Jabrane Labidi - methane clumped
Lina Taenzer, Ed young, Will Leavitt and others (including yours truly) just published a nice article in GCA! we show that the methane clumped isotopologue signatures of biological methane is the result of an effect coined "combinatorial effect" by others. Basically, we conventionally calculate deviations of clumped signatures with respect to a stochastic distribution. We show that is some instances, the stochastic distribution is a poor representation of the isotopic budget in a given molecule. When that happens, the stochastic abundance of doubly-substituted isotopologues is over-estimated. This causes anomously low signatures in natural samples.
This doesn't prevent interpreting the negative anomalies in CH4 clumped signatures as tracers of biogenic methane, but this yields new information on the genesis of such peculiar deficits.
Hit me up for a pdf version of the article!
or find it here: https://doi.org/10.1016/j.gca.2020.06.026