位重叠较大的情况.主要乔木和灌木种的生态位特征反映了森林群落演替的变化规律,该地区呈现出以自然恢复为主,同时又伴随着人为干扰的森林群落次生演替系列.展开更多
基金Project(41372329) supported by the National Natural Science Foundation of ChinaProject(2014CB744701) supported by the National Basic Research Program of China
文摘To predict the soil-water characteristic curve(i.e.SWCC)of natural and remoulded Malan loess from soil physical properties,one-point methods for determining the SWCC that are much simpler than experimental methods are proposed.The predicted SWCC is presented in the form of the BRUTSAERT equation,in which the four model parameters can be estimated from soil physical properties using the best correlations obtained in the present study along with one measured data point.The proposed one-point methods are validated using the measured SWCC data reported in the literature.The results of validation studies suggest that the proposed one-point methods can provide reasonable prediction of the SWCC for natural and remoulded Malan loess.The measured data point should be within the transition zone;the measured suction is suggested between25to100kPa for natural loess,while between100to500kPa for remoulded loess.
基金funded by the project Ecological Agricultural Geological Survey and Demonstration Research of Xinli Village in Pinggu District, Beijing under the Central Research Institutes of Basic Research and Public Service Special Operations K1201 and the geological survey project (Grant No. 1212011300010)
文摘The platforms on both sides of the Malangou River （a lateral ditch of the Qingshui River that is a tributary of the Yongding River） where Malan Village in Zhaitang Town of Mentougou District of Beijing is located are the place of China＇s typical section of the Quaternary Malan loess. During the investigation in the eastern suburbs of Beijing City, the authors not only clarified 5 grades of terraces on the Pinggu piedmont plain, but also found a clayey silt section mixed with a small amount of alluvial-diluvial gravel layers at a height of 15-25 m above the river level near a Fishpond in Xinli Village of Nandule Town. Results of the study of grain size of the section document that the loess mostly is silty soil （0.05--0.005 mm）, and that the grain size probability cumulative curves of the section are dominated by single-peak, coarse-grained segment I and coarse-grained segment II types, reflecting that its depositional environment is similar to eolian phase. Identification results of heavy minerals from the section show that their contents account for 0.01%-0.11%, averaging 0.04%. There are 24 kinds of heavy minerals, most of which are stable heavy minerals, and the clay minerals mostly are illite, which is consistent with the Malan loess on the Loess Plateau. The chemical composition data reflect that the source area of the loess is relatively arid. The six grade classification of sporopollen in the section further shows the subdivision of the history of alternating warm and humid phases in this geological period. The thermoluminescence dating results range from 21.0 ka to 59.2 ka, convincingly demonstrating that the section indeed consists of Malan loess. The above studies provide a new basis for overall understanding of the distribution of the Malan loess at the northeast margin of the North China Plain and its environment change in the Late Pleistocene.
基金supported by the National Natural Science Foundation of China (Nos. 40402021 and 40830748)the China-Russia International Cooperation and Exchange Project of NSFC-RFBR (No. 40711120189)+4 种基金the Key Project of Chinese Ministry of Education (No. 104038)Program for New Century Excellent Talents in University (NCET-07-0773)the Aid Project of Science and Technology Ministry of China to Developing Countries (2008041012)National High Technology Research and Development Program 863 (2007AA06Z337)the Excellent Young Teachers Program of China University of Geosciences (CUGQNL0303)
文摘Loess has unique compositions and structural characteristics and can be used for environmental protection.Differences between the surface characteristics of the Malan loess from the suburbs of Taiyuan,Shanxi Province before and after reaction with Cr(Ⅲ) solution were studied by SEM/EDS,IR and XRD.The results showed that the Malan loess has a strong ability to remove Cr(Ⅲ) from the solution.The surface characteristics of loess include an effect on Cr(Ⅲ) in solution,as supported by the strong test evidence including the disappearance of Cr peak in the EDS spectrum,the disappearance of carbonate characteristic peaks in the infrared spectrogram,and the positive correlation between Fe and Cr peaks.
基金This work was supported by the Centuria Program of the Chinese Academy of Sciences(CAS)(Grant No.2004401)the National Natural Science Foundation of China(Grant Nos.40525001 and 40121101)+1 种基金the Key Research Project of the Knowledge Innovation Program of CAS(Grant No.KZCX3-SW-339-3)the Chinese National Basic Research Program(Grant No.2005CB422003).
文摘In this paper, climatic and environmental changes were reconstructed since 1129A.D. based on the Malan ice core from Hol Xil, the northern Tibetan Plateau. The record of δ 18O in the Malan ice core indicated that the warm-season air temperature variations displayed a general increase trend, the 20th-century warming was within the range of natural climate variability, and the warmest century was the 17th century while the warmest decade was the 1610s, over the entire study period. The “Medieval Warm Epoch” and “Little Ice Age” were also reflected by the ice core record. The dust ratio in the Malan ice core is a good proxy for dust event frequency. The 870-year record of the dust ratio showed that dust events occurred much frequently in the 19th century. Comparing the variations of δ 18O and the dust ratio, it is found that there was a strong negative correlation between them on the time scales of 101―102 years. By analyses of all the climatic records of ice cores and tree rings from the northern Tibetan Plateau, it was revealed that dust events were more frequent in the cold and dry periods than in the warm and wet periods.
基金the National Natural Science Foundation of Chinathe Fund for Returned Overseas Scholars' Starting Work
文摘A preliminary study of the Malan loess on the eastern margin of the Qinghai-Xizang(Tibetan)Plateau and its adjacent area shows that along the boundary of Kunlun Mts.-Buqing Mts.-A’nymaqnMts.-South Qinling(Motianling),the Malun loess falls roughly into two main depositional regions:to itsnorth,a hot loess region in which dusts come mainly from the Asian inland arid area;to its south,a coldloess region in which dusts come chiefly from the Qinghai-Xizang Plateau.The possible causative fac-tors and processes for the loess difference are the uplift of the Plateau and the effects of its resultant particuolar landform,the interactions of its induced Asian monsoon,by-flowing westlies and plateau monsoon,and thedifference of sediments of source areas.
基金Project supported by the National Natural Science Foundation of China.
文摘Loess of China, especially the Malan loess distributed along the middle reaches of the Huanghe River, has attracted great attention of many geologists throughout the world because of its extensive occurrence and close relation with the living environment of mankind. As the Malan loess was formed relatively late, and thus has not been affected by hysterogenic diagenesis, it has well preserved the primary characteristics at the time of
基金Project supported by the Xi'an Lab of LoessQuaternary Geology.
文摘The Quaternary loess deposits in the arid-semiarid area in northwestern China are composed of eolian sedimemts which are continuous in terms of sedimentation and have undergone little alternation after deposition.They provide an ideal place for the preservation of the extraterrestrial falls on the earth.The Late Pleistocene Malan loess is chosedn for our study of the preserved cosmic dusts.
基金This work was supported by the knowledge Innovation Project of the Chinese Academy of Sciences(Grant Nos.KZCX1-10-02 und KZCX2-314)the Key Research Project of the Chinese National Committee of Science and Technology(Grant No.G1998040800)the Innovation Rescarch Project of the National Natural Science Foundation of China.
文摘By comprehensive analyses, it was found that the variations in d 18O recorded in Malan ice core from theKekexili Region on the Tibetan Plateau could represent thechanges in air temperature during the summer half year (from May to October) over the Kekexili Region and the northern margin of the Tibetan Plateau. The general increase trend in d18O in this ice core during the past century indicated climate warming, and it was estimated that air temperature during the summer half-year rose about 1.2C over there then. However, this ice core record documented that the study area has been cooling while most of the world has been dramatically warming since the late 1970s. A teleconnection was foundbetween the variations in d 18O in the Malan ice core and the North Atlantic Oscillation. Moreover, the variations in d 18O in this ice core were similar to that in the summer half-year air temperature over the southern Tibetan Plateau on thecenturial time scale, but opposite on the multidecadal timescale.
文摘In order to understand the relationship be- tween the community structure of bacteria in ice core and the past climate and environment, we initiated the study on the microorganisms in the three selected ice samples from the Malan ice core drilled from the Tibetan Plateau. The 16S ribosomal DNA (rDNA) molecules were directly amplified from the melt water samples, and three 16S rDNA clone li- braries were established. Among 94 positive clones, eleven clones with unique restriction pattern were used for partial sequence and compared with eight reported sequences from the same ice core. The phylotypes were divided into 5 groups: alpha, beta, gamma proteobacteria; CFB, and other eubac- teria group. Among them, there were many “typical Malan glacial bacteria” pertaining to psychrophilies and new bacte- ria found in the ice core. At a longer time scale, the concen- tration distribution of “typical Malan glacial bacteria” with depth showed negative correlation with temperature varia- tions and was coincident with dirty layer. It implied the in- fluence of temperature on the microbial record through im- pact on the concentrations of the “typical Malan glacial bac- teria”. In addition, the nutrition contained in ice was another important factor controlling the distribution of microbial population in ice core section. Moreover, the result displayed an apparent layer distribution of bacterial community in the ice core section, which reflected the microbial response to the past climatic and environmental conditions at the time of deposition.
基金supported by the Century Program(Grant No.2004401)the Innovation Research Project of Chinese Academy of Sciences(Grant No.KZCX3-SW-339-3)+2 种基金National Basic Research Program of China(Grant No.2005CB422003)National Natural Science Foundation of China(Grant No.40121101)the Knowledge Innovation Project of CAREERI(Grant Nos.2003107 and 2004102).
文摘By analyses of the dust layers in the Malan ice core from the northern Tibetan Plateau, it was found that dirty ratio in this core might be a good proxy for dust event frequency. The variations in the dirty ratio displayed a de- crease trend over the past 200 years, which implies that dust events became less frequent during the study period. The decrease trend in the variations in dust event frequency might be caused mostly by the natural processes, including increasing precipitation and weakening westerly which might be related with global warming. Furthermore, significant negative correlation was found between the dirty ratio and δ 18O in the Malan ice core. This is highly important for studying the effect of atmospheric dust on climate change.
文摘应用L ev ins、Shannon-W iener生态位宽度公式和P ianka生态位重叠公式,定量研究了黄土高原马栏林区主要植物种的生态位宽度和生态位重叠特征,同时对主要种在演替系列上的生态位变化规律进行了分析.结果表明,在该地区森林群落演替系列中,乔木种生态位宽度的平均水平小于灌木种,建群种的生态位宽度小于主要伴生种;生态位宽度较大的种与其它各物种间生态位重叠的平均值较大,生态位宽度较小的种则相反,甚至没有重叠.由于物种生物生态学特性的不同和环境的异质性,具较宽生态位的物种间的生态位重叠也可能较小,生态位宽度较窄的物种间也可能有较大的生态位重叠,同属植物种对间也存在生态位重叠较大的情况.主要乔木和灌木种的生态位特征反映了森林群落演替的变化规律,该地区呈现出以自然恢复为主,同时又伴随着人为干扰的森林群落次生演替系列.
