Stable carbon isotope fractionation by marine phytoplankton during photosynthesis |
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Authors: | C DESCOLAS-GROS M FONTUNGNE |
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Institution: | UA 117 Laboratoire Arago. 66 650 Banyuls sur mer;Centre des faibles radioactivities. Laboratoire mixte CEA-CNRS. BPI, 91190 Gif sur Yvette. France |
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Abstract: | Abstract. In the marine environment, the range of values of carbon isotope fractionation between particulate tissue of phytoplankton and inorganic carbon can be more than 20‰ (? 35‰ < δ13C < ? 14‰). This review considers the influence of seawater temperature, lipid content of phytoplanktonic cells, kinetic fractionation, and carbon pathway on δ13C values observed at sea. In order to study the contribution of carboxylases (RUBISCO and the β-carboxylases phosphoenolpyruvate carboxylase, phosphoenoplpyruvate carboxykinase and pyruvate carboxylase) to variations of particulate δ13C values at sea, we present results obtained simultenously on carboxylase activities and δ13C in various environmental conditions. The lowest δ13C values are clearly associated with predominance of ribulose-1.5-bisphosphate carboxylase activity, but it was more difficult to explain the high δ13C values. Different hypotheses are discussed. |
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Keywords: | Phytoplankton photosynthesis carbon δ13C carboxylases |
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