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1、土壤化學題庫1.Explainhowlayerchargeinfluencesthefollowinglayersilicateproperties:(a)Interlayerbonds(b)Crystalsize(c)Swelling(d)Surfacearea(e)cspacing(f)Exchangeabilityofadsorbedcations2.Writethehalf-unit-cellformulaforamontmorillonitemineralwithalayerchargeof0.3,with90%ofthesubst
2、itutionintheoctahedrallayer2+3+(MgforAl)and10%ofthesubstitutioninthetetrahedrallayer3+4++(AlforSi).ThesaturatingcationisNa.Drawadiagramofthis2+3+4++mineral,indicatingthepositionofMg,Al,SiandNa?3.Whatismeantbythezeropointofcharge?WhatarethefunctionalgroupsresponsibleforpH-de
3、pendentchargeinsoil?4.AnacidicpesticideofpK5isbeingappliedtosoilsofagivenregion.Wouldleachingbegreatestforsoilsof(a)pH>5?(b)pH6to8?(c)pH<5?Why?-15.AsoilofpH5.5retains60mmol(+)kgofexchangeablebasesandhas-1aCECatpH7of80mmol(+)kg:(a)Whatisitspercentbasesolution?(b)Whatisitsapp
4、roximateCECatpH5.5?-16.Anirrigationwatercontains750mgLsolublesalts.Ifusedatanaverageleachingfractionof0.15,whatwouldbetheaverageECofthedrainagewaterleavingthebottomofthecroprootzone?7.A30-cmdepthofsurfacesoilcontains28%exchangeablesodiumand-1hasaCECof150mmol(+)kg.Howmanyton
5、nesperhectareofsulfurwillberequiredtoloweritsESPto5%?-1+8.Avermiculitesurfacesoilhastheabilitytofix25mmolkgofKor+-1NH4.Whatrateof(NH4)2SO4orKClfertilizer(inkgha)wouldberequiretosaturatethisfixationcapacityfora30-cmdepthofsoil?+9.ForaCECprocedurethatusesNaastheindexcation,H2
6、O/ethanolas2+thewashsolvent,andMgasthedisplacingcation,discusstheeffectofeachofthefollowingonCECmeasurements:(a)Hydrolysisduetoexcesswashing(b)Presenceoflargeamountsoflimeorgypsuminthesoil(c)Incompleteindex-cationsaturation+(d)PrecipitationofaninsolubleNasaltintheethanol2+(
7、e)IncompleteremovaloftheindexcationbyMg10.Tocalculateb(maximumamountofadsorbate)andK(affinityconstant)ofapesticidewithLangmuirequationfromthedata:Each25mL20,40,60,80,100mg/Lrespectivelyaddtoeach0.5gmsoil,andfinalsolutioncocentrationrespectivelyis0.4,2,20,35,50mg/L.11.Whatki
8、ndsoffunctiongroupsorsegmentscontributetothehydrophobicityofsoilorganicmatters?Wha