Fractal Characteristics of Grain Size of Sand and Dust in Aeolian Sand Movement in Cele Oasis-Desert Ecotone in Xinjiang, China
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Supported by the Scientific Research Projects for Higher Educational Universities in Xinjiang Uygur Autonomous Region (No. XJEDU2016I035) and Start-up Fund of Doctoral Research of Xinjiang Normal University (No. XJNUBS1527) and the National Natural Science Foundation of China (Nos. 41601595, 41661002 and 41561051)

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    Abstract:

    【Objective】 Aeolian sand movement is very frequent in the Cele oasis-desert ecotone in Xinjiang of China. So it is of great importance to explore rules of the near-surface aeolian sand movements, in expectation of providing certain theoretical basis for prevention and control of sandstorms in the southern fringe of the Taklimakan Desert. 【Method】 In-lab measurements and assays, linear regression analysis and correlational statistical analysis were adopted to explore particle size and fractal characteristics of grain size of the sand and dust materials in sand movements on land surface and near surface over different terrains of the Cele oasis-desert ecotone. 【Result】 Results show that the sand and dust materials in various sand movements consist of five kinds of sand and dust materials, from very coarse silts to very fine sands, and coarse silts are the major component of the atmospheric dustfall, with fractal dimension varying in the range of 0.25 ~ 2.25 and the five kinds of aeolian sand and dust vary in mean fractal dimension of particle size, exhibiting an decreasing order of sand materials on the surfaces of nebkhas > those in dustfall > those on bare flat sandy land > those transported near ground surface > those shifting with sandy, averaging 1.03 ~ 1.67 in fractal dimension of particle size, while standard deviations of their fractal dimension values are in an opposite trend. Along the prevailing wind direction from shifting sandy land to oasis, with growing vegetation coverage, fractal dimension of aeolian sand and dust materials increases, while wind speed declines. The very coarse silt and very fine sand particles in the air higher above the ground surface tend to get deposited around shrubs in the oasis-desert ecotone, so the fractal dimension of the sand and dust materials in nebkhas are the highest in value, while the surface wind speed on shifting sand dunes sparse in vegetation is high, more coarser sand particles get deposited on the surfaces of the shifting sand dunes, being the lowest in fractal dimension. Fractal dimension of the sand materials on the surfaces of nebkhas is linearly related to mean particle size, sorting coefficient and some others. But no such correlation is found with the sand materials on the surfaces of shifting sand dunes. Fractal dimension of the sand materials in nebkhas, shifting sand dunes and sand transported near ground surface is positively related to their clay content at the 0.01 significance level, but negatively related to their content of sand grade of material in nebkhas and sand transported near ground surface; positively related to content of silt grade materials in sand dunes on bare flat land and sand transported near ground surface; negatively related to silt content at the 0.05 significance level in dustfall; but it has nothing to do with silt and sand contents on the surfaces of shifting sand dunes. 【Conclusion】 Particle size fractionation, movement mode, vegetation coverage, wind forces and terrain are the main causes responsible for the differentiation of characteristics of particle size and fractal dimension of the aeolian sand and dust materials in the oasis-desert ecotone.

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MAO Donglei, CAI Fuyan, FANG Dengxian, LEI Jiaqiang, LAI Fengbing, XUE Jie, WANG Xuemei. Fractal Characteristics of Grain Size of Sand and Dust in Aeolian Sand Movement in Cele Oasis-Desert Ecotone in Xinjiang, China[J]. Acta Pedologica Sinica,2018,55(1):88-99.

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History
  • Received:May 27,2017
  • Revised:August 31,2017
  • Adopted:September 19,2017
  • Online: October 30,2017
  • Published: