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Method Article
Sequential extraction procedure to obtain the composition of terrigenous detritus in marine sediments
Margit H. Simon
a,b,c,∗, Daniel P. Babin
c,d, Steven L. Goldstein
c,d, Merry Yue Cai
c, Tanzhuo Liu
c, Xibin Han
e, Anne A. Haws
f, Matthew Johns
c,d, Caroline Lear
g, Sidney R. Hemming
c,daNORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway
bSFF Centre for Early Sapiens Behaviour (SapienCE), University of Bergen, Post Box 7805, 5020, Bergen, Norway
cLamont-Doherty Earth Observatory of Columbia University, 61 Rt 9W, Palisades, New York 10964-80 0 0, USA
dDepartment of Earth and Environmental Sciences, Columbia University, New York NY USA
eKey Laboratory of Submarine Geosciences, SOA Second Institute of Oceanography, Hangzhou, China
fDepartment of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA 02467, USA
gSchool of Earth and Ocean Sciences, Cardiff University, Park Pl, Cardiff CF10 3AT UK
abstract
The geochemicaland isotopiccompositionofterrigenousclays frommarine sedimentscan provideimportant informationonthesourcesandpathwaysofsediments.Inordertoextractthedetritalsignalfrombulkmarine sediments,standardsedimentleachingmethodsarecommonlyappliedtoremovecarbonateandferromanganese oxides.Incomparisontomostpreviousstudiesthataimedtoextracttheterrestrialsignalfrommarinesediments weadditionallyappliedaCsClwashthroughoutthesamplepreparationSimonetal.[1].Themotivationbehind thatextrastep,notfrequentlyapplied,istoremoveionsthataregainedontheclaysurfaceduetore-adsorption of authigenic trace metals in the ocean orduring the leaching procedure and thus could alter the original compositionofthedetritalfractionifnocationexchangewasapplied.Herewepresentanimprovedanddetailed step-by-step leachingprotocolfor theextraction ofthedetrital fraction ofbulkdeep-seasedimentsincluding commonlyusedbufferedaceticacidandacid-reductivemixsolutionsincludingafinalcationexchangewash.
• standard method to remove carbonate and ferromanganese oxides and Stokes settling to isolate the clay fractions
• additionalapplicationofcationcationexchangewash(CsCl)
• removalofionsthataregainedontheclaysurfaceduetoadsorptionofauthigenictracemetalsintheocean orduringtheleachingprocedure
DOI of original article: 10.1016/j.chemgeo.2007.03.021
∗ Corresponding author at: NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway . E-mail addresses: [email protected] (M.H. Simon), [email protected] (D.P. Babin), [email protected] (S.L. Goldstein), [email protected] (M.Y. Cai), [email protected] (T. Liu), [email protected] (X. Han), [email protected] (A .A . Haws), [email protected] (M. Johns), [email protected] (C. Lear), [email protected] (S.R. Hemming).
https://doi.org/10.1016/j.mex.2020.100888
2215-0161/© 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license.
( http://creativecommons.org/licenses/by/4.0/ )
© 2020TheAuthor(s).PublishedbyElsevierB.V.
ThisisanopenaccessarticleundertheCCBYlicense.(http://creativecommons.org/licenses/by/4.0/)
article info
Method name: Sediment leaching protocol including a cation exchange wash
Keywords: Cation exchange wash, Sediment leaching protocol, Composition of detrital fraction Article history: Received 7 January 2020; Accepted 2 April 2020; Available online 20 April 2020
Specificationstable
Subject Area •Earth and Planetary Sciences
Method name: Sediment leaching protocol including a cation exchange wash
Name and reference of original method The following method is a sediment leaching procedure for marine sediments that can be applied to approximately a batch of 10–20 samples at the time.
Procedures in part modified after [2] .
Methoddetails
Followingisthe outlineanddetailedprotocol(Fig.1) forthe preparationofequipment,labware, reagents and solution used in the protocol for sediment sample leaching in order to extract the detritalsignalfrommarinesediments.Becausethisisnotamethodofanalysis,subsectionsnormally found relating to risks of contaminations and quality control of the chemical analyses have been omitted. For more information on these subjects the reader is referred to the main publication [3]wherethesedetailsarepublishedandstandardtreatmentisdescribed.
Hardware/glassware
Glasswareandimplementsusedintheseproceduresincludethefollowing:
- reagentbottles:1000mLand2000mL - 400mLglassbeaker
- 50mLcentrifugetube - 15mLcentrifugetubes - squirtbottle250mL
- finetestsieve,poresize63μm
- ph-indicatorstripsph0–14universalindicator
Chemicals
Chemicalsusedinthisprocedureincludethefollowing:
- Hydrogenperoxide3%(H2O2,FisherChemical,Certified,CatalogNo.H324-500)
- Sodiumacetate(C2H3NaO2Anhydrous,FisherChemical,CertifiedACS,F.W.=82.03,S210-2) - Glacialaceticacid(CH3COOH,FisherChemical,CertifiedACS,F.W.=60.05,productA38C-212) - Hydroxylaminehydrochloride(H3NO•HCl,AlfaAesar,99%purity,F.W.69.49,Stock#:A15398) - Sodiumhydroxidepellets(NaOH,FisherChemical,CertifiedACS,F.W.=40,Catalogue#:S318-
1)
- 0.5% sodium metaphosphate solution ((NaPO3)6, Fischer Chemical,Laboratory GradePowder, Catalogue#:S333-500)
- Cesiumchloride(CsCl,INDOFINE,ResearchGrade,F.W.=168.36,Product#:MB1006)
- Ethanol (C2H6O, Ethyl Alcohol Denatured (Proprietary Solvent), Certified, Fisher Chemical, F.W.=46.069,Catalogue#:A407-500)
- deionizedwater(Milli-Q® purifiedwaterthathasresistanceof18.2M•cmat25°C)
Step 1: Initial Weighing & Disaggregating of samples
• 2-3 g of thebulk sedimentsample
Step2: Sediment Sieving
• Ground bulksedimentis separate in fine
(<
63μm)and coarse fraction(>
63 μm),step 3 continous with fine fraction, coarse fraction is storedStep3: Organic matter removal usingHydrogen peroxide (H O )2 2 (3%)
Step : Decarbonation of the sediment with Acetic cid eachl
• 1M buffered acetic aci d
Step6: Settling of clay fraction
• Milli-Q® purified water and 0.5% sodium metaphosphate solution, i.e calgon.
Step7: CsCl cation exchange wash
• 0.1N Cesium chloride solution
• double rinse with ethyl alcohol
Extraction procedure to obtain the composition of terrigenous detritus in marine sediments
Step :
a 4
A
5 Leach of Fe-Mn oxyhydroxide fraction with a buffered cetic acid/
Sodium acetate solution (pH ~ 4)
• 0.05 Mhydroxylamine hydrochloride–15% acetic acid–0.3M NaOH
Total sample digestion Centrifuge& decant supernatant
Centrifuge& decant supernatant
Centrifuge& decant supernatant
Centrifuge& decant supernatant
• oven dry samples
Triple rinse with Milli-Q® purified water
seperate material for XRD analysis
Fig. 1. Schematic view of the applied sediment treatments (leaches, rinses, total digestions) and their order.
Solutions
Preparationof2Lofofbufferedaceticacidsolution(Step4):
1. Beginwith1LMQwaterina2Lbottle(MQwater=Milli-Q® purifiedwaterthathasresistance of18.2M•cmat25°C)
2. Add164gsodiumacetate (C2H3NaO2Anhydrous,Fisher Chemical,Certified ACS,F.W.=82.03, S210-2)
3. Add114mL glacial aceticacid(CH3COOH, Fisher Chemical,Certified ACS,F.W.=60.05,product A38C-212)
4. Fillto2LwithMQ
Preparationof500mLofbufferedaceticacid/sodiumacetate(pH4)solution(Step5):
1. startwith250mLMQ
2. Add1.84ghydroxylaminehydrochloride(H3NO•HCl,AlfaAesar,99%purity,F.W.69.49,Stock#:
A15398)
3. Add76mLglacialaceticacid(CH3COOH)
4. Add10gNaOHpellets(FisherChemical,CertifiedACS,F.W.=40,Catalogue#:S318-1) 5. Fillto500mLwithMQ
6. CheckpHafter1hr;shouldbe~4 Sieving,leaching,&settlingprocedure
Step1:InitialWeighing&DisaggregatingofSamples
1. Weigh 2-3g of thesample to be sievedin a dry, tared50mL centrifugetube and record the mass.
2. Alsoweighaclean,labeled63μmsieveforeachsampleandrecordthemass.
3. Filleachtubeto~30mLwithdeionizedwatertodisaggregatethesamples.Disaggregatingmay be facilitated by vortexing andsonicating(the better the samplesare disaggregated, the less waterwillbenecessarytosievethesamples,thussavingtimelater).
Step2:SedimentSieving
1. Place a sievein a 400mL beaker witha corresponding label, and pour the sample onto the sieve;useasquirtbottlewithdeionizedwatertoensurethewholesampleistransferred.
2. Use the spraybottle to wash thefine fraction through thesieve. Thisis complete when the watercomingoutofthesieveisclearandthecoarsefractiondoesnot appeartocontainany clumpswhenviewedunderamicroscope.
3. Place the sieves with the coarse fraction in the oven at 50°C, and weigh them when dry.
Transferthecoarsefractionstosmallglassvialsforstorage.Thisisbestdonebyemptyingthe sieveonto creasedweighing paperandusingthe weighingpaperto pour thecoarse fraction intothevial.
4. Allowthefinefractionstosettleinthebeakersovernight;iftheyarestillcloudythenextday (or longer if needed), a few drops of buffered acetic acid(recipe see Step 4 above) maybe addedtofacilitatesettling.
5. Afterthefinefractionshavesettled,removeasmuchwateraspossibleandrecombinemultiple beakersifnecessary.
6. Returnthefinefractiontotheoriginalcentrifugetube;itmaybenecessarytofillthetubesto 50mL,centrifugefor30minat2400rpm,decantthewater,add therestofthewaterandfine fraction,andcentrifugeanddecantagain.
Step3:OrganicmatterremovalusingHydrogenperoxide(H2O2)(3%)
1. Place a samplein each beaker andadd about50-100mLof dilute hydrogen peroxide (H2O2).
Stireach beakerwiththe glassrodtosuspendthesample. Rinsetheglass rodbetweeneach sample anddry witha lab tissue. When bubbling stops or slows,add another 50-100mL of dilutehydrogenperoxide(H2O2)andrestirthesuspension.
NOTE:Thisstepcanalsobeperformedathighertemperature(60–70°C),withyourbeakerinahotwater bath. Moreoverthe hydrogen peroxideconcentration canbe increased to e.g. 6% if OMconcentration is high.
2.Whentheadditionofhydrogenperoxidetothesamplesnolongercausesbubbling,theorganics have been removed. Allow the suspension to settle and carefully siphon or pour off the supernatantliquid,orwashthesamplebycentrifuging.
NOTE: It should be considered that in some cases, depending on the sediment properties, an organic oxidativeleachingstepwithhydrogenperoxide(3%)wouldstillnotbesufficienttoremovevariousorganic phases.StrongertreatmentsforOMremovalcanhoweverattacktheclaysandleachawaysolubleelements includingtheREEthatwouldaffectthetraceelementmeasurementsintheend.Hencethisstepmighthave tobeadaptedindividuallyaccordingtothesetting.
Step4:DecarbonationofthesedimentwithAceticacidLeach(Adaptedfrom[2])
1.Vortexthesamplestodisaggregatethemabit,andfillthetubeto~30mLwiththe1Mbuffered aceticacid.LiberateanyCO2 produced.
2.Vortextodisaggregatecompletely.
3.Release CO2 againandensure that the caps are tightbefore placing onthe rockingtable for 6-12hr,orovernight.
4.Centrifugefor30minat2400rpm,anddecanttheclearacidsolutiontowaste.
5.Repeat Steps1–4 until thesedimentno longer appears to react withthe acid;there will be no morecarbondioxideformed,andno bubbleswill formwhentheacidis added(however, bubbles mayformasthesedimentshiftswhen theacidispoured overit, andtheaciditself mayfoamwhenvortexed,evenifnoreactionistakingplace).
Step5:LeachofFe-MnoxyhydroxidefractionwithabufferedAceticacid/Sodiumacetatesolution (pH~ 4)
1.Filleachtubeto~20mLwithbufferedaceticacid/sodiumacetatesolutionandplaceonrocking tableforatleast8hrorovernight.
2.Centrifugefor30minat2400rpm,anddecantclearsolution.
3.If the supernatant wascolorless, only one leach is necessary. If it is tinted, repeat until the supernatantisclear.
4.Fillthe tubes to~30mL withMQwater,vortexto disaggregate,centrifuge at2400rpmfor30 min,anddecant.
5.Repeatstep5twoadditionaltimes.Astheacidisremoved,settlingmaybecomemoredifficult, socentrifugingatahigherspeedandforalongertimemaybenecessary.
INFO: This step deals with the leaching of Fe-Mn oxides fraction with the acetic acid/sodium acetate buffer (pH 4). The acetic acid (CH3COOH) reacts with sodium (NaOH) to produce the sodium acetate (CH3COONa).Thetwocompoundsareincontactwithhydroxylaminehydrochloride(NH2OH,HCl)inorder tobufferthesolutionatpH4.
NOTE: This sequence of procedures deviates from that of Gutjahr et al. [2] who followed the initial carbonateleaching witha cationexchangestep withMgCl2 inorder to desorbcationspriorto leaching the dispersed Fe-Mn oxy-hydroxide forauthigenic Nd isotope measurements. Moreover, we did not use thecomplexingreagentEDTAasoriginallysuggestedintheprotocolduringtheleachingoftheauthigenic Fe-Mn oxyhydroxide fraction.We recommend the application of a sequenceincluding EDTA (HH–acetic acid–Na–EDTA)followingGutjahretal.[2].
Step6:Settlingofclayfraction
Separations ofgrainssmallerthan20micronsarecarriedoutby settlingina columnofwaterin glasscylinders.ParticleswillsettleinthewateraccordingtoStokesLaw:
V=2/9(
ρ
g–ρ
f)gr2/η
where:
V=thesettlingvelocityincm/sec
ρ
g=densityofthemineralgrains(2.6-2.8g/cm3forclayminerals)ρ
f=densityoffluid(1g/cm3 forwater) g=accelerationduetogravity(980cm/sec2) r=radiusofthemineralparticle(10−4cmforclays)η
=viscosityofwater(10−2 gcm/sec2)1. Label as many clean, 100mL graduated cylinders as you have samples with a piece of tape placed 5cmdown from the100mL mark.Alsolabel a setof clean centrifugetubes with the samplenamesandsizefraction(forourpurposes,<2μm).
2. Add ~30mL MQwater and~2mL 0.5% sodium metaphosphate solution,i.e calgon((NaPO3)6, Fischer Chemical, Laboratory Grade Powder, Catalogue #: S333-500) to each tube after decantingthe3rdMQrinse.Sodiummetaphosphate,adetergent,helpsdispersetheclaysand preventflocculation.
3. Vortexuntilsamplesaredisaggregated.
4. Pourthecontentsofeachtubeintotheappropriatecylinder,usingtheMQsquirtbottletomake surethatallsedimentistransferred(andsavetheoriginaltubeforthe2-63μmfraction).
5. Fillthecylinderstothe100mLmarkwithMQwaterandcoverwithasquareofparafilm.
6. Sonicate the cylinders for about 5 min, then shakeand invert them a few times to evenly dispersethesedimentthroughoutthecylinder.Atthispoint,itisextremelyimportanttomake surethesampleisfullydisaggregated. Ifheavy clumpingis observed,sonicate andshakethe cylinderuntiltheclumpsdisappear-thismaytakesomeeffortandmultiplesonicatingrounds.
7. Placethecylindersina safeplaceonthecounter wherethey won’tbe bumpedorotherwise agitated,andstartatimerfor3hr52min.Besuretoleaveenoughroombetweenthecylinders soyoucanreacharoundthemalittlemoreeasilylater.Staggeringthemisalsoagoodidea.
8. After time is up, use a turkey baster to transfer the top 5cm of water(25mL) to the clean centrifugetubeslabelledearlier.Clods(forAr)maybemadeatthispointifdesired.
9. Toresetthecylinders foranother roundofsettling,add ~2mLcalgon(forone ortwosettling rounds only) to eachand fillto100mL withMQ andcoverwithparafilm, sonicate forabout fiveminutes,shakeandinvert,andresetthetimer.Onlyaddmorecalgonpriortothesecond roundofsettling.
10. Centrifuge the tubes at 4000rpm for 30min to settle the <2μm fraction. The resulting supernatant should be translucent, andit will likely be tinted. Ifthe solution is still cloudy whenremovedfromthecentrifuge,returnittothecentrifugeforalongerlengthoftime.
11. RepeatSteps8–10untilsettlingiscompleteoruntilenough2μmfractionhasbeencollectedto performdesiredanalyses.Ifbringingsettlingtocompletion,agoodwaytotellifitiscomplete is tohold up a paperwithblack andwhitetype onit. The blackand whiteshould contrast sharplyandthelettersshouldn’tlookclouded.
12. Transfer the2-63μm fractionto theoriginal centrifuge tubes (ifsettling is complete orclose to complete, allowing the remaining sedimentto settle for a while andthen pipetting clear wateroff will savetime when transferring).Use theMQsquirt bottle to ensureall sediment is transferred. This can be done by pouring the sediment directly into the tubes from the cylinders,andthencentrifugingfor30min,decanting,andcontinuingtoaddtothetubesuntil thecylinderisempty.Alternatively,ifyouare inahurryandneedthe cylindersimmediately, transferringthesedimenttoabeakerfirstandthen thetubes(followingthesameprocedure) isalsoan option.Additionally,ifsettlingwasstoppedafteraparticularnumberofroundsand wasnot fullycompleted,be suretonote onthe tubesthat thereis still some<2μmfraction present).
Step7:CsClCationExchangeWash(Adaptedfrom[3])
1. Filleach50mLcentrifugetubeuptothe15mLlinewithMQwater.
2. Labelnew15mLcentrifugetubeswiththesamplename+“w/CsCl”
3. Vortextocompletelydisaggregatesample.
4. Quickly,whilesampleisstillcompletelysuspended,pipette5mLofsamplefromthe50mLtube tothenew15mLtube.
5.Usingthesametip,pipette5mLofMQwaterintothe15mLcentrifugetubetwicetoclearany remainingsamplefromthepipettetip.
6.Pipette5mLofMQ3timesintowastetowashthepipettetipandavoidcontamination.
7.ObtainfreshMQwaterandrepeatSteps3–6fortheremainingsample.
8.Centrifuge15mLtubesfor90minat4000rpm,andremovethewaterwithapipet.Donotpour.
9.Pipet 10mL0.1NCesiumchloride (CsCl,INDOFINE,ResearchGrade,F.W.= 168.36,Product#:
MB1006)solutionintoeachtube.
10.Vortex each sample to completely disaggregate and suspend it; this will be difficult and sonicatingmaybenecessary.
11. Rotate thetubesfor24hours to ensurecompleteinteractions betweenthesedimentandthe reagent.
12. Centrifuge samples at2000rpm for20min; the Cs ions will help the clay settle much more easily.
13. Decanteachsample;youshouldbeabletopourwithoutlosinganysample.
14.Add 10mL MQ,vortexuntil suspended, centrifugeat2000 RPMfor 20min,and decant.Add 10mLethanol(C2H6O,EthylAlcoholDenatured(ProprietarySolvent),Certified,FisherChemical, F.W.=46.069,Catalogue#:A407-500),vortex,centrifuge,anddecantasabove;repeatthisstep asecondtime.
15.Letsampledryintheoven at50°C.Thesesamplescannotbefreezedriedduetolowfreezing pointofethanol.
DeclarationofCompetingInterest
The authors declare that they have no known competing financial interests or personal relationshipsthatcouldhaveappearedtoinfluencetheworkreportedinthispaper.
Acknowledgments
M.H.S. and C.L. acknowledge funding for this project from UK NERC IODP Moratorium grant:
NE/N020286/1: “Pliocene palaeoclimate off SE Africa: Insights from IODP expedition 361.” M.H.S.
additionally received salary funding from the European Research Council under the European Community’s SeventhFrameworkProgramme(FP7/2007-2013)/ERCgrantagreementn°61005.This work was partly supported by the Research Council of Norway, through its Centres of Excellence fundingscheme,SFFCentreforEarlySapiensBehaviour(SapienCE),projectnumber262618.Wethank theCaptain,officers,crewandespeciallyallscientistssailingonIODPexpedition361.Wealsothank Alison Corley and Louise Bolge at LDEO for help with laboratory and analytical work on sample materialofcoreU1478.
References
[1] M.H. Simon , et al. , Development of a protocol to obtain the composition of terrigenous detritus in marine sediments -a pilot study from international ocean discovery program expedition 361, Chemical Geol. 535 (2020) 119449 .
[2] M. Gutjahr , et al. , Reliable extraction of a deepwater trace metal isotope signal from Fe–Mn oxyhydroxide coatings of marine sediments, Chem. Geol. 242 (3) (2007) 351–370 .
[3] J.L. Bischoff, J.P. Fitts , J.A. Fitzpatrick , Responses of sediment geochemistry to climate change in Owens Lake sediment: An 800-k.y. record of saline/fresh cycles in core OL-92, in: G.I. Smith, J.L. Bischoff (Eds.), An 80 0,0 0 0-year Paleoclimatic Record from Core OL-92, Geological Society of America, Owens Lake, Southeast California, 1997 .
