Wednesday, September 5, 2007


I have lots of things to do lately. New classes to take and teach, bright young minds to nurture with science, and thinking up new and creative ways to put off what I should really be doing. I’m taking a class called “Advanced Biological Oceanography”. Let’s break that down: Advanced – ruh roe. Biological – haven’t taken biology in years (poop sandwich). Oceanography – THIS I got nailed. We’re lookin’ at 1 outta 3. Part of this class is answering a few questions given to us in lecture. We got 3 questions last week:

1.) Why are the chemical properties of water (H2O) different than hydrogen sulfide (H2S)?
2.) How long has the chemical composition of the oceans remained constant? What is the evidence?
3.) How long has the pH of the ocean remained constant? What is the evidence?

Now, I’ll admit that I barely know earth history. I have only absorbed enough to nod at all the right times because I’ve been in close quarters with geologists for the last 2 years, and believe me when I say that close quarters with geologists can get a little rank. The poor microbiologists in this class couldn’t possibly know where to begin, bless their hearts. Can’t say I’m in much better shape, but I guess all I can do is my best. Let’s tackle one of these questions right now, shall we?

#3. Trick question. The pH of the oceans is currently changing due to uptake of CO2. The ocean is an enormous sink for CO2 on the surface of the Earth, taking up approximately 1/3 of anthropogenic (man-made) CO2 (1). As the ocean takes up this CO2, a series of reactions takes place starting with the production of carbonic acid (H2CO3), then bicarbonate (HCO3), then carbonate (CO3). Each reaction frees up a hydrogen ion:

CO2 (g) + H20 (l) <--> H2CO3
H2CO3 <--> H + HCO3
HCO3 <--> H + CO3

The more free hydrogen ions we have floating around, the lower the pH of our oceans. Remember that lower pH means more acidic. The evidence that the pH of the oceans is changing can be gathered from field measurements or by monitoring oceanic calcifiers. As the ocean becomes less alkaline, there is less of the carbonate ion around for these plants and critters to use to make shells and/or skeletons. Bad news for corals.

Well, that’s one down, two to go. Maybe Advanced Biological Oceanography won’t be that bad*.

1: Orr, J. C. et al. (2005). Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437, 681-686.
*Or it will be soul-crushingly hard.

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