Carbon14 Dating

Carbondating is known as one of the most reliable and common method that isuseful for dating given its ability to date (Pearson and Hanshaw277). Many fossils currently are over one billion years old evenolder and the only technic that has been used to determine the age ofsuch objects is the carbon 14 dating method. Therefore, carbon datinghas been quite significant in the scientific world given itsapplication in several fields which include geology, hydrology,oceanography, archeology, paleoclimatology and atmospheric science.Discovered in 1949 by Frank Libby, he laid basis of his arguments onplant absorption of carbon during photosynthesis as well as someamounts of Carbon 14. Numerous scientists have used carbon-14 datingto estimate the age of organic materials. This method has been hasbeen used for over 70 years by scientists who were dating organicmaterials such as wood, skeleton, charcoal and fish and bones.Although this branch of science has existed for a long period, therehas not been clear understanding of the ideas behind the Carbon-14dating. Therefore,Carbon 14 dating remains a significant dating method for organicmaterials.

Thecarbon element occurs naturally and is in 3 nuclides which includeC12, C13 and C14. Most of the carbon atoms are C12 and this could beestimated to be around 98.89% (Libby and Frederick 4). Thus, thereis approximately 800 billion atoms for every C14 atom and theremaining is C13. Out of the 3 atoms, C12 and C13 are known to besteady (Attendorn and Bowen 11). However, C14 is radioactive withhalf-life estimated to be 5730 years (Libby and Frederick 6).Additionally, C14 is progressively composed of nitrogen-14 in theupper segment of the atmosphere. Given that carbon is an integralelement in any living organism, C14 appears in almost all the livingorganisms in the land in the same portion as it is in the atmosphere.Thus, atoms of any element have different isotopes and the isotopesare known to be atoms of the same element (Attendorn and Bowen 6).This implies that they have the same number of Protons and Electronsin the atom though with different number or composition of Neutrons.Thus, they ultimately have distinct atomic masses. Usually, normalnitrogen is converted to Carbon 14 though it is unstable elementwhich emerges as radioactive and decays over a period. All organicmaterial is made up of Carbon 14 decaying in them (Pearson andHanshaw 271). Living plants and animals are known to have exchange ingaseous breathing between oxygen and carbon thus the amount of C14 intheir systems remains constant. When plant or animal dies there is noregeneration of carbon that takes place and decaying of Carbon-14commences. In this manner, through getting the C14 amount in any bodyof an ancient plant or animal, a scientist can tell the time of deathof the examined organism. The concept of carbon dating is based onthe fact that all radioactive substances have a half-life and ifthere are certain amounts of a radioactive material, the half-life istaken as the time it takes for half of the material or substanceunder study to decay (Pearson and Hanshaw 276). In decaying,Carbon-14 decays back to nitrogen and it is the first order reactionthat occurs. Use of equations is employed to model the rate at whichthe reaction occur with time.

Rate=k[C14][C14 at t=t] = [C14 at t=0](e^-kt)

Ln[C14 at t=0] – Ln[C14 at t=t] = ktLn ([C14 at t=0] / [C14 att=t]) = kt

Toget the half-live of Carbon-14 we let [C14 at t=t] = .5[C14 at t=0]and the equation simplifies to: Ln2 = k (half-life), where k isthe rate constant from C14. Therefore,the first half-life order reaction is the same as the reaction shownin the equation and does not depend on the initial concentration.Thus a reaction known to have a large rate constant has a shorthalf-life. It is confirmed that plants acquire carbon 14 from theenvironment while animals and fungi get C14 from the tissue of plantsand animals from where they rely for food consumption (Bowen 7). Upon the demise of an organism, the uptake of C14 ceases. However,the C14 that is already in the organism continues to decay so that astime progresses less amounts of C14 remains within the organisms(Libby and Frederick 21). Upon scientifically measuring the amount ofC14 that is within the organisms or that remains in the organisms,scientists can easily tell the point in time when the organism died(Laj, Mazaud, and Duplessy 3). This is done by finding out how muchC14 was in the organism when it died and the amount that has decayed.Upon establishing the amount of C14 that has decayed, scientists caneasily tell the age of the sample under study. Most of thearcheological sites that exist have been dated using the radiocarbondating on bone, wood and even cloth samples that were found at thesite.

Thereare numerous assumptions under which radiocarbon dating operate.First, it is assumed that the material under study or being dated hasan organic foundation. Therefore, carbon dating is not applied forsubstances that are inorganic like rocks and fossils. Therefore, theapplication is limited to only items that were once alive and thencurrently are dead and such items could include bones, flesh, teethand leaves (Pearson and Hanshaw 271). Second, the organism underinvestigation or study is assumed to have got its carbon from theatmosphere. Therefore, the source of C14 is atmosphere. Third thatthe item under study has continued to acquire C14 from the time theorganism of its source or creation demised (Libby and Frederick 26).Lastly, there is enough information regarding the concentration ofC14 in the atmosphere when the organism lived and when the organismdied (Bowen 13). The last assumption is very significant than anyother of the assumptions as it helps in estimation of carbon amountavailable. Upon developing the concept of C14 dating, Frank Libbybased his assumption on the fact that C14 atmospheric amount wasconstant. After few studies and researches in the field, there werecorrective measures that were adopted to ensure that dates obtainedby C14 method tallied with the dates got through other means (Libbyand Frederick 15). Therefore, the dates that were obtained had to berevised. Such a reference that was adopted on radiometric datinglists was entire array of corrective factors for the change in amountof atmospheric C14 over time. Thus, C14 was an illustration of theimportance radiometric dating was and the challenges that arose fromthe untested assumptions. Currently, the use of Carbon dating is seenin any item that individuals want to date, thus acting as evidence toget information regarding the earth and its past occupants.

Inconclusion, the understanding of the idea behind Carbon-14 datingrequires that one gets to know the origin of carbon dating, isotopesof carbon, and the calculations of half-life as well as theassumptions underlying carbon – 14 dating. The paper has explainedeach of these facets in depth hence the understanding of the conceptsimplified. Through this, a clear picture of the carbon 14 dating hasbeen given and its wide applicability in the field of science henceits significance.

WorksCited

Attendorn,H-G., and R. N. C. Bowen. "Carbon-14 dating." Radioactiveand Stable Isotope Geology. Springer Netherlands, 1997. 244-267.

Bowen,Robert. "Carbon-14 Dating." Isotopes in the Earth Sciences.Springer Netherlands, 1994. 247-263.

Laj,C., A. Mazaud, and J. C. Duplessy. "Carbon 14 dating."(2004).

Libby,Willard F., and Frederick Johnson. Radiocarbon dating. Vol. 124.Chicago: University of Chicago Press, 1955.

Pearson,F. J., and B. B. Hanshaw. "Sources of dissolved carbonatespecies in groundwater and their effects on carbon-14 dating."Isotope hydrology 1970 (1970): 271-286.