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Radioisotopes in corals can be used to date fossil corals and as ocean circulation tracers.

==Dating of corals==

Dating of fossil corals has been done using radioisotopes incorporated within the skeleton at the time of accretion (e.g., 14C, 228Ra, 210Pb) and those who have grown in since the time of accretion (e.g., 230Th, 231Pa) <ref name="druffel1997">Druffel, E. R. M. (1997). Geochemistry of corals: Proxies of past ocean chemistry, ocean circulation, and climate. Proceeding of the National Academy of Sciences, 94, 8354-8361. </ref>.

Edwards et al. (1986/87) <ref>Edwards, R. L., Chen, J. H., & Wasserburg, G. J. (1986/87). 238U-234U-230Th-232Th systematics and the precise measurement of time over the past 500,000 years. Earth and Planetary Science Letters, 81, 175-192. </ref> revolutionized dating of fossil corals when they developed techniques for measuring 230Th by using isotope dilution thermal ionization mass spectrometry ([https://en.wikipedia.org/wiki/Thermal_ionization_mass_spectrometry TIMS]). This method allows to make the measurement on a small amount of material (from tens to 250mg of coral) and reduces the uncertainty on the age estimates compared with the previously used alpha-spectrometry methods. Errors associated with 230Th age determination are generally less than 1% for samples that are 100 to 200,000 year old <ref>Gagan, M. K., Ayliffe, L. K., Beck, J. W., Cole, J. E., Druffel, E. R. M., Dunbar, R. B., & Schrag, D. P. (2000). New views of tropical paleoclimates from corals. Quaternary Science Reviews, 19(1-5), 45-64. doi:10.1016/S0277-3791(99)00054-2</ref>. [[Density Banding in Coral | Density bands]] can then be used to obtain annual time control on this "floating" chronologies.

==Oceanic Tracers==

===14C===

[https://en.wikipedia.org/wiki/Hermatypic_coral Hermatypic Corals] growing in the upper 40m of the temperate and tropical oceans (32°N to 32°S) record the input and spatial distribution of 14C in the oceans. These records provided evidence of past changes in surface-subsurface mixing <ref>Nozaki, Y., Rye, D. M., Turekian, K. K., & Dodge, R. E. (1978). 13C and 14C variations in a Bermuda coral. Geophysical Research Letters, 5, 825-828.</ref><ref>Druffel, E. R. M. (1989). Decade time scale variability of ventilation in the North Atlantic determined from high precision measurements of bomb radiocarbon in banded corals. Journal of Geophysical Research, 94, 3271-3285. </ref><ref>Druffel, E. R. M. (1997). Pulses of rapid ventilation in the north Atlantic surface ocean during the past century. Science, 275, 1454-1457.</ref>, major current shifts <ref>Druffel, E. R. M., & Griffin, S. (1993). Large variations of surface ocean radioacarbon: evidence of circulation changes in the southwestern Pacific. Journal of Geophysical Research, 98, 20249-20259.</ref>, and changed in thermocline depth <ref>Guilderson, T. P., & Schrag, D. P. (1998). Abrupt shift in subsurface temperatures in the tropical Pacific associated with recent changed in El Niño. Science, 281, 240-243.</ref>.

'''References'''

Radioisotopes in Corals - Revision history

Khider: Create a stub for radioisotopes in corals