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Spatial-temporal variance of reclamation soil physical and chemical character in opencast mine region

By Micheal Carroll,2014-02-18 22:22
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Spatial-temporal variance of reclamation soil physical and chemical character in opencast mine regionof,OF,Soil,and,soil

    Spatial-temporal variance of reclamation

    soil physical and chemical character in

    opencast mine region

    JOURNALOFCOALSCIENCE&ENGINEERING

    (CHINA)DOIl0.1007s12404-009-0411-3

    PP399-403Vo1.15No.4Dec.2009

    Spatialtemporalvariance0freclamationsoilphysicalandchemical

    CharacterinopencastmlnereRmnl???干

    HuYe.cLIXin-ju,FANGYu.dong.,LIUXue.ran,ZHONGWei-jing

    (1.SchoolofLandSciencesandTechnology,ChinaUniversityofGeosciences,Beijing100083,China;2.CollegeofRe

    sourcesandEnvironment,ShandongAgriculturalUniversity,Tai'an271018,China;3.NationalNaturalScienceFounda?

    tionofChina,Beijing100085,China)

    AbstractInordertostudytheeffectsofsoiIcompaction.andsoiIphysicalandchemicaI characterjsticsafterIandreclamation,selectedlandsthatwerereclaimedafter1,2,3,4, and5a,respectively,intheMajiataMineoftheShendongOpenPit;testedtheeffectsof soiIcompaction;andcollectedsoilsamplesfr0m5differentdepths,whichare0-7.62, 7.62-15.24,15.24~22.86,22.86-30.48,and30.48-38.10cm,respectively~Theresults showthat:(1)LandreclamationIeadstosoiIcompaction.TheIowesteffectofsoiIcom

    pactionisinthetopIayerandthehighestoneatthedepthof20-30cm:(Thebulkden- sityofreclaimedsollishigherthanthatofundisturbedsoil;thisdeclineswiththereclama- tionandnearlyreachestheIevelofundisturbedsoiIafter5yearreclamation;@Thecon-

    tentofreclaimedsoilnutrientsjsIowerthanthatofundisturbedsoil.Thelowestonejsin thesoiIdumpingsite.whichreachestheIeveIofundisturbedsoilafter5yearreclamation;

    ?ThepHvalueofreclaimedsoiIisIowerthanthatofundisturbedsoil.Thehighestoneis

    inthesoiIdumpingsite;thisdeclineswiththereclamation. Keywordsopencast,reclaimedsoil,soilcharacteristics,spatialtemporalvariation lntr0ductiOn

    Atpresent.thelandsurfacesubsidenceofChina incoalminingareascausesthetotaldestructionof over400millionhm.andtheamountstillincreasesat arateof3.3-4.7millionhmeveryyearfHueta1.. 2005).ThelOSSoflandcausedbytheexcavationof opencastminesaddsupto75millionhm:therefore. thetaskofChina'slandreclamationisarduous.States havestrengthenedtheworkof1andreclamationsince thepromulgationandimplementationoftheLand ManagementLawf1986)and,especially,theen

    forcementofthenewLandManagementLawf1999). Landreclamation,animportantmeasuretobalance farmlandshasbeenawidespreadconcerninthecom

    munity.

    However,alargemajorityofsoilcharacteristics changeduetothedistributionofsoilintheprocessof landreclamation.Avarietyofengineeringmeasures thatareimposedintheprocessofreconstructionlead toagreatchangeinthesoilbulkdensity:thebulk densityofreconstructedsoilisalmost1.5-1.8g/cm whilethatofnaturalsoilisusually1.35-1.53g/cm (Pottereta1.,1988;Cheneta1.,1999;Wangeta1., l999;BianandZhang.2000;Hueta1.,2002;Wueta1., 2002;Suneta1.,2003;Zhangeta1.,2003;Bian,2004; Zhangeta1..2004);thesoilporosityissmaller,the infiltrationrateislessthanthatofagriculturalsoil.and

thesoilmoistureishigher(Gueta1..2000;Sunetal

    2003;Zhangeta1..2003).Reclaimedsoilisgenerally Received:26June2008

    SupposedbytheChinaPostdoctoralScienceFoundationofChina(20060400532,2006DS0

    8018)

    Correspondingauthor:LiXinju

    Tel:865388246203,Email:lxj09ll@126.tom

    .

    1ourxlalol'CoalScience&EngineeringfChina, lOwinorganicmatter,nitrogen.andrapidlyavailable phosphorus,andrichinpotassiumandrapidlyavail

    ablepotassium;besides,itspHvalueisgreaterthan8. tooalkaline(Hu,1997;AkalaandLal,2001;Yueta1., 2002;Shuklaeta1.,2004).Nevertheless,thereisrare researchonthespatia1.temporalvariationofsoilchar. acteristics,whichhassomethingtodowiththesoiluse andmeansofimprovement.We'1ltakethereclaimed soilofanopencastmineasanexampleandexplore thespatia1.temporalvarianceregulationviathe changesinsoilcharacteristicsinvariousreclamation yearsinordertoeventuallyprovideareferenceforthe useofreclaimedsoilanditsimprovement.

    10verviewofstudyarea

    TheMajiataMineoftheShendongOpencast

    ownedbytheShenhuaGroup.locatedinYiniinhuoluo County,JlanmuluntownOrdoxcityofInnerMon.

    goliaAutonomousRegion.ischosenasasample.The mineof4.94kmwasconstructedstartinginl987. andcompletedandputintoproductionin1990.The mineisexploitedfromthesouthtothenorth.andits

    productioncapacitywasdesignedtobe1milliont/a forthefirsttwoyears.1.8milliont/aforthethirdyear, and2milliont/aforthefollowingyears.Exploitby meansofdumpingthestrippers,combinedwithmin

    ingreclamation,directlybackfillingcoalminingwith thestrippingtopsoilandgravels,elevatingtheheight ofreclaimedlandbydesign.

    Underthissituation,toensureplantgrowthafter landreclamationtheapproachofseparatepeelingand separatearrangementshouldbetakenintoconsidera

    tionintheprocessofexploiting.Firstofall,placethe lowerpartofrockatthebottom.followedbysandand gravellayersinthecentralpart,andtopsoillayersat thetop.Inordertoreducethecoefficientof1ooseness. compactlayerbylayerwhenarrangingseparately. Thenlevelthegroundwithasmallbulldozerora patchofartificialstripperaftertheheightreachesthe standard,sothatthewholedumpcanachievethefor

    mationaftertheheightreachesthestandard,andthe wholesoildumpingsitecanachievethesameeleva

    tioninacertainrange.Lastly,plantadsurgens,clover, andotherforagesinreclaimed1and.

    2CollectionandanalysisofsoiIsample

    TheMajiataminingareabegantoreclaimlandifl 2002andhadformedfivereclaimedlandsatdifferent timesofreclamationby2006.Wemeasuredthedegree ofsoilcompactionineachlandwiththeAmerican DICKEY_iohnatfivelevels:0-7.62em(3inches), 7.62-15.24cmf6inches),15.24-22.86cm(9inches), 22.86-30.48cmf12inches),and30.48-38.10cmr15

    inches).Theauthorsmeasured5samplepointsof blossomshapeineachlayer,andthencalculatedthe average;meanwhile,diggingthesoilprofileto40cm, collectedsoiIsamplesaccordingtotheIeve1.Fig.1 showshowthesamplepointsdistribute.Analyzedthe indoorsoilorganicmatter,totalNeffectiveP.quick

    impactK,moisturecontent,andbulkdensity. Fig.1Distributionofsoilsamplehits

    2.1Spatialtemporal

    properties

    2.1.1Spatialtemporal

    compaction

    variationofsoilphysical

    variationofreclaimedsoil

    Fig-2fa)showsthesoilcompactiondifferences, 1year-reclamationofthelandsurfaceisthesmaller firms,followedby2yearsreclamation.1essthallthat ofthedestructionoflandinthetwoyears.ThesoiI after3yearreclamationislarger,andthesoildumping siteisthelargest.Thereasonisthatthenewlyre. claimedlandsurfaceisgenerallyloose;thecorre

    spondingsoilcompactionissmaller,sointheprocess oflanduse.wateringandotheragriculturalmeasures increasedsoilcompaction.

    Theverticalprofilechangesofthesoilbetraya commontrend:withthedeepeningofthedepthofthe soil,soilcompactionincreasesbylargeamounts,with the1argestreaching3-4layers.andwiththereclama. tion.thevariationinverticaldirectiondiminishes.

    2.1.2Spatialtemporalvariationofsoilbulkdensity Variationsinthetopsoilbulkdensityalmostcon

    fiITnthatofsoilcompaction.Fig.2(b1:thelowestone isintheundisturbedlandandthehighestoneinland after1.yearreclamation;thisishigherthanthatofthe dumpingsite,graduallydiminisheswiththereclama

    tion.andisclosetothelevelofundisturbedat5.year reclamation.

    Seenfromtheverticalprofile.thebulkdensityof thetopsoilisthelargestlayer2'sisthelowest.and 1ayer3'sdidnotchange.Thecoefficientofvariation ofthesoi1bulkdensitywasgraduallyreducedin1-3 years'reclamationandhadanincreasingtrendinthe HUYccuicta1.Spatial[Clllt301'alVarianceofrecla1111!l1?!!!!14()

    following4hand5myears.

    2.1.3Spatialtemporalvariationofsoilmoisture Fig.2(c)showsthesurfacesoilmoistureraisedas 38.10

    30.48

    g22.86

    l5.24

    0

    7.62

    0

    

    O

    38

    30

    Soilcompaction(kPa)

    (a)

    05O0.050.100.150.2O0.250-3O SoiltotalN(g/kg)

    (e)

    38.1O

    30.48

    22.86

    15.24

    7.62

    0

    thereclamationwenton,buttherewaslittledifference

    inthepreviousyearsandthemajorchangeshappened

    inthe5thyear

    ,

    hasoverpassnodamagedland. 38.1O

    30.48

    22.86

    15.24

    7.62

    0

    1451.551.651.751.851.95 Soilbulkdensity(g/cm) (b)

    Soilorganicmatter(g/kg) (d)

    2.53.54.55.56.57.5

    SoilavailableP(mg/kg) (f)

    SoilavailableK(mg/kg)

(g)

    Fig.2Verticaldistributionsofsoilcompaction,bulkdensity,watercontent,organicmatter,

    totalN,availablePandavailableK

    Seenfromthesoil'sverticalprofiles.mesoil moistureofthedumpingsiteisthesmallestandthatof undisturbedisthehighest.nearlyreachingthelevelof undisturbedlandatthe5myear.Thevariationinthe vertica1directionhasitsmaximuminthe4"year (85.3l%)andminimuminthe5".year,only14.01%; besides.thevariationatreclamationOf1or2years wasalsolarger,morethan50%.Atthesametime. fromFig.2fc1itisclearthatthemoistureoflevel2is outstandingduringthevariousreclamationyears. 2.2Spatia1.temporalvariationofreclaimedsoil nutrient

    2.2.ISpatia1.temporalvariationofsoilorganicmatter ItcanbeseenfromFig.2(d)thattheorganicmat

    terofthedumpingsiteisthelowestineachlayer.The surfacesoil'sorganicmatterincreaseswiththerec

    lamationbeingcarriedout:inparticular,theorganic mattercontentofthe5.yearreclaimedlandisoversix timesmorethanthatofthedumpingsite.Andtheor- ganicmattercontentofthefiveyearreclaimedlandis

    slightlyhigherthanthatoftheundamagedland.Inthe ve~ica1profile.thedumpingsiteandtheundisturbed land'snutrientschangedalittleandincreasedwiththe reclamation;thecoefficientofvariationofthesoil organicmatterreached76.65%inthe4yearofrec

    lamation.butin5yearthatinthesoilvertica1profile alsoinline(23.23%).Themainreasonisiustthatthe

variabilityofthesoilmixturewassmallatthebegin

    ningofthelandreclamation.whilewithincreasinguse, (_g0一暑?00

    )qldQ

    1u_)q1Q0

    7

    3)若口

    uI3)a?0

    lIlno

    402.]ouma]ol,CoalScience&Engineering(China, thesoillevelgraduallydevelopedandthethediffer

    encebetweenthevarious1evelsgraduallybecamesig. nificant.Fig.2rd1alsoshowsthecommontrend:the contentoforganicmatterinthesurfaceishigherthan thatbelowthesurfacelevel,withthepeakappearing inlevel3(22.86cm).Thisphenomenonmaybeex. plainedasfollows:theplantrootsmainlydistributed inthislayerarecoupledwiththehighsoilcompaction 0fthislayer(ascanbeseenlater);additionally,the nutrientsdecomposeslowlytheresothenutrientsac. cumulateinthelayer.

    2.2.2Spatialtemporalvariationofsoi1totalN

    Fig.2fe1showsthatthecontentsoftotalNinall thereclaimedsoilaremuchlowerthanthatofundis. turbedland,andithasanincreasingtrend,themaxi. mumappearedinthefifthyearandtheminimumin the2".year.ThecontentoftotaINinthetopsoilthatis reclaimedfor3yearswasevenlowerthanthatofthe soildumpingsitebecausethevegetationonthere. claimedsoilconsumesapartofNandduetothelack

ofmeasuresoffertilizing.

    Tlhedistributionoftheentireprofile(Fig.2(e))il- lustratesthattheaverageofundisturbedlandislargest (0.12g/kg),followedbythatof5-year-reclaimedland (0.11g/l(g).ThecontentofNfollowsthetrend:the longerthereclamationperiod.thelargerthecontent andthegreaterthechangesinverticaldirection.Seen fromFig.2(e1,indistributionofvariouslevelsofsoil thecontentinlayers3-4(22.86-30.48cm)where rootsconcernedshowsanincreasingtrendasthesame withsoilnutrient.

    2.2.3SpatialtemporalvariationofsoilavailableP ThecontentofavailablePinthetopsoilincreases withthereclamation,Fig.2(f),reaching2.36times moreinthefiRhyear.Thereisasimilartrendinthe averageofthevariouslevelsandsurfacesoil.From theviewofthedifferentsoillevel'sdegreeofvariation. italsoincreaseswiththereclamation.Thecontent reachedthelevelofundisturbedlandinthe4recla

    mationyearbutdeclinedsharplyinthefifthyear. TheverticaldistributionoftheeffectivePisthe sameasthatofthesoilorganicmatter,andthetotalN alsohasaregulation:asuddenincreasecameuDbe

    tween2-3layersforthesamereasonsreferencedpre

    viously.

    2.2.4SpatialtemporalvariationofsoilavailableK SeenfromFig-2(g),thesoildumpingsitehasa minimumofavailableK.andnearlynochangeinthe profiletookplace.Exceptforthehigherquick-impact

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