78.238.249.83: /* References */

2014-08-16T04:52:58Z

References

en>Svvenkatakrishnan at 22:19, 19 January 2014

2014-01-19T22:19:30Z

← Older revision		Revision as of 00:19, 20 January 2014
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	~~Crop Farmers~~ ~~Miguel Furguson from Alma~~, ~~really loves reading, yeast infection no more~~ and ~~diecast collectibles~~. ~~Did~~ a ~~cruise ship experience that was comprised~~ of ~~passing~~ by ~~Konso Cultural Landscape~~.<br><br>~~Feel free~~ to ~~visit my homepage~~ - ~~what causes yeast infection~~ in ~~esophagus~~ (~~[http~~://~~www~~.~~yeastinfectionnomoresystem~~.~~info~~/~~what~~-~~causes~~-~~yeast~~-~~infections~~/ ~~http~~://~~www~~.~~yeastinfectionnomoresystem~~.~~info~~/~~what~~-~~causes~~-~~yeast~~-~~infections~~/])		{{Infobox isotope

			\| alternate_names =
			\| symbol =C
			\| mass_number =13
			\| mass = 13.00335
			\| num_neutrons =7
			\| num_protons =6
			\| abundance =1.109%
			\| halflife =
			\| error_halflife =
			\| background =#F99
			\| text_color =
			\| image =
			\| decay_product =
			\| decay_symbol =
			\| decay_mass =
			\| decay_mode1 =
			\| decay_energy1 =
			\| decay_mode2 =
			\| decay_energy2 =
			\| decay_mode3 =
			\| decay_energy3 =
			\| decay_mode4 =
			\| decay_energy4 =
			\| parent =
			\| parent_symbol =
			\| parent_mass =
			\| parent_decay =
			\| parent2 =
			\| parent2_symbol =
			\| parent2_mass =
			\| parent2_decay =
			\| spin = −½
			\| excess_energy =
			\| error1 =
			\| binding_energy =
			\| error2 =

			}}'''Carbon-13''' ('''<sup>13</sup>C''') is a natural, [[Stable isotope\|stable]] [[isotopes of carbon\|isotope]] of [[carbon]] and one of the [[environmental isotopes]]. It makes up about 1.1% of all natural carbon on [[Earth]].<ref>[http://periodic.lanl.gov/6.shtml Carbon]</ref>

			== Detection by mass spectrometry ==
			A [[mass spectrum]] of an organic compound will usually contain a small peak of one mass unit greater than the apparent molecular ion peak (M). This is known as the M+1 peak and originates due to the presence of <sup>13</sup>C atoms. A molecule containing one carbon atom will be expected to have an M+1 peak of approximately 1.1% of the size of the M peak as 1.1% of the carbon atoms will be <sup>13</sup>C rather than [[carbon-12\|<sup>12</sup>C]]. Similarly a molecule containing two carbon atoms will be expected to have an M+1 peak of approximately 2.2% of the size of the M peak,{{citation needed\|date=February 2013}} as there is double the previous likelihood that a molecule will contain a <sup>13</sup>C atom.

			In the above the mathematics and chemistry have been simplified, however it can be used effectively to give the number of carbon atoms for small to medium sized organic molecules. In the following formula the result should be rounded to the nearest [[integer]]:

			<math>C = \frac{100Y}{1.1X}</math>

			''C'' = number of C atoms ''X'' = [[amplitude]] of the M ion peak ''Y'' = amplitude of the M+1 ion peak

			<sup>13</sup>C-enriched compounds are used in the research of metabolic processes by means of mass spectrometry. Such compounds are safe because they are non-radioactive. In addition, <sup>13</sup>C is used to quantify proteins (quantitative [[proteomics]]). One important application is in "Stable isotope labeling with amino acids in cell culture" ([[SILAC]]). <sup>13</sup>C-enriched compounds are used in medical diagnostic tests such as the [[Urea breath test]]. Analysis in these tests is usually of the ratio of 13-C to 12-C by [[Isotope ratio mass spectrometry]]

			The ratio of <sup>13</sup>C to <sup>12</sup>C is slightly higher in plants employing [[C4 carbon fixation]] than in plants employing [[C3 carbon fixation]]. Because the different isotope ratios for the two kinds of plants propagate through the food chain, it is possible to determine if the principal diet of a human or other animal consists primarily of C3 plants or C4 plants by measuring the [[isotopic signature]] of their collagen and other tissues. Deliberate increase of proportion of <sup>13</sup>C in diet is the concept of [[i-food]], a proposed way to increase [[longevity]].

			== Uses in earth science ==
			Due to differential uptake in plants as well as marine carbonates of <sup>13</sup>C, it is possible to use these isotopic signature in earth science. In aqueous geochemistry, by analyzing the [[δ13C\|δ<sup>13</sup>C]] value of surface and ground waters the source of the water can be identified. This is due to the fact that atmospheric, carbonate, and plant derived δ<sup>13</sup>C values all differ with respect to [[Δ13C#Reference standard\|Pee Dee Belemnite]] (PDB) standard.

			To calculate δ<sup>13</sup>C:

			<math>\delta ^{13}C_\text{Sample} = \left(\frac{^{13}C/^{12}C_\text{Sample}}{^{13}C/^{12}C_\mathrm{PDB}} - 1\right) \cdot 1000</math>

			The same calculation can be used to distinguish between biomass produced by C3 and C4 metabolic pathways (e.g. trees versus tropical grasses), which allows for spatiotemporal reconstruction of species and ecosystems range shifts based on the isotopic characterization of soil organic matter.<ref>SILVA L.C.R, GIORGIS M., ANAND M., ENRICO L., PÉREZ-HARGUINDEGUY N., FALCZUK V., TIESZEN L.L., CABIDO M. (2011) Evidence of shift in C4 species range in central Argentina during the Late Holocene. Plant & Soil 349: 261-279.</ref><ref>SILVA L.C.R., STERNBERG L. da S.L., HAIDAR R.F., VALE G.D. (2010) Deciphering earth mound origins in central Brazil. Plant & Soil 336: 3–14</ref><ref>SILVA L.C.R., HARIDASAN M., STERNBERG L.S.L., FRANCO A.C., HOFFMANN W.A. (2010) Not all forests are expanding into central Brazilian savannas. Plant & Soil 333: 431-443.</ref><ref>SILVA L.C.R., ANAND M. (2011) Mechanisms of Araucaria (Atlantic) forest expansion into southern Brazilian grasslands. Ecosystems 14: 1354-1371.</ref><ref>SILVA L.C.R., STERNBERG L.S.L., HARIDASAN M., HOFFMANN W.A., MIRALLES-WILHELM F., FRANCO A.C. (2008) Expansion of gallery forests into central Brazilian savannas. Global Change Biology 14:1-11.</ref>

			Within C3 plants processes regulating changes in δ<sup>13</sup>C are well understood, particularly at the leaf level,<ref>Farquhar, G.D., Ehleringer, J.R. & Hubick, K.T. (1989) Carbon isotope discrimination and photosynthesis. Annual Review of Plant Physiology and Plant Molecular Biology, 40, 503-537.</ref> but also during wood formation.<ref>McCarroll D, Loader NJ (2004) Stable isotopes in tree rings. Quaternary Science Reviews 23: 771–801 doi:10.1016/j.quascirev.2003.06.017. . doi: 10.1016/j.quascirev.2003.06.017.</ref><ref>Ewe SML, Da Silveira Lobo Sternberg L, Busch DE (1999) Water-use patterns of woody species in pineland and hammock communities of South Florida. Forest Ecology and Management 118: 139–148 doi:10.1016/S0378-1127(98)00493-9. . doi: 10.1016/S0378-1127(98)00493-9.</ref> Many recent studies combine leaf level isotopic fractionation with annual patterns of wood formation (i.e. tree ring δ<sup>13</sup>C) to quantify the impacts of climatic variations and atmospheric composition on physiological processes of individual trees and forest stands.<ref>SILVA L.C.R., ANAND M., OLIVEIRA J.M., PILLAR V.D. (2009) Past century changes in Araucaria angustifolia (Bertol.) Kuntze water use efficiency and growth in forest and grassland ecosystems of southern Brazil: implications for forest expansion. Global Change Biology 15: 2387–2396.</ref><ref>SILVA L.C.R., ANAND M. (2013) Probing for the influence of atmospheric CO2 and climate change on forest ecosystems across biomes. Global Ecology and Biogeography.DOI:10.1111/j.1466-8238.2012.00783.x</ref><ref>SILVA L.C.R., HORWATH W.R. (2013) Explaining global changes in water use efficiency: Why have we overestimated forest responses to rising atmospheric CO2? PLoS One 8(1): e53089. doi:10.1371/journal.pone.0053089</ref> The next phase of understanding, in terrestrial ecosystems at least, seems to be the combination of multiple isotopic proxies to decipher interactions between plants, soils and the atmosphere, and predict how changes in land use will affect climate change<ref>GÓMEZ-GUERRERO A., SILVA L.C.R., HORWATH W.R., BARRERA-REYES M., KISHCHUK B., VELÁZQUEZ-MARTÍNEZ A., TRINIDAD-HERNÁNDEZ T., PLASCENCIA-ESCALANTE O. (2013) Growth decline and divergent tree-ring isotopic composition (δ13C and δ18O) contradict predictions of CO2 stimulation in high altitudinal forests. Global Change Biology. DOI: 10.1111/gcb.12170</ref><ref>ROSSATTO D.R., HOFFMANN W.A., SILVA L.C.R., HARIDASAN M., STERNBERG L.S.L., FRANCO A.C. (2013) Seasonal variation in leaf traits between congeneric savanna and forest trees in Central Brazil: implications for forest expansion into savanna. Trees DOI 10.1007/s00468-013-0864-2</ref><ref>SILVA L.C.R., CORRÊA R.S., DOANE T., PEREIRA E., HORWATH W.R. (2013) Unprecedented carbon accumulation in mined soils: the synergistic effect of resource input and plant species invasion. Ecological Applications. http://dx.doi.org/10.1890/12-1957.1</ref>

			==See also==
			* [[Isotopes of carbon]]
			* [[Isotope fractionation (disambiguation)\|Isotope fractionation]]

			==Notes==
			{{reflist\|33em}}

			{{isotope\|element=carbon
			\|lighter=[[carbon-12]]
			\|heavier=[[carbon-14]]
			\|before=[[boron-13]], [[nitrogen-13]]
			\|after=stable
			}}

			[[Category:Isotopes of carbon]]
			[[Category:Geochemistry]]
			[[Category:Environmental isotopes]]

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