[dopkew]

Could you please explain what is "isotopic composition" and "isotopic profile"? Or give some links to read up on?

[maxerickson]

They mean the atomic structure of the atoms in the molecules:

https://en.wikipedia.org/wiki/Isotope

Not sure what biological processes are sensitive to that though.

[yomly]

Here is a review of some of the studies going into the isotopic chemistry of living organisms:

https://www.omicsonline.org/open-access/biogenic-chemical-el...