Under construction
I’ll cover –
- the occurrences/ origins of stable isotopes;
- the means of quantifying the relative amounts of stable isotopes in a sample of rock or chemical compounds – some workhorses, some remarkable machines;
- how they differentially affect rates of chemical reactions (heavier isotopes make a molecule slower to react because their quantum-mechanical ground states lie lower in energy to begin the reaction) – that’s the kinetic isotope effect;
- how they differentially affect the proportion of molecules with light or heavy isotopes – that’s the equilibrium isotope effect;
- the evidence that isotopic ratios present for the reactions or transport processes through which the chemical compounds have gone- e.g., the discrimination against heavy carbon-13 in photosynthesis is the primary cause for its markedly lower content in “C3” plants (wheat, rice) than in “C4” plants (maize or corn)… or the temperature at which rain and snow over broad regions of Earth formed to be stored as icecaps;
- deliberately added stable isotopes make very useful, safe tracers for the transport and reactions of compounds – as in tracing the various fates of added nitrogen fertilizers (uptake by plants, uptake by soil microbes, loss as gaseous N2O)