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Geobiology 2007 Lecture 10The Biogeochemical Carbon Cycle

Readings: Assigned Reading:Stanley Chapter 10, pp 221-244Kump et al., Chap. 7Hayes, J. M., Strauss, H. & Kaufman, A. J.., 1999. The abundance of 13C in marine

organic matter and isotopic fractionation in the global biogeochemical cycle of carbon during the past 800 Ma Chem. Geol. 161, 103–125.

Kerr R.A. 2005. The story of O2. News focus article from Science 308, 1730 (MIT Server)

Catling et al., 2005. Astrobiology 5, 415

Other readings: Logan G.A., Hayes J.M., Hieshima G.B. and Summons R.E., 1995, Terminal

Proterozoic reorganisation of biogeochemical cycles. Nature 376, 53-56.Rothman D. H., Hayes J. M., and Summons R. E., 2003, Dynamics of the

Neoproterozoic carbon cycle. Proceedings of the National Academy of Science (USA) 100, 8124-8129.

Acknowledgements: John Hayes and Dan Rothman who provided figures used in this lecture


Need to know: • Elements of the geological C-cycle and exogenic or

biological (ocean/atm/biology) C-cycle that affect carbon burial

• ‘Idealized’ redox structure of the surface environment• Concept of mass balance and use of isotopic data to

model C-cycle over different timescales• What this tells us about progressive oxygenation of the

crust/atm/ocean• Excursions in the δ13C record of inorganic carbon,

concept of ‘oxidation’ events and significance for biology


• Isotopes are fractionated during chemical and physical equilibrations and during enzyme mediated reactions

• Patterns in the distributions of C, H, N, S &O isotopic tracers can be related to uptake mechanisms (assimilation), energy-yielding redox reactions (dissimilation) and biosynthetic processes

• Patterns in the distributions of C, H, N, S &O isotopic tracers in rocks can be understood by analogies to modern processes

Courtesy Sam Gon III. Image from Wikimedia Commons, http://commons.wikimedia.org.

LifeLife’’s History on Earths History on EarthProkaryote

World

1

Multi-cell Life

0.1 Humans

0.01First

EukaryotesFirst

Invertebrates

P O2(

atm

)

GOE0.001

0.0001

0.000014.5 4 3.5 3 2.5 2

Time before Pre1.5 1 0.5

sent (Ga)0

100-10-20-30

Carbon Input

CO HCO2 3=

Microorganisms

0.80.2

Kinetic Isotope Effect

Crustal Average

Isotopic Mass Balance of Crustal Carbon Reservoirs

C13δ

Reduced Carbon

Carbonate

(Des Marais, 2002)Courtesy of Dave Des Marais, NASA Ames. Used with permission.

Image removed due to copyright restrictions.

Please see Fig. 2 in Shields, Graham, and Veizer, Ján. “Precambrian marine carbonate isotope database: Version 1.1.”Geochemistry Geophysics Geosystems 3 (June 6, 2002): 12 pages.

© Rothman et al., 2005 Courtesy of Dan Rothman. Used with permission.

© JM HayesMarine Isotopic Signals

800Ma-presentCourtesy of Elsevier, Inc., http://www.sciencedirect.com. Used with permission.

Courtesy John Hayes. Used with permission.

Courtesy of Dan Rothman. Used with permission.

© JM Hayes

δi

ε

f


Marine Isotopic Signals 150Ma-present

Courtesy Elsevier, Inc., http://www.sciencedirect.com. Used with permission.

Courtesy John Hayes. Used with permission.© JM Hayes

Massive Mesozoic-Cenozoic Seven Sisters Fossils (East Sussex) Plankton Deposits

Chl a+c PhytoplanktonDiatoms

DinoflagellatesCoccolithophorids

Courtesy Dan Taylor. Image from Wikimedia Commons, http://commons.wikimedia.org.

White Cliffs of Dover

Courtesy NASA

Diatomaceous Earth Mine,Kenya

SeaWiFS views a phytoplankton bloom near the Grand Banks of Newfoundland.

Courtesy Adrian Barnes© J Waldbauer

© JM Hayes

So, how did it all start?


Biogeochemical C Cycles before O2 PhotosynthesisFluxes, x 1012 Moles per Year

0 - 10

10 - 10

10 - 10

10 - 10

3

3 8

6 9

7 9

Cycle Timescales, years

?>20

20Metamorphic and Igneous

Reduced Carbon

Mantle Carbon

4

Marine HCO3-

Carbo-nates

>15

Marble

16

CO : Sea,Atm.

2

Fresh Organic Matter

Sedimentary Organic Matter

~40

~40-?

Courtesy of Dave Des Marais, NASA Ames. Used with permission.

Biogeochemical Carbon CycleFluxes, x 10 Moles per Year12

0 - 10

10 - 10

10 - 10

10 - 10

3

3 8

6 9

7 9

Cycle Timescales, years

10

C13-40 -30 -20 -10 0 +10

10 960

6

2

45

Metamorphic and Igneous Reduced Carbon

Mantle Carbon

0.4

2

Marine HCO3-

Carbo- nates

50

Marble

1.6

CO : Sea,Atm.

2

Fresh Organic Matter

Sedimentary Organic Matter

9000

8990

(Des Marais, 2001)Courtesy of Dave Des Marais, NASA Ames. Used with permission.

LifeLife’’s History on Earths History on EarthProkaryote

World

1

Multi-cell Life

0.1 Humans

P O2(

atm

) 0.01 First EukaryotesDinosaursFirst

Invertebrates

0.001

0.0001

0.000014.5 4 3.5 3 2.5

Time befo2

re Pre1.5 1 0.5 0

sent (Ga)

*

(Des Marais, 2001)

-1.0-2.0-3.0-4.0-4.0-70-60-50-40-30-20-10

01020

C13δ

Carbon Isotopic Recordin Sedimentary Carbonates and Organic Matter

Age, Ga

Organics

Oxidized Paleosols

BIF Disappear

Carbonates

Courtesy of Dave Des Marais, NASA Ames. Used with permission.

C-Cycle Models; Des Marais et al., 1992, Carbon Isotopic Evidence for Stepwise Oxidation of the Proterozoic Environment. Nature 359, 605

εp for well-preserved organic matter

and modeled using a moving 30Ma window

In steady state, and assuming δ ~ δa

δi = f * δo – (1-f) δo

δa = δi + f * ε


Please see Fig. 2 in Des Marais, David J., et al. “Carbon Isotope Evidence for the Stepwise Oxidation of the Proterozoic Environment.”Nature 359 (October 15, 1992): 605-609.


and modeled using a 200 or 100 Ma running average

evidence for changes in f over time




Evidence for an increasing crustal inventory of Corg



Ocean RedoxStates through

Time

The first order approximation


Please see Fig. 2 in Shields, Graham, and Veizer, Ján. “Precambrian Marine Carbonate Isotope Database: Version 1.1.”Geochemistry Geophysics Geosystems 3 (June 6, 2002): 12 pages.

Figure by MIT OCW.

Major Divisions of Earth History

I II III

Sola

r Sys

tem

For

mat

ion

Late

Hea

vy B

omba

rdm

ent

Earli

er S

now

ball

Epis

odes

Late

r Sno

wba

ll Ep

isod

es

Archean Proterozoic Phanerozoic

pO2 < 0.002 pO2 > 0.03 pO2 > 0.2bar bar bar

ferrousoceans

sulfidicoceans

oxicoceans

cyano-bacteria

algae,protists

complexanimals& plants

5.0 4.0 3.0 2.0 1.0 0.0

© JM HayesMarine Isotopic Signals

800Ma-presentCourtesy John Hayes. Used with permission.

δa (inorganic carbon) for the past 800Ma (Hayes et al., 1999)

Steady State Carbon Burial Model

Sedimentδa δo

δi Oceanδ

In steady state, and assuming δ ~ δaδi = f * δo – (1-f) δoδa = δi + f * ε Where ε = δa – δo

weathering volcanism


A Carbon Cycle with Two Timescales

Sedimentδa δo

δi Oceanδ1, τ1 δ2, τ2δ2− ε

δ2weathering volcanism

inorganic-C organic-C


A Carbon Cycle with Two Timescales

δa

δo

δi δ1, τ1 δ2, τ2

δ2−ε

δ2weathering, volcanism

carbonate carbon

organic carbon


A Biogeochemical Model of the Proterozoic Ocean


Please see Fig. 3a in Logan, Graham A., et al. “Terminal Proterozoic Reorganization of Biogeochemical Cycles.” Nature 376 (July 6, 1995): 53-56.

After Ventilation


Please see Fig. 3b in Logan, Graham A., et al. “Terminal Proterozoic Reorganization of Biogeochemical Cycles.” Nature 376 (July 6, 1995): 53-56.

Text removed due to copyright restrictions.

Please see Julian Cribb, “Faeces rain spawned humans,” The Australian, July 7, 1995.

and

Deborah Smith, “Scientists May Have Found the Origin of the Faeces,” The Sydney Morning Herald, July 7, 1995.

f organic-C buried

13C fractionationεTOC

Carbon Isotopic Excursions 800-500Ma

δ13C limestones

δ13C marine organic matter

More complete sediment record

+

Improved chronology

=

More detailed picture showing abrupt and extreme C-isotopic shifts

750 Ma 720 Ma 580 Ma

Marinoan/Varangerglacial(s)

Sturtianglacial(s)

Image courtesy of Elsevier, Inc., http://www.sciencedirect.com. Used with permission.


http://www.sciencedirect.com

Composite carbon isotopic curve for the Neoproterozoic compared to glacial intervals and absolute geochronology

Varanger Glaciation

1000

0

δ13C (VPDB)-10 -5 0 5 10

Arth

ropo

dsCambrian

Vendian

Edia

cara

531

U-Pbages(Ma)

543.3 1+_

545.1 1+_

548.1 1+_

580?

Spin

y pl

ankt

on

650

+_746 2+_758 4

+_827 6

Stra

tigra

phic

thic

knes

s(c

omm

on sc

ale

exce

pt a

rbitr

ary

for g

laci

atio

n)

-10 -5 0 5 10

Seawater proxy δ13Ccarb850-530 Ma

MoroccoAdoudounian FormationMagaritz et al. (1991)A.C. Maloof (unpubl.) SiberiaTurkut FormationBartley et al. (1998) NamibiaNama GroupSaylor et al. (1998) AustraliaWonoka FormationCalver (2000) OmanHuqf Group - Shuram FmBurns and Matter (1993) NamibiaOtavi GroupHalverson and Hoffman (2003)

SvaibardAkademikerbreen GroupHalverson (2003) AustraliaBitter Springs FormationHill and Walter (2000)

Compilation modified fromHalverson (2003: in prep.)

Marinion Glaciation

Sturtian Glaciation NamibiaGariep GroupFolling and Frimmel (2002)"

Figure by MIT OCW.

Paradigm• The C-cycle has evolved radically through

time• Prior to 2.2 Ga anaerobic prokaryotes

dominated; wide spread of δorg (δo) values; oxygenic photosynthesis extant but oxygen remained low as sinks >> sources

• Mantle may have been an important sink for oxidising power (Cloud/Holland)

• Extreme δcarb(δa) values around 2.2 Gaprobably signify the ‘GOE’ and rise to prominence of aerobes; Decreased spread of δorg (δa) values may reflect dominance of aerobic autotrophs and reductive pentose (Benson-Calvin; C3) cycle

Paradigm• Although ample evidence for aerobes, the

abundance of O2 in atm and ocean remained low (sulfidic ocean) until another major oxidation event caused a second ‘reorganization’ In the Neoproterozoic. This was also signified by extreme δafluctuations.

• The Neoproterozoic ‘reorganization’ led to pO2 rising to near PAL allowing animals to flourish and stabilizing the new regime (Hayes, Rothman, Summons et al.)

• Environmental evolution reflected changes in the balance between thermal, crustal, atmospheric & biological processes

Fig. 1 in Fike, D. A., et al. "Oxidation of the Ediacaran Ocean." Nature 444 (December 7, 2006): 744-747. Courtesy of Nature. Used with permission.

Fractionation of C-Isotopes during AutotrophyPathway, enzyme React & substr Product ε ‰ OrganismsC3 10-22Rubisco1 Rubisco2 PEP carboxylasePEP carboxykinase

CO2 +RUBPCO2 +RUBP

-HCO3 +PEPCO2 +PEP

3-PGA x 23-PGA x 2oxaloacetateoxaloacetate

30222

plants & algaecyanobacteriaplants & algaeplants & algae

C4 and CAM 2-15PEP carboxylaseRubisco1

-HCO3 +PEP CO2+RUBP

oxaloacetate3-PGA x 2

230

plants & algae (C4)

Acetyl-CoACO dehydrogPyruvate synthasePEP carboxylasePEP carboxykinase

CO2 + 2H+ CoASHCO2 + Ac-CoA

-HCO3 +PEPCO2 +PEP

AcSCoApyruvateoxaloacetateOxaloacetate

15-3652

2

bacteria

Reductive or reverse TCA

CO2 + succinyl-CoA (+ others)

α-ketoglutarate

4-13 Bacteria espgreen sulfur

3-hydroxypropionate HCO3- + acetylCoA

Malonyl-CoA Green non-S

0

10

0 10 20 30 40 50

0

10

0

10

0

10

Reduct ive TCA Cycle

Reduct ive Acetyl CoA Pathway

Reduct ive Pentose Phosphate Cycle

3 -Hydroxypropionate Cycle

Numberof Taxa

Δδ C Compiled by C. House13Courtesy of Dave Des Marais, NASA Ames. Used with permission.

Total Global Bacteria: 4 - 6 x 1030 Cells

Elemental Inventories, 10 g

TerrestrialBacteria Bacteria/Plantsplants

C

N

P

350 - 550 560 0.6 - 1

85 - 130 10 8.5 - 13

9 - 14 1 9 - 14

Number Division PercentageLocation

Soil

TerrestrialSubsurface

1030 Cells Time, yrs of Total

0.26 2.5 5

1.4 1500 27

Open Ocean

OceanicSubsurface

0.12 0.02 - 0.8 2

3.5 1500 67

15

Figure by MIT OCW.


Geobiology 2007 Lecture 10�The Biogeochemical Carbon CycleGeobiology 2006 Lecture 9�The Biogeochemical Carbon CycleGeobiology 2006 Lecture 9�The Biogeochemical Carbon CycleCarbon Isotopic Excursions �800-500MaParadigmParadigmFractionation of C-Isotopes during Autotrophy

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