Delta values are how we report the relative amounts of the different isotopes of a single element. For example δ13C (said delta-thirteen-see) provides a measure of the relative amounts of carbon-13 and carbon-12 in a material.
The “delta notation” or delta value used in stable isotope geochemistry is often confusing, especially to people outside of the science trying to understand our work. It’s confusing because these delta values are reported in “permil” (‰) which is often interpreted as a concentration like percent (%). But the permil in the delta notation is not a concentration at all, which becomes a little more clear when we realize that delta values can be negative, but concentrations cannot. (You can’t buy lemonade that -15% lemon juice!) Continue reading “D is for Delta #AtoZChallenge”