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ActaOc删noh*F州Sinica.
VolPublishedbyChinaOceanPrcssISSN0253.
505XNitrogenformsanddecompositionoforganiccarboninthesouthernBohaiSeacoresediments.
SongJinming'一.
MaHongbo.
.
Li】Xiaoxial,2(Rece扎edNcyoember2,2001;acceptedI)etembe,2.
2001Abstract—————Studyonformcharacteristicsofnitrogenini11.
1ie"sedimentsistheprinmrymethodtore—searchitsbiogm,chemicalcyclingandnitrogenformcharacteristicsincoresedimentsCallreflecttheprocessandresultsofearlydlagene.
sisinacertaindegreeInthispapeac.
SequentialextractionprocaasinnaturalgrainsizewasL】sedforstudyingtheexistentformsofuitrogeninfivecoresedimentsofthtsouth—ernBahalseaforthefirsttimeNitrogenwasdividedintotwopgltS——transferableandfixedbasedonwbethetitc,auldbeextractedbythereagent.
Distributiotlsandearlydiageno*isoftraMerablenitrogenformsinthesouthernBohaiSeawereresearcheclintegratedlyResultsindicatethatIEFNandOSF—Narepredominantfommintransferablepartinthestudiedcokesediments.
Contentsofdifferentnitrogenfom,.
svarydifferentlywithdepth.
andhavediffereradiageue4sproems岬itiouc.
tlt4atlttoforgamcnitrogen(ON)and(rareah}ut15.
51x103a1and4.
79*103arespectively,andthede.
compositioncontentofbiogcnicelementsC,N.
P,SihasthesequenceN2>P>C>SiOC/TN(simplifiedasC/Ninthefollowing)ratioismuchlowerthanOC/ON.
whichindicatesthat蛳'dimentpreservesplentyofinorganicnitmgen(IN)and/orfixednitrogen.
andthedecrexseof(rJ/ONratiowithdepthisduetoONr…ationinsedirnents(}enerally,trausferablenitrogenaccountsformoreproportionofTNinthesur{aeelayerthaninthedeeplayero【旺Ⅱesediments.
whereas.
H疆nestabhfcaxasdnitrogencanactivateandb吼r讯etransferableunderappropriateenvirortrnent.
whichinducestheproportionoltrans—ferablenitrogeninTNinthedeeplayeri()healrac,stthe&RlrleⅫthatintbesurfacelayerKeywordsSouthemBahaiSea,coresediments,nitrogenfomB,decompositionoforganiccar&mINTRODUCTIoNMarinesedimentsarethemainpoolofnitrogeninmarineenvironment,andhavegreatsignificanceonnitrogencycling.
Mostpreviousresearchesonsedimentnitrogenwereconcen—tratedontotalnitrogen(7I'N),totalorganicnitrogen(ON)andtotalinorganicnitrogen(IN),*Thisstudy…supportedbytheNationalSelenceFoundationforOutstandiiNYoungScientistsofChinaundercontracrNo49925614andtheKnowled.
geInnovationPH碹rm"oftheChineseAcademyofSciencesundercontfactNoKZCXl一SW~0l08llnstitmedOceanology.
.
ChineseAcademyofScience!
s,Qingdao266071.
China2KeyLabofMarineEcology&Env2ronmentalSeletmes.
ChineseAcademyofSciences.
Qingdao266071.
ChinaSongJinmingetalinwhichsedimentsweregrindedaccordingtoacertainsizeandthenTN,ONandINweredetermined'l'hismethodisnecessaryforstudyingbackgroundvalueofnitrogeninsediments,butcain'tgivevaluableinfomlationaboutnitrogencyclingResearchesshowthatnotallnitro—geninsedimentscanbeinvolvedincyclitljg,ononehandbecauseofthedifferentcombination(incudngphysicalandchemical)intensitybetweennitrogenandsediment+andontheotherhandbecauseofthesedimentsizeeffectsuchthatbiggergrainsarenotliabletObecrashedeveninintenseenvironmentchange,andnitrogencontainedcan'tbereleased.
ThatmeansonlyasmallpartofnitrogeninsedimentsisinvolvedincyclinginnaturalgrainsizeTherefore,itisveryimportanttoresearchnitrogenforrncharacteristicsinnaturalgrainsizeinsedimentnitro—gencyclingstudy,yetithasnoquantitativeresearchinthisfieldAccordingly,thispaperisdevotedtostudyingnitrogenf01TncharacteristicsofthesouthernBohalSeasedimentsinnaturalgrainsizewithsequentialextractionprocess,anddecompositionconstantofON,(X;/TN(C/N)andOC/I'NratiochangeduringearlydiagenesisarediscussedatthesanletimeSamplingMATERIALSAND~正_r咖SSedimentsamplesweretakenbycoresamplerin5samplingsitesinthesouthemBohaiSeawithR/v心XueNo.
1inSeptemberl998.
ExceptforM912,whichwassampledwithinthedepthof100CTn.
other4siteswereabove200cnlandmostofwhichwereabout400cm.
Sam—pieswereseededinplasticbagimmediatelyaftersampling.
takenbacktolab.
anddriedunder60℃for12hours,thenmashedwithglassstickslightlytoretainitsnaturalgrainsize,andputintodesiccatortobeused(SongandLuo,2000).
ThesamplingsiteswereshowninFig.
1.
8()0011901y12n叫.
12l00.
E(_\/一.
@.
譬警,譬≯救、rV仉乏一7、Fig.
1SamplingsitesinthesouthernBohaiSeaDetermination1.
0gsedimentsampleWastakenaccurately,andpromotedRuttenburg'S(1992)SequenNformsanddecompositionofOCin:sedimcnts惶7tialExtractionProcesswasusedtodetermine")ntentsofnitrogenformsfourdifferentnitrogenforn_ls:ion—exchangeablefornl(IEF),carbonateform(CF),iron—nxanganeseoxidesform(I—M()F)andorganicmatter-sulfidefornl(OSF)werereceived,allofwhichweredefinedastransferablenitrogen.
Alkalinepotassiumpersulphateoxidationmethodwasusedt()determinetotalnitrogen(TN),andfixednitrogenwasgainedby7I'NminustransferahlenitrogenNitro—geninextractionliquidwasdeterminedwithspectrophotometer,inwhichNkh—Nwasoxi—dizedby划iumhypobromiteandN03一NwasreducedbyZnCAdeoxidationmeth'xt(Song,1997)Characteristicsofnitrogen如rtN$RESULTSANDDISCUSSIONSFigure2displaystheverticaldistributionsofnitrogenfornlsinfivesedimentcores.
andtheirgeochemicalcharacteristicsare/:kSf01]ows:(1)IEF—N:Theaveragecontents(越儋)ofIEF—Nin5coresediments&reM912(60.
36)M95(531.
14)>M3—7(417.
93)>M9—12(297.
58)>M6—5(271.
06)'rhediffer—eneeofOSF——Ncontentincoresedimentsreflectsdifferentsubstanceoriginanddifferentsedi—-mentenvironment.
Affectedbyterrestrialinput,OSF—NvalueofMl0一l,locatedinwesternshoreoftheBohaiBay,istwiceofM65,whichwasinthemiddleoftheBohaiBayGenearal—ly,()SF—NofM3—7,MlolandM9—12increaseswithdepth,indicatingthatdecompositionoforganicmattexweakenswithdepthOSF—NdistributionofⅣk5andM9—5doesnotshowob—viousregularity.
(5)TN:TNdistributionofMq—12,M95andM6—5displaysthesametrendwithdepth,firstlyincreasingremarkablyandthendecreasing,butwithdifferentchangedepths.
M95andM65reachthelTIaXatl00CITI,increasing88.
3%and216%respectively,indicatingthatearlydiagenesisofnitrogenisveryactiveandreduceswithdepth.
Italsocanbedrawnthatsedimentationspeedinthisareawasveryhigh.
OSF—Nin地12reachesitslnaxat25cm.
indicatingthatitsdiagenesisdepthismuchlowerthanM95andMm一1'rbedecreaseofTNindepthunder100ctnindicatesthatearlyterrestrialinputcontainslessnitrogenthantoday'sTNinM3.
IandMlo—ldisplayscomplexchangeandincreaseswithdepthgenerallyOCdecom加siti.
onn越earlydiagenesisinLR)vesedimentsDistributionofdifferentnitrogenforrnschangingwithdepthcanindicatethetransforma—tionprocessduringearlydiagenesisONchangewithdepthdisplaystherateandcourseofmin—eralizatkm.
andvariationofC/NandoC/oNratiocanindicatethecompositionoforganicmat—ter.
mineralizationcourseandorganicmatterreplenishmentrate(Andersonandsarmiento,1994).
Researchonthemcanprovidevaluahieinforelationaboutearlydiagenesis.
Decompositio"rateconstantofOCandON.
Itearlbedrawnfromtheverticaldis—tributionofnitrogenfornlsthatcontentsofOC,oN,BPandBSidecreaseremarkablywithinthedepthof0~10cm(SongandLLl.
,2000),indicatingthatorganicmatterdeoompositionmainlv()ccurredinsuffaccandsub—surface.
Decompositionrateconstantof()Ccanbeevaluatedbvitsdecrease(Hongetal,1996).
TakeM95asanexample,decompositionrateconstantof()C.
ON.
BPandBSicallbeestimated.
Itissupposedthat0cdecompositionisfirstdegreereaction,Zissedimentdepth(cnl),CoandZ0are0(2contentsindepthof0etnandZcnlre—130SongJinmingetalspectively,Kisdecompositionrateconstant(a.
1),andSissedimentatkmrate(cnl/a),thereisthefommlaasfollows:K=in(Co/C:)/(Z/S).
Accordingtothefommlaabove,thedecoInpo.
sitionrateconstantsofOC,ON,BPandBSiarecalculated(Table1)TaMeI.
DecrJmIxgltiort坤tc嘲sf鲫tsofC.
N.
P.
SiOC(%)ON(/*g咆)BP(ftg瞻)Ikqi(mg/gCu049377667187C10038334351179K*103(a一1)47891551251850831DecomtxldtionrsteSis0.
19qn/a.
zis10cmItiSdrawnthatthedecompositionrateconstantofClNjsl5.
51*10—3a一1.
andthecon—stantsofbiogenieelementshavethefollowingsequence:N>P>C>Si.
whichisaccordantwithHongHuasheng'sresultinstudyingbiogenicelementsofthesouthernTaiwanStraitSedi—ment,buttheabsolutevalueoftheforlTlerismuchhigherthanthelatter,whichindicatesthatdifferentsedimentationenvirolmmnthasdifferenteffectondiagenesis.
Mo5studiedinthispa—perislocatedintheBohaiGulf,belongingtosiltclaysedinlent,isabundantwithorganicmat—terduetoterrestrialinput,andbenthosactivitiesareveryactive,allthesefactolsarefavorabletoorganicmattermineralization.
However,sedimentgraininthesouthern'l'alwanStraitismuchbiggerduetoitsstronghydrodynamicactivity.
andconcentrationsofoC.
ON,PandSiaremuchlower,whichcrusesitsmineralizationweakened.
Furthermore,decompositionratecanbeusedasindextoorganicmatterres(-rvationtimeinsediment.
Higherdecompositionrateconstantmeanshigherdecompositionrate,whichindi—catesthatthesedimentisrelativelynewanditsreservationtimeiscorrespondinglyshortReservationtimeofeverybiogenicelementcanbeobtainedbytakingreeipr(xzalofthedecompo—sitionrateconstant.
Accordingtothis,reservationtimeof0C,ON,PandSiinthesouthemBohaiSeaSedimentare208.
64.
5,192and1204arespectively.
ItisknownthatOCreserva—tiontimeinFnsrinesedimentisinrangefromseveralweeksto10%,regenerationofPisrela—tivelyquickandregeneratedpartlyeveninthecourseofsedimentationprocess.
Nitrogenisbe—tweencarbonandphosphate,andSihaslongreservationtime(Hommondetal,1996).
Ob—viously,resultinthisstudyisnotconsistentcompletelywiththisconclusion,phosphatedis—playslongreservationtime,whichismainlybecauseofitscomplexdiagenesis:inspiteoftheitsquickdegradation,nota11phosphatedegradatedrelease,instead,itmayberetainedinsedi—mentwithvariouscombinationstylethroughdiagenesistransitionandredistribution.
Asare—suh.
phosphatedisplayslowdecompositionrateandlongreservationtimeinalargetimescaIe.
C/NandOC/ONratiochangeindiagenesis.
c/NratioinmarineSedimentde—pendsonthecompositionoforganicmatter,mineralizationcourseandreplenishnrantrateofor—ganicmatter.
IngenerN,C/Nratioof.
sedimentmainlyfrommarinebiogenicmatterislowerthansedimentfromterrestrialinput.
Inacertainrangeofdepth.
C刷ratioincreaseswithNfornlsanddec.
()mpositionofOCinsedimentsdepthduetoorganicnmttermineralization,andOC/ONalsoshowsanincreasebecauseofmi—croorganismpreferentialutilizationtoONrelativeto0(2.
Therefore,ratiochangeofC/NandOC/ONwithdepthcxqnreflectearlydiagenesisandnitrogenreservation.
Figure3isC/Nand(K;/ONratiochangeof4coresedimentsofthesouthemBohaiSea.
040营摹三}:6000Mq"01020300三200s{ro3000(】言80o{守o120160M,70246Mtt0203000()(1Mml1020FOg.
3VariationofC/NandOC/ONratioswithdepthin.
)resedimentsItcanbeseenfromthefigurethatM3—7andMlo—lhavesimilarchangetrendinC/Nand()C/ONrario,C/Nratiodecreasesslightlyatthebeginningandthenkeepsconstant,andOC/ONrariodecreasestoaminimumandthenincreasesslightly.
TheaverageC/NandOC/ONratiosofMs-7are1.
04and3.
73respectively,andthoseofMmlare1.
67and8,55respec—tively.
M0一'andM日一12havesimilartrend,ratiosoftheformerare1.
3and11.
24,andthe扫f阳8aM0.
7and8.
3jC/NratiooffourcoresedimentsismuchlowerthanOC/ON,indicat+132SongJinmingetalingthatthereisplentyofinorganicnitrogenorfixedONcontainedinsediments.
andthechangeof()C/ONratioindicatestheamountofreservednitrogenItalM)canbcshownthatOC/ONratiosoffoorcoresedimentsdecreasewith_depth,whichisinconsistenLwiththecon—clusionthatON'spreferentialdegradationrelativetooC.
indicatingsedimentretainsONinSolveway.
Therearetwomainreasonstosuchenrichment:oneisthedifferentcompositiuIlofONinsedimentsItisknownthatorganicmatterinsedimemcanbedividedintotWOparis:activepartandinactivepart,thefortllerincluding0211iiloacid,carbohydrateandfattyacidetc.
.
theactivityofthesecomponentscanbeshownbytheircontentschangewithdepthIthasbeenshownthatinactivecomponentsincreasedistinctlywithdepth(Cowieeta1.
,1992)7l'herefore,alargeamountofinactivecomponentsinONisonereasonforoC/()Nratioreduc—tionwithdepth.
Anothercauseisorganicnitrogencompoundsadsorptiontoclaymineral,whichprohibitsdegradation,andOC/ONreductionextentreflectsthealnountofadsorbedor—ganicnitrogen.
TransferablenitrogenincoresedimentsGenerally,transferablenitrogen,includingIEF—N,CF—N,IMOF—NandOSF—N,canbetransforrnedandinvoloedinrecyclingunderappropriateconditionUsually,thepropor—tionoftransferablenitrogentoTNinsurfacesedimentishigherthandeeplayersediment,sincenitrogenindeeplayersedimentstransformsintomorestablestatesduringearlydiagenesisTable2givestheproportionoftransferablenitrogentoTNindifferentdepthofstudied5core,'sedimentsTaBle2.
Proportionoftransferabtemt虻qenin'FN(%)Theaveragevalueisbednedbytheproportionofallsamplesinthesamplingdepthofeverycore№-dimentbutthetableabovelistsonlyapartoftheresultsItcanbeseenthattransferablenitrogeninSUrfacesedimentsofthesoulhernBohaiSeaaCcountsforl3.
55%to53.
75%inTN.
InsedimentsofM37,M6—5andM95,theproportionincreasesremarkablywithdepth,whichmeansthattheproportioninsurfaceIayerisnmchhigherthandeeplayer.
ButM912andMloldisplaydifferentcharacteristics.
inwhichtheproportioninsurfacelayeranddeeplayerisalmc*stthesame'l'hisdifferencereflectsgecchemi—calenvironmentdifference.
Fromthepointofthelocationofthe5coresediments,themainsourcesofsedimentaretheHuanghe,LuanheandHaiheRivers,especiallyHuanghePdver(SongandLuo,2000).
TheeffectstrengthOftheHuangheRiveronthe5rx)re8hastheW—quence:M9—5>M9一12≈M65>Ms一7≈Mlo—l-AffectedbytheHuangheRiverinputenrichedNformsanddeeom|xxsilionofOCinsedimentswithorganicmatter,asforM912,t11cstablenitrogenformedinearlydiageneslsc;lnbercacti—vatedindeeperlayersediment,andbecametransferableform,whichisthemaillreasonthattransferablenitrogenindeeplayerisahnostsainewithsurfacelayer.
M10l,mainlyaffectedbytheHaiheRiverinputs,showsthesamecharacteristic.
&mg(1997)haHfoI】ndthal"activcfer-rous'concentrationindeeperlayersedimentishigherthansurfaceintiffsarea.
provingthatsuchactivation1sexistentNitrogeninsedimentmayhavethesimilaractivationaxferrous.
CONCI,USIONSIncoresedimentswithnaturalgrainsizeofthesC>uthern&)haiSea.
OSF—NMdIEF—NarepreponderantfoHnsintransferablenitrogenandshowsdifferentverticaldistributions:IEF—NdecreaseswithdepthandIMOFNhasabrupttransitionwithdepthduet()redoxenvi—ronnlciltchange,andOSF—Nismainlyaffectedbysedimentre:v)urceandmineralizationPH)一cessDecomtx】sitionrateconstantsofONand0(2inthesedimentare15.
5I*103a1and4.
79*103arespectively,constantsofC,N,11,SihavethesequenceN>P>L:>SiIkcausethereisplentyofnitrogencombinedintothesedimentsinearlydiagenesis.
t'/Nratioismuchlowerthan(X:")NAlargeaniountofinactiveconlponentscontainedinorganicnitrogenandONadsorptiontoclaymineralsresultsinONenrichmentinsediment,whichisthemainreasonforCKl=/ONreductionwithdepthInthesurfacesediment,thereisabout34.
25%()fnitrogenthatcanbeinvolvedinrecycling.
Astocoresediments,thepmtx)rtionoftransferablenitrogento7l'Ninsurfacelayerishigherthandeeperlayer,butSornespecialsedimt、ntationellvironmentwithhighorganicmattercaninducethetwoproportionsbecomealmostthesameRFFERENCESAnderg)r】LA,JLSarmiento(1994)RedfieldratkbufremineralizationdetertllInedbyI…IrlentdataarmlvH、G1c4MlBioM女…ufCwles,8,65~80o,…GL,】.
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