The Characteristics Of Clay Mineral In Particles Of Four Zonal Soils

Clay mineral is the important component of the soil,and also constitutes an important material of the clay soil. Type of mineral composition and chemical properties of the nanoparticles(< 100 nm) in different particles carries the information of soil mineral evolution. In this study, four typical zonal soils(Latosol, Red soil, Yellow cinnamon soil, Brown soil) were chose as material, divided them to different size of fractions(450-2000, 100-450, 25-100 and 1-25 nm), combined with modern analytical techniques(XRD, SEM, TG) to study mineral evolution and material change characteristics of soil particles, provide the basis and reference for the occurrence and evolution theory on zonal soil. The results are as follows:(1) With the latitude increases, gibbsite and kaolinite decreased, but 1.4 nm minerial and illite increased in the four soils. The main clay mineral in Latosol was kaolinite, followed by 1.4 nm intergrade mineral, goethite and quartz. The clay minerals of Red soil were kaolinite, illite, quartz and goethite. Yellow cinnamon soil and brown soil have the similar clay mineral composition, and the illite and vermiculite are the main components, and the quartz and goethite as well existed.(2) With the size of the soil particles decreasing, the mineral species were reduced. The quartz and gibbsite were disappeared and the intensity of 1.4 nm minerals were weak in 25-100 nm particles. The main clay mineral of nanoparticles of Latosol and Red soil(25-100 nm)was kaolinte, followed by trace dose of 1.4 nm transition minerals. The main clay minerals of nanoparticles of Yellow cinnamon soil and Brown soil were illite, followed by vermiculite and kaolinte.(3) With the size of soil particles decreasing, the content of iron oxide was increased and the content of silicon was increased. Silica, alumina, iron oxide among particles which accounts for around 90% of total element. The content of iron oxide of 25-100 nm particles was higher than large size particles and the molar ratios of Si O2 to Al2O3 and Si O2 to R2O3(Al2O3 + Fe2O3) was smaller.Comparing the same particle size of different soil found that iron oxide content of Latosol was higher than the other soils, while the proportion of silica content was lower. The molar ratios of Si O2 to Al2O3 of Latosol and red soil were lower than the other two soils. In addition to the ratio of(Feo/ Fet) of the Red soil increased with the particle size decreased, the ratio of(Feo/ Fet) of the other three soils while increased at first and then reduced with particle size reduced. The ratios of(Feo/ Fet) were higher and ratios of(Fep/ Feo) were lower in Latosol and Red than those in other soils.(4) Different size particles have different morphology. With the size of particle decreasing, the reunion phenomenon was more obvious in 25-100 nm particles. The morphology containing flocculent, granular and sheet-like material. The thermostability had changed with the particle size decreased. According as the decreasing of particle size, Zeta potential of Latosol and Yellow cinnamon soil while increased at first and then reduced.