• dioxide
  • 1995). Plants find it easier to use the lighter isotopes (12C) when they convert sunlight and carbon dioxide into food. (wikipedia.org)
  • The ratio of carbon-13 and carbon-12 isotopes in these types of plants is as follows: C4 plants: -16 to -10 ‰ CAM plants: -20 to -10 ‰ C3 plants: -33 to -24 ‰ Limestones formed by precipitation in seas from the atmospheric carbon dioxide contain normal proportion of 13C. (wikipedia.org)
  • Conversely, calcite found in salt domes originates from carbon dioxide formed by oxidation of petroleum, which due to its plant origin is 13C-depleted. (wikipedia.org)
  • Their main function is to act as centres of carbon dioxide (CO2) fixation, by generating and maintaining a CO2 rich environment around the photosynthetic enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). (wikipedia.org)
  • nitrogen
  • El nitrógeno nuevo sedimentado alcanzó un 10 a 11 % del total originalmente adicionado a la columna de agua en la forma de nitrato, sin que se observara una sedimentación masiva de P. minimum durante los días de duración de este experimento Resumen en inglés Stable isotopes were used as tracers to characterize and quantify the downward flux of carbon and nitrogen. (worldwidescience.org)
  • A similar pattern in the concentration of chlorophyll a (Chl-a), particulate organic nitrogen (PON) and particulat (mas) e organic carbon (POC) was observed in both mesocosms. (worldwidescience.org)
  • 11 C → 11 B + e+ + ν e + 6987153808942752000♠0.96 MeV 11 C + e− → 11 B + Electron neutrino + 6987317230944426000♠1.98 MeV It is produced from nitrogen in a cyclotron by the reaction 14 N + p → 11 C + 4 He Carbon-11 is commonly used as a radioisotope for the radioactive labeling of molecules in positron emission tomography. (wikipedia.org)
  • His research focuses on biochemical mechanisms such as C₄ carbon fixation which spatially separate one of the anaplerotic reactions of CO₂ fixation by Phosphoenolpyruvate carboxylase within mesophyll tissues and RuBisCO in an inner bundle sheath cell: CO₂ concentrations are elevated and offset the wasteful oxygenase activity and the salvage pathway, photorespiration, leading to improved radiation, water and nitrogen use by C₄ plants. (wikipedia.org)
  • organic carbon
  • δ13C varies in time as a function of productivity, organic carbon burial and vegetation type. (wikipedia.org)
  • when organic carbon is buried, more 12C is locked out of the system in sediments than the background ratio. (wikipedia.org)
  • Mass extinctions are often marked by a negative δ13C anomaly thought to represent a decrease in primary productivity and release of plant-based carbon The evolution of large land plants in the late Devonian led to increased organic carbon burial and consequently a rise in δ13C. (wikipedia.org)
  • methane
  • For example, different sources and sinks of methane have different affinity for the 12C and 13C isotopes, which allows distinguishing between different sources by the 13C/12C ratio in methane in the air. (wikipedia.org)
  • fossil
  • Wang Y, Cerling T. A model of fossil tooth and bone diagenesis: Implications for paleodiet reconstruction from stable isotopes. (springer.com)
  • Carbon isotope analysis of fossil bone apatite. (springer.com)
  • Stable isotopes in fossil hominin tooth enamel suggest a fundamental dietary shift in the Pliocene. (springer.com)
  • Carbon in artificially made chemicals is usually derived from fossil fuels like coal or petroleum, where the 14C originally present has decayed below detectable limits. (wikipedia.org)
  • The standard established for carbon-13 work was the Pee Dee Belemnite (PDB) and was based on a Cretaceous marine fossil, Belemnitella americana, which was from the Peedee Formation in South Carolina. (wikipedia.org)
  • fatty acids
  • The δ13C values of individual fatty acids can be useful for interpreting carbon utilization by D. hydrogenophilus in natural environments. (wikipedia.org)
  • Biosynthetic control of the natural abundance of carbon 13 at specific positions within fatty acids in Escherichia coli. (wikipedia.org)
  • analysis
  • We will demonstrate the new absorption analysis technique at wavelengths of 1.5 microns in Phase I and demonstrate that the approach can be used to record the relative isotopic abundance of carbon 12 and 13 with great accuracy. (sbir.gov)
  • In situ laser microprobe techniques for stable isotope analysis. (nii.ac.jp)
  • This process is called isotope analysis. (wikipedia.org)
  • citation needed] More recent techniques have been introduced such as Carbon Isotopic Analysis of recovered bones, which can be used as direct evidence of diet, and life History Traits. (wikipedia.org)
  • He was named a fellow of the American Association for the Advancement of Science (AAAS) for his major contributions to climate and carbon cycle modeling and to climate data analysis, and because he is "one of the world's foremost experts on climate change and one of the most highly cited scientists in the discipline. (wikipedia.org)
  • examination
  • An extension of this research resulted in development of DNA-based stable-isotope probing, which allows examination of links between metabolic function and taxonomic identity of microorganisms in the environment, without the need for culture isolation. (wikipedia.org)
  • metabolic
  • These variations are thought to arise from biosynthetic isotope effects and different metabolic routes, especially those associated with the biosynthesis of sugars which are converted into ethanol during fermentation. (wikipedia.org)
  • indicates
  • This indicates the possibility of isotope effects with both positive and negative signs in the GDC reaction. (diva-portal.org)
  • The amount of 14C currently present in a sample therefore indicates the proportion of carbon of biogenic origin. (wikipedia.org)
  • plants
  • He has a major collaboration funded by Biotechnology and Biological Sciences Research Council (BBSRC) and National Science Foundation (NSF) to explore the possibility of introducing elements of the algal carbon concentrating mechanism into vascular plants. (wikipedia.org)
  • ethanol
  • However, D. hydrogenophilus is a facultative lithoautotroph, and may also use acetate, pyruvate, or ethanol as both an electron donor and carbon source. (wikipedia.org)
  • algae
  • From there on, the pyrenoid was studied in the wider context of carbon acquisition in algae, but has yet to be given a precise molecular definition. (wikipedia.org)
  • method
  • With such a sensitive method of accurately determining carbon isotope levels we hope to significantly advance the prospects for making in-situ tests for evidence of life on nearby planets, such as Mars. (sbir.gov)
  • different
  • Density functional theory calculations: equilibrium isotope effects at the position-specific levels can be computed through DFT calculations for different temperatures. (wikipedia.org)
  • however
  • However, unlike many SRB, D. hydrogenophilus is a facultative lithoautotroph, and can grow using H2 as an electron donor and CO2 as a carbon source. (wikipedia.org)
  • reaction
  • This is also the only carbon radioisotope found in nature-trace quantities are formed cosmogenically by the reaction 14N + 1n → 14C + 1H. (wikipedia.org)
  • exchange
  • 12C and 13C are measured as the isotope ratio δ13C in benthic foraminifera and used as a proxy for nutrient cycling and the temperature dependent air-sea exchange of CO2 (ventilation) (Lynch-Stieglitz et al. (wikipedia.org)
  • positive
  • The Steptoean Positive Carbon Isotope Excursion (SPICE) was a geological event which occurred about 500 million years ago at the end of the Cambrian Period. (wikipedia.org)
  • levels
  • With the exception of Iraq ed-Dubb, the earliest carbon-14 dated remains of domesticated emmer wheat were found in the earliest levels of Tell Aswad, in the Damascus basin, near Mount Hermon in Syria. (wikipedia.org)