Quantitatively determining the sources of dune sand is one of the problems necessarily and urgently to be solved in aeolian landforms and desertification research. Based on the granulometric data of sand materials fro...Quantitatively determining the sources of dune sand is one of the problems necessarily and urgently to be solved in aeolian landforms and desertification research. Based on the granulometric data of sand materials from the Hulun Buir Sandy Land, the paper employs the stepwise discriminant analysis technique (SDA) for two groups to select the principal factors determining the differences between surface loose sediments. The extent of similarity between two statistical populations can be described quantitatively by three factors such as the number of principal variables, Mahalanobis distance D 2 and confidence level 琢for F-test. Results reveal that: 1) Aeolian dune sand in the region mainly derives from Hailar Formation (Q 3 ), while fluvial sand and palaeosol also supply partially source sand for dunes; and 2) in the vicinity of Cuogang Town and west of the broad valley of the lower reaches of Hailar River, fluvial sand can naturally become principal supplier for dune sand.展开更多
The Kumtag Desert, the fourth largest sand desert covered mainly by mobile dunes and shifting sands, had remained as the last untouched natural desert to be fully investigated in a scientific way. Therefore,＂Integrat...The Kumtag Desert, the fourth largest sand desert covered mainly by mobile dunes and shifting sands, had remained as the last untouched natural desert to be fully investigated in a scientific way. Therefore,＂Integrated Scientific Expedition of the Kumtag Desert Programme＂was listed as one of nine key research programmes of China National Science and Technology Basic Research Programmes in December, 2006. The expedition team carried out two large-scale and multidisciplinary scientific expeditions from June 2007 to December 2009, to the Kumtag Desert and collected more than 20 sets of field samples and ground observations. Finally, the expedition team completed not only systematic and integrated scientific expedition of the Kumtag Desert and filled in the gap of the last unexplored desert in China, but also gained fruitful research results in many scientific research subjects. These research results included that：（i） A unique aeolian landform unit, sand-gravel-moraine, developed in the Kumtag Desert, was defined and named for the first time, and the morphologic characteristics of feather-like longitudinal sand dune and its formation process are initially proved;（ii） Two sources and mineral element composition of the surface sedimentation of the Kumtag Desert was determined, and the characteristics of the desert sedimentation and stratum chronology of the Later Cenozoic Era was illustrated;（iii） The chronology of the paleo-aeolian sand was essentially determined and the formation courses and evolution process of the desert was illustrated;（iv） The thorough investigations of water system distribution, hydrology,chemical characteristics of water of the Kumtag Desert were made and six Water System Evolution Maps of the Kumtag Desert were compiled from the Later Cenozoic Era to the contemporary age;（v） The types, formation processes and distribution of soil in the Kumtag Desert were fully determined;（vi）An all-direction, all-weather, full-coverage desert meteorology observation was established and the characteristics and trend of climate change of the Kumtag Desert and nearby districts were adequately illustrated;（vii） It is the first time that the distribution areas of six plant species, including Tamarix taklamakanensis, Tamarix albiflonum, Agriophyllum lateriflorum etc., were catalogued in the Desert;（viii） The varieties, population, quantity and distribution of the wild animal such as the Bactrian Camel （Camelus ferus Przewalski）, are now documented;And （ix） it is the first time that the ecological services and economic function subdivision zones of the Kumtag Desert were classified;the Framework of the Great Dunhuang Special Ecological-Economic Zone was proposed to realize the sustainable development strategy in population, resources, environment, ecology and economics in the Kumtag Desert and nearby districts.展开更多
While saltation bombardment of sand grains on a fine substrate can produce considerable dust, the well-sorted nature of sand dunes tends to preclude them from consideration as major dust sources. Recent research, howe...While saltation bombardment of sand grains on a fine substrate can produce considerable dust, the well-sorted nature of sand dunes tends to preclude them from consideration as major dust sources. Recent research, however, has revealed that sand dunes can, in some cases, be large sources of dust. We used the PI-SWERL(Portable In-Situ Wind Erosion Laboratory) to measure in the field the potential of sand dunes and other desert landforms to emit particulate matter <10 μm(PM-10) dust in the Tengger, Ulan Buh, and Mu Us deserts of northern China. Combined with high resolution particle size measurements of the dune sand, an assessment of sand dunes as a dust source can be made. Large active transverse dunes tend to contain little to no stored PM-10, yet they produce a low dust flux. Coppice dunes stabilized by vegetation contain appreciable PM-10 and have very high dust emission potential. There is a positive correlation between the amount of PM-10 stored in a dune and its potential dust flux. Saltation liberates loose fines stored in dunes, making them very efficient dust emitters compared to landforms such as dry lake beds and washes where dust particles are unavailable for aeolian transport due to protective crusts or sediment cohesion. In cases where large dunes do not store PM-10 yet emit dust when active, two hypotheses can be considered:(1) iron-oxide grain coatings are removed during saltation, creating dust, and(2) sand grains collide during saltation, abrading grains to create dust. Observations reveal that iron oxide coatings are present on some dune sands. PI-SWERL data suggests that low dust fluxes from dunes containing no stored dust may represent an estimate for the amount of PM-10 dust produced by removal of iron oxide coatings. These results are similar to results from dunes in the United States. In addition, PI-SWERL results suggest that dust-bearing coppice dunes, which cover vast areas of China's sandy deserts, may become major sources of dust in the future if overgrazing, depletion of groundwater, or drought destabilizes the vegetation that now partially covers these dunes.展开更多
文摘Quantitatively determining the sources of dune sand is one of the problems necessarily and urgently to be solved in aeolian landforms and desertification research. Based on the granulometric data of sand materials from the Hulun Buir Sandy Land, the paper employs the stepwise discriminant analysis technique (SDA) for two groups to select the principal factors determining the differences between surface loose sediments. The extent of similarity between two statistical populations can be described quantitatively by three factors such as the number of principal variables, Mahalanobis distance D 2 and confidence level 琢for F-test. Results reveal that: 1) Aeolian dune sand in the region mainly derives from Hailar Formation (Q 3 ), while fluvial sand and palaeosol also supply partially source sand for dunes; and 2) in the vicinity of Cuogang Town and west of the broad valley of the lower reaches of Hailar River, fluvial sand can naturally become principal supplier for dune sand.
基金China National Science and Technology Infrastructure Programme(2006FY110800)Academician Consulting Project of Chinese Academy of SciencesCentral Public-interest Scientific Institution Basal Research Fund(CAFYBB2010001-03)
文摘The Kumtag Desert, the fourth largest sand desert covered mainly by mobile dunes and shifting sands, had remained as the last untouched natural desert to be fully investigated in a scientific way. Therefore,＂Integrated Scientific Expedition of the Kumtag Desert Programme＂was listed as one of nine key research programmes of China National Science and Technology Basic Research Programmes in December, 2006. The expedition team carried out two large-scale and multidisciplinary scientific expeditions from June 2007 to December 2009, to the Kumtag Desert and collected more than 20 sets of field samples and ground observations. Finally, the expedition team completed not only systematic and integrated scientific expedition of the Kumtag Desert and filled in the gap of the last unexplored desert in China, but also gained fruitful research results in many scientific research subjects. These research results included that：（i） A unique aeolian landform unit, sand-gravel-moraine, developed in the Kumtag Desert, was defined and named for the first time, and the morphologic characteristics of feather-like longitudinal sand dune and its formation process are initially proved;（ii） Two sources and mineral element composition of the surface sedimentation of the Kumtag Desert was determined, and the characteristics of the desert sedimentation and stratum chronology of the Later Cenozoic Era was illustrated;（iii） The chronology of the paleo-aeolian sand was essentially determined and the formation courses and evolution process of the desert was illustrated;（iv） The thorough investigations of water system distribution, hydrology,chemical characteristics of water of the Kumtag Desert were made and six Water System Evolution Maps of the Kumtag Desert were compiled from the Later Cenozoic Era to the contemporary age;（v） The types, formation processes and distribution of soil in the Kumtag Desert were fully determined;（vi）An all-direction, all-weather, full-coverage desert meteorology observation was established and the characteristics and trend of climate change of the Kumtag Desert and nearby districts were adequately illustrated;（vii） It is the first time that the distribution areas of six plant species, including Tamarix taklamakanensis, Tamarix albiflonum, Agriophyllum lateriflorum etc., were catalogued in the Desert;（viii） The varieties, population, quantity and distribution of the wild animal such as the Bactrian Camel （Camelus ferus Przewalski）, are now documented;And （ix） it is the first time that the ecological services and economic function subdivision zones of the Kumtag Desert were classified;the Framework of the Great Dunhuang Special Ecological-Economic Zone was proposed to realize the sustainable development strategy in population, resources, environment, ecology and economics in the Kumtag Desert and nearby districts.
基金supported by the National Natural Science Foundation of China(Grant Nos.4132106241371203)
文摘While saltation bombardment of sand grains on a fine substrate can produce considerable dust, the well-sorted nature of sand dunes tends to preclude them from consideration as major dust sources. Recent research, however, has revealed that sand dunes can, in some cases, be large sources of dust. We used the PI-SWERL(Portable In-Situ Wind Erosion Laboratory) to measure in the field the potential of sand dunes and other desert landforms to emit particulate matter <10 μm(PM-10) dust in the Tengger, Ulan Buh, and Mu Us deserts of northern China. Combined with high resolution particle size measurements of the dune sand, an assessment of sand dunes as a dust source can be made. Large active transverse dunes tend to contain little to no stored PM-10, yet they produce a low dust flux. Coppice dunes stabilized by vegetation contain appreciable PM-10 and have very high dust emission potential. There is a positive correlation between the amount of PM-10 stored in a dune and its potential dust flux. Saltation liberates loose fines stored in dunes, making them very efficient dust emitters compared to landforms such as dry lake beds and washes where dust particles are unavailable for aeolian transport due to protective crusts or sediment cohesion. In cases where large dunes do not store PM-10 yet emit dust when active, two hypotheses can be considered:(1) iron-oxide grain coatings are removed during saltation, creating dust, and(2) sand grains collide during saltation, abrading grains to create dust. Observations reveal that iron oxide coatings are present on some dune sands. PI-SWERL data suggests that low dust fluxes from dunes containing no stored dust may represent an estimate for the amount of PM-10 dust produced by removal of iron oxide coatings. These results are similar to results from dunes in the United States. In addition, PI-SWERL results suggest that dust-bearing coppice dunes, which cover vast areas of China's sandy deserts, may become major sources of dust in the future if overgrazing, depletion of groundwater, or drought destabilizes the vegetation that now partially covers these dunes.
