[thirty] Specifically, xenon is useful for calculations of water decline after a while. Not simply could it be a noble gas (and as a consequence isn't removed from the environment by chemical reactions with other things), but comparisons involving the abundances of its 9 secure isotopes in the fashionable environment https://kevalaniru.com/best-mineral-water-for-kids-why-it-matters-more-than-you-think/