AbstractsChemistry

"Mass spectrometric analysis of the xenon isotopes in natural gas wells demonstrates that radioactive isotopes of element number 53 (I) and element number 94 (Pu) were present at the time of the Earth's formation. Evidence for the now extinct nuclide ¹²⁹I ([subscript 1/2 = 17 x 10⁶ years) was found in CO₂ -rich gas while evidence for the now extinct ²⁴⁴Pu (t[subscript 1/2] = 82 x 10⁶ years) was discovered in other natural gas wells. The amounts of ¹²⁹I in thyroids was measured by combining neutron activation analysis with noble gas mass spectrometry. The current mammalian thyroid glands contain iodine with an isotopic composition ¹²⁹I:¹²⁷I ≈ 1 x 10⁻⁸:1.0" – Abstract, page iii.