Photosynthesis carbon isotope fractionation

Early reviews by O Leary (1981) and Farquhar et al. (1989) have provided the biochemical background of carbon isotope fractionations during photosynthesis, with more recent accounts by Hayes (2001) and Freeman (2001). 

Park R, Epstein S (1960) Carbon isotope fractionation during photosynthesis, Geochim Cosmochim Acta 21 110-126... 

Vogel J. C. (1993) Variability of carbon isotope fractionation during photosynthesis. In Stable Isotopes and Plant Carbon Water Relations (eds. J. R. Ehleringer, A. E. Hall, and G. D. Farquhar). Academic Press, pp. 29-46. 

Stable isotopes studies. Numerous researchers have taken advantage of the difference in carbon isotope fractionation during photosynthesis of plants with C3 and C4 photosynthetic pathways as a natural tracer to study soil carbon dynamics (Balesdent et al., 1987). If a C3 forest is converted to a C4 pasture or C4 agricultural field, the whole soil carbon turnover time (t) can be calculated as... 

To summarize, the most probable explanation of the C isotope spread in the shallow-water facies of the Manjeri Formation (Spring Valley and Shavi sediments and Rupemba (Spring Valley) stromatolites), and in the Cheshire Formation stromatohtes and black shales is thus that carbon isotope fractionation records a diverse ecology that existed based primarily on oxygenic photosynthesis, but with associated organisms... 

Fig. 6.20 Estimated carbon isotopic fractionation during photosynthesis (broken line) and derived atmospheric 02/C02 ratio (solid line) in comparison with mass-balance model of atmospheric 02/C02 ratio (half-tone band) spanning the Carboniferous-Permian glaciation (after Beerling et al. 2002).

Descolas-Gros C, Fontugne M (1990) Stable carbon isotope fractionation by marine phytoplankton during photosynthesis. Plant Cell Environment 13 207-218... 

Oxburgh ER, Andrews-Speed CP (1981) Temperature, thermal gradients and heat flow in the southwestern North Sea. In Illing LV, Hobson GD (ed) Petroleum geology of the continental shelf of the north-west Europe. Heyden and Son, London, pp 141-151 Park R (i960) Carbon isotopic fractionation during photosynthesis. Geochimica and Cosmochimica Acta 21(1-2)... 

Hollander, D. J. J. A. MacKenzie, 1991. CO2 control on carbon-isotope fractionation during aqueous photosynthesis A paleo-/>C02 barometer. Geology 19 929-932. 

Park R. and Epstein S. (1963) Carbon isotopic fractionation during photosynthesis. Geochim. Cosmochim. Acta 21, 110-115. 

There is evidence that oxygenic photosynthesis occurred at this time, but typically produced only trace amounts of O2 in the water. Molecular fossils indicate oxygen-producing microbes as does the tendency of carbon isotopic fractionation to behave like that with modern photosynthesis [29,30]. 

Vogel, J.C. 1980 Fractionation of the Carbon Isotopes During Photosynthesis. New York, Springer. 

Similar terms can be derived for other flux components based on knowledge of the isotopic composition of the source material (e.g., atmospheric CO2, ocean-surface inorganic carbon, soil organic carbon) and knowledge of the associated, process-based, isotopic fractionation (e.g., sp for photosynthesis, cr for respiration). Note also that terms such as 5a -b Sao in Equation (14) are also approximations of A. ... 

Berry J. A. (1988) Studied of mechanisms affecting the fractionation of carbon isotopes in photosynthesis. In Stable Isotopes in Ecological Research, vol. 68 (eds. P. W. Rundel, J. R. Ehleringer, and K. A. Nagy). Springer, pp. 82-94. 

Vogel J. C. (1980) Fractionation of the carbon isotopes during photosynthesis. In Sitzungsberichte der Heidelber-ger Akademie der Wissenschaften, Mathematisch-Natur-wissenschaftUche Klasse Jahrgang 1980. 3. Abhandlung Springer, pp. 111-135. 

Some plants employ a photosynthetic pathway creating at first a three-carbon phosphoglyceric acid (C3 or Calvin-Benson photosynthesis). These plants fractionate isotopes more intensely, and so have more negative values (-33%o to —22%o PDB) than plants which use a photosynthetic pathway creating at first a four-carbon malic and aspartic acid (C4 or Hatch-Slack photosynthesis -16%o to -9%o PDB). Crassulacean acid metabolism (CAM) is yet another photosynthetic pathway, which creates organic matter of intermediate isotopic composition (-35%o to -ll%o PDB). Methanogenic microbes are even more extreme in their fractionation of the light isotope (5 C down to -110%o and typically -60%o PDB ... 

Although photosynthesis is the ultimate source of O2 to the atmosphere, in reality photosynthesis and aerobic respiration rates are very closely coupled. If they were not, major imbalances in atmospheric CO2, O2, and carbon isotopes would result. Only a small fraction of primary production (from photosynthesis) escapes respiration in the water column or sediment to become buried in deep sediments and ultimately sedimentary rocks. This flux of buried organic matter is in elfect net photosynthesis , or total photosynthesis minus respiration. Thus, while over timescales of days to months, dissolved and atmospheric O2 may respond to relative rates of photosynthesis or respiration, on longer timescales it is burial of organic matter in sediments (the net photosynthesis ) that matters. Averaged over hundreds of years or longer, burial of organic matter equates to release of O2 into the atmosphere - - ocean system ... 

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