| 粉尘颗粒的形成机制与影响因素 |
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| 引用本文： | 宁波,秦小光,穆燕,殷志强.粉尘颗粒的形成机制与影响因素[J].第四纪研究,2008,28(5):939-948. |
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| 作者姓名： | 宁波 秦小光 穆燕 殷志强 |
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| 作者单位： | 中国科学院地质与地球物理研究所,北京,100029 |
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| 摘 要： | 通过测定沉积物粒度来获取环境信息已经成为环境变化研究的常规手段之一,多组分分离的方法也逐渐被广泛采用,但对于粒度分布中不同组分的成因存在着不同的看法。Alfaro的碰撞理论认为当母质所遭受的碰撞能量大于母质中集合体的内聚力时,能够产生与之对应的特征组分,即特定的风速能量决定了特定组分的形成。为了对Alfaro碰撞理论进行论证检验,研究选择屏蔽了搬运分选过程、纯经机械碰撞形成的岩石碎屑和粮食表面附着物,进行粒度分析。分析发现:1)不论无机质组成的岩石还是有机质组成的粮食,其颗粒粒径主要受控于母质成分,且粒度分布均具有与种类密切相关的特征。2)虽然少部分物质的粒度分布也存在Alfaro风洞实验中出现的中值粒径较稳定的组分,但其碰撞理论很难解释大量的不相符现象和各种物质种内差异小于种间差异等现象。证明了粉尘颗粒的粒径与其物质成分特点存在密切联系,而与外界碰撞过程没有直接对应关系,能量碰撞作用并不能直接导致粉尘颗粒优势组分的形成。因此,本研究认为形成粉尘不同粒度组分的影响因素是多方面的,其中风力(能量)只是其中之一,起尘区和降尘区的大气动力条件、粉尘在搬运过程中的分选作用以及粉尘的形成母质性质和环境都是影响粉尘粒径多组分特征的重要因素。
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| 关 键 词： | 岩石碎屑 粮食表面附着物 多组分粒度 粉尘颗粒形成 Alfaro碰撞能量理论 |
| 收稿时间： | 2007-11-30 |
| 修稿时间： | 2008-03-13 |
FORMATION MECHANISM AND INFLUENCING FACTORS OF DUST |
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| Ning Bo,Qin Xiaoguang,Mu Yan,Yin Zhiqiang.FORMATION MECHANISM AND INFLUENCING FACTORS OF DUST[J].Quaternary Sciences,2008,28(5):939-948. |
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| Authors: | Ning Bo Qin Xiaoguang Mu Yan Yin Zhiqiang |
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| Institution: | Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 |
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| Abstract: | This paper mainly studies the grain size distribution of crop surface attachments and rock debris produced by the mechanical collision process to verify the Alfaro's collision energy theory of windblown dust's multimode.Measuring sediment grain size has become the conventional method to obtain environmental information on climate change.The approach of separation of multi-components is gradually widely used.However,there are different views about the cause of different components.Alfaro's collision theory says that when the energy received by the parent material is greater than the energy of aggregate cohesion,it can produce corresponding characteristic components,i.e.,specific wind energy decides the formation of specific component.In order to the verify Alfaro's collision theory,we analyzed rock debris and crop surface attachments that are purely formed by mechanical collision.Fourteen rocks and nine crops including granite,lava,quartz-syenite,amphibolites,orthoclase-granites,metamorphic quartz fine sandstone,volcanic tuff,sandstone,metamorphic shale,shale,limestone,quartz-sandstone,quartz,calcite and rice,sticky rice,brown rice,barley,buckwheat,millet,broomcorn,corn,and wheat were analyzed.The rocks were from Beidaihe and Huailai in Hebei Province and the crops were from common commodity markets.We also used some loess samples from Xifeng in Gansu and Lingshan in Beijing,sand dust from Beijing,slope material from Yangyuan in Shanxi,surface layer sediment in Henan Sanmenxia reservoir,and river sands in Huanghe River running through Henan Mangshan.To acquire enough granules,we hammered at rocks in clean containers until 0.2g debris of less than 450μm were obtained.It was then added into 100ml de-ionized water.For crops,they were washed in de-ionized water repeatedly to get 100ml suspensions.0.2g crop powder was added into 100ml de-ionized water directly.For other sample,0.2g of each was boiled in a beaker which contains 10ml 10% peroxide,10ml 10% dilute hydrochloric acid and adequate de-ionized water until no bubble is flashed,and it was then also added into 100ml de-ionized water.Every prepared sample was allowed to stand for 24 hours.After that 10ml 0.05mol/L(NaPO3)6 solution was added to it and vibrated on ultrasonic cleaner for 10minutes.Finally,all samples were measured on Mastersizer 2000 laser particle analyzer.Analytical results showed that:1)The grain size was mainly controlled by the parent material composition and the granule size distributions are all closely related to the types and characteristics of the parent material;2)Although a small portion of the granule size distribution resembles the stable components the Alfaro wind tunnel test obtained,the collision theory can hardly explain the phenomenon that the difference within the same kind is less than that between various kinds of crops.We thus believe that the size of dust particles is closely related to the material components but is not directly related collision energy.Therefore,this study suggests that the dust grain size is controlled by many factors,which may include the wind energy,the atmospheric dynamic conditions both the forming and falling areas,the sorting role during the process of transit,the properties of parent material as well as the environmental factors. |
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| Keywords: | granule size distribution Alfaro's collision energy theory multimode multi-component |
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