Background, I have come across a chemical reaction system, occurring in nature, that apparently involves the presence of dissolved organic matter (in a catalytic role).
My research returns, for example, the following as examples of DOM per an educational source:
Dissolved organic matter (DOM) consists of soluble organic materials derived from the partial decomposition of organic materials, including soil organic matter, plant residues, and soluble particles released by living organisms, including bacteria, algae, and plants.
So my question is basically other than grinding up a plant, are there other examples of dissolved organic matter that I can conveniently employ?
One idea is perhaps organic tea (which is still a bit general) as a dissolved organic colored solution.
But, possibly better (in terms of convenience and reactivity) suggestions would be appreciated.
The cited reaction, by the way, is as follows:
$\ce{ O2 + 2 .CO3- + DOM -> 2 .O2- + 2 CO2 + DOM }$
Namely, the conversion by the action of oxygen on the carbonate radical anion to the superoxide radical anion and CO2, all in the presence of DOM.