5.0

4.5

4.0

3.5

3.0

Ben

thic

δ18

O (‰

)

Juan de Fuca Ridge 05PC Biological Pump

Warmer

Cooler

Interglacial

Glacial

MIS

1M

IS 2

MIS

3

MIS

4

MIS

5

MIS

6

MIS

7

MIS

8

MIS

9

MIS

10

MIS

11

MIS

12

MIS

13

MIS

14

MIS

15

MIS

1M

IS 2

MIS

3

MIS

4

MIS

5

MIS

6

MIS

7

MIS

8

MIS

9

MIS

10

MIS

11

MIS

12

MIS

13

MIS

14

MIS

15

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

δ13 C

(‰)

Planktonic

Benthic

-2.0

-1.5

-1.0

-0.5

δ13 C

(‰),

Ben

thic

- N

pL

Mea

n In

terg

laci

alM

ean

Gla

cial

Strong

Weak

Stre

ngth

of

Bio

logi

cal P

ump

0 50 100 150 200 250 300 350 400 450 500 550 600

Age (ka)

15

10

5

0

Corg

Flux

(mg/

cm2 /kyr)

Moving Average

Uvigerina spp.Planulina wuellerstorfi, adjusted +0.55‰

N. pachyderma, sinistralPlanulina wuellerstorfiUvigerina spp.

44˚30’

44˚40’

44˚50’

45˚00’

45˚10’

131˚ 130˚20’ 130˚130˚40’

39BB

38PC 35PC

12PC

05PC

09PC

20PC

2520 2610 2700 2790 2880Water Depth (m)

Surface Temperature (˚C)

145˚ 135˚ 125˚

35˚

45˚

55˚

40˚

50˚

8101214161820TheCarbonPump

AGlacial-InterglacialRecordoftheNorthPaci6icBiologicalPumpforthePast600,000Years

TianjiaLiu1(tl2581@columbia.edu),JerryF.McManus1,2(jmcmanus@ldeo.columbia.edu),KassandraM.Costa1,2(kcosta@ldeo.columbia.edu),andTanzhuoLiu2(tanzhuo@ldeo.columbia.edu)1DepartmentofEarthandEnvironmentalSciences,ColumbiaUniversity,NewYork,NY2Lamont-DohertyEarthObservatoryofColumbiaUniversity,Palisades,NY

+δ13C(moreenriched)

-δ13C(moredepleted)

Atmosphere

DeepOcean

Depth

Ca2++HCO32-èCaCO3+H2O+CO2CO2+H2OèCH2O+O2SurfaceOcean

CO2 CO2 CO2

CO2

GasExchange

CarbonatePump

CH2O+O2èCO2+H2O

Respiration

Photosynthesis

Introduction

KeyQuestions

Conclusions

Results

Methods

Acknowledgements

•  TheNorthPaciWicdeepoceanisaprimelocationforcarbonsequestrationandstorage.

•  Nodeepwatersource•  Nostrongupwelling

•  Throughphotosynthesisandgasexchange,thesurfaceoceansequestersCO2fromtheatmosphere,anditsbiologicalpumpsubsequentlyburiesthecarboninthedeepocean.

•  δ13Cisaproxyformarineproductivitybasedonthepreferentialutilizationofthelighter12Cforphotosynthesisandreintroductionof12Cintoseawaterduringrespiration.

•  Organiccarbon,ororganicmatterthatfailstodecompose,accumulatesontheseaWloor,andissubsequentlypreservedinsediments.

(1)DoestheNorthPaciWicforaminiferalrecordatJuandeFucaRidgeshowthatthesurfaceoceanismore13C-enriched(photosynthesis-dominated)anddeepocean,13C-depleted(respiration-dominated)?Andhowdoesthedifferenceinδ13Cbetweenbenthicandplanktonicforaminiferachangewithrespecttoglacial-interglacialcycles?

(2)HowdoestheCorgWluxrecordatthesamelocationchangewithrespecttoglacial-interglacialcycles?

(3)HowsuccessfularetheaforementionedproxiesatreWlectingchangesinthebiologicalpumpwithrespecttoglacial-interglacialcycles?

BenthicforaminiferaUvigerinaperegrina(left)andPlanulinawuellerstor2i(right)

PlanktonicForaminiferaNeogloboquadrinapachyderma,sinistral

(1)TheAT-26-19-05pistoncorefromJuandeFucaRidgewassampledat4cmintervals.Thesampleswerewashedinsievestoseparatethecoarse(>63μm)andWine(<63μm)fractions.

(2)Threespeciesofforaminifera(Uvigerinaspp.,Planulinawuellerstor2i,andN.pachyderma,sinistral)werepickedandanalyzedforδ18Oandδ13Cbymassspectrometry.

(3)TheremainingtotalsedimentfractionsweredecalciWiedwithconcentratedHCl,whichthen,afterleftovernight,wasdilutedwithde-ionizedwaterandremovedfromthesamples.Thesampleswerefreeze-driedandpreparedforCorganalysisbymassspectrometry.

SamplingWashing

Picking

Loading

FutureWork

Figure3.•  PhotosynthesisremovesCO2fromtheatmosphereandenrichessurfacewatersin13C.

•  RespirationandCaCO3formationdepletestheoceanbyreleasing12Cintosurroundingwaters.

•  Theδ13CproWileintheoceanwithrespecttodepthisshownontheleft.

•  CaCO3shellsfromtheopenwatereventuallysettleontheseaWloorandarepreservedinthesediment.

Glacialshaveastrongbiologicalpump.Interglacialshaveaweakbiologicalpump.

ComplicationsforInterpretingδ13CandCorg2luxasProxiesforBiologicalProductivity:

(1)Dependingonthestrengthofoceancirculation,theageoftheNorthPaciWicdeepwaterisvariable,andtherefore,thetimethatallowsrespirationtoreintroduce12Cinthedeepocean.

(2)Duringglacials,theentireoceannegativelyshifts~0.3‰inδ13Cfromterrestrialcarboninput,buttakingthedifferenceinδ13CofbenthicsandNpLeliminatesthesepotentialerrorsofabsoluteproductivityforeithersurfaceordeepocean.

(3)Unlikethatofdeepwater,whichisderivedfromothersourcesandnotincontactwiththeatmosphere,theisotopiccompositionofsurfacewatermaybemoresusceptibletoair-seainteractionandregionalclimatechanges.

(1)Becausephotosynthesisenrichesthesurfacewaterin13Candrespirationdepletesthedeepwaterin13C,thedifferenceinδ13Cfractionationbetweenbenthicandplanktoniccharacterizesthebiologicalpump.

(2)TheNorthPaciWicbiologicalpumpisrelativelystrongduringglacialsandweakduringinterglacials.

(3)Variationsintheorganiccarbon6luxsupporttheweakbiologicalpump-interglacial,strongbiologicalpump-glacialconclusion.

(4)However,factors,suchasregionalclimatechanges,agingoftheNorthPaciWicdeepwater,andair-seainteraction,cancomplicateproxyinterpretation.

(1)TheMIS11enigma:Whatcausedtheδ13Cfractionationtosuggestanabnormallystrongbiologicalpump,yetCorgWluxaweakbiologicalpumpat~400ka(circledonFig.4)?Whydidtheδ13CofNpLbecomeveryenriched,whentheδ13Cofbenthicspecieswasrelativelystable?

(2)MoreData:Proxies,suchasopal,andrecordsfromothercoresareneededtoreWineandcorroborateconclusionsonthebiologicalpumpreconstruction.

FundingwasprovidedbytheEarthInstituteandNationalScienceFoundation.SpecialthankstoKellyLuis,AnnaLoPresti,andChristyJenkinsfortheirhelp,dedication,andworkontheSeaVOICEproject,andDr.WeiHuangforstableisotopeandorganiccarbonmeasurements.

Figure1.AsseenintheVostokicecorerecord,changesinsolarinsolationdroveglacial-interglacialcycles,duringwhichatmosphericCO2varied,withlowCO2duringglacialsandhighCO2duringinterglacials(Petitetal.,1999).

ReferencesLisieski,L.E.andM.E.Raymo.(2005).APliocene-Pleistocenestackof57globallydistributedbenthicδ18Orecords.Paleoceanography,20(PA1003).Petit,J.R.etal.(1999).Climateandatmospherichistoryofthepast420,000yearsfromtheVostokicecore,Antarctica.Nature,399(429-436).

JuandeFucaRidgeSiteMap

Figure2.Tectonicallyspreading,JuandeFucaRidgeisanactiveunderwatervolcanicmountainrangeintheNorthPaciWicoffWashingtonstatecoast,asshownontheright.ThelocationofJdFRpistoncores(PC)areshownontheleft.05PC(circledinred),farthestfromtheJuandeFucaRidge(lightgrayband),wasanalyzedforthisstudy. Source:NOAA

OrganicCarbonPump

SEDIMENT

Figure4.Thestrengthofthebiologicalpumpischaracterizedbytwoproxies:1)thedifferenceinδ13CfractionationbetweenbenthicforaminiferaandplanktonicspeciesN.pachyderma,sinistral;and2)Corg2lux.

(2)CorgWluxishighduringglacials,andlowduringinterglacials.Itpeakslateindeglaciationperiods.

(1)Thedifferenceinδ13Cbetweenbenthicforaminifera(P.wuellerstor2iadjusted-0.735‰)andNpLisrelativelylargeduringglacialsandsmallduringinterglacials.

Theδ13CrecordsofNpL,Planulinawuellerstor2i,andUvigerina,spp.showsthedepletionofδ13Cwithdepthinthewatercolumnasrespirationreintroduces12Cintotheseawater.Thedifferenceinδ13CbetweenP.wuellerstor2iandNpLrepresentsrespirationinthewatercolumn,andthatbetweenUvigerinaspp.andP.wuellerstor2irepresentsrespirationinthemud.

Source:Lutze(1978)

Source:Schweizeretal.(2005)

Source:T.Struve,IFM-GEOMAR

B24A-0305