moldybluecheesecurds 2

Sunday, January 22, 2006

Earn some extra credit

I'm finishing my master's in public policy this semester, and this excerpt from a course on energy use and the environment should explain why I'm not suffering from an abudance of free time:
The relative importance of land plants (versus uptake by the ocean) is also indicated by a latitudinal gradient in the isotopic ratio of atmospheric CO2, which is fractionated by photosynthesis, but not by dissolution in seawater.

(Reproduced without permission).

5 points if you can identify the source of this obscure quote.
15 points if you can post a comment explaining what it actually means.

3 comments:

S P H said...

I'm not sure where the quote comes from, but I can make a pretty good stab at what it is saying. Here goes:

Believe it or not, the oceans are actually a MAJOR source of CO2 uptake thanks to those little critters called plankton (they change CO2 into carbonate structures, kind of like limestone rock).

Land plants also take in atmospheric CO2 through the process of photosynthesis (thank you middle school science)....but to a lesser extent than the oceans.

The degree to which plants take in CO2 also varies depending on how far from the equator you are. Lower latitudes generally house more tropical forests, and hence more plant life, and hence take in more CO2 than northern climes. The oceans, on the other hand, do not vary quite as significantly in their CO2 uptake, as plankton and other CO2 "eating" organisms are found in all of the worlds oceans.

So, both land plants and ocean dwelling organisms are important in sequestering global CO2...its just that plants are better near the equator than the poles, whereas the ocean is good anytime, anyplace.

s p h said...

Did a little research and learned more about the "latitudinal gradient in the isotopic ratio of CO2"....evidentally plants prefer C-12 over C-13, but ocean critters don't have a preference. Thus, photosynthesis from land plants imparts a noticeable change on the C-12 vs. C-13 ratio in the atmosphere from equator to poles, or over continents vs the seas.

Not only that, but you can track differences in the oxygen isotopes (O-16 verses O-18) to get an idea of how much oxygen is being transferred from CO2 to H2O in plants (during CO2 uptake in photosynthesis and H2O release in leaf evaporation). It seems that forest plants prefer O-18 over plains plants (at least in Brazil).

Info summarized from:
www.igac.noaa.gov/newsletter/16/co2.php
www.esajournals.org/.../?request=get-document&issn=1051-0761&volume=015&issue=01&page=0058

jff said...

For extraordinary effort in research and explanatory phrases, I award s p h a full 20 points! Go Gryffindor!