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Bertrand,Erin Marie - ebertran@MIT.EDUBhatia,Maya Pilar - mayab@MIT.EDUCox,Alysia Danielle - alysia@MIT.EDUEsch,Helen Carter - hce@MIT.EDUFischer,Curt R. - curt@MIT.EDUFrame,Caitlin H - cframe@MIT.EDUGibbons,Fern Tolley - ferng@MIT.EDULemkau,Karin Lydia - klemkau@MIT.EDULincoln,Sara Ann - slincoln@MIT.EDUMcDonnell,Andrew - drewmcd@MIT.EDUNoble,Abigail Emery - anoble@MIT.EDUOates,Richard Hunter - hoates@MIT.EDUPonton,Camilo - cponton@MIT.EDURichberg,Kevin - richberg@MIT.EDU

MOG 2007 email list

Dan Repeta 508-289-2635 drepeta@whoi.edu Watson BGC

DOC and major carbon reservoirs and fluxes

Terrestrial Plants900 GT C

Soil 2000 GT C

Carbonates 60,000,000 GT C

Kerogen 20,000,000 GT C

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DOC and major carbon reservoirs and fluxes

Terrestrial Plants900 GT C

Soil 2000 GT C

Carbonates 60,000,000 GT C

Kerogen 20,000,000 GT C150 GT C

DOC 700 GT C

POC 15 GT C

DOC and major carbon reservoirs and fluxes

Atmosphere 750 GT (CO2) Terrestrial Plants900 GT C

Soil 2000 GT C

Carbonates 60,000,000 GT C

Kerogen 20,000,000 GT C150 GT C

DOC 700 GT C

POC 15 GT C

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DOC and major carbon reservoirs and fluxes

Atmosphere 750 GT (CO2) Terrestrial Plants900 GT C

Soil 2000 GT C

Carbonates 60,000,000 GT C

Kerogen 20,000,000 GT C150 GT C

DOC 700 GT C

POC 15 GT C

Marine PrimaryProduction 60-75 GT C/yr

Terrestrial PrimaryProduction 75 GT C/yr

River flux0.5 GT C/yr

Burial 0.1-0.2GT C/yr

Biomass 2 GT C

Classification (definitions) of organic matter in seawater

Particulate organic carbon (POC)

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Classification (definitions) of organic matter in seawater

Particulate organic carbon (POC)

Colloidal organic carbon (COC)

Classification (definitions) of organic matter in seawater

Particulate organic carbon (POC)

Colloidal organic carbon (COC)

Dissolved organic carbon (DOC)

Organic matter classes are defined by the filters used tocollect them !! They are operational definitions only!!!

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Dissolved organic matter; DOM (includes C, H, O, S, P…)

Dissolved organic nitrogen or phosphorus (DON, DOP)

Ultrafiltered dissolved organic matter (UDOM)

Chromophoric dissolved organic matter (CDOM)

Low and High molecular weight dissolved organic matter (LMWDOM, HMWDOM)

Humic substances (HS) (marine humic and fulvic acids)

The lexicon of organic matter in seawater

High Temperature Catalytic Oxidation100 µL seawater

Inject directly ontoPt or M column

Water vaporized andtrapped

DOC oxidized by Ptto CO2

LiCOR detector

Precision + 0.5- 1µM

Analytical methods for measuring DOC

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Analytical methods for measuring DOC

Used for large volume samples (stable and radioisotope analyses)

Add acid, spargeadd persulfate

Heat 24 hr

SpargeMeasure CO2

UV photooxidation Chemical oxidation

Vertical profiles of dissolved organic carbon in the ocean

Measured by HTCO

Often measured as TOC

Surface values typically 60-80 µM

Deep water values @ 40 +1 µM(implies some unknown feedback/control of DOC values)

Global inventory about 680 GT C

Data from Peltzer and Hayward (1996) DSR

TOC (µM)

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Data from Dennis Hansell (www.rsmas.miami.edu/groups/biogeochem/Data.htm)

Distribution of DOC in the Pacific and Atlantic Basins

Jan 05

Mar 06 Jun 03

Feb 03

Data from Dennis Hansell (www.rsmas.miami.edu/groups/biogeochem/Data.htm)

Distribution of DOC in the Pacific and Atlantic Basins

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A16

P16

A16

P16

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A16

P16

A16: DOC on δθ 26.4 – 26.7

Input on the Equator(solubilization of sinking particles

or advective input?)

Depth (m

)

Data from Dennis Hansell (www.rsmas.miami.edu/groups/biogeochem/Data.htm)

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Depth (m

)A16: DOC on δθ 27.0 – 27.3

Data from Dennis Hansell (www.rsmas.miami.edu/groups/biogeochem/Data.htm)

Depth (m

)

Expected Mixing Curve

A16: DOC on δθ 27.0 – 27.3

Data from Dennis Hansell (www.rsmas.miami.edu/groups/biogeochem/Data.htm)

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P16: DOC on δθ 26.4 – 26.7

Input on the equator(sinking particles?)

Depth (m

)

Data from Dennis Hansell (www.rsmas.miami.edu/groups/biogeochem/Data.htm)

P16: DOC on δθ 27.75– 28.0

Decrease in the far north North Pacific

Depth (m

)

Data from Dennis Hansell (www.rsmas.miami.edu/groups/biogeochem/Data.htm)

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DOC in the Deep Global Ocean (Hansell and Carlson, 1998)

Annual cycle of DOC production in the mixed layer at BATS*

*Bermuda Atlantic Time Series, a JGOFs LTEM site Carlson et al.1994; Nature

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Interannual variations in DOC concentration and inventory at BATS

1994 1995 1996 1997 1998

0.4-1.4 mol C m-2 removed in overturn (10-41% C remineralized)

93 94 95 96 97 98 99 00 Church et al L&O 2002

Accumulation of DOC in the tropical N. Pacific Ocean (HOTS)0

100

200

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Export of DOC from the surface to the mesopelagic ocean

DOC and AOU- why is there a relationship?

Data from Peltzer and Hayward, 1996 DSR II v 43 p1155

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Natural abundance radiocarbon and DOC

DOC cycling via DO14C

UV photooxidation

Williams, Oeschger, and Kinney; Nature v224 (1969)

1880m -351 ‰ -3470+330 ybp

1920m -341 ‰ -3350+300 ybp

Depth Δ14C(‰) Age

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Accelerator Mass Spectrometry (AMS)NOSAMS at Woods Hole

C-14 PP measurements use 106x more C-14 than natural abundance!!!!!

Radiocarbon in the Atlantic and Pacific OceansPeter M. Williams and Ellen Druffel; Nature 1987, JGR 1992

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Radiocarbon in the Atlantic and Pacific Oceans

DIC 14C in surface watersof the Atlantic and Pacifichas the same isotopic value.

Radiocarbon in the Atlantic and Pacific Oceans

DIC 14C in surface watersof the Atlantic and Pacifichas the same isotopic value.

DOC is always older than DIC(by 4 kyrs in surface water)

DIC-> POC -> DOC

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Radiocarbon in the Atlantic and Pacific Oceans

DIC 14C in surface watersof the Atlantic and Pacifichas the same isotopic value.

DOC is always older than DIC(by 4 kyrs in surface water)

ΔΔ14C of DIC and DOCis about the same in thedeep Atlantic and Pacific

Radiocarbon in the Atlantic and Pacific Oceans

DIC 14C in surface watersof the Atlantic and Pacifichas the same isotopic value.

DOC is always older than DIC(by 4 kyrs in surface water)

ΔΔ14C of DIC and DOCis about the same in thedeep Atlantic and Pacific

Deep ocean values of DOCare equal to a radiocarbonage of 4-6 kyrs

Either there is a source of“old” DOC, or DOC persistsfor several ocean mixingcycles

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Δ14C

Dep

th (m

)

Druffel et al., 1992; Druffel and Bauer, 1998

DO14C and DI14C in different A/P/S ocean basins

Δ14C

Dep

th (m

)

Druffel et al., 1992; Druffel and Bauer, 1998

DO14C and DI14C in different A/P/S ocean basins

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DOCΔ14C

Druffel et al. (1992) JGR

(DIC=150‰)

DOC cycling in surface seawater

New DOCΔ14C=DIC

Old

DO

CΔ

14C

= D

OC

(dee

p)

DOCΔ14C

Druffel et al. (1992) JGR

(DIC=150‰)

DOC cycling in surface seawater

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xsdeepsfc DOCDOCDOC +=

xsxsdeepdeepsfcsfc DOCCDOCCDOCC 141414 Δ+Δ=Δ

where Δ14Cxs = DI14Csfc and deep = (3500-4000 m)

Radiocarbon Mass Balance For Surface Ocean DOC

After Williams and Druffel, 1987

-372 ‰-398 ‰32 ‰25 ‰.1995Southern Ocean (54°S, 176°W)

-153 ‰-155 ‰147±16 ‰135 ‰1987North Central Pacific (31ºN, 159ºW)

-210 ‰-214 ‰138 ‰127 ‰1989Sargasso Sea (31º50’N, 63º60’W)

DO14CmeasDO14CcalcPO14CsuspDI14CDATELOCATION

Druffel et al., 1992; Druffel and Bauer, 1998

Using a simple 2 component mixing model of old “non-reactive” DOCwith deep sea 14C and [DOC] values, and a new “reactive” component with

DICΔ 14C, and [DOC] = [DOC]total-[DOC]deep,Modeled and measured DOC 14C values agree pretty well…

Depth

DOC Δ14C

Williams and Druffel, 1987; Druffel et al. 1992

DOC Δ14C

Sargasso Sea

N. Pacific

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-600

-500

-400

-300

-200

-100

0

0.01 0.015 0.02 0.025 0.03 0.035

1/[DOC] (μM)

Δ14

C-DO

C (‰

)

Eastern North PacificSouthern OceanNorth AtlanticCentral North Pacific

))(1( 14141414

xsCbDOCbCbDOCzDOCxsCzC Δ−Δ+Δ=Δ

Two Endmember Carbon Mass Balance Reproduces the Δ14C Depth Profile of DOC (Requires Addition of DOC from Sinking Particles)

73±23‰ (’91-’95)105±62‰ (’95/’96)135±26‰ (’89)162 ±39‰ (‘87)

Δ14Cxs

(Mortazani and Chanton, 2004)

Radiocarbon measurements show that the average ageof deep sea DOC is > 5000 yr. If the global inventory is

700 GT C, then the annual flux of C to maintain the systemat steady state can be calculated as:

700 GT/ 5000 yr = 0.14 GT C yr-1

The annual input of DOC from rivers is 0.2-0.4 GT C yr-1, while annual marine primary production is 60-75 GT Cyr-1

Either source adds enough C per year to maintain the system.

So what is the source of oceanic DOC?

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What is the source of oceanic DOC ?

Stable C isotopes

Marine C

-21‰

Terrestrial C

C3 plants -27‰

C4 plants -15‰

Druffel et al., JGR 1992

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DOC is operationally defined by the filter used.

DOC is the largest reservoir of organic carbon in seawater (>98%of organic carbon). It has high concentrationsin the euphotic zone indicating net production (or at least input).Values at depth are low (about half surface water values) and nearlyconstant throughout much of the deep ocean.

DOC values are highest where mixing is the least. Mixingexports DOC to the meso- and bathypelagic ocean where it is oxidized.Deep oxidation represents about 20% of NCP and AOU.

Radiocarbon values of DOC enriched in surface waters but highlydepleted at depth. They can be modeled as two end member mixing.Deep sea values are consistent with an average residence time of5000-6000 years. Several ocean mixing cycles!!! No one knows why,but surely this impacts organic nutrients.

Today’s highlights

A16

P16

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Seasonal accumulation of DOC in the mixed layer at BATS

100-250 m

Σ 250 m