5-9 oct 2009 bergen final carboocean meeting 1 continental shelf pump revisited k.-k. liu inst. of...
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5-9 Oct 2009Bergen
Final CarboOcean Meeting 1
Continental Shelf Pump Revisited
K.-K. Liu Inst. of Hydrological & Oceanic Sciences
National Central University, Taiwan
16-20 June 2008Busan
2008 AOGS Annual Meeting 2
-35 gC/m2/y
Continental Shelf Pump
POC+DOC=12.7 TgC/y
Carbon export by isopycnal mixing: Diffusion pump
5-9 Oct 2009Bergen
Final CarboOcean Meeting 3
Kuroshio
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Final CarboOcean Meeting 4
Cross-shelf exchange
Currents varying on time-scales of days or longer tend to be constrained by geosptrophy to flow along depth contours; ..... Thus geostrophy inhibits ocean-shelf exchange, .....
On smaller time and space scales, geostrophy is broken, allowing excursions [of the ocean current] onto the shelf.Huthnance (1995) Circulation, exchange and water masses at the ocean margin...., [Progr. in Oceanogr.]
Physical processes
• Diffusion pump• Injection pump• Bypass pump• Cascading pump
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Injection pump:
Wash-out of POC by
“new water” (Thomas et al., 2005)
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Final CarboOcean Meeting 6
Bypass pump: Sweeping-out of shelf water
by oceanic currents
(Thomas et al., 2005)
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Final CarboOcean Meeting 7
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Final CarboOcean Meeting 8
Cascading pump: Flushing of shelf water and its content into the deep
ocean by brine or dense water formation (R. Macdonald)
Biogeochemical processes
• Nutrient-enhanced bio-pump– Nutrient-shuttle pump
• Iron pump• Ballast pump• Alkalinity pump
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Final CarboOcean Meeting 9
Nutrient-enhanced bio-pump
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Final CarboOcean Meeting 10
Chl-aDIN
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Final CarboOcean Meeting 11
Iron pump: benthic Fe-flux enhanced bio-pump
Fe (II)
Pennington et al. (2009)
California Current System:Sea-air CO2 flux
Coastal upwelling-EBC system
5-9 Oct 2009Bergen
Final CarboOcean Meeting 12
Ballast pump:Enhanced delivery and preservation of
organics by ballasting materials
(e.g. minerals, shells)
OMEX
Burial
Delivery
Efficient delivery & burial of POC due to ballast effect of sediments
Taiwan
Delivery & burial efficiency of POC wrt PP in margins: SW Taiwan vs Bay of Biscay (OMEX-I) (Kao et al., 2006, CSR)
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Final CarboOcean Meeting 13
Alkalinity pump
• Suboxic and anoxic respiration results in production of alkalinity.
• Alkalinity helps increase pH and decrease pCO2.
The effective alkalinity flux resulting from denitrification (in Mid Atlantic Bight) is large compared to estimates of anthropogenically driven coastal acidification. (Fennel et al., 2008, GRL)
5-9 Oct 2009Bergen
Final CarboOcean Meeting 14
Synergistic processes in the North Sea(Thomas et al., 2005)
-17 gC m-2 yr-1
• Nutrients-enhanced bio-pump• Nutrient-shuttle: Over-
consumption of C due to preferential recycling of nutrients
• Bypass pump
Prefer.N,P recycle
5-9 Oct 2009Bergen
2008 AOGS Annual Meeting 15
Synergistic processes in
the East China Sea
SeaWiFS Chl-a(mg/m3)Flow field (Lee et al., 2004)
• Nutrients-enhanced bio-pump
• Ballast pump• Bypass pump
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Final CarboOcean Meeting 16
Impact of continental shelf pump on ocean interior: fate of CO2 injected by
shelf pump
Increase of DIC (uM) from margin injection (Yool & Fasham, GBC, 2001)
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Final CarboOcean Meeting 17
We may find that the vital organs in the body of Gaia are not on land surfaces but in estuaries, wetlands, and muds on the continental shelves. There, the rate of carbon adjusts automatically to regulate the concentration of oxygen and essential elements are returned to the atmosphere.
Egon T. Degens1928-1989
A pioneer biogeochemist
To be posted @ http://cmtt.pangaea.de
16-20 June 2008Busan
2008 AOGS Annual Meeting 18
16-20 June 2008Busan
2008 AOGS Annual Meeting 19
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Final CarboOcean Meeting 20
SeaWiFS Chl-a in the East China Sea (Summer)
Why not just continental
shelves?
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East China Sea: TOC in sediments
(Kao et al. 2003)
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Estimated Global Riverine loads of nutrients
(Gmol/yr)Species
1970a 1990
LOICZb
1990 NEWS
c
Natural Anthro Total Natural Anthro Total Natural Anthro Total DIN 321 500* 821 400 950 1340 643 1129 1771 DON 714 714 706 115 821 PN 1500 1500 2114 2114 TN 2536 500 3036 3463 1244 4707
DIP 13 13 26 21 53 74 27 51 78 DOP 19 19 39 39 9 48 PIP 387 387 645** 645** POP 258 258 TP 677 32 710 711 60 771
*No distinction between organic or inorganic forms was specified.**No distinction between organic or inorganic forms or between natural or anthropogenic origins was specified.
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2008 AOGS Annual Meeting 23
P-cycling in continental shelf
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Final CarboOcean Meeting 24
Demand & riverine supply of nutrients in margins
Riverine fluxes from Global NEWS model (Seitzinger et al., 2005)
FluxesOC (PgC/y)
OC (Tmol/y)
N (Tmol/y)
P (Tmol/y)
Margin uptake of anth CO2 0.5 42 6.3 0.39
Riverine Diss. Inorg. Nutrients 1.77 0.078
Riverine Total Nutrients 4.7 0.77
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2008 AOGS Annual Meeting 25
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2008 AOGS Annual Meeting 26
Contents of terrigenous & marine organic carbon off SW
TaiwanKao et al., 2006, CSR
119.0 119.5 120.0 120.5 121.0
Longitude (E)119.0 119.5 120.0 120.5 121.0
Longitude (E)
21.5
22.0
22.5
23.0
Lat
itu
de
(N)
(d)(c)
0
0.1
0.2
0.3
0.4
0.00.20.30.40.50.60.70.8TOCmar (%)TOCterr (%)
TOCmar burial = 2.3% PP
16-20 June 2008Busan
2008 AOGS Annual Meeting 27
-10 -8 -7 -6 -5 4 -3 -2 -1 0 1 2 3 4 5 6 10 Net flux (1012 grams C/ yr in each 4 x 5 o area)
JGOFS/WOCE: Global air-sea CO2 flux
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Final CarboOcean Meeting 28
Pre-anthropocene: C cycle at steady state with
land-sea C sub-cycle
Fred Mackenzie
0.8
Most shelf production + OrgC from land respired: R
> PCurrents varying on time-scales of days or longer tend to be constrained by geosptrophy to flow along depth contours; ..... Thus geostrophy inhibits ocean-shelf exchange, .....Huthnance (1995)
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Final CarboOcean Meeting 29
X
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Final CarboOcean Meeting 30
Continental shelf pump
• Simplified view: Cross shelf exchange is rapid enough to allow export of organic carbon from shelf to deep ocean.
• The reality is more complicated.
Carbon export by isopycnal mixing: Diffusion pump
16-20 June 2008Busan
2008 AOGS Annual Meeting 31
Kuroshio