CG: n
CT: Carbon is the main element of all biological processes. Natural carbon consists predominantly of the stable isotope 12C. The isotopes 10C and 11C have half-lives, 19 s and 20.5 min, respectively, and half-life of 14C is 5730 years. At its decay, 14C emits only beta particles with the maximum energy of 154 keV. The isotope 14C is widely used in radiocarbon dating.
Carbon-14 is generated in the atmosphere on interaction of cosmic rays with atmospheric nitrogen and is rapidly oxidized to a state of 14CO2. As a result, an equilibrium concentration is established. In preindustrial period, the concentration ratio 14C/12C was equal to 1.2·10−12. This concentration ratio characterizes organisms that consume carbon dioxide during perspiration. When the organism dies, the carbon exchange stops, new portions of 14C do not come, and it just decays. Subsequently, the concentration ratio falls. By measuring the residual concentration of 14C, one can calculate when the organism is dead. Carbon is one of the main elements of which almost all body molecules are built. Therefore radionuclide is distributed to tissues and organs in accordance with the fraction of carbon; it participates in metabolic processes and is excreted from the body.
The major way by which 14C enters the body is food of plant and animal origin, as radiocarbon accumulates in plants. Radioactive carbon, accumulated in soft tissues and fat, has a biological half-life of approximately 12 days, which is markedly longer deposited in bones. 14C is a pure beta emitter. Beta decay particles are completely absorbed in the body, so the dose load can be estimated either by calculation or also as for tritium by measuring the radionuclide content in the liquid phase of the body’s secretions, i.e., in the condensate of water vapor from the exhaled air and in the urine. At present, a certain equilibrium concentration of radiocarbon in organic objects and in the human body, in particular, has been established.
The average equilibrium activity of 14C in the body is 3–4 kBq, which results in about 10 μSv/year. Atmospheric nuclear weapon tests in the 1950s and 1960s led to a rapid increase in the concentration of 14C. In 1963, the concentration of atmospheric 14C exceeded preatomic era by about twofold. After the ban of nuclear tests in the atmosphere, 14C content began to decline and now it is approaching the preatomic time.
S: SDir – https://www.sciencedirect.com/topics/physics-and-astronomy/carbon-14 (last access: 20 January 2025)
N: 1. – carbon (n): non-metallic element occurring naturally as diamond, graphite, or charcoal, 1789, coined 1787 in French by Lavoisier as charbone, from Latin carbonem (nominative carbo) “a coal, glowing coal; charcoal,” from PIE root ker- (3) “heat, fire.”
Carbon 14, the long-lived radioactive isotope used in dating organic deposits, is from 1936. Carbon-dating (using carbon 14) is recorded from 1958. Carbon cycle is attested from 1912; carbon footprint was in use by 2001. Carbon-paper “paper faced with carbon, used between two sheets for reproduction on the lower of what is drawn or written on the upper” is from 1855, earlier it was carbonic paper (1850).
– 14 (adj): isotope of mass number 14 eight neutrons and six protons.
2. A naturally occurring radioisotope of carbon having a mass number of 14 and half-life of 5780 years; used in radiocarbon dating and in the elucidation of the metabolic path of carbon in photosynthesis.
3. Carbon-14, the longest-lived radioactive isotope of carbon, whose decay allows the accurate dating of archaeological artifacts. The carbon-14 nucleus has six protons and eight neutrons, for an atomic mass of 14. The isotope also is used as a tracer in following the course of particular carbon atoms through chemical or biological transformations.
- In carbon-14 dating, measurements of the amount of carbon-14 present in an archaeological specimen, such as a tree, are used to estimate the specimen’s age. Carbon-14 present in molecules of atmospheric carbon dioxide enters the biological carbon cycle. Green plants absorb it from the air, and it is then passed on to animals through the food chain. Carbon-14 decays slowly in a living organism, and the amount lost is continually replenished as long as the organism takes in air or food. Once the organism dies, however, it ceases to absorb carbon-14, so that the amount of the isotope in its tissues steadily decreases. Carbon-14 has a half-life of 5,730 ± 40 years (i.e., half the amount of the isotope present at any instant will undergo spontaneous disintegration during the succeeding 5,730 years).
- Because carbon-14 decays at this constant rate, an estimate of the date at which an organism died can be made by measuring the amount of its residual carbon-14. American physicist Willard F. Libby proposed the technique of carbon-14 dating in the mid-1940s and for it won the Nobel Prize for Chemistry in 1960. It has proved to be a versatile technique of dating archaeological specimens from 500 to 50,000 years old.
4. According to the Oxford English Dictionary and the Webster Third New International Dictionary of the English Language “radiocarbon” refers to any radioactive isotope of carbon and hence has a more general sense than “carbon-14”. They point out, however, that “radiocarbon” refers specifically to the carbon-14 isotope. All the other sources consulted do not make that distinction and give those terms as perfect synonyms, which, we feel, reflects the current usage.
5. Cultural Interrelation: We can highlight the novel Carbon-14: The Shroud of Turin (2017) by R. A. Williams, a suspenseful Christian story that delves into the mystery of the Shroud’s authenticity through the use of modern carbon-14 dating techniques. The title aptly references the isotope central to the plot, which is employed to scientifically date the relic.
Additionally, we can mention The Name of the Rose (1986), directed by Jean-Jacques Annaud, a thriller in which carbon-14 dating plays a pivotal role in determining the age of an ancient manuscript. Similarly, The Time Traveler’s Wife (2009), directed by Robert Schwentke, touches on concepts of time and incorporates references to carbon-14 as a scientific method for measuring temporal intervals.
S: 1. Etymonline – https://www.etymonline.com/search?q=carbon (last access: 19 January 2025); MW – https://www.merriam-webster.com/dictionary/carbon%2014 (last access: 19 January 2025). 2. TERMIUM PLUS – https://www.btb.termiumplus.gc.ca/tpv2alpha/alpha-eng.html?lang=eng&i=1&srchtxt=CARBON+14&index=ent&codom2nd_wet=1#resultrecs (last access: 19 January 2025 ). 3. EncBrit –https://www.britannica.com/science/carbon-14 (last access: 19 January 2025). 4. TERMIUM PLUS – https://www.btb.termiumplus.gc.ca/tpv2alpha/alpha-eng.html?lang=eng&i=1&srchtxt=CARBON+14&index=ent&codom2nd_wet=1#resultrecs (last access: 19 January 2025 ). 5. Amazon – https://www.amazon.com/Carbon-14-Shroud-Turin-Amari-Johnston-ebook/dp/B075R5SR4Y?utm (last access: 20 January 2025); IMDB –https://www.imdb.com/es-es/title/tt0091605/ , https://www.imdb.com/es-es/title/tt0452694/ (last access: 20 January 2025).
SYN: 14C, radioactive carbon, radiocarbon. (depending on context)
S: GDT – https://vitrinelinguistique.oqlf.gouv.qc.ca/fiche-gdt/fiche/26522383/carbone-14 (last access: 23 January 2025)
CR: carbon, carbon-14 dating, nuclear energy, radioactive contamination, radioactive decay, radioactivity.
