the 45th international liège colloquium liège, belgium 13th – 17th may 2013
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The 45th International Liège ColloquiumLiège, Belgium 13th – 17th May 2013
Primary production and the carbonate system in the Mediterranean Sea
Cossarini G., Lazzari P., Solidoro C.
OGS – National Institute of Oceanography and Experimental Geophysics
Trieste (Italy)
Touratier and Goyet, 2012
Few data on carbonate chemistry are available for the Mediterranean Sea
Intense gradients from west to east
Introduction: understanding Ocean Acidification calls for the resolution of the carbonate system and its variability
Carbonate system: DIC (CT) and Alkalinity (AT)
Introduction: Mediterranean Sea circulation and boundaries
Surface circulation Siokou-Frangou et al., 2010
Anti estuarine circulation at Gibraltar
Alkalinity profile at Gibraltar Huertas et al., 2009
Nile
Input from Dardanelles:Alk 1.15 1012 mol/yDIC 12.6 1012 gC/yChopin-Montegut, 1993
Input from rivers:Alk 0.92 1012 mol/yDIC 11.23 1012 gC/yMeybeck and Ragu, 1995; Ludwig et al., 2009
PoRhone
EbroDardanelles
Longitudinal and latitudinal transects of chlorophyll a
Integrated vertical net primary production
LEVION
TYRALB SWE
NWM
Controlling mechanism: extinction factor coefficient (k)Declining DCM moving eastward
Lazzari et al., 2012
Introduction: spatial variability of trophic conditions
• Aim: evaluate scales of variability of carbonate system (DIC and alkalinity) in the Mediterranean Sea and quantify the contribution of physical & biological processes
1. 3D physical-biogeochemical model: OPATM-BFM
2. Reconstruction of alkalinity and DIC spatial patterns & validation
3. Decomposition of physical and biological contributions on spatial and temporal variability
4. Air-sea CO2 exchanges
Method: 3D coupled OPATM-BFM-carbonate model
BFM – Biogeochemical Flux Model Carbonate system
OCMIP II modelOrr et al., 1999
Wolf-Gladrow et al., 2007
OCMIP II modelSchneider et al.1999
Wanninkhof,1992
NutrientsConsumption/production
Alkalinity:Production: denitrification
phytoplankton uptake of NO3- and PO4
3-
mineralization and realise of NH4+
Consuption: phytoplankton uptake of NH4+
nitrification mineralization and realise of PO4
3-
DIC=[CO2]+[HCO3-]+[CO3
2-]consumption:photosynthesys
production: respiration by phyoplankton, zooplankton and bacterial functional type groups
www.bfm-community.eu
Atmopheric pCO2=360-390ppmPhysical and biogeochemical setup and validation Beranger et al., 2010; Lazzari et al. 2012 & poster Lazzari et al
Results: Alkalinity – spatial patterns and validation
mol/kg
Taylor Diagram: B0, B400, B1000: Boum 2008 cruise at 0, 400 and 1000 m; M0,M400, M1000: Meteor51 cruise at 0, 400 and 1000 m; Sm0, Sm400, So0, So400 Sesame dataset at 0 and 400 m, March and October cruises; P0: Prosope cruise, Dyf0, Dyf400, Dyf1000: Dyfamed site at 0, 400 and 1000 m.
1
2
3 4 5 6
1
23
4 56
mol/kg
Taylor Diagram: B0, B400, B1000: Boum 2008 cruise at 0, 400 and 1000 m; M0,M400, M1000: Meteor51 cruise at 0, 400 and 1000 m; Sm0, Sm400, So0, So400 Sesame cruises at 0 and 400 m, March and October cruises; P0: Prosope cruise, Dyf0, Dyf400, Dyf1000: Dyfamed site at 0,400 and 1000m.
1
23
4 56
1
2
3 4 5 6
Results: DIC – spatial pattern and validation
Longitudinal transectLatitudinal transect
Results: spatial variability DIC along W-E transect and its temporal variability
Annual average DIC concentration
Amplitude of the seasonal cycle
pH = 0.1-0.2
LEVION
TYRALB SWM
NWM
Decomposition of physical and biological part of the amplitude of the seasonal cycle
variability of physical fluxes: [mmol/m3/d]
flux at air-sea interface, advection and diffusion
LEVION
TYRALB SWM
NWM
variability of biological fluxes[mmol/m3/d]
Results: biological and physical contributions on DIC
Photosynthesis - respiration
Upwelling transport and diffusion of the adsorbed atmospheric CO2
Decomposition of physical and biological annual average fluxes
Results: biological and physical contributions on DIC
Biological carbon pump
LEVION
TYRALB SWM
NWM
physical process
Photosynthesis - Respiration
Decomposition of physical and biological effects: average annual signal
Results: biological and physical contributions on DIC
Biological carbon pump
LEVION
TYRALB SWM
NWM
Seasonal cycle of phytoplankton production and community respiration
mmol/m3/d mmol/m3/d
OPATM-BFM: sink of 1.6 x 1012 mol/y (-0.65 mol/m2/y)
Results: CO2 flux at air-sea interface
molC/m2/y
From D’Ortenzio et al., 2009
Other estimates:0.35-1.85 x 1012 mol/y
Copin-Montegut, 1993
2.1 x 1012mol/y Huertas et al., 2009
Sink source
OPATM-BFM: sink of 1.6 x 1012 mol/y (-0.65 mol/m2/y)
Results: CO2 flux at air-sea interface
molC/m2/ySink source
Switching off the biology from the system
-20% of atmospheric CO2 sink quantification (€) of the role of biology (ecosystem service) in carbon cycle
Conclusions:
•Mediterranean sea has strong spatial variability of carbonate system (model can help in reconstructioning patterns)
•Physical processes impact the spatial and temporal variability
•Biology has lower effect on seasonal scale but impacts on longer time scale
• CO2 flux affected by biological pump (~20%) at the present atmospheric pCO2 conditions
THANK YOU
Reseach founded by
http://www.ritmare.it/http://medsea-project.eu/
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