| Soil nanoparticles not only carry the information of soil mineral evolution, but also directly affect the physical and chemical properties of the soil. However, due to the restrictions of the means of nano-particle separation, currently characteristics of nanoparticles of clay mineral need to be further explored. In this study, we choose the vertical zonal soils (meadow soil, mountain yellow-brown soil, mountain yellow-red soil, brown-red soil) from high altitude to low altitude of Jiugong mountain in Hubei Province as the materials, separate them to different size soil fractions (450-2000,100-450,25-100and1-25nm), combine with modern analytical techniques, to study the characteristics of material composition and evolution of clay mineral of vertical zonal soil nanoparticles. The results indicate that:(1) It is obvious that the changes of soil clay minerals in Jiugong mountain along with vertical. With the lower of the altitude, the content of kaolinite increased gradually, and the content of1.4nm mineral,1.2nm mixed layer mineral and gibbsite reduced. At high altitude (>1266m), the contents of amorphous and complexing iron and aluminum are higher. And at low (<95m), it is given priority to free iron and aluminum, and it is easy to form the between hydroxyl vermiculite.(2) At different altitude of soil, with the increase of depth profile,1.4nm minerals and illite in soil decreases. And at higher altitude of soil, with the deepening of soil profile, the content of kaolinite reduce, but the conntent of gibbsite increased. At lower elevation of soil, the contents of gibbsite and kaolinite have a contrast rule.(3) With decrease of the size of inorganic soil particles, the morphology and crystal get bad of clay mineral, and they have an obvious reunion phenomenon and a big specific surface area, and their peaks’intensity of XRD diffraction are decrease. Inorganic soil nanoparticles (25-100and1-25nm) contain a hexagonal shape, round, sheet, strip and small globular material. XRD and FTIR spectra show that inorganic particles at size of<2000,450-2000,2000-450and25-100nm contain kaolinite, illite and quartz. With the lower of the altitude, the content of gibbsite reduce, but goethite and hematite contents increase. At four sizes soil particle, the changes of clay minerals in25-100nm inorganic particles are obvious than larger size (<2000,450-2000and100-2000nm) soil particles along with the variation of altitude and soil depth. (4) It is much complex of composition and morphology at different sizes of A layer of soil organic-inorganic complex particles than inorganic particles, and their average particle sizes of determination are bigger than of the inorganic soil, and their specific surface area are smaller than inorganic soil. FTIR spectra showed that it is same that the clay minerals of A layer of organic-inorganic complex particles at the size of450-2000,100-450and25-100nm with inorganic particles. But in A layer of organic-inorganic composite and inorganic particles of meadow soil in size of1-25nm, it is given priority to difficult to weathering of quartz and illite, which is2:1type of clay mineral. While in A layer of inorganinc brown-red loam at lower altitude, it is given priority to kaolinite with1:1type, and may contain goethite and hematite. |
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