最新土壤胶体幻灯片

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1、土壤胶体第一节、土壤胶体及其特性Thesoilcontainsminuteparticlescalledsoilcolloids.Theyaresmallerthanonehundredth-thousandofamillimeter.Soilcolloidsarethinanddisc-like.Therearemineralaswellasorganicsoilcolloids.Mineralcolloidsareusuallyfoundtobefineparticlesofclayminerals.SimplifiedR

2、epresentationsofSilicateStructures硅氧四面体互相联结示意图TarbuckandLutgens,2003硅氧四面体联结成硅氧片,在平面上形成六角形网眼TarbuckandLutgens,2003TectosilicateTarbuckandLutgens,2003B、硅氧片和水铝片硅氧四面体和硅氧四面体之间通过共用氧原子互相联结就形成了硅氧片。每六个硅氧四面体相连就形成一个六边形网孔。铝氧八面体与铝氧八面体通过共用氧原子互相连接就形成了水铝片。硅氧片与铝氧片（水铝片）称为基本晶片。晶片与晶片按一

3、定方式堆叠就形成了粘土矿物的晶层。铝氧八面体结构示意图（2）主要的层状铝硅酸盐矿物高岭石(1:1型)蛭石与蒙脱石(2:1型)硅酸盐矿物的一般结构示意图ClayMineralsTherearethreemaingroupsofclayminerals:Kaolinite-alsoincludesdickiteandnacrite;formedbythedecompositionoforthoclasefeldspar(e.g.ingranite);kaolinistheprincipalconstituentinchinacla

4、y.Illite-alsoincludesglauconite(agreenclaysand)andarethecommonestclayminerals;formedbythedecompositionofsomemicasandfeldspars;predominantinmarineclaysandshales.Smectitesormontmorillonites-alsoincludesbentoniteandvermiculite;formedbythealterationofmaficigneousrocksri

5、chinCaandMg;weaklinkagebycations(e.g.Na+,Ca++)resultsinhighswelling/shrinkingpotentialClayMineralsarePhyllosilicatesAllhavelayersofSitetrahedraandlayersofAl,Fe,Mgoctahedra,similartogibbsiteorbruciteSEMviewofclaySitetrahedralandAloctahedralsheetsformedbysharingoxygen

6、moleculesClayMineralsThekaoliniteclaysare1:1phyllosilicatesThemontmorilloniteandilliteclaysare2:1phyllosilicates1:1silicateclay(kandite)2:1silicateclay(smectite&vermiculite)1:1and2:1ClayMinerals高岭石单位晶层由一层硅氧片和一层铝氧片构成，故称1：1型矿物。晶层之间以氢键连接，联结力强。塑性、粘结性、粘着性、膨胀性很弱。对

7、水和阳离子的吸附力弱，CEC=3-15cmol(+)/kg。主要存在于风化程度较高的土壤中。KaoliniteAl2Si2O5(OH)2Kaoliniteclayshavelongbeenusedinthecera