the use of δ 18 o in atmospheric co 2 matthias cuntz research school of biological sciences (rsbs),...
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The use ofδ18O in atmospheric CO2
Matthias CuntzResearch School of Biological Sciences (RSBS), ANU, Canberra, Australia
Philippe Ciais, Georg Hoffmann, Philippe Peylin, Jérôme OgéeLaboratoire des Sciences du Climat et de l’Environnement (LSCE), Gif-sur-Yvette, France
Roger J. Francey, Colin E. AllisonDivision of Atmospheric Research (DAR), CSIRO, Melbourne, Australia
Pieter P. Tans, James W. C. WhiteClimate Monitoring and Diagnostic Laboratory (CMDL), NOAA, Boulder, Colorado and Institute of Arctic and Alpine Research (INSTAAR) and Department of Geological Sciences, University of Colorado, Boulder, Colorado
Wolfgang KnorrMax Planck Institute of Biogeochemistry (MPI-BGC), Jena, Germany
Ingeborg LevinInstitute of Environmental Physics (IUP), University of Heidelberg, Germany
Graham D. Farquhar, Lucas A. CernusakResearch School of Biological Sciences (RSBS), ANU, Canberra, Australia
The idea
The idea: deconvolution
x = O2/N2 Ocean/Biosphere x = 13C O2 Ocean/Biospherex = 14C O2 Fossil Fuelx = CO17O Stratosphere-Troposphere Exchangex = CO18O Gross Biosphere Fluxesx = 18O2,17O2 Gross Biosphere Fluxes on Paleo
Time Scales (Dole Effect)
i
i2 (t)F
dt
COd
i
ii (t)F(t)Δdt
dx
CO2 equilibrates isotopically with H2O in 18O
Equilibration: COO + H218O CO18O + H2O
eqα
soil/leaf-water
airαkin
CO18O: αeqRw
H218O: Rw
CO18O: αkin αeqRw
diffusivezone
Example: Respiration isoflux
soil
atmosphereεs
δa
δs
RassRR FδεδFΔ
δs: δ18O of CO2
equilibratedwith soil water
εs: kineticfractionation of diffusion out of soil
soildepth
ca.15 cm
18O vs. 13C
Global Values 18‰
13‰
18FGtC‰/yr
13FGtC‰/yr
Respiration R -16 -18 -1600 -1800
Assimilation A 19 18 1900 1800
Ocean O 1 2 100 200
Burning processes B -18 -18 -180 -180
minorBΔOΔAΔRΔdt
δdBOAR
a
Double deconvolution
AΔRΔdt
dδ2)
ARdt
dC1)
ARa
a
Adt
dCR,
ΔΔdt
dCΔ
dt
dδ
A a
AR
aR
a
Themeasurements
CO2 and δ18O SSC at Alert, Canada
340
345
350
355
360
365
370
1992 1992.5 1993 1993.5 1994
(p
pm
) (
‰ V
PD
B-C
O2)
CO2
δ18O
-3
-2.5
-2
-1.5
-1
-0.5
0
1992 1992.5 1993 1993.5 1994
CO2 and δ18O stations worldwide
CO2, δ13C, δ18O diurnal cycles, Tver forest, RussiaLangendörfer et al. (2002)
The globalpicture
CO2
Fdiff +300
Ffos6
Fao102
Foa100
Surface water0 ‰ VSMOW
Fretro-diff = Fassimilation+ 200 = -100
Fbur3
Leaf water+7 ‰ VSMOW
Frespiration100
Soil water9 ‰ VSMOW
Evapotranspiration
Evaporation
Distillation 13 ‰VSMOW
18 ‰VSMOW
RainRain
Tropopause
Fassimilation-100
5 ‰ VSMOW10 ‰ VSMOW
, H2O, δ18O-H2O cyclescycle cycles
CO2, H2O, δ18O-H2O, δ18O-CO2 cycles
Fdiff +300
Ffos6
Fao102
Foa100
Surface water0 ‰ VSMOW
Fretro-diff = Fassimilation+ 200 = -100
Fbur3
Leaf water+7 ‰ VSMOW
Atm. O2
17 ‰ VPDB-CO2
Frespiration100
Soil water9 ‰ VSMOW
Evapotranspiration
Evaporation
Distillation 13 ‰VSMOW
18 ‰VSMOW
Rain5 ‰ VSMOW
Rain10 ‰ VSMOW
Finvasion±20 (140)
Troposph. δ18O-CO2 +0.5 ‰ VPDB-CO2
Tropopause
Stratosph. δ18O-CO2 +2.5 ‰ VPDB-CO2
Fste ±100 (+200)
(-30) (-80)
(1540)
(2220) (1540)(680)
(-116)(-58)
CIAISO
SiB2CO2
GISS δ18O-H2O
other CO2
sources
δ18O-CO2
TM2 – Atmosphere:
Isotopic comp.of precip. & vapour
CO2
fluxes
CO2
fluxesVeg. & soilparam.
CO18Ofluxes
CO2
fluxes
CO2δ18O-CO2
CO2
fluxes
Ciais et al. (1997a,b), Peylin et al. (1999)
δ18O-CO2 SSC CIAISO
Alert
Cape Grim
Peylin et al.(1999)
Point Barrow
Mauna Loa
ECHAM4
Meteo., cloud, etc.
Isotopic comp.
of precip., soil and vapour
BETHY
Atmosphere
CO2
fluxes
other CO2
sources
Leaf
Soil
OFRAC Others
Transport
Fractionationphysics
CO2
fluxes
CO2
fluxes
Meteo., soil, etc. param.
Veg. & soilparam.
CO18Ofluxes
δ18O-CO2
CO2
fluxes
WFRAC
H218O
CO2
fluxes
δ18O-H2O
MECBETH
: δ18O-H2O CO2δ18O-CO2
Cuntz et al. (2003a,b)
δ18O-CO2 SSC MECBETH
Alert
Kumukahi
Seychelles
American Samoa
Cape Grim
South Pole
Cuntz et al. (2003b)
Cuntz et al. (2003b)δ18O-CO2 SSC MECBETH
Why?
CO2 net fluxes CO2 gross fluxesInner-stomatal CO2 concentrationIsotopes in precipitation
at high northern latitudes?}Isotopes in soil water ? Relative influence of respiration and assimilation
Soil water isotope gradient (Riley et al. 2002)
Night-time leaf gas exchange (Cernusak et al. 2004)
Nocturnal leaf water values (Ogee et al. 2003, Cernusak et al. 2002)
Cuntz et al. (2003a,b)
ECHAM5
Meteo., soil, cloud, etc.
Atmosphere
CO2
fluxes
other CO2
sources
Transport
Fractionationphysics
CO2
fluxesCO18Ofluxes
δ18O-CO2
WFRAC
H218O δ18O-H2O
Future MECBETH
: δ18O-H2O CO2 δ18O-CO2
OFRAC
BETHYLPJ
CO2
fluxes
δ18O-H2ORainVapour
[CO2]
CO2
fluxes
[CO2]
Land surface parameters
CCM
Meteo., soil, cloud, etc.
Atmosphere
CO2
fluxes
other CO2
sources
Transport
Fractionationphysics
CO2
fluxesCO18Ofluxes
δ18O-CO2
CCMISO
H218O δ18O-H2O
Future CCM-ISO-LSM
: δ18O-H2O CO2 δ18O-CO2
ISOLSM
LSMCO2
fluxes
δ18O-H2ORainVapour
[CO2]
CO2
fluxes
[CO2]
Land surface parameters
Summary
• Idea: use δ18O-CO2 to separate assimilation from respiration
must know Δ’s, i.e. water isotopes in biosphere
• Built global model of δ18O in atmospheric CO2: MECBETH
• δ18O-CO2 not yet fully resolved, i.e. big error on Δ’s
soil water description night-time δ18O-CO2 exchange
know leaf/soil water know Δ’s separate assimilationfrom respiration better biosphere parameterisations better source/sink determination
, one day!
FIN