Well the process of decomposition is not only performed by beetles and worms, 
It is mostly the breaking down of chemical bonds and the activities of microorganisms, 
and their digestion process is enzyme based, with a number of various biochemical 
processes. And as it is, the lighter isotopes form weaker chemical bounds than heavier 
ones. Ergo the compounds with the heavier isotopes are more stable and it takes more 
energy to break them down and consequently the breaking down of the compounds with 
heavier isotopes occurs in a lower rate than for the compounds of with the light elements. 
Therefore you get "heavier" the more you decay.

The term     "Rayleigh decomposition"    fits pretty well.... 

Actually a topic to include in a lecture, especially in the context of soil processes 
it could make it easier for the students to remember 

Rolf



On 26 Jul 2007, at 22:11, Mihali A. Felipe wrote:

On Thu, 26 Jul 2007, Siegwolf Rolf wrote:

you become increasingly "heavier" until there is nothing left of you,
sounds paradoxical doesn't it?

Rolf

Yes it does.

It's difficult to imagine why the bugs eating you will have a preference for your light isotopes though.


- Mihali

----
.  Mihali A. Felipe
.  Gerstein Lab : Bioinformatics
.  Yale University Molecular Biophysics and Biochemistry
.  203-432-6337

__________________________________
Dr. Rolf Siegwolf
Lab for Atmospheric Chemistry
Stable Isotopes and Ecosystem Fluxes
Paul Scherrer Institut CH-5232 Villigen PSI
Switzerland

e-mail: [log in to unmask]
Phone: +41 56 310 2786
Fax     : +41 56 310 4525

Website:
http://isotope.web.psi.ch
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