Tuesday, October 30, 2007

Places of Interest

The class I TA for is learning all about the geologic history of Western North America this week. Much like Janice Dickenson, western North America has seen a lot of action in the past and now bears the scars of its wild ways. Here are a couple of places that I find especially interesting:

The Salton Sea:

The Sea itself is nothing more than a topographic low caused by the divergent plate motion which is ripping Baja away from the continent of North America. This man-made cesspool came to be in the early 1900s when water was diverted from the Colorado River whilst engineers were building an aqueduct intended to serve agriculture in the Imperial Valley. Its creation was an accident, but the sea became a popular tourist destination in the 1920s and 30s because it is hotter than shit out there in the desert. Water fowl also love the Salton Sea and the lake was stocked with fish like Tilapia. The problem with the Salton Sea is that there is no more freshwater input so as evaporation whisks away water, all the dissolved salts and chemicals stay behind and become more concentrated. The salinity of the Sea is upwards to 40 parts per thousand (ocean water has about 35 parts per thousand). Throw in some harmful algal species and a lot of dead fish and you have a tragically disgusting situation.

Yellowstone National Park:


Yellowstone is a SUPERVOLCANO! Or Supaire Volcano. Yellowstone Park in northwestern Wyoming sits atop a large caldera that heaves and hoes up and down about 1.5 centimeters per year. This “breathing” in and out of the caldera makes me nervous, for one, but is indicative of what’s going on in the magma chamber below. As pressure increases and decreases, the land rises and falls. This will happen until the caldera explodes and obliterates everything from here to kingdom come. The good news is that eruptions are estimated to be several hundreds of thousands of years apart. We humans can blow ourselves up by then, thank you very much Yellowstone.

Willamette Valley, Oregon:

What’s so interesting about this little valley? Well, besides being a rich and bountiful place to grow agriculture, this valley was formed by the backlogging of water after the Great Missoula Floods. The Missoula Floods are floods of unimaginable proportion that roared across western North America at the end of the last glacial – about 18,000 years ago. Seriously, you can’t even imagine how crazy huge these floods were. So huge that the entire Willamette Valley served as a holding tank for water that was dumping into the Pacific Ocean via the Columbia River. Looking at the satellite image gives you some perspective of how much water that must have been. It was a lot. Like, a lot a lot.

See, places can be fun sometimes!

Wednesday, October 24, 2007

I've got a fire in my heart for you, California

Holy Jesus, friends. Your favorite Geochemist has had a fire in her heart and a fire in her backyard for the past few days, both of which appear to be all but extinguished. We will brush aside the topic of the former, but on the topic of the latter we will discuss today why the empty regions of Southern California are ablaze yet again.

If you’ve been living underground for the past week, you’ve missed the pseudo Apocalypse that has born down upon Southern California. FIRE SEASON. I grew up in Southern California and can remember years and years of yellow skies and soot dust and chapped lips and sneezing. Fire Season coincides with the appearance of the Santa Ana Winds, also known as The Winds That Drive Everybody Apeshit.

The picture above is a super-great illustration of how the Santa Anas form. We get a region of high air pressure building up in the Great Basin between the Sierra Nevadas and the Rocky Mountains. This air escapes the Great Basin via the Mohave Desert and continues on toward the ocean, following topographic lows like canyons and valleys (I’m looking at you, Los Angeles). The air is heated by adiabatic compression.

Adiabatic compression means that when you squeeze something, it heats up. You should be somewhat familiar with this if you’ve ever pumped up a bike or car tire. Even though you’re not heating the tire directly, pressurizing the gas inside increases the tire’s temperature. The diagram above illustrates this point with a Pressure vs. Volume plot which includes two isotherms (or lines of constant temperature). Any point that lives on an isotherm has the same temperature even if it has a different pressure and volume than a neighboring point. Adiabatic change means that you’re going to jump from one isotherm to another by changing your volume or pressure. Increase in volume and you decrease the pressure, so you’ll jump to a lower isotherm (cooling). Decrease the volume and you’ll increase the pressure, in which case you’ll move up to a higher isotherm (heating).

That’s why the Santa Ana Winds are so gosh darn hot and dry. Until next time, keep safe out there, gang.

Friday, October 12, 2007

Again with the Iron

Let's continue with our look at dissolved iron in the oceans, shall we?

You might be asking, “Wait a minute, lady. If phytoplankton are so great and iron in the ocean is so scarce, why don’t those phytoplankton evolve already and use something else that is more abundant? Like, Magnesium, or whatever.” Good point. Iron availability in the oceans is down around the part per billion concentrations, so why do organisms still use it? The answer is that iron is such a great electron acceptor, phytoplankton make due with the little that is around. The whole subject of electron donors and acceptors and how biology makes use them gets a little complicated. It deals with things like enzymes and biochemical pathways and other biological topics I don’t really understand. Biologists understand these things, so touché Biologists. You’ve bested me at understanding chemosynthesis, but I’ll smoke you when it comes to Eulerian and Lagrangian water transport.

Iron comes in two flavors: Ferrous and Ferric. Ferrous iron (Fe+2) is soluble, meaning that it will hang out in the ocean until some little critter or phytoplankton snatches it up. Ferric iron (Fe+3) is insoluble, meaning that it will form a molecule with something else (usually oxygen) and “precipitate” out of solution. Ferric iron is pretty much useless to phytoplankton. They are beggars AND choosers in this game.

Up until about 2 billion years ago, the Earth’s oceans were anoxic (lacking oxygen). Ferrous iron was super abundant in the Earth’s early ocean because there was no oxygen around that would oxidize it. All of the little algae and cyanobacteria and whatever else that was evolving prior to 2 billion years ago loved having all this Ferrous iron around, they were in hog heaven! That is, until photosynthesis showed up. Photosynthesis ruined the Ferrous iron party by pumping the atmosphere full of free oxygen. Atmospheric oxygen ended up in the oceans by way of air-sea gas exchange and all that lovely, useful Ferrous iron was oxidized to Ferric iron. It precipitated out of the Earth’s oceans and created something that geologists know as “Banded Iron Formations”These formations can be found in places like Australia. The bands are layers of iron oxides (rust!) that sank all the way down to the seafloor as photosynthesizers oxidized the Earth’s atmosphere all those billions of years ago. So on the one hand we can thank those prehistoric photosynthesizers for filling our atmosphere with oxygen, but on the other hand they kinda shot themselves in the proverbial foot by creating a world where Ferrous iron is in short supply.

But, like I said, iron is so great at what is does that biology makes due with what little is around. Biologists even have a term for the overindulgence of iron by phytoplankton – it’s called “luxury” uptake. Luxury, not in the sense of a Diatom relaxing on the tiniest chez lounge you can imagine, but in the respect that it will take up more iron than it needs and store it for later use. Whenever I hear the term "luxury uptake" I can only think about obese single celled organisms wearing monocles and driving Rolls Royces. Luxury, ha ha.

Tuesday, October 9, 2007

Iron, man

I have to read a lot of science papers. Science papers are not fun to read because they are confusing. They don’t have to be confusing, but unfortunately most of them turn out that way. This is something I have a beef with. I want to know what these science papers are saying, I want to know what your models do or what your data shows, but I can’t do that when you don’t paint a clear picture for me. I could go on and on about my hang-ups with this topic, but instead I would like to describe to you a science paper in my own words. Today, we take a look at a paper by Boyd, et al. that was published in 2007 in Science, titled: “Mesoscale Iron Enrichment Experiments 1993 – 2005: Synthesis and Future Directions”. I think by doing this, I will digest this paper a little bit better and you’ll get to find out some interesting things pertaining to the field of oceanic iron research.

So what’s the deal with iron anyways? Well, phytoplanktons in the ocean need iron just like you and I. They become wimpy and anemic without iron just like we would. This is a big, BIG topic right now seeing as we (humans) would very much like to increase the amount of primary production in the oceans. Primary production, that is to say photosynthesis, is one way that we might save our asses from the looming Greenhouse Apocalypse because plants remove CO2 from the atmosphere and turn it into oxygen. Yay plants!

The ocean is FILLED with plants in the form of phytoplankton. The problem is that phytoplankton don’t grow everywhere, they can only grow in places that have the nutrients they need. Nutrients like nitrate, phosphate, silica. There are a couple places on Earth where it seems like conditions are perfect for phytoplankton growth, but nothing is going on. These places are called High Nutrient Low Productivity zones or HNLP zones. The Southern Ocean is a HNLP zone.
Conditions should be perfect for primary production in the Southern Ocean. Lots of cold water, lots of nutrients, plenty of mixing, and sunlight for part of the year. Problem is those phytoplanktons don’t grow there. Why?

A guy by the name of John Martin proposed that phytoplankton don’t grow in these regions because they are limited by iron. I should take this opportunity to say that iron is a really, really, REALLY hard thing to measure in the oceans because you so many possibilities for contamination. It took years for researchers to figure out why their iron numbers looked so wonky. The problem is that iron is everywhere – your boat, your collection devices, your bottles, your cables, your hands…you yourselves are a tremendous source of iron. When you’re measuring iron in parts per billion concentrations, every little bit counts. This problem was somewhat remedied by instituting clean rooms and anal-retentive practices that would limit the amount of iron contamination. But nothing is perfect.

Anywho, John Martin and those folks lucky enough to work with him set sail for the Southern Ocean armed with tons and tons of iron sulfate that they intended to dump in the water and see what might happen. What happened was exactly what he predicted – phytoplankton went apeshit. They grew like crazy and their bloom lasted for weeks. The picture below is a satellite image of chlorophyll (an indicator of phytoplankton) in the region where the ship dumped its load. You can see that the bloom pretty much follows the ship tracks.

(image from http://www.csa.com/discoveryguides/oceangard/images/soiree.jpg)

Is the story over? Fuck no, but I have to get back to work. Tune in on Friday for more on John Martin and oceanic iron fertilization…

PS: This article has a pretty cool description of John Martin and his research. Check him out. He was a cool dude who unfortunately passed away in 1993 right as his work was coming to fruition.

Friday, October 5, 2007

This abstract really needs to lighten up

I wish all scientific writing was as easy as these little discussions that we have here at Get Your Science On. It would be wonderful if I was allowed send off papers to Science and Nature in the format of a casual conversation amongst friends. I do not, however, believe that Science or Nature would appreciate jokes about poop and masturbation peppered in to serious data analysis. They really don’t know what they’re missing.

My advisor surprised me this week by telling me I “should really” submit an abstract for this conference dealio in early March 2008. Something I’ve learned over the past 2 years is that when an advisor says “ You should really ______”, it means “You have to _______” in advisor-speak. Advisor-speak is a dialect that spans all human languages and is only understood by graduate students. It takes time and patience to understand this dialect and by the time you fully comprehend its subtleties, you’re done with grad school. Anyways, the conference is for the American Society of Limnology and Oceanography – ASLO for short. ASLO is a nice conference for oceanographers because you get to see colleagues from around the nation and check in on what fun and interesting things your buddies are up to. The only catch is that it’s being held in Orlando. ORLANDO, FLORIDA. Blech. My family and I went to Orlando once when I was young and did all the requisite Disneyworld business. I can’t say I remember much about it, but my grown-up opinion of Orlando is not a good one.

My abstract was submitted in time (a whole 4 hours before the cutoff time!), I paid my registration fee, so I guess I’m in it to win it. I thought I’d give you all a sneak peek at what it’s like to write a real scientific abstract. Here you go!


TITLE: Where does high Si originate in Cascadia Basin?

Deep waters in Cascadia Basin have silicic acid concentrations that may exceed 200 uM and show progressive enrichment northward, from the 180 uM in water entering at the southern end. The two possible sources of silicic acid in the deep ocean are (1) dissolution of biogenic opal in seafloor sediments and (2) hydrothermal seeps. These sources have different germanium to silica ratios and δ30Si values. Ge/Si ~ 0.7 umol/mole and δ30Si > +0.9‰ for biogenic sources. Hydrothermal sources have Ge/Si of 11-35 umol/mole and δ30Si ~ - 0.3‰. Core incubations determined the average silicic acid flux from seafloor sediments is 0.81 ± 0.05 umol m-2 day-1 and benthic flux is characterized by a mean Ge/Si of 0.6 – 0.7 umol/mole. The observed values in deep waters (>2500m) indicated inputs with Ge:Si ratios of 0.7 umol/mole and δ30Si of +1.4‰ (similar to that measured for sedimentary diatoms and more enriched than other deep Pacific and hydrothermal waters). These results indicate that opal dissolution must be the dominant source of silicic acid added to Cascadia Basin.


Droll, huh? Nary a fart joke to be had.