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The carbon budget for coastal waters of the eastern United States
R. Najjar, M. Friedrichs, W.-J. Cai, D. Butman,K. Kroeger, W. M. Kemp,
M. Herrmann, L. McCallister, Z. Wang, S. Signorini, C. Pilskaln,
D. Burdige, P. Vlahos, R. Vaillancourt
Outline1. Importance
of coastal ocean
2. NACP Coastal Synthesis
3. East coast carbon budget
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Importance of the coastal ocean (depth < 200 m, 4.7% of ocean area)
Pg C yr-1 % ocean total
Primary Production
6.5 12
Export Production
2.0 21
Burial 0.67 86
Source: Dunne et al. (2007)
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NACP-OCB Coastal Synthesis ActivityObjective: “Stimulate the synthesis and publication of recent observational and modeling results on carbon cycle fluxes and processes along the North American continental margin”
• Phase 1: Regional carbon budgets• Phase 2: Community modeling & database development
• NASA & NSF support for regional workshops and post-doc• One workshop held (2012 East coast), one scheduled (Gulf
of Mexico, March 27-28, 2013 in St. Petersburg, FL)• Get involved! NACP web site Synthesis Activities
4Nationalatlas.gov
(Mathis)
Great Lakes(McKinley)
(Cai, Freidrichs, Najjar)
(Alin, Hales)
(Coble, Lohrenz)
Tidal wetlands Estuaries Continental shelfNPP Degassing
Burial
River input
BPP
Air-water exchange
POC export
The carbon cycle of the coastal ocean
POCDOC
DIC
Respiration (R)
Resuspension
NPP, RNPP, R
POCDOC
DIC
Sediments
Advective exchange
Open Ocean
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Coastal zone of the eastern
U.S.:Head-of-tide to
shelf break (~200 m)
% Area
Tidal wetlands
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Estuaries 14Shelf waters
83
Gulf of Maine (GoM)
Georges Bank + Nantucket Shoals (GB + NS)
Mid-Atlantic Bight (MAB)
South Atlantic Bight (SAB)
See workshop report on
NACP web site (Najjar et al.
2012)
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River inputUSGS statistical models
TOCTg C yr-1
DICTg C yr-1
GoM 0.57 0.30MAB 1.45 1.63SAB 1.86 0.56East Coast 3.9 2.5
Also using process-based model (DLEM—see Tian et al. poster)
SPARROW (Shih et al. 2010)
LOADEST (Stets and Striegl 2012)
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Tidal wetlands
Delaware Bay
New Jersey
Delaware
Estuarine and marine wetlands
Current approach:• NWI• Break up wetlands by
subregion and salinity• Literature survey of
burial & lateral export• Average• Two estimates of NPP
www.smithtrail.net
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Tidal wetlands budget (Tg C yr-1)NPP
13-24Degassing
3-19
Burial1-2
2 DIC2-6 DOC? POC
Respiration (R) = 5-21
Lateral export
NPP – R = TOC export + Burial
R – NPP = DIC export + Degassing
Net uptake5-10
Empirical model (Childers et al. 2002) being adopted/refined
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Estuarine processes
• See Herrmann et al. poster
• Net ecosystem production (NEP = NPP – R) function of riverine DIN:TOC loading ratio
• Burial function of estuarine residence time
64 estuaries
Based on NOAA’s National Estuarine Eutrophication Assessment survey (Bricker et al. 2007)
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IntegrateEast coast estuarine NEP = -1.9 Tg C yr-1
Estuarine organic C budget (Tg C yr-1)
3.40.6
0.9
-1.9 NEP
Canada not included yet!
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Gulf of Maine (GoM)
Georges Bank + Nantucket Shoals (GB + NS)
Mid-Atlantic Bight (MAB)
South Atlantic Bight (SAB)
• Currently a literature synthesis
• Also using satellite algorithms and numerical models
• Respiration poorly constrained
120 ± 30 Tg C yr-1 primary production on continental shelf
47 ± 20
34 ± 10
35 ± 10
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Continental shelf air-sea exchange (Signorini et al. poster)
Surface pCO2 algorithm exploiting satellite data
Observed pCO2
Algo
rithm
pCO
2
UptakeTg C yr-1
GoM -0.1GB+NS 1.3MAB 2.1SAB 1.0East Coast 4.3
Flux = f(DpCO2, wind, SST)
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Continental shelf sedimentsDIC flux from sediments• DIC flux: estimated
from water depth • Similar approach
taken with DOC flux• Particle flux,
resuspension, burial data synthesized
• See Pilskaln et al. poster
Surface water POC export
Resuspension flux
Benthic DIC + DOC flux POC burial
>8 12 14 1
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Cross-shelf transport• Tracer-based approach: Vlahos et al. poster• MAB a DOC source and DIC sink (net autotrophic)
Numerical modeling approach: Friedrichs et al. poster
• Gives similar OC results but IC budget not in balance
Tidal wetlands Estuaries Continental shelf
NPP13-24
Degassing3-19
Burial1-2
River input3.9 TOC2.5 DIC
BPP
Air-water exchange
POC export >8
Overall US east coast budget
POC1 DOC+DIC
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Respiration (R)5-21
Resuspension12
-1.9 NEP
120 NPP, ? R
Burial0.9
Sediments
Advective exchange
Open Ocean
2 DIC2-6 DOC
3-7 TOC
?4.3
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Lots of progress made,but still much to do
• Constrain air-water CO2 flux for estuaries close inorganic C budget
• Burial measurements• Tracer techniques to get NEP on shelf and
cross-shelf transport• Numerical model evaluation and application
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Thank you
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References
Bricker, S.B., Longstaff, B., Dennison, W., Jones, A., Boicourt, K., Wicks, C., Woerner, J., 2007. Effects of nutrient enrichment in the nation’s estuaries: A decade of change, NOAA Coastal Ocean Program Decision Analysis Series No. 26. National Centers for Coastal Ocean Science, Silver Spring, MD. 328 pp.
Childers, D.L., J.W. Day Jr, H. N. Mckellar (2002). Twenty More Years of Marsh and Estuarine Flux Studies: Revisiting Nixon (1980), M. P. Weinstein and D. A. Kreeger (eds), Concepts and Controversies in Tidal Marsh Ecology, Springer, Netherlands, 391-423.
Dunne, J. P., J. L. Sarmiento, and A. Gnanadesikan (2007), A synthesis of global particle export from the surface ocean and cycling through the ocean interior and on the seafloor, Global Biogeochem. Cycles, 21, GB4006, doi:10.1029/2006GB002907.
Najjar, R.G., Friedrichs, M.A.M., Cai, W.-J. (Editors), 2012. Report of the U.S. East Coast Carbon Cycle Synthesis Workshop, January 19-20, 2012, Ocean Carbon
and Biogeochemistry Program and North American Carbon Program, 34 pp.Shih, J.S., Alexander, R.B., Smith, R.A., Boyer, E.W., Schwarz, G.E., Chung, S., 2010. An
Initial SPARROW Model of Land Use and In-Stream Controls on Total Organic Carbon in Streams of the Conterminous United States, U.S. Geological Survey Open-File Report 2010–1276, 22 pp.
Stets, E.G. and R.G. Striegl (2012). Carbon export by rivers draining the conterminous United States. Inland Waters, vol. 2., pp. 177-184.