4 ms·
> On Earth, life preferentially uses 12C over the heavier 13C, bioaccumulating it, so we observe significantly more 12C than 13C in ancient rocks where life gre
by thatcherc 5y ago
> On Earth, life preferentially uses 12C over the heavier 13C, bioaccumulating it, so we observe significantly more 12C than 13C in ancient rocks where life grew.
If (like me) you're wondering why life prefers to use carbon-12 over carbon-13, it appears to be because carbon-12 is simple lighter and thus more likely to diffuse into an organism:
From [1]: Due to differential uptake in plants as well as marine carbonates of 13C, it is possible to use these isotopic signatures in earth science. Biological processes preferentially take up the lower mass isotope through kinetic fractionation.
NOAA has a bit more detail on the diffusion of carbon isotopes into organism [2].
[1] - https://en.wikipedia.org/wiki/Carbon-13#Uses_in_science https://en.wikipedia.org/wiki/Carbon-13#Uses_in_science
[2] - https://gml.noaa.gov/outreach/isotopes/stable.html https://gml.noaa.gov/outreach/isotopes/stable.html
- nousermane 5y agoFrom [1] above: > atmospheric, [marine] carbonate, and plant derived δ13C values all differ. So, there is a mineral process that can explain change in isotope ratio, which requires water. And also a biological process with the same outcome, also requiring water. In other words, this looks like a solid new piece of evidence in support of presence of liquid water on Mars in the past. Evidence of life though? That is less certain.