DOC Reactivity & Age Flashcards
How does Age of DOC correspond to its Reactivity/Lability
The older the DOC is, the less reactive/labels it is.
Labile DOC - Youngest
Semi-Labile DOC- Younger/Average
Refractory DOC - Oldest
How does the Change in Radiocarbon Concentration correspond to Age of DOC?
Concentration of Radiocarbon corresponds to concentration of DOC.
If Change in Radiocarbon concentration is greater, DOC is older.
If Change in Radiocarbon concentration is smaller, DOC is younger.
We can also use the half-life (the age the concentration of Radiocarbon is half its original concentration), which is 5740 years old, to age DOC as well.
DOC Age & Ocean Age
DOC Age is not equal to age of water
What is the Difference in DOC Aging and Ocean Circulation?
High Ocean Circulation makes for more younger DOC, therefore, less difference in DOC concentrations by depth. (Atlantic) There is a greater concentration of younger DOC.
Low Ocean Circulation makes for older DOC (more time for DOC to decay) so there is a greater difference in DOC concentrations by depth. (Pacific)
Hypothesis for DOC Age Conundrum. (Why majority of DOC measured is Very Old)
- The stability of DOC is due to resistant molecular structures (polycyclic aromatic compounds are associated with high radiocarbon ages)
- DOC decomposition is limited by availability of essential resources. (seen in accumulation of labile DOC in Black Sea)
What makes types of Carbon more reactive versus less reactive?
Reactivity is determined by how easy and beneficial DOC can be for organisms to break down/use. More organic carbon (like macromolecules) are more likely to be recognized and used, making it more reactive.
