δ13C varies in time as a function of productivity, the signature of the inorganic source, organic carbon burial, and vegetation type. Biological processes preferentially take up the lower mass isotope through kinetic fractionation. However some abiotic processes do the same. For example, methane from hydrothermal vents can be depleted by up to 50%.[3]
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. This material had an anomalously high 13C:12C ratio (0.0112372[4]), and was established as δ13C value of zero. Since the original PDB specimen is no longer available, its 13C:12C ratio can be back-calculated from a widely measured carbonate standard NBS-19, which has a δ13C value of +1.95‰.[5] The 13C:12C ratio of NBS-19 was reported as .[6] Therefore, one could calculate the 13C:12C ratio of PDB derived from NBS-19 as . Note that this value differs from the widely used PDB 13C:12C ratio of 0.0112372 used in isotope forensics[7] and environmental scientists;[8] this discrepancy was previously attributed by a wikipedia author to a sign error in the interconversion between standards, but no citation was provided. Use of the PDB standard gives most natural material a negative δ13C.[9] A material with a ratio of 0.010743 for example would have a δ13C value of −44‰ from . The standards are used for verifying the accuracy of mass spectroscopy; as isotope studies became more common, the demand for the standard exhausted the supply. Other standards calibrated to the same ratio, including one known as VPDB (for "Vienna PDB"), have replaced the original.[10] The 13C:12C ratio for VPDB, which the International Atomic Energy Agency (IAEA) defines as δ13C value of zero is 0.01123720.[11]
Causes of δ13C variationsEdit
Methane has a very light δ13C signature: biogenic methane of −60‰, thermogenic methane −40‰. The release of large amounts of methane clathrate can impact on global δ13C values, as at the Paleocene–Eocene Thermal Maximum.[12]
More commonly, the ratio is affected by variations in primary productivity and organic burial. Organisms preferentially take up light 12C, and have a δ13C signature of about −25‰, depending on their metabolic pathway. Therefore, an increase in δ13C in marine fossils is indicative of an increase in the abundance of vegetation.[citation needed]
An increase in primary productivity causes a corresponding rise in δ13C values as more 12C is locked up in plants. This signal is also a function of the amount of carbon burial; when organic carbon is buried, more 12C is locked out of the system in sediments than the background ratio.
Geologic significance of δ13C excursionsEdit
C3 and C4 plants have different signatures, allowing the abundance of C4 grasses to be detected through time in the δ13C record.[13] Whereas C4 plants have a δ13C of −16 to −10‰, C3 plants have a δ13C of −33 to −24‰.[14]
Mass extinctions are often marked by a negative δ13C anomaly thought to represent a decrease in primary productivity and release of plant-based carbon. Conversely, positive δ13C excursions are interpreted as the result of increased carbon fixation by primary producers and the subsequent burial of this organic carbon in sedimentary rocks, signifying the proliferation of life.[15]
^Libes, Susan M. (1992). Introduction to Marine Biogeochemistry, 1st edition. New York: Wiley.
^Schwarcz, Henry P.; Schoeninger, Margaret J. (1991). "Stable isotope analyses in human nutritional ecology". American Journal of Physical Anthropology. 34 (S13): 283–321. doi:10.1002/ajpa.1330340613.
^McDermott, J.M., Seewald, J.S., German, C.R. and Sylva, S.P., 2015. Pathways for abiotic organic synthesis at submarine hydrothermal fields. Proceedings of the National Academy of Sciences, 112(25), pp.7668–7672.
^Craig, Harmon (1957-01-01). "Isotopic standards for carbon and oxygen and correction factors for mass-spectrometric analysis of carbon dioxide". Geochimica et Cosmochimica Acta. 12 (1): 133–149. Bibcode:1957GeCoA..12..133C. doi:10.1016/0016-7037(57)90024-8. ISSN 0016-7037.
^Brand, Willi A.; Coplen, Tyler B.; Vogl, Jochen; Rosner, Martin; Prohaska, Thomas (2014-03-20). "Assessment of international reference materials for isotope-ratio analysis (IUPAC Technical Report)". Pure and Applied Chemistry. 86 (3): 425–467. doi:10.1515/pac-2013-1023. hdl:11858/00-001M-0000-0023-C6D8-8. ISSN 1365-3075. S2CID 98812517.
^Meija, Juris; Coplen, Tyler B.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Holden, Norman E.; Irrgeher, Johanna; Loss, Robert D. (2016-01-01). "Isotopic compositions of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 293–306. doi:10.1515/pac-2015-0503. ISSN 1365-3075.
^Michener, Robert; Lajtha, Kate, eds. (2007-07-14). Stable Isotopes in Ecology and Environmental Science. Oxford, UK: Blackwell Publishing Ltd. doi:10.1002/9780470691854. ISBN978-0-470-69185-4.
^Overview of Stable Isotope Research. The Stable Isotope/Soil Biology Laboratory of the University of Georgia Institute of Ecology.
^Miller & Wheeler, Biological Oceanography, p. 186.
^"Reference and intercomparison materials for stable isotopes of light elements" (PDF). International Atomic Energy Agency. 1995.
^ Panchuk, K.; Ridgwell, A.; Kump, L.R. (2008). "Sedimentary response to Paleocene-Eocene Thermal Maximum carbon release: A model-data comparison". Geology. 36 (4): 315–318. Bibcode:2008Geo....36..315P. doi:10.1130/G24474A.1.
^Retallack, G.J. (2001). "Cenozoic Expansion of Grasslands and Climatic Cooling". The Journal of Geology. 109 (4): 407–426. Bibcode:2001JG....109..407R. doi:10.1086/320791. S2CID 15560105.
^O'Leary, M. H. (1988). "Carbon Isotopes in Photosynthesis". BioScience. 38 (5): 328–336. doi:10.2307/1310735. JSTOR 1310735.
^Canfield, Donald E.; Ngombi-Pemba, Lauriss; Hammarlund, Emma U. (15 October 2013). "Oxygen dynamics in the aftermath of the Great Oxidation of Earth's atmosphere". Proceedings of the National Academy of Sciences of the United States of America. 110 (42): 16736–16741. Bibcode:2013PNAS..11016736C. doi:10.1073/pnas.1315570110. PMC3801071. PMID 24082125.
^Joachimsk, M.M.; Buggisch, W. "THE LATE DEVONIAN MASS EXTINCTION – IMPACT OR EARTH-BOUND EVENT?" (PDF). Lunar and Planetary Institute.
Further readingEdit
Miller, Charles B.; Patricia A. Miller (2012) [2003]. Biological Oceanography (2nd ed.). Oxford: John Wiley & Sons. ISBN978-1-4443-3301-5.
Mook, W. G., & Tan, F. C. (1991). Stable carbon isotopes in rivers and estuaries. Biogeochemistry of major world rivers, 42, 245–264.
August 30, 2023
δ13c, geochemistry, paleoclimatology, paleoceanography, pronounced, delta, thirteen, isotopic, signature, measure, ratio, stable, isotopes, carbon, reported, parts, thousand, measure, also, widely, used, archaeology, reconstruction, past, diets, particularly, . In geochemistry paleoclimatology and paleoceanography d13C pronounced delta c thirteen is an isotopic signature a measure of the ratio of the two stable isotopes of carbon 13C and 12C reported in parts per thousand per mil 1 The measure is also widely used in archaeology for the reconstruction of past diets particularly to see if marine foods or certain types of plants were consumed 2 Foraminifera samplesThe definition is in per mille d C 13 C 13 C 12 s a m p l e C 13 C 12 s t a n d a r d 1 1000 displaystyle delta ce 13 C left frac left frac ce 13 C ce 12 C right mathrm sample left frac ce 13 C ce 12 C right mathrm standard 1 right times 1000 where the standard is an established reference material d13C varies in time as a function of productivity the signature of the inorganic source organic carbon burial and vegetation type Biological processes preferentially take up the lower mass isotope through kinetic fractionation However some abiotic processes do the same For example methane from hydrothermal vents can be depleted by up to 50 3 Contents 1 Reference standard 2 Causes of d13C variations 3 Geologic significance of d13C excursions 4 Major excursion events 5 See also 6 References 7 Further readingReference standard EditThe 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 This material had an anomalously high 13C 12C ratio 0 0112372 4 and was established as d13C value of zero Since the original PDB specimen is no longer available its 13C 12C ratio can be back calculated from a widely measured carbonate standard NBS 19 which has a d13C value of 1 95 5 The 13C 12C ratio of NBS 19 was reported as 0 011078 0 988922 0 011202 displaystyle 0 011078 0 988922 0 011202 6 Therefore one could calculate the 13C 12C ratio of PDB derived from NBS 19 as 0 011202 1 95 1000 1 0 011202 1 00195 0 01118 displaystyle 0 011202 1 95 1000 1 0 011202 1 00195 0 01118 Note that this value differs from the widely used PDB 13C 12C ratio of 0 0112372 used in isotope forensics 7 and environmental scientists 8 this discrepancy was previously attributed by a wikipedia author to a sign error in the interconversion between standards but no citation was provided Use of the PDB standard gives most natural material a negative d13C 9 A material with a ratio of 0 010743 for example would have a d13C value of 44 from 0 010743 0 01124 1 1000 displaystyle 0 010743 div 0 01124 1 times 1000 The standards are used for verifying the accuracy of mass spectroscopy as isotope studies became more common the demand for the standard exhausted the supply Other standards calibrated to the same ratio including one known as VPDB for Vienna PDB have replaced the original 10 The 13C 12C ratio for VPDB which the International Atomic Energy Agency IAEA defines as d13C value of zero is 0 01123720 11 Causes of d13C variations EditMethane has a very light d13C signature biogenic methane of 60 thermogenic methane 40 The release of large amounts of methane clathrate can impact on global d13C values as at the Paleocene Eocene Thermal Maximum 12 More commonly the ratio is affected by variations in primary productivity and organic burial Organisms preferentially take up light 12C and have a d13C signature of about 25 depending on their metabolic pathway Therefore an increase in d13C in marine fossils is indicative of an increase in the abundance of vegetation citation needed An increase in primary productivity causes a corresponding rise in d13C values as more 12C is locked up in plants This signal is also a function of the amount of carbon burial when organic carbon is buried more 12C is locked out of the system in sediments than the background ratio Geologic significance of d13C excursions EditC3 and C4 plants have different signatures allowing the abundance of C4 grasses to be detected through time in the d13C record 13 Whereas C4 plants have a d13C of 16 to 10 C3 plants have a d13C of 33 to 24 14 Mass extinctions are often marked by a negative d13C anomaly thought to represent a decrease in primary productivity and release of plant based carbon Conversely positive d13C excursions are interpreted as the result of increased carbon fixation by primary producers and the subsequent burial of this organic carbon in sedimentary rocks signifying the proliferation of life 15 The evolution of large land plants in the late Devonian led to increased organic carbon burial and consequently a rise in d13C 16 Major excursion events EditLomagundi Jatuli event 2 300 2 080 Ma Paleoproterozoic Positive excursionShunga Francevillian event 2 080 Ma Paleoproterozoic Negative excursionShuram Wonoka excursion 570 551 Ma Neoproterozoic Negative excursionSteptoean positive carbon isotope excursion 494 6 492 Ma Paleozoic Positive excursionCenomanian Turonian boundary event 93 9 Ma Mesozoic Positive excursionPaleocene Eocene Thermal Maximum 55 5 Ma Cenozoic Negative excursionSee also Editd 18O d 15N d 34S Isotopic signature Isotope analysis Isotope geochemistry Isotopic labelingReferences Edit Libes Susan M 1992 Introduction to Marine Biogeochemistry 1st edition New York Wiley Schwarcz Henry P Schoeninger Margaret J 1991 Stable isotope analyses in human nutritional ecology American Journal of Physical Anthropology 34 S13 283 321 doi 10 1002 ajpa 1330340613 McDermott J M Seewald J S German C R and Sylva S P 2015 Pathways for abiotic organic synthesis at submarine hydrothermal fields Proceedings of the National Academy of Sciences 112 25 pp 7668 7672 Craig Harmon 1957 01 01 Isotopic standards for carbon and oxygen and correction factors for mass spectrometric analysis of carbon dioxide Geochimica et Cosmochimica Acta 12 1 133 149 Bibcode 1957GeCoA 12 133C doi 10 1016 0016 7037 57 90024 8 ISSN 0016 7037 Brand Willi A Coplen Tyler B Vogl Jochen Rosner Martin Prohaska Thomas 2014 03 20 Assessment of international reference materials for isotope ratio analysis IUPAC Technical Report Pure and Applied Chemistry 86 3 425 467 doi 10 1515 pac 2013 1023 hdl 11858 00 001M 0000 0023 C6D8 8 ISSN 1365 3075 S2CID 98812517 Meija Juris Coplen Tyler B Berglund Michael Brand Willi A De Bievre Paul Groning Manfred Holden Norman E Irrgeher Johanna Loss Robert D 2016 01 01 Isotopic compositions of the elements 2013 IUPAC Technical Report Pure and Applied Chemistry 88 3 293 306 doi 10 1515 pac 2015 0503 ISSN 1365 3075 Meier Augenstein Wolfram 28 September 2017 Stable isotope forensics methods and forensic applications of stable isotope analysis Second ed Hoboken NJ ISBN 978 1 119 08022 0 OCLC 975998493 a href Template Cite book html title Template Cite book cite book a CS1 maint location missing publisher link Michener Robert Lajtha Kate eds 2007 07 14 Stable Isotopes in Ecology and Environmental Science Oxford UK Blackwell Publishing Ltd doi 10 1002 9780470691854 ISBN 978 0 470 69185 4 Overview of Stable Isotope Research The Stable Isotope Soil Biology Laboratory of the University of Georgia Institute of Ecology Miller amp Wheeler Biological Oceanography p 186 Reference and intercomparison materials for stable isotopes of light elements PDF International Atomic Energy Agency 1995 Panchuk K Ridgwell A Kump L R 2008 Sedimentary response to Paleocene Eocene Thermal Maximum carbon release A model data comparison Geology 36 4 315 318 Bibcode 2008Geo 36 315P doi 10 1130 G24474A 1 Retallack G J 2001 Cenozoic Expansion of Grasslands and Climatic Cooling The Journal of Geology 109 4 407 426 Bibcode 2001JG 109 407R doi 10 1086 320791 S2CID 15560105 O Leary M H 1988 Carbon Isotopes in Photosynthesis BioScience 38 5 328 336 doi 10 2307 1310735 JSTOR 1310735 Canfield Donald E Ngombi Pemba Lauriss Hammarlund Emma U 15 October 2013 Oxygen dynamics in the aftermath of the Great Oxidation of Earth s atmosphere Proceedings of the National Academy of Sciences of the United States of America 110 42 16736 16741 Bibcode 2013PNAS 11016736C doi 10 1073 pnas 1315570110 PMC 3801071 PMID 24082125 Joachimsk M M Buggisch W THE LATE DEVONIAN MASS EXTINCTION IMPACT OR EARTH BOUND EVENT PDF Lunar and Planetary Institute Further reading EditMiller Charles B Patricia A Miller 2012 2003 Biological Oceanography 2nd ed Oxford John Wiley amp Sons ISBN 978 1 4443 3301 5 Mook W G amp Tan F C 1991 Stable carbon isotopes in rivers and estuaries Biogeochemistry of major world rivers 42 245 264 Retrieved from https en wikipedia org w index php title D13C amp oldid 1163085007, wikipedia, wiki, book, books, library,
