布朗大學(xué)同位素地球化學(xué) Carbonisotope(1)

1、Excluding carbonate in carbonaceous chondrite, the terrestrial range of d13C values exceed 100 46. 1*102322COCOHCOpaK35. 6*110323COHHHCOaaaK33.10210323HCOHCOaaaKpH02468101214log ai-8-7-6-5-4-3-26.3510.33H2CO3*HCO3-CO32-H+OH-Common pHrange in natureBjerrum plot showing the activities of inorganic car

2、bon species as a function of pH for a value of total inorganic carbon of 10-3 mol L-1.In most natural waters, bicarbonate ion is the dominant charged carbonate species in the alkalinity definitionClosedOpen13D = a + (b-a)Ci/Caa: Fractionation of diffusionb: Fractionation of RubiscoCi: Substomatal CO

3、2Ca: Atmospheric CO2When Ci = 0 (not realistic for plants), 13D=a, diffusion onlyWhen Ci = Ca (infinite conductance), 13D=bFarquhar et al. (1982) Aust. J. Plant Physiol. 9, 121-1376 . 1)/1 ()()(aiaaiwiacPPPeegPPgEAGc:Conductance to diffusion of CO2Gw:Conductance to diffusion of H2O. In the air, Gw/G

4、c=1.6:Difference in intercellular and atmospheric vapor pressure of water, ei-ea6 . 1)/1 ()1 (aiaPPPwW is proportionate to Pi/Pa, which can be conveniently determined for large number of plants from analyses of carbon isotope ratiosKranz Anatomy, most common, but not required (Voznesenskaya et al.,

5、Nature 414, 543-546, 2001)3-phosphoglyceric acid (PGA): a C3 compoundoxaloacetic Acid: a C4 compoundMost CAM plants have similar d13C values as C4 plants, but some CAM plants can switch to C3 pathway when conditions allowC4 plant: Zea Mays (corn), Poaceae, Gramineae of warm regions (by Peter v. Seng

6、busch)C4 plant: Saccharum officinarum (sugar cane), Poaceae (by Peter v. Sengbusch) A salt marsh C4 plantsFarquhar, 1983, Aust. J. Plant Physiol. 9, 121-137.C4 plants tend to occur in hot, intense sunlight ecosystemsDecreased carbon accumulationIncreased stomatal conductanceFrom Maherali et al., 2000 ESALeafCO2H2O200400pCO2Today: Closed Canopy200400pCO2LGM: Open CanopyGasp!Gasp!Most CAM plants have similar d13C values as C4 plants, but some CAM plants can switch to C3 pathway when condi