Chlorine-36: Difference between revisions
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'''Chlorine-36''' is an [[isotope of chlorine]]. [[Chlorine]] has two [[stable isotope]]s and one [[radioactive]] isotope: the cosmogenic isotope <sup>36</sup>Cl. Its half-life is 301,000 ± 2,000 years.<ref name=nndc>{{cite web |title=Interactive Chart of Nuclides |url=http://www.nndc.bnl.gov/chart/chartNuc.jsp |accessdate=15 |
'''Chlorine-36''' is an [[isotope of chlorine]]. [[Chlorine]] has two [[stable isotope]]s and one [[radioactive]] isotope: the cosmogenic isotope <sup>36</sup>Cl. Its half-life is 301,000 ± 2,000 years.<ref name=nndc>{{cite web |title=Interactive Chart of Nuclides |url=http://www.nndc.bnl.gov/chart/chartNuc.jsp |accessdate=15 Dec 2012 }}</ref> <sup>36</sup>Cl decays primarily (98%) by beta-minus decay to <sup>36</sup>[[argon|Ar]], and the balance to <sup>36</sup>[[Sulfur|S]].<ref name=nndc /> |
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Trace amounts of [[radioactive]] <sup>36</sup>Cl exist in the environment, in a ratio of about (7-10) × 10<sup>−13</sup> to 1 with stable chlorine isotopes.<ref name=Zreda>{{cite journal | author = M. Zreda ''et al.'' | year = 1991 | title = Cosmogenic chlorine-36 production rates in terrestrial rocks | journal = Earth and Planetary Science Letters | volume = 105 | pages = 94|bibcode = 1991E&PSL.105...94Z |doi = 10.1016/0012-821X(91)90123-Y }}</ref> |
Trace amounts of [[radioactive]] <sup>36</sup>Cl exist in the environment, in a ratio of about (7-10) × 10<sup>−13</sup> to 1 with stable chlorine isotopes.<ref name=Zreda>{{cite journal | author = M. Zreda ''et al.'' | year = 1991 | title = Cosmogenic chlorine-36 production rates in terrestrial rocks | journal = Earth and Planetary Science Letters | volume = 105 | pages = 94|bibcode = 1991E&PSL.105...94Z |doi = 10.1016/0012-821X(91)90123-Y }}</ref><ref>{{cite journal | author = M. Sheppard and M. Herod | year = 2012 | title = Variation in background concentrations and specific activities of 36Cl, 129I and U/Th-series radionuclides in surface waters | journal = Journal of Environmental Radioactivity | volume = 106 | pages = 27–34}}</ref> This corresponds to a concentration of approximately 1 Bq/(kg Cl). |
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<sup>36</sup>Cl is produced in the atmosphere by [[spallation]] of <sup>36</sup>[[argon|Ar]] by interactions with [[cosmic ray]] [[proton]]s. In the top meter of the lithosphere, <sup>36</sup>Cl is generated primarily by [[thermal neutron]] activation of <sup>35</sup>Cl and spallation of <sup>39</sup>[[Potassium|K]] and <sup>40</sup>[[Calcium|Ca]].<ref name=Zreda |
<sup>36</sup>Cl is produced in the atmosphere by [[spallation]] of <sup>36</sup>[[argon|Ar]] by interactions with [[cosmic ray]] [[proton]]s. In the top meter of the lithosphere, <sup>36</sup>Cl is generated primarily by [[thermal neutron]] activation of <sup>35</sup>Cl and spallation of <sup>39</sup>[[Potassium|K]] and <sup>40</sup>[[Calcium|Ca]].<ref name=Zreda /> In the subsurface environment, [[muon capture]] by <sup>40</sup>[[Calcium|Ca]] becomes more important.<ref name=Zreda /> The production rates are about 4200 atoms <sup>36</sup>Cl/yr/mole <sup>39</sup>K and 3000 atoms <sup>36</sup>Cl/yr/mole <sup>40</sup>Ca, due to spallation in rocks at sea level.<ref name=Zreda /> |
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The half-life of this nonreactive isotope makes it suitable for [[geologic dating]] in the range of 60,000 to 1 million years.<ref> |
The half-life of this nonreactive isotope makes it suitable for [[geologic dating]] in the range of 60,000 to 1 million years.<ref>{{cite web |last= |first= |date= |title=Chlorine |url=http://www.sahra.arizona.edu/programs/isotopes/chlorine.html |work=Isotopes & Hydrology |publisher= |accessdate= }}</ref> |
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Additionally, large amounts of <sup>36</sup>Cl were produced by irradiation of [[seawater]] during atmospheric detonations of [[nuclear weapon]]s between 1952 and 1958. The residence time of <sup>36</sup>Cl in the atmosphere is about 2 years. Thus, as an event marker of 1950s water in [[soil]] and [[ground water]], <sup>36</sup>Cl is also useful for dating waters less than 50 years before the present. <sup>36</sup>Cl has seen use in other areas of the geological sciences, including dating ice and sediments. |
Additionally, large amounts of <sup>36</sup>Cl were produced by irradiation of [[seawater]] during atmospheric detonations of [[nuclear weapon]]s between 1952 and 1958. The residence time of <sup>36</sup>Cl in the atmosphere is about 2 years. Thus, as an event marker of 1950s water in [[soil]] and [[ground water]], <sup>36</sup>Cl is also useful for dating waters less than 50 years before the present. <sup>36</sup>Cl has seen use in other areas of the geological sciences, including dating ice and sediments. |
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Revision as of 00:57, 14 April 2014
| General | |
|---|---|
| Symbol | 36Cl |
| Names | chlorine-36, 36Cl, Cl-36 |
| Protons (Z) | 17 |
| Neutrons (N) | 19 |
| Nuclide data | |
| Natural abundance | 7 × 10-13 |
| Half-life (t1/2) | 301,000 |
| Isotopes of chlorine Complete table of nuclides | |
Chlorine-36 is an isotope of chlorine. Chlorine has two stable isotopes and one radioactive isotope: the cosmogenic isotope 36Cl. Its half-life is 301,000 ± 2,000 years.[1] 36Cl decays primarily (98%) by beta-minus decay to 36Ar, and the balance to 36S.[1]
Trace amounts of radioactive 36Cl exist in the environment, in a ratio of about (7-10) × 10−13 to 1 with stable chlorine isotopes.[2][3] This corresponds to a concentration of approximately 1 Bq/(kg Cl).
36Cl is produced in the atmosphere by spallation of 36Ar by interactions with cosmic ray protons. In the top meter of the lithosphere, 36Cl is generated primarily by thermal neutron activation of 35Cl and spallation of 39K and 40Ca.[2] In the subsurface environment, muon capture by 40Ca becomes more important.[2] The production rates are about 4200 atoms 36Cl/yr/mole 39K and 3000 atoms 36Cl/yr/mole 40Ca, due to spallation in rocks at sea level.[2]
The half-life of this nonreactive isotope makes it suitable for geologic dating in the range of 60,000 to 1 million years.[4]
Additionally, large amounts of 36Cl were produced by irradiation of seawater during atmospheric detonations of nuclear weapons between 1952 and 1958. The residence time of 36Cl in the atmosphere is about 2 years. Thus, as an event marker of 1950s water in soil and ground water, 36Cl is also useful for dating waters less than 50 years before the present. 36Cl has seen use in other areas of the geological sciences, including dating ice and sediments.
Decay-rate fluctuations
There have been recent reports (2010) identifying fluctuations in the detection rates from 36Cl and other isotopes.[5] At the time of writing it has not been determined if these represent genuine anomalies in the decay rate or have some more mundane explanation.
On August 14, 2012, Purdue University professor of physics Ephraim Fischbach hypothesized these decay fluctuations are tied to solar flare activity. If proven, these fluctuations could be used to predict impending solar flares hours or days in advance. E. Fischbach (2012). "New system could predict solar flares, give advance warning".
See also
References
- ^ a b "Interactive Chart of Nuclides". Retrieved 15 Dec 2012.
- ^ a b c d M. Zreda; et al. (1991). "Cosmogenic chlorine-36 production rates in terrestrial rocks". Earth and Planetary Science Letters. 105: 94. Bibcode:1991E&PSL.105...94Z. doi:10.1016/0012-821X(91)90123-Y.
{{cite journal}}: Explicit use of et al. in:|author=(help) - ^ M. Sheppard and M. Herod (2012). "Variation in background concentrations and specific activities of 36Cl, 129I and U/Th-series radionuclides in surface waters". Journal of Environmental Radioactivity. 106: 27–34.
- ^ "Chlorine". Isotopes & Hydrology.
- ^
D. Javorsek II; et al. (2010). "Power Spectrum Analyses of Nuclear Decay Rates". Astroparticle Physics. 34: 173. arXiv:1007.0924. Bibcode:2010APh....34..173J. doi:10.1016/j.astropartphys.2010.06.011.
{{cite journal}}: Explicit use of et al. in:|author=(help)