A N N A L E S
U N I V E R S I T A T I S M A R I A E C U R I E - S . à 2 ' 2 : S . A
L U B L I N – 3 2 L 2 N I A
V2L L;I; SECTI2 AAA 2014
CARB2N IS2T2PIC C2MP2SITI2N 2)
EARL<-'IA*ENETIC MET+ANE VARIATI2NS :IT+
SE'IMENTS 'EPT+
Mariusz 2riRQ -Ċdrysek
1, StaQisáaw +aáas
2, TRPasz PieĔkRs
21LaERratRry RI IsRtRSe *eRORJy aQd BiRJeRFKePistry, IQstitute RI *eRORJiFaO SFieQFes, UQiYersity
RI :rRFáaw, 50-205 :rRFáaw, PROaQd
2Mass SSeFtrRPetry LaERratRry, M Curie-SkáRdRwska UQiYersity 20-031 LuEOiQ, PROaQd
ABSTRACT
:e dePRQstrate tKe aQQuaO FyFOe RI PetKaQe iQ IresK sediPeQts RI twR Oakes – MRszQe (E PROaQd) aQd SkrzyQka (: PROaQd) TKe YertiFaO JradieQt iQ į13C(C+
4) YaOues Yaried
wideOy IrRP aERut -45Å(-1 P) iQ Oate suPPer 1 3 tR aERut 25Å(-1 P) iQ Oate wiQter, iQ tKe uSSerPRst sediPeQt SrRIiOes RI aERut 3-Peters iQ OeQJtK TKese YertiFaO YariatiRQs aSSareQtOy are QRt due tR R[idatiRQ Rr tePSerature FKaQJes, Eut ratKer tR tKe KiJKer JradieQt RI tKe dRwQward deFrease RI SrRduFtiRQ rates Yia tKe aFetiF aFid IerPeQ-tatiRQ SatKway ratKer tKaQ Yia tKe C22-+2 SatKway TKe SrRduFtiRQ RI PetKaQe aQd
į13C(C+
4) YaOues are tKe KiJKest duriQJ suPPer wKiOe tKe ORwest duriQJ wiQter,
reIOeFt-ed esSeFiaOOy duriQJ surIaFe saPSOiQJ TKe dRwQward JradieQt RI į13C iQ wiQter, Oate
autuPQ aQd, at Jreater deStKs, iQ Oate suPPer resuOts IrRP isRtRSe eQriFKPeQt RI tKe residuaO SRRO RI SreFursRrs RI PetKaQe, SredRPiQaQtOy C22
Keywords: FarERQ, isRtRSe, PetKaQe, Oake, sediPeQt, diaJeQesis, JreeQKRuse eIIeFt,
isRtRSe EudJet
30 M. ORION -ĉDR<SE., S. +AàAS, T. PIEē.OS
1. INTRODUCTION
MethaQe prRductiRQ is aQ iPpRrtaQt part RI the JOREaO carERQ cycOiQJ (e.J. CraiJ aQd ChRu 1 82, .haiO aQd RasPusseQ 1 83, SteeOe et aO. 1 8) aQd PethaQRJeQic pathways are deterPiQed Ey cRe[istiQJ RrJaQic Patter, water, aQd EacteriaO actiYity. The IROORwiQJ IactRrs haYe EeeQ prRYed Rr prRpRsed tR aIIect PethaQRJeQesis aQd PethaQe IOu[ IrRP QaturaO wetOaQds: (1) saOiQity (De LauQe et aO. 1 83), (2) IertiOizatiRQ RI paddy sRiO (:ada 1 0), (3) sRiO redR[ pRteQtiaO (CicerRQe et aO. 1 83, SYeQsRQ aQd RRssewaOO 1 84), (4) QutrieQt aQd RrJaQic cRQteQt RI surIace sRiOs aQd their thickQess (+arriss aQd SeEacher 1 81). (5) suEstrate aQd YROatiOe eQd-prRduct cRQceQtratiRQ (De LauQe et aO. 1 8), () pOaQt type aQd its physiRORJicaO state (YeQtiOatiRQ rate, aJe, heiJht Dacey aQd .OuJ 1 , Dacey 1 81, CicerRQe et aO. 1 83, SeEacher et aO. 1 85), aQd () priPary prRductiRQ (:hitiQJ aQd ChaQtRQ 1 3).
IQ additiRQ PaQy e[terQaO IactRrs Oike (1) wiQd speed (SeEacher et aO. 1 83), (2) atPRspheric pressure (MatsRQ aQd LikeQs 1 0), (3) PRisture cRQteQt Rr water OeYeO (+arriss et aO. 1 82, SYeQsRQ aQd RRsswaOO 1 84), aQd (4) tePpera-ture (Baker-BORcker et aO. 1 , SYeQsRQ aQd RRsswaOO 1 84, SeEacher et aO. 1 8) Pay cRQtrRO the PethaQe IOu[ IrRP QaturaO wetOaQds. IQ this paper we repRrt seasRQaO YariatiRQs iQ YerticaO prRIiOes iQ cRQceQtratiRQ aQd carERQ isRtRp-ic cRPpRsitiRQ RI PethaQe.
BasiQJ RQ the therPRdyQaPics, aQ iPpOicit assuPptiRQ cRuOd Ee appareQtOy Pade that carERQ isRtRpe IractiRQatiRQ IactRr EetweeQ the PethaQe precursRrs aQd PethaQe Jas, depeQds RQ tePperature. LRJicaOOy, at the ORwer tePperature RI the Oake eQYirRQPeQt, the IractiRQatiRQ IactRr cRuOd Ee e[pected tR Ee OarJer. Other IactRrs cRQtrROOiQJ isRtRpe cRPpRsitiRQ RI PethaQe are isRtRpe ratiR iQ suEstrates (PethaQe precursRrs) aQd PethaQe cRQsuPptiRQ Ey PicrREiaO R[ida-tiRQ. IQ QaturaO Ireshwater systePs, the IerPeQtatiRQ RI acetate, C+3COO+ ĺ
C+4 CO2 (Barker 1 3), aQd the reductiRQ RI carERQ diR[ide, CO2 4+2 ĺ
C+4 +2O (Takai 1 0), are the PaiQ PethaQRJeQic pathways. Based upRQ
Ireshwater paddy sRiO iQcuEatiRQ e[periPeQts, the eQdPePEer į13C YaOue RI
PethaQe prRduced IrRP acetate dissiPiOatiRQ is -3Å aQd the į13C YaOue RI C+ 4,
IrRP CO2/+2 was estiPated tR Ee - tR -0Å (SuJiPRtR aQd :ada 1 3).
ThereIRre, chaQJes iQ the reOatiYe ratiRs RI PethaQe IRrPatiRQ pathways Pay Oead tR tePpRraO aQd spatiaO YariatiRQs RI the į13C YaOue iQ C+
4, thRuJh aQ
Rr-JaQic Patter precursRr Pay shRw hRPRJeQeRus carERQ isRtRpic cRPpRsitiRQ. It has EeeQ shRwQ that, iQ QaturaO cRQditiRQs, diurQaO YariatiRQs RI į13C(C+
4)
iQ sRPe cases dRes Eut, usuaOOy dRes QRt cRrrespRQd tR the diurQaO YariatiRQs RI water Rr sediPeQts tePperature, Eut rather cRrrespRQds tR the aEuQdaQce aQd isRtRpe characteristics RI the PethaQe precursRrs with QeJOiJiEOe rROe RI PethaQe R[idatiRQ (-Ċdrysek 1 5, 1 ). ThereIRre, uQkQRwQ IactRr(s) stiOO rePaiQ IRr
CARBON ISOTOPIC COMPOSITION O) EARL<-DIA*ENETIC MET+ANE« 31 QaturaO cRQditiRQs RI Ireshwater Oakes systePs, Eecause RI Oack RI iQIRrPatiRQ RQ spatiaO aQd tePpRraO YariatiRQs RI PethaQRJeQesis iQ Ireshwater sediPeQts, par-ticuOarOy iQ Oakes (e.J. :ROtePate et aO. 1 84, :hiticar et aO. 1 8).
It was IRuQd receQtOy that į13C(C+
4) YaOues RI Ireshwater PethaQe teQds tR
EecRPe PRre QeJatiYe with depth RI the water cROuPQ aQd depth RI sediPeQts (-Ċdrysek et aO. 1 4, -Ċdrysek 1 , 2005a). CRQseTueQtOy, RQe Pay state that data puEOished iQ preYiRus wRrks Pay QRt IirPOy represeQt isRtRpic cRPpRsitiRQ RI tRtaO PethaQe ePitted IrRP Ireshwater sediPeQts. ThereIRre, the JRaOs RI the preseQt study are: 1) tR REtaiQ Qew data RQ C+4 JeQerated IrRP Oakes with
re-spect tR spatiaO aQd tePpRraO distriEutiRQs, 2) Eetter uQderstaQdiQJ RI the Pecha-QisPs RI PethaQRJeQesis, 3) tR prRYide Qew data IRr isRtRpic Pass EaOaQces RI carERQ cycOiQJ iQ earOy diaJeQesis iQ Ireshwater systePs aQd JreeQhRuse Jases IOu[.
2. MATERIALS AND MET+ODS
2.1. STUD< AREA
MethaQe was saPpOed iQ twR Oakes, RQe iQ EasterQ aQRther iQ :esterQ PR-OaQd. A Oake iQ EasterQ PROaQd, ORcated ca. 50 kP NE IrRP LuEOiQ (5O.4N, 23.1E), was seOected iQ this study as the PaiQ saPpOiQJ site. It EeORQJs tR the reJiRQ RI the àĊczQa–:áRdawa LakeOaQd. The water EaOaQce cOearOy shRws that this reJiRQ is shRrt RI water. MeaQ precipitatiRQ, RI PaQy years Peasured, is 50 PP aQd eYapRratiRQ is 450 PP. AERut 110 PP is ruQRII RI which 52 Pakes the uQderJrRuQd ruQRII. SPaOO perPeaEiOity aQd water capacity RI POeistRceQe depRsits uQderOyiQJ the Oake aQd the Iact that the area is IOat, with a dRzeQ Rr sR Peters RI Pa[iPuP reOatiYe heiJht, are the reasRQs that the water OeYeO is QRt deep aQd the surIace is swaPpy (:iOJat et aO. 1 1). Lake MRszQe is iQ its IiQaO staJe RI the Oake deYeORpPeQt, it is surrRuQded Ey peat-ERJs, swaPps aQd Parshes. It is a dystrRphic, Yery shaOORw (Pa[. depth 0.8 P), sPaOO (0.1 kP2)
Oake. NR seasRQaO YariatiRQs iQ the water OeYeO has EeeQ REserYed. The ERttRP is Yery IOat aQd practicaOOy Iree IrRP aQy PacrRphytes. AOO the EaQk RI the Oake arRuQd is cRYered Ey a IORatiQJ peat-ERJ. The sediPeQts are e[trePeOy sRIt aQd cRPpRsed Qear e[cOusiYeOy RI in situ RrJaQic Patter detritus (CRrJ iQ the dry
32 M. ORION -ĉDR<SE., S. +AàAS, T. PIEē.OS
FIG. 1. Map shRwiQJ the ORcatiRQs RI saPpOed Oakes iQ PROaQd. SaPpOiQJ sites are
de-scribed iQ: -Ċdrysek (1 5, 1 , 1 ).
OccasiRQaOOy saPpOiQJ haYe beeQ carried Rut aOsR iQ Lake SkrzyQka (52.15N, 1.0E, ca. 30 kP sRuthward IrRP PRzQaĔ, : PROaQd). Lake SkrzyQka is Pa[. 2.0 Peters depth aQd shRws Qear ideQticaO OiPQRORJicaO aQd hydrRORJicaO character as Lake MRszQe, but is situated iQ Puch Oess Parshy reJiRQ.
2.2. SAMPLIN* AND )IELD OBSERVATIONS
IQ Rrder tR reduce the iQIOueQce RI diurQaO YariatiRQs (-Ċdrysek 1 4, 1 5) each saPpOiQJ caPpaiJQ was carried Rut betweeQ 12:00 aQd 3:00 PM. VerticaO saPpOiQJ prRIiOe was dRQe by seTueQtiaO aJitatiRQ RI deeper zRQes RI sediPeQt by PeaQs RI a scaOed (with 1 cP accuracy) paddOe. The depth RI water iQ the saPpOiQJ sites was 0.5 P. The YisuaOOy estiPated saPpOiQJ depth resROutiRQ was appareQtOy better thaQ 5 cP. BubbOes were RbtaiQed IrRP subPerJed sediPeQts by aJitatiRQ, aQd theQ trapped by aQ iQYerted IuQQeO a 20 cP iQ diaPeter iQtR a JOass bRttOe IiOOed with Jas-Iree water. The upperPRst Oayer RI sediPeQt was aJitated Iirst, uQtiO aOO the PethaQe had appareQtOy beeQ reOeased. TheQ, the Qe[t, deeper zRQe RI sed-iPeQts was stirred, aQd iQ each subseTueQt zRQe the thickQess RI the stirred sedi-PeQts was QarrRwer. This prRcedure appareQtOy preYeQted cRQtaPiQatiRQ RI Pe-thaQe IrRP a JiYeQ zRQe by PePe-thaQe IrRP aQRther RYerOayiQJ zRQe.
SaPpOiQJ tiPe RI bubbOe Jases was usuaOOy QRt ORQJer thaQ 2 PiQutes. SRPe water rePaiQed iQ the bRttOe. The bRttOes were seaOed with a butyO rubber cap aQd aQ aOuPiQuP seaO, aQd the saPpOes were iPPediateOy treated with +JCO2. BRttOes
with saPpOes were stRred iQ a reIriJeratRr (3–4C) iQ aQ iQYerted pRsitiRQ. E[-periPeQts with aQaOysis repeated at diIIereQt tiPes IRr seYeraO tiPes prRYed that the OeQJth RI the periRd IRr which saPpOes were heOd beIRre they were aQaOyzed did QRt iQIOueQce resuOts. MRreRYer, it was prRYed preYiRusOy that saPpOes cRO-Oected at the saPe tiPe IrRP the saPe depth RI water cROuPQ, IrRP the saPe depth RI sediPeQts (0–25 cP) aQd IrRP reasRQabOy siPiOar sediPeQts, but at
CARBON ISOTOPIC COMPOSITION O) EARL<-DIA*ENETIC MET+ANE« 33 diIIereQt saPpOiQJ statiRQs, shRwed the saPe į13C resuOts withiQ aQaOyticaO errRr
which was IrRP 0.05 tR 0.2Å (-Ċdrysek et a1. 1 4, -Ċdrysek 1 4, 1 5). Ver-ticaO prRIiOes RI tePperature iQ sediPeQts were Peasured with a precisiRQ RI 0.1C, usiQJ a 3-Peter ORQJ therPRcRupOe prRbe Pade by Czaki.
2.3. ANAL<TICAL TEC+NIQUES
:ith PROecuOar sieYes, a dry-ice-ethaQRO Pi[ture, aQd OiTuid QitrRJeQ, the PethaQe was cryRJeQicaOOy puriIied uQder YacuuP IrRP Rther hydrRJeQ aQd carbRQ cRQtaiQiQJ Jases. SubseTueQtOy, the PethaQe, tRJether with hydrRJeQ aQd carbRQ-Iree Jases was passed thrRuJh a cRpper R[ide IurQace (850– 00C) twice. The prRducts RbtaiQed, +2O aQd CO2, were separated cryRJeQicaOOy.
Car-bRQ isRtRpe aQaOyses were Pade RQ a PRdiIied MI-1305 Pass spectrRPeter with duaO iQOet (+aOas, 1 ) aQd hRPe-Pade detectiRQ systePs (+aáas aQd SkRrzyĔ-ski, 1 80). The isRtRpe ratiRs are e[pressed as į13C YaOues reOatiYe tR the PDB
staQdard, usiQJ a Pass spectrRPetric cRPparisRQ RI wRrkiQJ CO2 Jas with CO2
prepared IrRP NBS 1 aQd NBS 22 staQdards. The iQterQaO precisiRQ RbtaiQed was 0.05Å. The reprRducibiOity RI isRtRpe preparatiRQ was IrRP 0.05 tR 0.2). The chePicaO cRPpRsitiRQ RI saPpOe Jases was aQaOyzed by TCD Jas chrRPatRJraphy (EOwrR chrRPatRJraph S04) aQd the cRQteQt RI RrJaQic Patter (CRrJ) was aQaOyzed by DiIIereQtiaO TherPaO AQaOysis aQd TherPRJraYiPetry
(DeriYatRJraph 1500D).
3. RESULTS
AOO data haYe beeQ preseQted iQ IiJures. SyPbROs, iQ each IiJure represeQtiQJ the saPe Oake, cRrrespRQds tR the saPe prRIiOe.
SiQce tePperature is the IactRr cRQtrROOiQJ isRtRpe eIIects, tePperature PeasurePeQts iQ the sediPeQts prRIiOes haYe beeQ carried Rut. IQ the spriQJ RI 1 3, prRIiOes RI tePperature ()iJ. 2a) iQ Lake MRszQe teQd tR decrease tR sedi-PeQt depth RI a0.8 P, aQd theQ iQcrease at the Jreater depths. IQ the earOy aQd Oate suPPer 1 3, the tePperature RI sediPeQts decreases dRwQwards. SRPe e[tra tePperature prRIiOes, which are QRt accRPpaQied by Jas saPpOiQJ, are shRwQ iQ )iJ. 2a. +RweYer, iQ Yery Oate suPPer, iQ the Lake SkrzyQka sedi-PeQts, the hiJhest tePperature has beeQ IRuQd at the depth RI abRut 0. P ()iJ. 2b). IQ the autuPQ 1 3 the tePperature teQded tR iQcrease tR sediPeQt depth RI a1.3 P, aQd theQ decreased at Jreater depth. IQ the wiQter 1 4 the tePperature iQcreased dRwQwards. SaPpOiQJ iQ 2.0 .2 (Lake MRszQe) aQd 3.05.23 (Lake SkrzyQka) haYe QRt beeQ assRciated with tePperature PeasurePeQts.
34 M. ORION -ĉDR<SE., S. +AàAS, T. PIEē.OS
FIG. 2a. TePperature YariatiRQs iQ YerticaO prRIiOes iQ the Lake MRszQe sediPeQts
(E PROaQd), each pRiQt cRrrespRQds tR the Jas saPpOiQJ iQterYaO, tePperature was Peas-ured iQ 10 cP RI YerticaO iQterYaOs. AOO the syPbROs iQ each IiJure represeQtiQJ Lake MRszQe reIer tR the saPe prRIiOe. SRPe additiRQaO tePperature prRIiOes has beeQ shRwQ here, but they are QRt represeQted by saPpOes.
FIG. 2b. TePperature YariatiRQs iQ YerticaO prRIiOes iQ the Lake SkrzyQka sediPeQts
(: PROaQd), each pRiQt cRrrespRQds tR the Jas saPpOiQJ iQterYaO, tePperature has beeQ Peasured iQ 10 cP iQterYaOs. AOO syPbROs iQ each IiJure represeQtiQJ Lake SkrzyQka cRrrespRQds tR the saPe prRIiOe.
CARBON ISOTOPIC COMPOSITION O) EARL<-DIA*ENETIC MET+ANE« 35
FIG. 3a. VerticaO YariatiRQs aQd seasRQaO cycOe iQ the YerticaO YariatiRQs iQ bubbOe C+4
cRQceQtratiRQ iQ the Lake MRszQe sediPeQts.
FIG. 3b. VerticaO YariatiRQs aQd seasRQaO cycOe iQ the YerticaO YariatiRQs iQ bubbOe C+4
cRQceQtratiRQ iQ the Lake SkrzyQka sediPeQts.
MethaQe cRQceQtratiRQ iQ bubbOes Yaried IrRP 1 tR 0 iQ the preseQt iQ-YestiJatiRQs ()iJ. 3ab, ab). CO2 cRQstituted IrRP Oess thaQ 1 tR abRut 8
seY-3 M. ORION -ĉDR<SE., S. +AàAS, T. PIEē.OS
eraO tR abRut 80 RI the JaseRus bubbOes. OQOy trace aPRuQts RI Rther Jases were detected. IQ JeQeraO, bubbOe JeQeratiRQ by sediPeQts weakOy Yary aORQJ the prRIiOes, the PethaQe cRQteQt duriQJ suPPer was hiJh iQ cRQtrast tR that duriQJ cROd seasRQs ()iJ. 3ab). IQ sRPe prRIiOes, especiaOOy takeQ iQ the spriQJ aQd au-tuPQ ()iJ. 3ab) the bubbOes IrRP Pid-depth zRQes which are reOatiYeOy rich iQ PethaQe. The ORwest cRQceQtratiRQ RI PethaQe has beeQ QRted iQ the deepest part RI the cROd seasRQs prRIiOes ()iJ. 3a).
Si[ prRIiOes RI the carbRQ isRtRpe cRPpRsitiRQ RI PethaQe iQ sediPeQts IrRP Lake MRszQe are shRwQ iQ )iJ. 4a, aQd the IRur Rther prRIiOes are shRwQ iQ )iJ. 4b (Lake SkrzyQka). IQ Lake MRszQe, saPpOiQJ statiRQs were abRut 1 P IrRP the ParJiQ RI the Oake. A JeQeraO treQd RI decreasiQJ į13C YaOues with iQcreasiQJ
depth was RbserYed iQ the prRIiOes takeQ iQ 2.0 .2, 3.05.01, 3.08.30 (Lake MRszQe, )iJ. 4a). This patterQ seePs tR cRrrespRQd tR sediPeQts tePperature, especiaOOy wheQ ORRk RQ the prRIiOes iQ:
í the suPPer ()iJ. 4ab)
í upper part RI the prRIiOe RI the Oate spriQJ ( 3.05.23, )iJ. 4b) - the upper-PRst parts RI sediPeQts are aOready warP ()iJ. 2a), aQd
í ORwer part RI the prRIiOe RI the earOy autuPQ ( 2.0 .2, 3.14.11 )iJ. 4a) í the deeper sediPeQts are stiOO warP ( 3.14.1 1, )iJ. 2a).
IQ Lake MRszQe duriQJ saPpOiQJ iQ 3.1 1.14 aQd 4.02.11 the Oake was IrR-zeQ (10 aQd 15 cP RI ice cRYer, respectiYeOy). These prRIiOes shRwed treQds RI iQcreasiQJ į13C YaOues with iQcreasiQJ depth ()iJ. 4a).
FIG. 4a. VerticaO YariatiRQs aQd seasRQaO cycOe iQ the YerticaO YariatiRQs iQ į13C(C+ 4)
YaOue iQ the Lake MRszQe sediPeQts.
CARBON ISOTOPIC COMPOSITION O) EARL<-DIA*ENETIC MET+ANE« 3
FIG. 4b. VerticaO YariatiRQs aQd seasRQaO cycOe iQ the YerticaO YariatiRQs iQ į13C(C+ 4)
YaOue iQ the Lake SkrzyQka sediPeQts.
DuriQJ wiQter PethaQe JeQeratiRQ IrRP the upper a1P was sR ORw that RQOy seYeraO PiOOiOiters RI Jas haYe beeQ reOeased due tR aJitatiRQ RI the sediPeQts (whereas iQ the saPe pOace duriQJ the suPPer the saPe YROuPe RI sediPeQt reOeased apprR[iPateOy thRusaQd OarJer YROuPe RI the Jas). Thus, the upperPRst saPpOe RI the 4.02.11 prRIiOe represeQts PethaQe IrRP as wide aQ iQterYaO RI sediPeQts as 0.0 P tR 1.2 P. The autuPQ 1 3 aQd 1 4 prRIiOes e[hibited a rather hiJh į13C YaOue as cRPpared tR that iQ the Oate spriQJ aQd earOy suPPer
prRIiOes, but the hiJhest YaOues were shRwQ by the Oate suPPer saPpOes aQd the ORwest YaOue by the Oate wiQter saPpOe.
4. DISCUSSION
A*EIN* O) SEDIMENTS AND ISOTOPE )RACTIONATION – A *ENERAL OVERVIE:
IQ JeQeraO, reOatiYeOy siPpOe, ORw-PROecuOar weiJht cRPpRuQds, such as QRQstructuraO carbRhydrates aQd prRteiQ-beariQJ PateriaOs, are PRre easiOy de-Jraded thaQ the cRPpOe[ pROyPeric cRPpRuQds such as the OiJQiQ RI wRRdy aQd ePerJeQt aTuatic pOaQts (MRRre 1 , :etzeO 1 5, .RyaPa et aO. 1 , +eaO
38 M. ORION -ĉDR<SE., S. +AàAS, T. PIEē.OS
aQd IQesRQ 1 84). )Rr e[aPpOe, BeOO (1 ) iQcubated IORRded sRiO aQaerRbicaOOy aQd IRuQd that JOucRse aQd peptRQe were deJraded tR PethaQe aQd carbRQ diR[-ide Puch Iaster thaQ ceOOuORse, aOthRuJh the tRtaO YROuPes RI PethaQe aQd carbRQ diR[ide eYeQtuaOOy prRduced IrRP the three substrates were rRuJhOy the saPe. SiPiOarOy, aOJaO PateriaO is decRPpRsed tR PethaQe aQd carbRQ diR[ide abRut 10 tiPes Iaster thaQ is OiJQRceOOuORses (BeQQer et aO. 1 84). ThereIRre, PethaQe prRductiRQ shRuOd decrease with sediPeQt PaturatiRQ. IQ Iact, tube iQcubatiRQs shRwed that the rate RI PethaQe prRductiRQ iQ Ireshwater Oake sediPeQts de-creased IrRP Pa[iPuP YaOues at surIace tR QearOy zerR at depths RI 40 tR 0 cP. Likewise, tRtaO RrJaQic carbRQ decreased IrRP surIiciaO YaOues (5 tR 2) at 40 tR 0 cP with QR Iurther decreases with depth (.RyaPa et aO. 1 , .RyaPa 1 0).
BOair aQd Carter (1 2) estiPated the carbRQ isRtRpe IractiRQatiRQ IactRr dur-iQJ PethaQe prRductiRQ iQ aQR[ic PariQe sediPeQts tR be 1.032. They haYe shRwQ that the į13C YaOue RI PethaQe prRduced IrRP acetate is PRre QeJatiYe
thaQ the į13C YaOue RI the PethyO JrRup RI the acetate. .rzycki et aO. (1 8) haYe
IRuQd that the carbRQ isRtRpe diIIereQce betweeQ the PethyO carbRQ RI acetate aQd PethaQe is 2OÅ. The į13C YaOue RI C+
4 prRduced IrRP acetate uQder steady
state cRQditiRQs was estiPated tR be siPiOar tR that RI PethyO carbRQ RI acetate (-43 tR -30Å) iQ suOIate depOeted Ireshwater areas aQd the iQtraPROecuOar isRtRpe distributiRQ RI acetate was -43Å tR -30Å IRr PethyO carbRQ aQd -24Å tR -15Å IRr carbR[yO carbRQ (SuJiPRtR aQd :ada 1 3). It was repRrted aOsR that, iQ the CO2-C+4 systeP, the IractiRQatiRQ is 1.04 at 3C (.rzycki et aO. 1 8) aQd
raQJes wideOy depeQdeQt RQ bacteriaO species IRr e[aPpOe, at 45C the Irac-tiRQatiRQ IactRr Yaries at Oeast IrRP 1.045 tR 1.01 (*aPes et aO. 1 8). MethaQe prRduced IrRP Rther substrates thaQ carbRQ diR[ide aQd acetate, cRuOd be cOassi-Iied as a third JrRup (OrePOaQd et aO. 1 82) but we dR QRt haYe eYideQce RI that aQd its į13C(C+
4) cRuOd be diIIereQt IrRP the YaOue IRr PethaQe prRduced IrRP
carbRQ diR[ide aQd acetate. TR this JrRup RI pathways Pay beORQJ IRr e[aPpOe, the prRductiRQ aQd cRQsuPptiRQ RI the PethyO JrRup RI PethiRQiQe aQd diPethysuOphide, PethyOated aPiQes, PethaQRO, ethaQRO, beQzRate, reductiRQ RI carbRQ PRQR[ide, IRrPate, etc. (=iQdOer aQd BrRck O 8ab, :eiPer aQd =eikus 1 8, PattersRQ aQd +espeOO 1 , OrePOaQd et aO. 1 82). +RweYer, RQOy uQder certaiQ speciaO cRQditiRQs this third JrRup RI PethaQRJeQic pathways dRes pOay aQ iPpRrtaQt rROe. .iQJ et aO. (1 83) repRrted that 35.1 – 1.1 RI PethaQRJeQesis RccurriQJ iQ sOurries RI suOIate-rich iQtertidaO sediPeQts was IrRP triPethyOaPiQe, whereas LRYOey aQd .OuJ (1 83) deterPiQed that 15 aQd 5 RI tRtaO PethaQRJeQesis iQ ORw suOIate Oake sediPeQts cRuOd be accRuQted IRr PethyO aPiQes aQd PethaQRO, respectiYeOy.
The IactRr OiPitiQJ acetate IerPeQtatiRQ is the prRductiRQ rate RI acetate, whereas the CO2/+2 prRductiRQ RI C+4 Pay be cRQtrROOed by +2 traQsIer
CARBON ISOTOPIC COMPOSITION O) EARL<-DIA*ENETIC MET+ANE« 39 dissiPiOatiRQ is the aYaiOabiOity RI acetate. Acetate prRductiRQ rate caQ be Yery hiJh, but RQOy a OittOe IractiRQ is cRQYerted tR PethaQe. II hydrRJeQ is prRduced iQ substaQtiaO aPRuQts by bacteria aQd dissRciatiRQ RI water, aQd Oikewise the CO2 cRQceQtratiRQ iQ water is reOatiYeOy hiJh, these Pay eQhaQce
PethaQRJeQesis Yia the CO2/+2 reductiRQ iQ the upperPRst hRrizRQs RI
sedi-PeQts. The abuQdaQces RI R[yJeQ aQd Rther pRteQtiaOOy iPpRrtaQt eOectrRQ ac-ceptRrs suppRrtiQJ the decRPpRsitiRQ RI RrJaQic Patter aOsR depeQd RQ the rates RI PicrRbiaO actiYities that are, iQ turQ, cRQtrROOed by OiJht aQd tePperature re-suOtiQJ IrRP day-QiJht YariatiRQs (-Ċdrysek 1994, -Ċdrysek et aO. 199). MRreR-Yer, the diIIereQt PechaQisP RI biRJeQic PethaQe prRductiRQ caQ resuOt iQ a wide raQJe RI isRtRpic cRPpRsitiRQ especiaOOy withiQ PiOOiPeters tR ceQtiPeters RI the sediPeQt-water iQterIace. IQ JeQeraO, the cRQceQtratiRQs RI CO2 aQd
ace-tate iQ PariQe sediPeQts iQcrease aQd decrease dRwQward, respectiYeOy (CriOO aQd MarteQs 198). BRth JrRss acetate prRductiRQ rate aQd acetate cRQceQtratiRQ iQ sediPeQts is the hiJhest iQ the surIace Oayer (0–2 cP) aQd it is seYeraO tiPes ORwer at depth RI 8-10 cP, aOthRuJh the YariatiRQ RI acetate R[idatiRQ rate with depth, Qeed tR be better cOariIied (ChristeQseQ 1984, MicheOsRQ et aO. 1989).
14C iQcubatiRQ e[periPeQts dePRQstrated that acetate cRQceQtratiRQ iQ
sedi-PeQts decreased substaQtiaOOy aIter ORQJ iQcubatiRQ periRds (MicheOsRQ et aO. 1989). Acetate turQRYer is hiJh Qear the surIace, but it is uQsure iI acetate dis-siPiOatiRQ siJQiIicaQtOy e[ceed the rate RI CO2/+2 reductiRQ, because +2
prRduc-tiRQ is the hiJhest Qear the surIace as weOO. Despite that this pRiQt is QRt weOO dRcuPeQted iQ the Oiterature, because RI the uQcertaiQties aQd pRteQtiaO artiIacts assRciated with the 14C-tracer acetate turQRYer PeasurePeQts, sRPe eYideQces,
IaYRriQJ the pRiQt that acetate dissiPiOatiRQ is reOatiYeOy PRre iPpRrtaQt iQ the surIiciaO sediPeQts, cRPes IrRP 13C e[periPeQts. NaPeOy, the siPiOar situatiRQ
was cOearOy RbserYed iQ paddy sRiO-water iQcubatiRQ studies, aQd the į13C(C+ 4)
YaOue was a useIuO iQdicatRr IRr assessiQJ the cRQtributiRQ RI acetate IerPeQta-tiRQ tR the tRtaO prRducIerPeQta-tiRQ RI PethaQe: the hiJh į13C+
4 YaOues cRrrespRQded tR
a hiJher cRQtributiRQ RI the acetate prRcess (SuJiPRtR aQd :ada 1993). PRO)ILES ANAL<=ED
:e specuOate that the iQput RI Iresh RrJaQic Patter iQtR sediPeQts, iQ the eQd RI suPPer, cRuOd sOiJhtOy eQhaQce the prRductiRQ RI acetic acid aQd prRYide the hiJher į13C YaOues IRr PethaQe. CRQseTueQtOy, the Oate suPPer/earOy autuPQ
PethaQe cRuOd shRw the PRre pRsitiYe į13C YaOue iQ the aQQuaO cycOe. IQ Iact,
hiJhest į13C(C+
4) YaOues ()iJ. 4a) aQd YisuaOOy MudJed hiJhest PethaQe
prRduc-tiRQ were RbserYed duriQJ Oate suPPer aQd earOy autuPQ. AbuQdaQt bubbOe Pe-thaQe is easiOy aQd eIIicieQtOy RbtaiQed by OiPited stirriQJ RI sediPeQt duriQJ suPPer, whereas ORw aPRuQts RI bubbOe PethaQe are RbtaiQed iQ siPiOar cRQdi-tiRQs by e[teQsiYe stirriQJ RI sediPeQts duriQJ wiQter. This RbserYatiRQ
cRrre-40 M. ORION -ĉDR<SE., S. +AàAS, T. PIEē.OS
Oates weOO with aQQuaO YariatiRQs RI ebuOOitiRQ (MarteQs et aO. 198, ChaQtRQ aQd MarteQs 1988, Burke et aO. 1988, -Ċdrysek et aO. 1994, -edrysek 199) aQd teP-perature seasRQaO YariatiRQs ()iJ. 2a). BRth ebuOOitiRQ aQd tePteP-perature are the ORwest duriQJ wiQter aQd the hiJhest duriQJ suPPer. This resuOt is caused prRb-abOy by the Iact that PethaQe is Oess sROubOe at ORwer tePperature (ChaQtRQ et aO. 1992) aQd by YaQishiQJOy ORw prRductiRQ RI PethaQe duriQJ wiQter (-Ċdrysek 199).
IQasPuch as IriQJiQJ YeJetatiRQ RI PacrRphytes is OikeOy tR be criticaO iQ aI-IectiQJ PethaQRJeQesis (e.J. *erard aQd ChaQtRQ 1993), because partiaO cRQ-suPptiRQ RI PethaQe by R[idatiRQ caQ siJQiIicaQtOy shiIt hydrRJeQ aQd carbRQ isRtRpic ratiRs pRsitiYeOy iQ the residuaO PethaQe (=yakuQ et aO. 199, Barker aQd )ritz 1981, CROePaQ et aO. 1981). )Rr this reasRQ iQ Rur saPpOiQJ statiRQs QR subPerJed Rr ePerJed PacrRphytes were preseQt withiQ seYeraO Peters. There-IRre, the decrease iQ į13C(C+
4) with iQcreasiQJ depth iQ sediPeQts ()iJ. 4ab)
was pRssibOy caused either by actiYe PethaQe cRQsuPptiRQ cORse tR the surIace aQd/Rr by hiJher cRQtributiRQ RI acetic acid IerPeQtatiRQ Qear the surIace Oayers aQd a reOatiYeOy Jreater cRQtributiRQ by the CO2/+2 reductiRQ iQ deeper parts RI
sediPeQts. +RweYer, aQR[ic cRQditiRQs were RbserYed Must seYeraO ceQtiPeters beORw the water-sediPeQt iQterIace, aQd the suOIate cRQceQtratiRQ iQ pRre waters was cORse tR zerR (-Ċdrysek 2005b). Thus, Oatter prRcess, RI Jreater cRQtributiRQ by the CO2/+2 pathway iQ deeper parts RI sediPeQts, is OikeOy ePphasized here,
siQce the pRsitiYe depth-į13C cRrreOatiRQ iQ sediPeQts cRuOd QRt pRssibOy be
a resuOt RI YaryiQJ deJrees RI bacteriaO R[idatiRQ RI trapped PethaQe.
NRQetheOess, despite aQaerRbic cRQditiRQs, R[idatiRQ shRuOd QRt be QeJOected, aQd thereIRre PRre Iacts shRuOd be cRQsidered. It cRQcerQ especiaOOy reOatiRQs be-tweeQ PethaQe cRQceQtratiRQ aQd į13C(C+
4) YaOue. Decrease iQ PethaQe
cRQceQ-tratiRQ iQ JeQeraO dRes QRt cRrreOate tR į13C(C+
4) YaOues ()iJ. 5ab) – a QeJatiYe
cRrreOatiRQ shRuOd be RbserYed iI R[idatiRQ was the dRPiQaQt IactRr cRQtrROOiQJ į13C YaOue. OQ the Rther haQd, twR prRIiOes RI 93.05.01 aQd 94.02.11 shRw
siJQiIi-caQt QeJatiYe cRrreOatiRQ ()iJ. 5a) which Pay suJJest appareQt R[idatiRQ eIIect. +RweYer, these twR prRIiOes are cRQtradictiYe. NaPeOy, iQ the prRIiOe RI 94.02.11 appareQtOy the PRst R[idized PethaQe (hiJh į13C YaOue) cRrrespRQds tR the deep
part RI the prRIiOe, but iQ the prRIiOe RI 93.05.01 appareQtOy the PRst R[idized Pe-thaQe (hiJh į13C YaOue) cRrrespRQds tR the surIiciaO part RI the prRIiOe. It wRuOd
iPpOy that R[idatiRQ has QR reOatiRQ tR depth iQ the sediPeQts which, RQ the Rther haQd, is cruciaO IRr R[idatiRQ pRteQtiaO, suOIate cRQceQtratiRQ etc. AdditiRQaOOy, the e[trePeOy OarJe YariatiRQs iQ the į13C YaOues iQ the prRIiOe RI 93.08.30 dRes QRt
cRrrespRQd tR aQy reParkabOe YariatiRQ iQ the C+4 cRQceQtratiRQ ()iJ. 5a).
MRre-RYer, a QeJatiYe cRrreOatiRQ iQ the CO2-C+4 systeP shRuOd be RbserYed iI
R[ida-tiRQ was iPpRrtaQt siQk RI PethaQe, but cRQtrary, a pRsitiYe cRrreOaR[ida-tiRQ ()iJ. b) Rr QR cRrreOatiRQ has beeQ RbserYed ()iJ. a).
CARBON ISOTOPIC COMPOSITION O) EARL<-DIA*ENETIC MET+ANE« 41
FIG. 5a. CRrreOatiRQ betweeQ į13C(C+
4) aQd cRQceQtratiRQ RI bubbOe C+4 cRQceQtratiRQ
iQ the Lake MRszQe sediPeQts.
FIG. 5b. CRrreOatiRQ cRQceQtratiRQ betweeQ į13C(C+
4) aQd bubbOe C+4 cRQceQtratiRQ iQ
the Lake SkrzyQka sediPeQts.
13
13
42 M. ORION -ĉDR<SE., S. +AàAS, T. PIEē.OS
FIG. 6a. CRrreOatiRQ betweeQ cRQceQtratiRQ RI bubbOe C+4 aQd cRQceQtratiRQ RI bubbOe
CO2 iQ the Lake MRszQe sediPeQts.
FIG. 6b. CRrreOatiRQ betweeQ cRQceQtratiRQ RI bubbOe C+4 aQd cRQceQtratiRQ RI bubbOe
CARBON ISOTOPIC COMPOSITION O) EARL<-DIA*ENETIC MET+ANE« 43
FIG. 7a. CRrreOatiRQ betweeQ į13C(C+
4) aQd cRQceQtratiRQ RI bubbOe CO2 iQ the Lake
MRszQe sediPeQts.
FIG. 7b. CRrreOatiRQ betweeQ į13C(C+
4) aQd cRQceQtratiRQ RI bubbOe CO2iQ the Lake
SkrzyQka sediPeQts.
13
44 M. ORION -ĉDR<SE., S. +AàAS, T. PIEē.OS
FIG. 8a. CRrreOatiRQ betweeQ į13C(C+
4) aQd tePperature RI sediPeQts iQ Lake MRszQe.
FIG. 8b. CRrreOatiRQ betweeQ į13C(C+
4) aQd tePperature RI sediPeQts iQ Lake
SkrzyQka.
13
CARBON ISOTOPIC COMPOSITION O) EARL<-DIA*ENETIC MET+ANE« 45 +RweYer, iQ Lake MRszQe, aQ iQcrease iQ CO2 cRQceQtratiRQ iQ bubbOes
pRRrOy pRsitiYeOy cRrreOate with į13C(C+
4) YaOues ()iJ. a). MRreRYer, the
Per prRIiOe RI 93.0.1 ()iJ. a), aQd especiaOOy prRIiOes RI the eQd RI the suP-Per i.e. 93.08.30 ()iJ. a) aQd iQ Lake SkrzyQka the prRIiOe RI 93.09.08 ()iJ. b) shRw a pRsitiYe cRrreOatiRQ iQ the CO2-į13C(C+4) systeP. This is iQ aJreePeQt
with aQ e[pected eIIect RI PethaQe R[idatiRQ as iPpRrtaQt IactRr cRQtrROOiQJ į13C RI PethaQe. +RweYer, the saPe prRIiOes are discussed beORw, as it shRws
a pRsitiYe cRrreOatiRQ iQ the tePperature-į13C(C+
4) systeP ()iJ. 8ab) aQd as it
was prRYed abRYe, PethaQe iQ these prRIiOes has QRt beeQ R[idized. MRreRYer, iQ cRQtrast tR Lake SkrzyQka ()iJ. b), besides the PeQtiRQed abRYe prRIiOes, a pRsitiYe cRrreOatiRQ iQ the CO2-į13C(C+4) systeP, iQ Lake MRszQe, is RbserYed
()iJ. a). This systeP seePs rather cRPpOe[, the DIC pRRO is reOatiYeOy OarJe, aQd PaQy prRcesses, QRt reOated tR PethaQRJeQesis, are respRQsibOe IRr carbRQ cycOiQJ iQ the Oake sediPeQts. Thus, prRbabOy Rther IactRr(s), cRiQcideQtaOOy act-iQJ iQ the saPe directiRQ, cRuOd be respRQsibOe IRr this CO2-į13C(C+4)
cRrreOa-tiRQ. PrRbabOy tePperature cRuOd be the cruciaO IactRr, as the wiQter aQd autuPQ prRIiOes shRw QeJatiYe Rr QR CO2-į13C(C+4) cRrreOatiRQ ()iJ. a). IQ suPPary,
we suJJest that the 13C-depOeted PethaQe at depth PiJht reIOect a Jreater cRQtri-butiRQ RI PethaQRJeQesis Yia the carbRQ diR[ide reductiRQ pathway.
ChaQJes iQ the reOatiYe rates RI PethaQe-prRduciQJ pathways are Puch PRre prRbabOe thaQ R[idatiRQ, aQd shRuOd be e[pected. NaPeOy, aIter the acetate re-Oeased iQ the shaOORwer sediPeQts was e[hausted thrRuJh PethaQe prRductiRQ, PethaQRJeQesis cRuOd stiOO prRceed iQ the deeper Oayer, usiQJ CO2 deriYed IrRP
RrJaQic aQd iQRrJaQic sRurces. ResuOts RbtaiQed by SuJiPRtR aQd :ada (1995) cRQYiQce that iQ cRQtrast tR acetate iQ Ireshwater sediPeQts, at depth, the hydrR-JeQ substrates IRr CO2 reductiRQ are stiOO preseQt wheQ the easiOy deJraded
Rr-JaQic cRPpRuQds (acetate precursRrs) haYe beeQ practicaOOy utiOized. +ere, aQ iPpOicit assuPptiRQ cRuOd be aOsR Pade that acetate diIIusiRQ withiQ the QaturaO eQYirRQPeQt was QeJOiJibOe, sR that aOO acetate prRduced withiQ a JiYeQ stratuP was iPPediateOy cRQsuPed by reactiRQ such as C+4 IerPeQtatiRQ, suOIate
reduc-tiRQ, sRrptiRQ Rr Rther prRcesses (SRreQseQ et aO. 1981, ChristeQseQ 1984, Mi-cheOsRQ et aO. 1989, -Ċdrysek 2005a).
Sebacher et aO. (198) IRuQd that PethaQe IOu[ IrRP AOaskaQ wetOaQds did QRt cRrreOate weOO with peat thickQess. It wRuOd be wRrth tR PeQtiRQ that this IiQdiQJ was cRQsisteQt with Rur RbserYatiRQs, based RQ YisuaO MudJPeQt Pade iQ this study, aQd prRbabOy resuOts IrRP the Iact that the ROder (deeper) sediPeQts are QRt as prRductiYe iQ terPs RI PethaQe as the yRuQJer RQe. IQ the MRszQe Lake sediPeQts, it has beeQ RbserYed that PaiQOy the tRp 2–3 Peters RI RrJaQic rich sediPeQts prRduced C+4, aQd beORw 1.5 P the aPRuQt RI Jas bubbOes
re-Oeased IrRP sediPeQts draPaticaOOy decreased. ObYiRusOy, bubbOe iQYeQtRries wiOO QaturaOOy decrease with depth as the sediPeQt cRPpacts aQd bubbOes are IRrced upward. OQ the Rther haQd, hiJher pressure at depth iQcreases PROar
iQ-4 M. ORION -ĉDR<SE., S. +AàAS, T. PIEē.OS
YeQtRry RI the sediPeQt iQterstices. +RweYer, aQy cRrrectiRQs IRr this IactRr are Iar beyRQd the scRpe RI this wRrk, as the PaiQ pRiQt here are YariatiRQs RI the
13C/12C ratiR iQ PethaQe. AQyway, iQ 94.02.11 YisuaOOy MudJed hiJhest
prRduc-tiRQ RI PethaQe was at the depth abRut 1 P, aQd it was Yery OiPited iQ the surIi-ciaO zRQes where the tePperature was abRut 2C ()iJ. 2a). MRst prRbabOy the tePperature iQ the upper O P iQterYaO was tRR ORw tR deYeORp aQ actiYe PethaQRJeQesis.
PrRIiOes RI 94.02.11 aQd deeper parts RI 93.11.14 aQd 93.08.30 prRIiOes, shRw QeJatiYe į13C(C+
4)-depth cRrreOatiRQ ()iJ. 4a). The seasRQaO YariatiRQ iQ
YerticaO prRIiOes RI the į13C(C+
4) YaOues iQ Lake MRszQe ()iJ. 4a) dR QRt aOways
cRrreOate weOO with the cRrrespRQdiQJ seasRQaO YariatiRQ RI tePperature iQ sedi-PeQts ()iJ. 2a), hRweYer, a JeQeraO treQd RI pRsitiYe cRrreOatiRQ betweeQ teP-perature RI sediPeQts aQd į13C YaOues haYe beeQ RbserYed iQ the twR Oakes
stud-ied ()iJ. 8ab). IQ JeQeraO, the cRrreOatiRQ iQ the tePperature-į13C(C+
4) systeP is
RbserYed RQOy wheQ we cRQsider aOO resuOts IrRP seYeraO saPpOiQJ actiRQs, but QRt iQ a separate prRIiOe ()iJ. 8a). The e[ceptiRQ is the suPPer prRIiOe RI 93.0.1 ()iJ. 8a), aQd especiaOOy prRIiOes RI the eQd RI the suPPer i.e. 93.08.30 ()iJ. 8a) aQd 93.09.08 ()iJ. 8b). IQ Lake MRszQe the dRwQward siJQiIicaQt iQ-crease iQ tePperature cRrrespRQds tR a QeJOiJibOe dRwQward deiQ-crease iQ į13C(C+
4) YaOues iQ the upperPRst part RI the 93.11.14 į13C(C+4) prRIiOe ()iJ.
2a, 4a). The tePperature aQd į13C(C+4) YaOue Yaries iQ the saPe directiRQ. IQ the
deeper part RI the saPe prRIiOe, the dRwQward YaQishiQJOy sPaOO decrease iQ tePperature cRrrespRQds tR the dRwQward reParkabOe iQcrease iQ į13C(C+4)
YaOues. IQ this case, the tePperature aQd į13C(C+
4) YaOue Yaries iQ the RppRsite
directiRQs. OQ the Rther haQd, the dRwQward iQcrease iQ the tePperature RI sed-iPeQts iQ 94.02.11 cRrrespRQds tR dRwQward iQcrease iQ į13C(C+
4) YaOues. The
tePperature aQd į13C(C+
4) YaOue aJaiQ chaQJes iQ the saPe directiRQ. The
93.05.01 tePperature prRIiOe shRws, iQ the iQterYaO 0 tR abRut 0.8 P, a dRwQward decrease, aQd beORw ca. 0.8 P, dRwQward iQcrease RI tePperature, but the į13C(C+
4) YaOue iQ this prRIiOe shRws RQOy a dRwQward decrease, bRth abRYe the
0.8 P aQd beORw 0.8 P. ThereIRre, tePperature aQd į13C(C+
4) YaOues Yary
iQde-peQdeQtOy. +eQce prRbabOy QR direct reOatiRQ e[ists betweeQ tePperature aQd į13C(C+
4) YaOues.
+RweYer, RQe PRre case cRuOd be cRQsidered. ShiIts betweeQ twR separate tePperature prRIiOes aQd the twR cRrrespRQdiQJ į13C prRIiOes are iQcRQsisteQt.
)Rr e[aPpOe, the tePperature prRIiOe RI 93.0.1 is Yery cORse tR the 93.08.30 prRIiOes ()iJ. 2a – RQ the riJht side RI the pORt) but the cRrrespRQdiQJ į13C
prR-IiOe RI 93.0.1 is Yery cORse tR the į13C prRIiOes RI 93.05.01, 92.09.2 aQd eYeQ
94.02.11 ()iJ. 4a – RQ the OeIt side RI the pORt). It cRQtradicts tR the iPpRrtaQce RI tePperature as a IactRr cRQtrROOiQJ į13C(C+
4) YaOue iQ YerticaO prRIiOes iQ
sed-iPeQts. Thus, aQRther PechaQisP thaQ tePperature YariatiRQ, prRbabOy directOy iQIOueQces the RbserYed isRtRpic patterQ.
CARBON ISOTOPIC COMPOSITION O) EARL<-DIA*ENETIC MET+ANE« 4 At hiJher tePperature RI suPPer the rate RI decRPpRsitiRQ RI RrJaQic Pat-ter iQ tePperate cOiPate is appareQtOy hiJher thaQ duriQJ cROder seasRQs. The sediPeQts studied are cRPpRsed PRstOy RI RrJaQic detritus. TePperature RI the Lake MRszQe sediPeQts Yaried IrRP 2C duriQJ wiQter tR 18C duriQJ suPPer. Thus, iQ the surIiciaO Oayers RI the sediPeQts iQ the Oakes studied, CO2 aQd acetic
acid, aQd iQ the deeper reJiRQs PRstOy CO2, appareQtOy are prRduced PRst
eIIi-cieQtOy at the eQd RI suPPer wheQ iQ the whROe prRIiOe tePperature is the hiJh-est. ThereIRre, duriQJ this seasRQ the pRrewater is saturated with respect tR Pe-thaQe precursRrs. It was RbserYed by ChaQtRQ aQd MarteQs (1988) that, due tR tePperature-cRQtrROOed sROubiOity aQd tePperature-depeQdeQt diIIusiRQ RI Pe-thaQe, iQYeQtRries RI sediPeQtary Jas bubbOes were seYeraO tiPes hiJher duriQJ suPPer thaQ iQ wiQter. Thus, the RbserYed iQ Lake MRszQe PRre iQteQsiYe bub-bOe prRductiRQ aQd hiJher į13C(C+
4) YaOues iQ the suPPer as cRPpared tR thRse
iQ wiQter, were the resuOt QRt RQOy RI PRre iQteQsiYe bacteriaO actiYity at hiJher tePperature but aOsR RI OiPited diIIusiRQ at hiJher tePperature. OQ the Rther haQd, it caQ be e[pected that tePperature decreases resuOts iQ ORwer cRQceQtra-tiRQ RI PethaQe precursRrs with PRst prRbabOy siJQiIicaQt isRtRpe eIIect. Acetate turQs RYer sR rapidOy (days) that at the eQd RI the wiQter, there shRuOd be YaQish-iQJOy ORw residuaO pRRO OeIt RYer IrRP warPer seasRQs. Likewise, despite that the CO2 (bicarbRQate) pRRO is reOatiYeOy OarJe, it Pay be OiPited iQ the deepest part RI
the sediPeQt, where the sediPeQt is PRre cRPpact aQd bacteriaO R[idatiRQ is appareQtOy suppressed due tR ORwer tePperature. +eQce, the hiJhest 13
C-eQrichPeQts were RbserYed iQ the deepest parts RI the wiQter aQd Oate autuPQ prRIiOes. This PRdeO Pay aOsR e[pOaiQ the ORwer decreasiQJ JradieQts RI the į13C(C+
4) YaOues at Jreater depths (93.05.0O, 93.0.1 aQd 93.08.30). Likewise,
the surprisiQJ iQcrease RI the į13C(C+
4) YaOues iQ the deepest part (beORw 3 P)
RI the 93.08.30 prRIiOe Pay be e[pOaiQed by the OiPited pRRO RI CO2 at this
depth, actiYe PethaQRJeQesis, aQd ORwer diIIusiRQ. ThereIRre, it caQ be prRpRsed that, the deeper seated CO2 Jets isRtRpicaOOy heaYy as PRre C+4 is prRduced due
tR CO2 pathway, aQd cRQseTueQtOy C+4 Jets heaYier tRR. :heQ sRPe 13
C-eQriched CO2 aQd C+4 diIIuse upwards it Pay resuOt 13C-eQrichPeQt iQ the
car-bRQ pRRO iQ the RYerOyiQJ OeYeOs. +RweYer, Puch PRre studies wRuOd be reTuired tR this pRiQt.
IQ the Oater staJe RI diaJeQesis, acetate aQd CO2 Pay RriJiQate IrRP diIIereQt
cRPpRuQds represeQtiQJ diIIereQt isRtRpic ratiRs, suppRsedOy eQriched iQ heaYy carbRQ isRtRpes. Thus, the YerticaO YariatiRQ iQ į13C(C+
4) QRt RQOy reIOects the
acetate/carbRQ diR[ide pathways aQd kiQetic eQrichPeQt iQ 13C RI the residuaO
precursRrs RI PethaQe, but aOsR the isRtRpe characteristics RI the precursRrs RI acetate aQd carbRQ diR[ide. )urther studies wiOO be reTuired RQ this pRiQt tRR. ParticuOarOy the YariatiRQs iQ the CO2/+CO3-/CO32- PROar ratiRs due tR iQcreasiQJ
pressure dRwQward withiQ the sediPeQt, tePperature aQd p+ aQd their pRteQtiaO iQIOueQce RQ the 13C/12C isRtRpic ratiRs iQ the reduced CO
precur-48 M. ORION -ĉDR<SE., S. +AàAS, T. PIEē.OS
sRr) shRuOd be cRQsidered. Such studies cRuOd prRYide aOsR aQ iPpRrtaQt basis RQ which a paOeReQYirRQPeQtaO recRQstructiRQ based RQ YerticaO YariatiRQs RI car-bRQ isRtRpe cRPpRsitiRQ RI carcar-bRQ-beariQJ cRPpRuQds RI sediPeQts (RrJaQic Patter, carbRQates) caQ be deYeORped.
5. CONCLUSIONS
1. IQ Ireshwater sediPeQts, YisuaOOy MudJed PethaQe prRductiRQ decreased with iQcreasiQJ depth iQ sediPeQts aQd JraduaOOy ceased at a depth RI abRut 2–3 Peters. IQ the sediPeQts studied, beORw abRut 3 P, QR substaQtiaO aPRuQts RI PethaQe were prRduced Rr reOeased duriQJ suPPer. The depth RI Qear zerR prR-ductiRQ Rr reOease was abRut 2 P duriQJ wiQter. ThereIRre, PethaQe IOu[ Pay QRt cRrreOate with sediPeQt thickQess, iI the sediPeQts iQ the preseQt IieOds are Puch PRre thaQ 3 P iQ thickQess.
2. IQ the sediPeQts studied, tePperature aQd R[idatiRQ are, iQ JeQeraO, QRt the IactRrs directOy respRQsibOe IRr the isRtRpic siJQature RI PethaQe.
3. It is prRpRsed that the CO2/+2 pathway becaPe PRre iPpRrtaQt with
iQ-creasiQJ depth iQ sediPeQts, aQd PethaQRJeQesis Yia acetic acid IerPeQtatiRQ decreased with iQcreasiQJ depth iQ sediPeQts. At depths beORw 1 P the CO2/+2
pathway e[cOusiYeOy dRPiQates. PrRbabOy, Rther pathways RI PethaQRJeQesis, such as Yia PethaQRO aQd PethyOaPiQes (which is QeJOiJibOe IrRP the isRtRpic pRiQt RI Yiew) aOsR decrease with depth. SRPe R[idatiRQ RI PethaQe at shaOORwer depths cRuOd Rccur but JeQeraOOy it is QRt the priPary reasRQ IRr the RbserYed patterQ.
4. DuriQJ suPPer at the depth abRut 3 P aQd duriQJ wiQter iQ the eQtire prR-IiOe, the prRductiRQ RI PethaQe precursRrs prRbabOy decreases tR YaQishiQJOy ORw YaOues. +RweYer, because RI cRQtiQuiQJ PethaQRJeQesis, a kiQetic eQrichPeQt iQ heaYy isRtRpes RI the residuaO carbRQ pRRO is respRQsibOe IRr the RbserYed Jradu-aO dRwQward decrease RI the JradieQt RI 13C isRtRpe depOetiRQ RI PethaQe.
IiQaO-Oy, this prRcess resuOts iQ dRwQward iQcrease RI the isRtRpe ratiRs RI PethaQe at the depth RI abRut 3 P duriQJ suPPer, aQd beORw the depth RI abRut 1 P duriQJ Oate autuPQ-wiQter.
AC.NO:LED*MENTS
The authRrs wish tR e[press their Jratitude tR M.S. )iOus, .. SRkRáRwski, :. àRpata, -. .RáRdzieM, aQd R. StryMecki IRr their heOp with saPpOiQJ aQd isR-tRpe preparatiRQs aQd tR T. Durakiewicz IRr his kiQd heOp with cROOectiQJ sRPe Oiterature. The authRrs are JrateIuO IRr a criticaO readiQJ RI the PaQuscript aQd cRPPeQts tR Derek +aQdOey aQd especiaOOy tR Dr. N. BOair.
CARBON ISOTOPIC COMPOSITION O) EARL<-DIA*ENETIC MET+ANE« 49 ThaQks are due tR PrRIessRr AJQieszka *aáuszka, U-. .ieOce, IRr careIuO reYiew RI the subPitted YersiRQ. This study was suppRrted by the State CRPPit-tee IRr ScieQtiIic Research, prRMect QR. 2PO4*04528 (PROaQd), *raQts S aQd : IN* U:r., aQd IAI.
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