natural)iron)fer/liza/on)in)the)polar)frontal)) zone) · atmosphere surface ocean deep-ocean co 2...
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Carbonate counter pump s/mulated by natural iron fer/liza/on in the Polar Frontal Zone
Ian Salter*, Ralf Schiebel, Patrizia Ziveri, Aurore Movellan, Richard Lampi>, George Wolff *Alfred-‐Wegner-‐Ins.tute for Polar and Marine Science, Bremerhaven, Germany
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
CaCO3 producMon in the surface and transport to depth increases atmospheric CO2. On millenial Mme-‐scales CCP leads to shiRs in the verMcal distribuMon of TCO2 and TA
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Constrain the opposing effects of these counter-‐acMng components of the biological carbon pump
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Island-‐associated blooms in Southern Ocean Iron-‐supply enhances ecosystem producMvity and POC export
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Pollard et al. 2009 Nature
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
[+Fe]-‐ferMlized bloom to the North; [HNLC] to the south
+Fe
HNLC
POC fluxes enhanced by a factor of ~2-‐3 as a result of iron ferMlizaMon
Driven by resMng spore formaMon of Eucampia antarc.ca var antarc.ca
Salter et al. 2012 Glob. Biogeo Cy.
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
+Fe HNLC
E. antarc)ca var. antarc)ca
Organic carbon pump
~x2 ~x3
POC fluxes enhanced by a factor of ~2-‐3 as a result of iron ferMlizaMon
Driven by resMng spore formaMon of Eucampia antarc.ca var antarc.ca
Salter et al. 2012 Glob. Biogeo Cy.
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
+Fe HNLC
E. antarc)ca var. antarc)ca
Organic carbon pump
-‐ Annual CaCO3 fluxes were 7-‐10 Mmes higher in [+Fe] regime -‐ Large excess CaCO3 fluxes than excess POC fluxes : POC:PIC ra/o
POC flux 2-‐3 fold increase
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
+Fe HNLC
~x7 ~x10
+Fe +HNLC
Inorganic carbon pump
(1) How are CaCO3 fluxes distributed across different calcifying groups? (2) How significant is the carbonate counter pump for iron-‐ferMlized sequestraMon of atmospheric CO2?
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
(1) How are CaCO3 fluxes distributed across different calcifying groups? (2) How significant is the carbonate counter pump for iron-‐ferMlized sequestraMon of atmospheric CO2?
Methods: Coccolith-‐derived CaCO3 -‐ fine-‐fracMon (< 20 um and 20-‐63 um) Ca (ICP-‐AES) Pteropod species enumerated, removed and weighed with fragments Foraminifera – automated image analysis (63-‐100 and >100 um) Manual species ID.
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Coccolith Foraminifer Pteropods
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Foraminifer dominate CaCO3flux (35-‐50%) Largest relaMve difference in pteropod flux Excess PIC fluxes > excess POC fluxes in all fracMons
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Salter et al. 2014 Nat. Geosci.
Foraminifer dominate CaCO3flux (35-‐50%) Largest relaMve difference in pteropod flux Excess PIC fluxes > excess POC fluxes in all fracMons
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Salter et al. 2014 Nat. Geosci.
Foraminifer dominate CaCO3flux (35-‐50%) Largest relaMve difference in pteropod flux Excess PIC fluxes > excess POC fluxes in all fracMons
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Salter et al. 2014 Nat. Geosci.
Foraminifer dominate CaCO3flux (35-‐50%) Largest relaMve difference in pteropod flux Excess PIC fluxes > excess POC fluxes in all fracMons
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Salter et al. 2014 Nat. Geosci.
Foraminifer dominate CaCO3flux (35-‐50%) Largest rela/ve difference in pteropod flux Excess PIC fluxes > excess POC fluxes in all fracMons
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Salter et al. 2014 Nat. Geosci.
Foraminifer dominate CaCO3flux (35-‐50%) Largest relaMve difference in pteropod flux Excess PIC fluxes > excess POC fluxes in all fracMons
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Salter et al. 2014 Nat. Geosci.
N. Pachyderma dominate foram-‐CaCO3 fracMon Larger species more important at iron ferMlized site Changes in foram-‐CaCO3: (i) increase producMon (ii) assemblage shiRs
Salter et al. 2014 Nat. Geosci.
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
(1) How are CaCO3 fluxes distributed across different calcifying groups? (2) How significant is the carbonate counter pump for iron-‐ferMlized sequestraMon of atmospheric CO2?
Atmosphere
Surface Ocean
Deep-Ocean
CO2
(i) Removal of CO2 plankton POC export – biological carbon pump
(ii) Production of CaCO3 above ventilation depth - conservative Ventilation
depth (iii) POC:PIC ratio
(v) Ψ = CO2 released:CaCO3 precipitated
No correction For dissolution
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Atmosphere
Surface Ocean
Deep-Ocean
CO2
(i) Removal of CO2 plankton POC export – biological carbon pump
(ii) Production of CaCO3 above ventilation depth - conservative Ventilation
depth (iii) POC:PIC ratio
(v) Ψ = CO2 released:CaCO3 precipitated
No correction For dissolution
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
1. {[(gross CO2 sink)-‐(net CO2 sink)]/(gross CO2 sink)}* 100 2. Gross CO2 sink= (FPOCWML) 3. Net CO2 sink = [(FPOCWML) -‐ (FPICWML x Ψ )
Expressed as % reducMon in deep-‐ocean CO2 storage CCP effect: 6-‐32% in [+Fe] region 1-‐4% in [HNLC] region
Salter et al. 2014 Nat. Geosci.
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Importance of bloom locaMon SAF transiMon from Si to CaCO3 dominated producMon/export Si:PIC raMos characterisMc of PFZ
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Salter et al. 2014 Nat. Geosci. SI
[+Fe] PFZ unique : opal dominated export, excess PIC over POC fluxes CCP due to increases in PIC producMon/transport relaMve to both Si and POC
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Southern Ocean data compila)on
Salter et al. 2014 Nat. Geosci.
[+Fe] PFZ unique : opal dominated export, excess PIC over POC fluxes CCP due to increases in PIC producMon/transport relaMve to both Si and POC
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Southern Ocean data compila)on
Salter et al. 2014 Nat. Geosci.
Opal
CaCO3
[+Fe] PFZ unique : opal dominated export, excess PIC over POC fluxes CCP due to increases in PIC producMon/transport relaMve to both Si and POC
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Southern Ocean data compila)on
Salter et al. 2014 Nat. Geosci.
Opal
CaCO3
POC PIC
[+Fe] PFZ unique : opal dominated export, excess PIC over POC fluxes CCP due to increases in PIC producMon/transport relaMve to both Si and POC
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Southern Ocean data compila)on
Salter et al. 2014 Nat. Geosci.
Opal
CaCO3
POC PIC
[+Fe] PFZ unique : opal dominated export, excess PIC over POC fluxes CCP due to increases in PIC producMon/transport relaMve to both Si and POC
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Southern Ocean data compila)on
Salter et al. 2014 Nat. Geosci.
Opal
CaCO3
POC PIC
[+Fe] PFZ unique : opal dominated export, excess PIC over POC fluxes CCP due to increases in PIC producMon/transport relaMve to both Si and POC
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Southern Ocean data compila)on
Salter et al. 2014 Nat. Geosci.
Opal
CaCO3
POC PIC
SUMMARY and Acknowledgements
[+Fe] enhances CaCO3 flux in PFZ Foraminifer dominant CaCO3 flux fracMon EffecMve CO2 transfer by BCP may be reduced 10-‐30% POC:PIC < 1 in Si:PIC>1 unique to polar frontal zone iron ferMlizaMon
Further Acknowledgments -‐ Raymond Pollard (NOC) -‐ Richard Sanders (NOC)
Thank you for your a_en/on
Test-‐size distribuMons Size-‐normalized test weights Foram-‐CaCO3 flux
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
LGM increases in export occurred in sub-‐antarcMc zone Increases in OC export were possibly accompanied by a strengthened carbonate counter pump Decreased significance of BCP for regulaMng glacial Interglacial tranisiMons in atmospheric CO2
Kohfeld et al. 2005 Science
MarMnez-‐Garcia et al. 2014 Science
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
INTRODUCTION AIMS METHODS RESULTS & DISCUSSION
Southern Ocean data-‐set compiled Classified in rela/on to frontal posi/on
-‐6
-‐4
-‐2
0
2
4
6
8
10
12
14
Increase with depth
POC:PIC Increase with depth
72%
28%
POC:PIC increase with depth
POC:PIC decrease with depth
POC:PIC CHANGES WITH DEPTH FROM MULTI-‐TRAP DEPTH MOORINGS