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(DOC) Chemical_2

By Bernard Black,2014-07-22 02:50
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Chemical_2

    Chemical

CHINESEJOURNALOFGEOCHEMISTRVo1.

    ;25(Supp1.)2006

    ;Belemnite(PDB).FieldinvestigationswereconductedinbothNorthandSouthChina,whicharestarklydifferentinbothannual

    ;precipitation(AP)andannualtemperature(AT).The80ofwaterinthenorthernregionrangesfrom5%oto.10%owitha

    ;decliningtrendnortheastwards,while8”CofDICinwatervariesbetween

    3%oand10‰withanincreasingtrend.Ontheother

    ;hand,8OintheshellsofC.flumineafromtheregionrangesfrom

    6%oto—l0‰,

    ;while8”Cfrom7‰and.12‰.111egeneral

    ;trendofbothisotopicsignaturesfollowsthatofthewater,althoughtheirfluctuationsmaynotbenecessaftlycompatible.Forwaters

    ;inthesouthernregion,8Ovariesbetween5‰and

    8%o.8”CofDICbetween,3%oand14%o.Fortheshells.8Oranges

    ;from5%oto10%0.and8Cfrom

    6%0tol2%o.Theisotopiccompositionsdemonstrateanoticeabletrendforneithershellsnor

    ;theenvironmentalwater.0urresultsindicatethattheshellsfollowthewaterin8

Othatisindicativeoftheregionalclimate

    ;changes.Whereas8”CindicatesthesourceofthecarbonandquantitativeprimaryproductivityfPP1:8”CislowwherethePPis

    ;high.Thenorthernregiondemonstratesprominentvariationsin8Oand8”CtrendsbecausetheyarehighinbomATandPP.

    ;Incontrast.thesouthernregionchangeslittleinATandPP.theisotopesignaturesinbothshellsandwaterhavenonoticeablegeneral

    ;changes.OurstudysuggeststhatC.flumineahasindeedadjustedshell’sisotop

    icsignaturesintheadaptationtotheenvironment

    ;changes.Studyoftheshellgeochemistry,therefore.canshedlightontheadaptabilityofthelivingorganisms.

    ;KeywordsCorbiculafluminea;oxygenisotope;carbonisotope;adaptation;globalchange

    ;ChemicalcompositionofwetprecipitationatadevelopingurbansiteinsoutheasternChina

    ;MiaoyunZHANG,ShijieWANG,FengchangWU,XianghongYUAN,YingZHANG

    ;StateKeyLaboratoryofEnvironmentalGeochemistry,InstituteofGeochemistry,ChineseAcademyofSciences,Gu~ang550002,China

    ;AcomprehensivestudyonthechemicalcompositionofwetprecipitationwascarriedoutfromJanuary2004toDecember2004at

    ;Jinhua,China.Allsampleswereanalyzedf0rpH,electricalconductivityand

majorions(F,C1’,N0’3,.504,l(.,N,Ca2,Mg

    ;andNH4).TheresultsshowedthatSO4isoneofthedominantanions,accountingfor66.1%ofthemeasuredanionsin

    ;precipitation.whileNH4~andCazaccountfor56.6%and33.4%ofthemeasuredcations.respectively.Eventhoughthe

    ;concentrationsof504andNO’werenothighrelativetothoseinthenorthernareasofchina.rainwaterinthestudiedareais

    ;typicallyacidicwithavolumeweightedmeanpHof4.54duetothelackofne

    utralizationinprecipitation.Thefractionalacidity

    ;valuesuggestedthatabout76%ofacidwasneutralizedbyalkalineconstituents.Ontheotherhand.Hshowednosignificant

    ;correlationwithotherionicspecies.whichindicatesthatitsaciditymightbeattributedtothecomprehensiveeffectofallthe

    ;acidifyingandneutralizingionsratherthanonemajorioninprecipitation.AgoodcorrelationbetweenCa2andM,aswellas

    ;betweenNaandC1’.indicatedtheseionsarecommonlyofcrustalandmarineorigin.respectively.0therrelativelygoodcorrelations

    ;wereobservedbetweenNH4+and504,

    ;Ca2and504,Mgand504,MgandN0’3,andMgandC1.Theseresultswere

    ;attributedtotheatmosphericchemicalreactionsoftheacidsH,SO4,HNOandHClwithalkalinecompoundssuchasNHand/or

    ;carbonatematerials.HighenrichmentfactorofmarinesourceforSOd.Ca2an

dl(indicatedthatlargeamountsoftheseionscame

    ;mainlyfromanonmarinesource.Similarly,ahighenrichmentfactorofsoilforS042.

    ;NOandC1.alsosuggestedthatmostofthese

    ;ionsdidnotcomefromsoilsource.ThemainsourceofCaandKisbelievedtobetheEarth.scrust.andthemainsourceofSO4

    ;andNO’isbelievedtobeduetoanthropogenicactivitiesintheregionstudied.Seasaltfraction.crustfractionandanthropogenic

    ;sourcefractionwerefurtherestimated.CrustfractionsofCazaccountfor99.4%.andanthropogenic.sourcefractionofSO4z’and

    ;NO’accountfor98.8%and99.9%.respectively.

    ;Keywordschemicalcomposition;neutralization;chemicalcomposition;precipitation

    ;AssessmentofnutrientsourcesandpaleoproductivityduringthepastcenturyinLonggan

    ;Lake,middlereachesofYangtzeRiver,China

    ;YanhongWU.SuminWANG

    ;KeyLaboratoryofLakeSedimentationandEnvironment,NanjingInstituteofGeographyandLimnology,ChineseAcademyofSciences,Nanjing210008,China

    ;A63

    cmsedimentcoredocumentsthattheconcentrationsofnutrientsinsediment,su

chasorganiccarbon,nitrogenandphosphorous,

    ;continuallyincreasedduringthelastcenturyinLongganLake,middlereachesoftheYangtzeRiver,China.C/Nratioand8?C.

    ;rg

    ;revealedthatorganicmatterinthesedimentderivedmainlyfromaquaticandterrestrialsourcesisaminorcontributor.Excess

    ;

    ;

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