我国土壤资源的现状及特点 (50).ppt

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1、8.1 The Definition and Structure of Soil Colloids8.1 土壤胶体的概念及构造Soil colloidal chemistry focuses on the tiniest solid particles in soil science,but it is closely related to the macroscopic processes of soil.Surface charges of soil colloids&The ability of soil to provide nutrients;The adsorption of an

2、ions and cations by soil colloids&Bioavailability of nutrients and contaminants;Coagulation and dispersion of soil colloids&Soil pore structure and water conductivity.Soil colloids and soil adsorptionSoil particles of different sizes:from micro to macro GoethiteHumic acidKaoliniteEscherichia coliAgg

3、rgateStructure Soild 2 mr1 nm100 nm1 m10 m1 mm10 nm100 m10 mmIn soil science,particles that are less than 2 microns or 0.002 millimeters in diameter are called colloids.If soil colloids are dispersed in an aqueous solution,they are called soil colloidal suspension.Definition of soil colloidsThe thic

4、kness of clay particles(2 m)is usually less than 100 nm in at least one dimension,and thus they act like colloids.KaoliniteMicaMontmorilloniteForm The nature and properties of soils,global edition,p349 Electron microscopic images of common soil colloidsSoil colloidal suspensionColloidal particleSoil

5、 solutionPotential-determining ion layerCompensation ion layerDiffusion layerInactive layerColloidal nucleusElectric double layer Structure of soil colloidSurface chargesCationAnion Inactive layerDiffusion layerd 2 m Schematic diagram of a soil colloidPotential-determining ion layerColloidal nucleusCompenation ion layerSoil bulk solution谢谢THANK YOU