And now for Box Models!

I’ve been set to the task of constructing a box model for my silica work in the North Pacific. A box model starts by thinking of your system as a 3 dimensional box, hence box model. Then you start adding up all the ways silica can enter your box and subtract from that all the ways silica can exit your box. Assuming that your box is in steady state (i.e.: there’s no tremendous buildup of silica in the box) then everything coming in has to equal everything going out. Simple, right?

Here’s my box model:Things going in = things going out. Now we get to apply numbers to this model and this is where I’m boned. The difference between choosing a number like 190 or 195 is a big deal in these calculations and to choose the right number means choosing the number my advisor can live with. I would storm on ahead and finish this already if only I knew that I wouldn’t have to do all this work over again once we decide that 192 is a more appropriate number than 193. And so, dear reader, such is the life of a graduate student. I guess we’ll have to find something else to do in the interim. Like read some science papers, but I’d rather watch baby monkey videos.

Sediments are so sedentary

Have YOU ever wondered how much sediment is dropped onto the seafloor in our world’s oceans? Have you ever wondered how it varies as you move away from the coasts? What’s that? You HAVEN’T!?? To be fair, I guess it’s not a topic one broaches on a daily basis, but today I’ve had to think a little about this question so I’ll tell you.

Sediments (i.e.: dirt, broken shells, fish poop, dead phytoplankton, and whatever else constitutes all the crap floating in the ocean) collect on the seafloor on the order of centimeters per thousands of years. That means that hardly anything makes it to the seafloor. Near the continent (land) we get a larger sedimentation rate, like a few millimeters per year in areas where junk is roaring out of rivers and where productivity in the surface waters is high. But out in the big, deep Pacific you’ll find maybe 2 or 3 centimeters of sediment accumulation for ONE THOUSAND YEARS. That means when you scoop up a sediment core, you’re looking tens of thousands of years into the past.

I had this idea while sifting through mud cores on our last expedition to bag up all the mud that we didn’t need and package it so as to sell it to fancy ladies for spa treatments. Could you imagine? People would eat that shit up. All I’d have to do is use lots of words like “vital” and “nutrients” and “exclusive” and “silky”. So long NSF, hello Lancôme. Not surprisingly, it was very nice mud. My hands were very soft after working in the lab for several grueling hours. I kick myself for not actually following through with this genius scheme.

Say it like you mean it. Or say it like you want to confuse everybody.

In the interest of trying new things here at Get Your Science On!, I’d like to shorten things up a bit. I’m trying to be more concise in my life these days. So instead of having few long winded discussions, we will have several short discussions encompassing one point. I came across this sentence in a paper: “If biological fractionation effects driven by secular changes in siliceous production and preformed silica concentrations in paleosurface waters were the cause of local changes in downcore Ge/Si_opal, then there must also be spatial gradients in Ge/Si_opal across paleoproductivity gradients in today’s Southern Ocean and across those inferred for the glacial ocean.”

I WANT TO KNOW WHAT THIS SENTENCE SAYS!

“If biological fractionation effects driven by secular changes in siliceous production and preformed silica concentrations in paleosurface waters”

Translation: If little phytoplanktons that lived in the oceans way way back when liked to take up more or less germanium (see: "Bizzy Bee" in the May section) because of the abundance or lack of silica in those ancient oceans…

“were the cause of local changes in downcore Ge/Si_opal”

Translation: and those phytoplanktons mucked up what we’re seeing in THIS mud core.

“then there must also be spatial gradients in Ge/Si_opal across paleoproductivity gradients”

Translation: then we must be able to find this mucking up in other places

“in today’s Southern Ocean and across those inferred for the glacial ocean”

Translation: like in the Southern Ocean today or someplace a lot like it.

You see what I have to contend with? That was just one sentence out of a 10 page paper filled with sentences just like it. It's enough to throw your hands up in the air in exhaustion.

Dear Get Your Science On,

I’m writing this to tell you something I should have told you about a long time ago. I’ve been cheating on you. I’ve been cheating on you with a Sketch Class offered by the Upright Citizens Brigade Theater. Wait! Before you turn your back on me, let me explain.

It started a few months ago. You are I were doing good together, but face it, we had become routine. I write you Tuesdays and Fridays, and you…well, you’re a blog so you don’t do much of anything. I’ll admit that my typing fingers longed for another challenge even as we discussed isotopes and iron fertilization and earthquakes and I just wanted something more. Then along came Sketch Writing Class. Sexy, time-consuming, Sketch Class. I thought to myself, “I’ve never been with a Sketch Class before. I wonder if it’s like how everyone says it’s like”. I couldn’t resist the allure of something so different, so non-scientific. I enrolled. I enrolled, but I immediately regretted my decision! My humor doesn’t translate well to a 3 page sketch. I don’t care about “the game” or “buttons”. I don’t want to sit around a table and spend 3 hours listening to other people’s sketches, especially when there’s nobody cute to look at. But the saddest part is that all my sketches were about science and nerds and field trips. I couldn’t escape you. The whole time I was with Sketch Class, I was thinking about you.

I’m so sorry, Get Your Science On!!! How could I ever betray you? I don’t want to be with Sketch Class anymore, I want to be with you. Let’s go back to the way things were, huh? Just forget about all this nonsense and go somewhere nice. Take a vacation together. Please, just take me back and I promise things will be how they were before I met Sketch Class.

I miss you.
Love always,
Tabitha

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:

ref

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!

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.

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.