Wednesday, December 5, 2007
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.
Thursday, November 15, 2007
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.
Tuesday, October 30, 2007
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
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
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
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
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.
Friday, September 28, 2007
It would be fair to mention that I DO know some of these Eras and Periods. I know that the Cambrian was the time where all sorts of life appeared on our planet. The Cambrian Explosion was the explosion (!) of life in a very anticlimactic way. It was during this time that we find lots of fossil evidence of worms and sea-bugs and sponges and even more worms, but this time with teeth. Earth sounds like a pretty gross place back in the Cambrian, right?
So the Cambrian explosion occurred around 544 million years ago and I’m going to ignore (for now) the times before the Cambrian which are the Proterozoic, Archean, and Hadean. These 3 are Eras when the Earth was juuust forming. Most Paleontologists ignore these times in Earth history because it’s really really hard to find shit that’s 2-3 billion years old. The life that did exist were things like algae, bacteria, single celled organisms, viruses, and so on. Borrrring.
Moving on, the Cambrian/Precambrian boundary was around 544 million years ago, and then the next exciting thing was the Permian/Triassic boundary which was about 248 million years ago. An aside here: Paleontologists have a pretty clever way of defining the boundary between eras and periods. What they do is look at some sedimentary rock formation that’s got fossils in it, start at the bottom of the formation (where the oldest fossils live), work their way up to the top of the formation (where the youngest fossils live), and wherever older fossilized critters disappear they go “Aha! There must have been some cataclysmic event around this time that wiped out most life on Earth and allowed all these new critters to take over!” I don’t exactly know where they get the numbers from – must be by age dating rocks within the formation using some radioactive isotope. Reason # 122 why I'm not a Paleontologist.
We’ve covered the Boring Era (Precambrian), and then the Gross Period (Cambrian), and then we get into more exciting Eras and Periods like everyone’s favorite the Triassic and Jurassic (248 mya and 206 mya, respectively). Maybe at this point we should create a mnemonic device to help us remember most of these. If we can’t get the dates right, we can at least get the order right. Starting from the oldest first...
Uh, well. That's a start. You know what? I'm just going to keep this chart handy in case I'm in a life threatening situation where I need to know when the Pennsylvanian was EXACTLY. Yes, that sounds like a good plan.
Tuesday, September 25, 2007
Let me begin by saying that the best and easiest way to make your point to a room of scientists is to make a graph. Scientists LOVE graphs. They love graphs more than they love New Balance and The North Face, which is a very telling statement if you’ve ever seen a scientist. Scatter plots, bar graphs, pie charts, whathaveyou. If you can put it in a graph, they’ll love you forever. When we plot nutrient concentration vs. depth in the ocean, we end up with a plot like this:It doesn’t matter if this is a graph of phosphate, nitrogen, or silica, most nutrient curves typically have this shape. Why, you ask? Well, let’s start from the top and move our way down.
Oceanic phytoplankton can only live in “The Mixed Layer’. Remember that phytoplankton are plants so they need sunlight to grow and nutrients to be happy. Depending on how murky your water is, sunlight can only penetrate about 60-100 meters down, at the most. The Mixed Layer is phytoplankton Party Time. Such Party Time, in fact, that they tend to use up every last molecule of available nutrients in the surface ocean – that’s why we have a concentration of practically zero in the top 10s of meters on our fancy graph above.
Particles like poo-poo are loaded with avalible nutrients. When that stuff falls through the mixed layer, the nutrients get recycled back into the water column. Below the mixed layer, the nutrients redissolve and are up for grabs again! It’s at this depth that we see a maxima in nutrient concentration.
The rest of our nutrient profile is pretty bland. As you can see, we have a pretty constant concentration except for a wee increase in the deep sea. This increase is no figment of your imagination or analytical error. It was a real head scratcher for ocean chemists for a long, long time because it shows up everywhere in the world and gets bigger as you move from the Atlantic to the Pacific. This, my friends, is evidence of the Thermohaline Circulation. If you were unfortunate enough to have seen “The Day After Tomorrow”, you would have gotten at least the jist of the Thermohaline Circulation – the deepwater “conveyor belt” that moves water from the surface ocean in the North Atlantic all the way around the world until it pops back up in the North Pacific. This current is super slow, but transfers heat all over the world, and apparently deadly storms, and Dennis Quaid, and then we all move to Mexico. The point is that the deep water is really, really old. Because it’s really old, it’s collected tons of particles that have rained down into it as it makes its way around the world. This gives us that slight bump at the very bottom of our graph.
See, now you know how to explain a nutrient profile to your friends! Use this knowledge wisely, as the power of oceanography is unwieldy at best.
Friday, September 21, 2007
Atoms are very excitable. Atoms and photons interact much like overweight children in a Bouncy Castle. Say your neighbor is having a very rowdy, very annoying party for their 5 year old. For this little thought experiment, imagine that the Bouncy Castle is an atom and all the kids inside are electrons. Everybody is having a good time in the Bouncy Castles, until the chubby kid arrives. The chubbiest kid at the party (who at this moment is outside the Bouncy Castle) represents one photon. He tanks down some cake and ice cream and barrels into the bounce house with a shitload of energy. He’s so energetic, in fact, that one of the other kids (an electron) gets shot out of the Bouncy Castle upon his entrance.
The parents that are loosely chaperoning (drinking at) this party see the commotion and promptly eject the cubby kid, thereby allowing another not-so-chubby kid back into the Bouncy Castle.
How can an atom get excited, you ask? One way is to burn it. Some chemicals burn different colors at juuuust the moment you ignite them. You can see purples and blues and greens, and remember that the difference colors you see represent photons with different energies. Harkening back to the Electromagnetic Spectrum, different colors equal different wavelengths which in turn means different energies. Get it?
This whole burning-with-different-colors thing is how Astrophysicists determine the chemical composition of celestial bodies that are far far away. The fancy name for it is Spectroscopy. As an aside here: my declared major when I transferred to UCLA was Astrophysics. But I hated the undergraduate advisor so much that I switched to Math. Astrophysics is certainly a wonderful field populated with very smart and interesting people, but I’d take a month out at sea over a month trapped in an observatory any day.
Wednesday, September 19, 2007
Much like delicious ice cream treats, electromagnetic radiation comes in all kinds of different flavors. We’ve got photons with long wavelengths which make-up things like radio waves, micro waves, and colors like reds and oranges. On the other end of the spectrum we’ve got waves with really short wavelengths like gamma rays, X-rays, and colors like violets and blues. When we talk about wavelengths, we’re talking about the distance from peak to peak OR trough to trough on a wave.
Any wave (EM, ocean, crowd at football stadium) will propagate with a speed that is the product of its wavelength multiplied by its frequency:
velocity = wavelength * frequency
All types of waves in the electromagnetic spectrum travel at the speed of light which is 3 x 10^8 meters per second. That’s 670 MILLION miles per hour (if I did my math right). Crazy fast. So fast, in fact, that nothing travels faster than the speed of light. Yet.
A consequence of this whole traveling-at-the-speed-of-light thing is that the speed of light never changes. For our purposes, it’s a constant. This means that if you increase wavelength you have to decrease frequency and vise versa. So waves like gamma rays that have super small wavelengths have really high frequencies and are super duper energetic. Radio waves and Infrared waves with long wavelengths have lower frequencies. When we talk about frequency, we’re talking about how many waves hit you in a given amount of time. Where gamma rays are like “bam, bam, bam, bam”, Infrared waves are like “bam…………bam…………bam………….bam”.
As an aside here: you ever wondered why your car’s antenna is as long as it is? That’s because the wavelength of radio waves is about 100 centimeters – just about how long your car’s antenna is!
Please excuse me now. I have an appointment to receive a wedgie and be stuffed in a locker.
Tuesday, September 11, 2007
You know how when you stick something like a straw into a glass of water, the straw looks kinda bent? You’re seeing Snell’s law in action. But before we talk about the law itself, we have to make sure everybody is on board with the definition of a “normal”. The normal is just an imaginary line perpendicular to any surface. Perfectly perpendicular at a 90 degree angle to the surface. Easy enough. The only tricky part comes in when you’re dealing with a curved surface like a lens.You can see from the diagram that the normal depends on where you are on the surface of the lens. We’ll come back to this in just a second because this is why lenses are so good at doing what they do.
Back to Snell’s law. Snell’s law says that if a beam of light moves from a medium of high velocity (like air) into lower velocity (like water or glass) the beam is going to be refracted TOWARDS the normal. We can see this in the picture below:
You can see that instead of traveling along its original path, the beam bent up towards the normal. The opposite happens when you move from a medium where the beam has a low velocity to one where the beam has a higher velocity, like moving from glass to air. In this scenario the beam moves AWAY from the normal. Now let’s check out what happens in a lens:
Do this to a lot of beams of light and you’ll be able to focus those beams onto a single point!
Ta-Da! Now that you understand the principles of Snell's law, you can feel good about being a juvenile misfit while you're burning a line of ants with a magnifying glass.
Friday, September 7, 2007
Ocean Anoxia Events (OAEs) are times in the earth’s history where the deep oceans lost most, if not all, of its dissolved oxygen. Lots of very smart people are spending very large amounts of money to figure out why these events occur because nobody has a straight answer just yet.
This is what an OAE is like: You ever been swimming in a lake? Chances are good that if you went in the summer, the upper couple of meters was nice and comfy; but if you swam (swum? swimmed?...oh, forget it) deeper you’d hit a boundary, below which the water gets really really cold. That boundary is called the thermocline and exists not just in lakes, but in oceans too.
The effects of sunlight can only be felt, at most, 60 to 100 meters deep. We call this layer the surface ocean. Everything below it is considered the deep ocean. The surface ocean and deep ocean don’t transfer water that easily. Upwelling and downwelling are pretty much the only ways the water "communicates". All that warm stuff on top wants nothing to do with the cold and salty stuff on the bottom. The only way to mix them is via ocean currents that move various bodies of water all around the earth through the deep sea.
During Ocean Anoxia Events, the world’s oceans become a lot like that lake. Communication between the surface and the deep is cut off, which limits the input of dissolved oxygen to the deep ocean. Without that input, all the fishes, and jellyfishes, and sharks, and shrimps, and crabs, and microorganisms that live in the deep sea eventually “breathe” up all the available oxygen until there is no more. No more oxygen = no more life = mass extinctions.
The chemistry of deep waters gets really screwy when all the oxygen is gone. Chemicals like hydrogen sulfide appear in the deep sea and we get a condition that is known as “euxinic”. These conditions are bad, bad, bad for the life that we know and love but great for organisms that thrive in low oxygen conditions. So, to bring all this back home to the question of pH, yes, the pH of the world’s oceans has remained relatively constant for a long long time. That being said, I'm going to stand my ground and say that I wasn’t totally wrong. Meh, whatevs. "A" for effort, right?
Wednesday, September 5, 2007
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.
Friday, August 31, 2007
Potassium is represented by the letter K which stands for kalium. How we got about calling this stuff potassium is a sordid history which you can glance at here. Potassium has 3 naturally occurring isotopes (the percent abundance is in parenthesis): 39K (93.3%), 40K (0.0117%) and 41K (6.7%). So you can see that the majority of potassium is stable, with 19 protons and 20 neutrons. Just a wee bit of all the potassium that exists on this planet is radioactive Potassium, which has 20 protons and 20 neutrons.
Potassium-40 is a radioactive isotope that decays sometimes to Calcium-40 and other times to Argon-40. How can an isotope have two different daughters? Before we take this question to Maurie Povitch, let’s take a look at a few ways a radio-isotope can decay.
(REFRESHER!Protons have a positive charge and live in the nucleus of an atom; neutrons have no charge and also live in the nucleus of an atom; and electrons have a negative charge and whizz around outside the nucleus of an atom )
Alpha decay: This is when the isotope shoots off an alpha particle. An alpha particle is basically a Helium atom without any electrons (i.e.: 2 protons and 2 neutrons). As long as we’re on the subject of alpha decay, I should note that alpha particles have a short mean free path, meaning that they loose a lot of their energy a short distance after they are ejected from their mother-atom. So if an alpha particle hits your skin, it’s not going to do much damage. But if you eat or inhale alpha particles, you’re in trouble. They’ll get inside your stomach and lungs and cause all sorts of problems. That’s why you don’t want to eat or drink anything while you’re workin’ with alpha emitters, so take those tacos outside the lab!
Alpha Decay, with pizazz.
Beta minus decay: Also called “electron capture” because this is what happens when a proton turns into a neutron in the nucleus of your atom. The nucleus acts like a tractor beam and sucks in an electron which negates the charge on one proton.
Beta plus decay: With this decay method, the nucleus kick out what basically amounts to an electron, thereby turning a neutron into a proton.
There are a couple more decay pathways that I won’t get into. Anywho, back to potassium. Potassium-40 decays about 11% of the time by electron capture to Argon-40, and it decays about 89% of the time by beta plus to Calcium-40. We like it when potassium decays to argon because we can use these two isototpes to age date igneous rocks! When igneous rocks solidify, they’ll trap any potassium and any subsequent argon that is created by radioactive decay. Argon is a gas, but it’ll hang out inside the crystal lattice of a mineral just so long as that mineral isn’t heated. It gets to be tricky business if your rock/mineral *has* been heated, but don't worry your pretty little heads about it. Geochronomitry is in good hands.
Wow! Radioactivity, explosions, impotence…potassium really is pretty awesome!
Tuesday, August 28, 2007
Alkali Metals have an atomic configuration that makes them want to give up an electron. This quality them very very reactive. So reactive in fact that they must be stored in mineral oil for fear that they will react with any moisture lingering in the air. All Alkali Metals are reactive with water, and they become more so as you move down the column of the periodic table. Sodium is more reactive than Lithium, Potassium is more reactive than Sodium and Rubidium and Cesium, forget about it. Potassium, especially, is HILARIOUSLY explosive when it comes in contact with water. Just look at what this idiot ended up doing:
I can't tell how much potassium went in there, but it was probably an amount no bigger than a dime. Now, I’m all for reckless science (obviously), but this instructor could’ve gotten seriously hurt, or injured her students or blown up her classroom completely. Alkali Metals, in their purest form, are nothing to fuck around with. Luckily, you’ll almost never find pure sodium or potassium or (God help you) Rubidium unless you’re a chemist and you really need them.
Potassium is found in lots of things, including minerals! Minerals like potassium feldspars, also known as Orthoclase, are frequently found in Granites. Minerals with potassium in them are pretty pretty pink, like this:
Friday, August 24, 2007
As you now know from our last entry, I’ve got lots of data. I’d like to graphically represent my data so that I can show lots of people my findings and have them go “Ooooo, Aaaaa. Tell me, young scientist, what does it all mean?” I can then look like a smarty pants by explaining to them that by plotting some quantity on the X-axis (the horizontal line) vs. something else on the Y-axis (the vertical line) we can make BROADER GLOBAL IMPLICATIONS with this data. Scientists love to graph things. Anything and everything looks better on a graph. It also helps the scientist presenting the graph to summarize their findings in order to avoid needless rambling. Scientists love rambling almost as much as they love graphs.
Let's build a graph together to better illustrate my point. We talked earlier in the week about auto-analyzers and all that jazzy business of precision and why auto-analyzers are rad if you have a buttload of samples, but not that rad if you want high precision. The data points we're gonna use are gotten by pumping samples with known concentrations through your auto-analyzer. The auto-analyzer spits out what we’ll call an Arbitrary Number. Your results might look like this:
38.41 uM -----------------------0.205
76.81 uM -----------------------0.410
101.51 uM ----------------------0.560
What we have in the left column is the concentration of our chemical in micro-Molar units. That’s 10^-3 moles per liter of solution and remember that a mole is 6.022 x 10^23 units (molecules or atoms), so we’re really talking about how many molecules are in our sample.
On the right is the Arbitrary Number that your auto-analyzer might display once it “digests” your sample. I say digest as an purely imaginative description because these machines do not actually feed on your sample. Or do they? Oh my.
Anyways, the next step is to arrange our graph. We’re going to put the Arbitrary Number on the X-axis and the Concentration on the Y-axis. If you reach WAY back into your mathematical memory, you’ll find an itsy-bitsy morsel of knowledge which tells you that when making a plot, the independent value goes on the X-axis and the dependant value goes on the Y-axis. Don’t remember? Well, I won’t hold it against you. Here is your data plotted by itself.
What happens next is that you, being the intrepid and fashionable young scientist you are, use the linear fitting function in Excel or some similar program to get a line running through (or close to) all your data points.
This line has an equation to it. Without getting into the nitty gritty of it, you’ll be able to use this equation to translate all the rest of your data into concentrations. All that’s left to do is eat Cheetos and let the auto-analyzer do its thing.
I think congratulations are in order because you just made your first calibration curve!! YAY!
Tuesday, August 21, 2007
Let me tell you about my data:
My data comes from the North Pacific and was collected on a cruise that I was on last August. We collected water samples at all ranges of depths – from very very deep (~ 3km) to very very shallow (~10m). We collected hundreds of little bottles of water which we keep here, in a cold room, so that we can reanalyze that water for nutrients like silica, nitrate, and phosphate. All those bottles have lived in that cold room for about a year and will probably live there for another 40 years or so. Not that that’ll do anybody and good, it’s just kinda the way things go around here. I’ve tripped over mud cores collected in the late seventies in that cold room. Seriously, scientists don’t know when to let go.
I say reanalyze because all these samples were run on the ship last summer. They were run by a dude from a lab hired out by the University of Washington. This guy had an instrument called an auto analyzer, which does exactly what it sounds like it does. It analyzes things automatically, hooray! We like auto analyzers because they’re fast. No messy pippetting, no headaches of tinkering with your spectrophotometer, just load your samples in and the numbers come roaring right out. The problem is that with speed, you loose precision.
Auto Analyzers suck/rule depending on your situation.
Precision is the ability to repeat the same measurement and get the same result. So say you run one sample three times and you get 180, 182, and 179, you’re in good shape. We like precision more than speed because precision means we can make statements about what we see and have the wherewithal to back it up. You don’t want to go out on a limb and make some big dramatic statement when you don’t know how good your data is.
I’m currently having data problems because of this business with the auto analyzer and it’s crappiness in the world of precision. You see, I’m looking for differences in the realm of 4% so we’re talkin’ small changes in nutrient content seen over hundereds of water samples taken from hundreds of depths at dozens of stations. If this auto analyzer can make only make measurements precise to 2-4%, we’re in trubs. The error inherent in the measurement overshadows any real signal I could hope to find. Now I’ve got to go back through all this data with a fine tooth comb and make sure the differences that are going to lead to BROADER GLOBAL IMPLICATIONS are really real and not just a figment of analyzation. Doesn’t that sound like fun, kids*???!!!
*Answer = No.
Friday, August 17, 2007
Peru sits snuggled up against one of the world’s gnarliest convergent plate boundaries. Remember that in the rhelm of plate tectonics, we’ve got 3 things plates can do: move apart from one another (divergent), crash into one another (convergent), or slide on by one another (conservative). Along the coast of South America we’ve got what’s called a subduction zone. Subduction zones are features of convergent plate boundaries where we’ve got one plate diving down underneath another
Some other major subduction zones around the world are over on the west side of the Pacific Ocean, nearby Japan (the Mariana Trench). We've also got the Aleutian Islands up in Alaska as well as along the coast of Washington and Oregon in North America which is named the Cascadia subduction zone. The Cascadia subduction zone is the reason why we have the Cascade mountain range right there (Mt. St. Helens anyone?).
The subduction zone along the West coast of South America involves the Nazca Plate and the South American plate. The Nazca plate is an oceanic plate which means it’s made up of dense stuff like basalt whereas the South American plate is made up of relatively light stuff like granite. Remember, these plates are in motion all the time because they’re riding along on the molten Asthenosphere underneath them, but they don’t move very much. When they do move, we get an earthquake.
Subduction zone earthquakes are so much bigger than transform fault earthquakes (ie: quakes on the San Andreas) because you’ve got a much much deeper fault which dips down into the earth at an angle. Let’s look at the figure below.
Ok, this might get confusing because we’re dealing with looking at the faults from the perspective of cross section. Imagine that you’ve taken a slice out of the earth way deep into the crust and are looking at the fault zones straight on. On the left we’ve got our transform fault (ie: the San Andreas). On the right we’ve got the setup as it is in a subduction zone (ie: Peru). Now, imagine that both these faults rupture the same amount, maybe 4 meters. Outlined in pink is the plane on which the rupture is going to happen. Because of the geometric setup (the hypotenuse of a triangle is always longer than the other two sides), the plane that ruptures in a subduction zone earthquake is larger than that for the transform fault. Larger plane of rupture equals more area of the fault broken and a larger area equals a larger earthquake. That’s why when faults at convergent zones rupture, they are such humongous earthquakes.
I’ll wrap it up by saying that if you’d like to help with relief efforts, check out this link to make a donation for the folks who need some assistance. Like I said, there’s lots of good people out there who could use a little help to get themselves out of such a crummy situation. All I’d hope for is that someone would do the same for me if I were in their shoes.
Tuesday, August 14, 2007
Moving on, all that hydrothermal activity leaves its mark on the surrounding water. One way to tell if you’ve got hydrothermal influence is by measuring 3He in the seawater. 3He is a non-radioactive isotope of Helium with 2 protons and 1 neutron. There is a shitload of it in the Earth’s mantle and it’s thought to have been trapped there as the Earth formed from hunks of spacerock mashing together. 3He is released in places where magma extrudes, like sea-floor ridges and hotspots (ie: Hawaii). Up in the North Pacific we indeed have a “plume” of 3He that extends from the Juan de Fuca ridge all the way into the mid-Pacific.
So what’s the big deal? Well, by sussing out the location of the plume we have an idea of how the water is moving around at this depth in this part of the world. The plume reaches out to the southwest and exists at a depth of 2000m. There must be some sort of current at 2000m that carries this 3He southwards and away from North America. That’s a start.
For me, I’m interested in understanding this plume of 3He because it coincides with the plume of silica my advisor and I are so interested in. Remember that silica is an ocean nutrient and can be pumped into bottom waters via hydrothermal sources. In the North Pacific we find 3He coinciding with lots of silica, but only in the northern part of the plumes. Once everything reaches the mid-Pacific the two plumes diverge: the helium plume stays a little north of the silica plume. So the question is: if these guys (both the 3He and the silica) are being pumped out of the Juan de Fuca ridged at the same time, at the same temperature, with the same water properties, why aren’t they sticking together as they get carried out into the Pacific? The short answer is that the silica isn't hydrothermal. The long answer will be avalible in dissertation form, and only God knows when.
Thursday, August 9, 2007
The New York Times reports: “The earthquake struck at 12:58 a.m (Thursday morning). Pacific time and caused no major damage. The United States Geological Survey estimated its magnitude at 4.6….The quake’s epicenter was located 3 miles northwest of Chatsworth and 7 miles northwest of Northridge, where a much stronger earthquake of 6.7 magnitude did major damage and killed more than 60 people in 1994. Today’s earthquake was followed by three minor aftershocks, according to the Geological Survey.”
How apropos. Let’s continue our discussion about earthquakes by turning our attention to the buildings they damage. You see, buildings are the problem here in earthquake country. If we could all live and work in yurts, things would be great. If a bunch of grass and felt falls on your head while you’re sleeping, it’s no big deal. But unfortunately yurts are not very practical workplaces, so we must turn to stone and steel.
Prior to 1933, buildings in Los Angeles were mostly made of unreinforced masonry. These buildings are usually made out of brick, adobe, or stone and held together by gravity. Unreinforced masonry doesn’t offer any resistance to shearing forces, so just like a stack of blocks these structures will topple over given sufficient shaking. Lucky for Angelinos is that there aren’t any of these buildings left in our city, or at least none that people live or work in. We don’t have these buildings around anymore because (as we talked about) the Long Beach Earthquake alerted everyone to the dangers of using unreinforced masonry for places like schoolhouses. Between 1933 and 1971 non-ductile reinforced concrete was the popular choice.
Ductility measures a material’s ability to deform without breaking. Something very ductile can be stretched and pulled and won’t snap apart. Think of pulling apart silly putty very slowly, that’s ductile. Most building built between 1933 and 1971 were of the non-ductile reinforced concrete variety, but after the 1971 San Fernando quake, we saw the rise of ductile reinforced buildings. The key difference between the two is the amount of confinement you get in your columns. We’ve all heard the term “rebar”, right? Rebar is stuff that makes up the steel skeleton of a building or structure. Ductile reinforced buildings have rebar vertically through a column but also rebar horizontally around a column to make kind of a cage. By having rebar wrap around a column, you can hopefully avoid column bowing that happens if/when the concrete making up the column crumbles during an earthquake.
Oi, the topic of building response to earthquakes is a broad one. I guess we’ll have to save the discussion of soft 1st floor for another entry because now it’s snack time! I’ve got cookies to eat, folks. I'll see you later.
Tuesday, August 7, 2007
I’d like to take this time to make sure all the folks I care about are prepared for the coming apocalypse. If you’re reading this, I probably know you, and even if I don't I wouldn’t want you to die in a horrible manner. Usually here at Get Your Science On we're all about having fun, but today we’re gonna get you informed about what you can do in the event of an earthquake and/or natural disaster of a similar fashion. But first we'll inform ourselves with some history of earthquakes in the LA area.
Southern California hasn’t had a humongous earthquake in a while. The last major earthquake on the southern section of the San Andreas Fault was in 1857 and was a whopper with Mw of 7.9 (that’s Moment Magnitude [see “MAGNITUDES!” for a hilarious refresher]). Since Southern California wasn’t too populated at the time, damage was minimal and only a couple folks got killed in this earthquake. Next up was the 1906 San Francisco quake where the San Andreas Fault ruptured in Northern California and we all know the consequences of that quake. Major damage to the city of San Fran, loss of life, fires, carnage, the works. But the population of San Francisco was only 410,000 at the time. The population in Los Angeles County was almost 10 million in 2006 according to the census bureau. Yipes.
A recurrence interval is defined as the time that it should take between earthquakes on a fault. If the Earth's crust was clockwork, we could expect an earthquake flawlessly on time. But the Earth is fussy and mostly unpredictable. However, the recurrence interval at least gives us a heads up as to when we can start biting our nails over the possibility of The Big One. The southern part of the San Andreas Fault has a recurrence interval of about 150 years which means we should have a big quake right…about…NOW! Aww, don’t be scared. There are lots of things you can do to prepare yourself for an earthquake!
First of all, congratulate yourself on living in a city with some of the most stringent and thoroughly enforced building codes in the world. YAY! The Long Beach earthquake of 1933 scared the pants off the citizens of Los Angeles when several school houses crumbled because they were built out of unreinforced masonry. The earthquake struck around 6 pm so children weren’t in school, but if they had been it would have been a major, MAJOR loss of life. Ever since then, laws have required retrofitting of older buildings (brick, masonry) and ensured that newer buildings be designed with earthquake safety in mind. That’s not to say that buildings can’t or won’t crumble given sufficient shaking. Remember: Earthquakes don’t kill people, buildings kill people.
After Hurricane Katrina, I wanted to make sure I had enough supplies to last for a couple days in the event of a catastrophe in the Los Angeles area. I started with two big rubber tubs that you can buy at Target for under 10 bucks. Buy the lids too. I put water (5 gallons), canned food, A CAN OPENER (!), other long-lasting food items like ramen and soy milk (which you do want to replace after a year or so), eating utensils, a few sweatshirts (in lieu of blankets), extra shoes and socks, a flashlight, one of those dynamo-powered radios, batteries, first aid shit like gauze, band aids, disinfectant, ace bandages, and I think some cash. Unless I “borrowed” that cash for booze. Anyways, you get the point. Above all else GET WATER! Don't plan on relying on a Brita filter either, spend the $4 and buy yourself a couple jugs of drinking water. The rule of thumb is you’ll want about a gallon for everyday use until utilities can be restored.
There are lots of good resources on the web about how to make yourself a survival kit, just Google it! But don’t feel like you have to run out and buy some fancy premade kit. Use your common sense and you’ll do alright.
Wednesday, August 1, 2007
One incarnation of calcium carbonate is chalk. You ever heard of the white cliffs of Dover? The cliffs in southern England that face Continental Europe? They’re famous for being the first thing that lots of folks see when they cross the English Channel. I guess that’s a big deal when it comes to wars and stuff, but what do I know, I’m no historian!
The white that you see in this formation is mostly coccolith fossils. Tons and tons and TONS of coccolith fossils make up this geologic structure. There are some remains of sponges and corals thrown in for good measure.
Anyways, we talked a long time ago about these other phytoplankton called Diatoms (see “Die, Die Diatoms my darling”). Diatoms protect themselves with silica whereas Coccolithophores protect themselves with calcium carbonate. The thing to know about phytoplankton is that they are all competing for nutrients in the surface ocean. Plants need nutrients like nitrate and phosphate to be happy campers, just look at the main ingredients in fertilizer the next time you’re at Home Depot.
The good news is that diatoms and coccolithophores thrive under very different oceanic conditions. Say there’s a huge rainstorm in Southern California. All the river runoff, sewage spills, and general poopieness supply nutrients (and diapers!) to the coastal surface water. Like we talked about before, diatoms are really good at swooping in and taking advantage of all nutrients. Given proper nutrients, a diatom population can grow crazy fast, resulting in what we call a “diatom bloom”. Coccolithophores, however, grow well in lower nutrient areas. They can be found way out in the middle of nowhere, thriving in waters with super-low nutrient levels. Good for them because this means they can out-compete a whimpier phytoplankton and take control of vast areas of ocean.
So now you’ve gotten a peak at the ancient competition for ocean nutrients between Diatoms and Coccolithophores. Two phytoplankton enter, one phytoplankton leaves!
Friday, July 27, 2007
The San Andreas Fault is the reason behind all sorts of landforms we see across California. Let’s start by looking at a map of this guy:
Ahh, the lovely California. What should stand out to you when you look at this map are the mountains that follow along the red line (the trace of the San Andreas Fault). The presence of these mountains makes sense seeing as all this movement along the fault mooshes the Earth's crust together in and around the fault zone. The whole Basin and Range province in the western part of North America is an after-effect of the Pacific/North American plate boundary, but we’ll leave that discussion for another day. Totally different topic.
Anywho, start with your eyes on the northern most part of the red line and then trace the red line southwards, towards Los Angeles. You’ll get to a point just south of the Great Valley (the Armpit of California) where you’ll see that the fault curves a bit inland. This curve is called “The Big Bend” and causes all sorts of interesting things to happen, geologically speaking.
For one, the Big Bend is responsible for the uplift of the Transverse Ranges.
This range of mountains is an oddball because it runs East-West, while everything else around us (the Coast Ranges, the Sierra Nevadas, the Rockies, the Cascades) runs North-South. Why you ask? Well, think of the Pacific plate moving northward and rubbin’ up against the North American plate. It’s cruisin’ along, carrying with it all those rocks and houses and dogs and buildings and burrito shops that exist west of the San Andreas. At the Big Bend, however, all that stuff is crashing into one another instead of smoothly moving along past one another. That seemingly innocuous curve in the fault has created a big, fat convergent zone in the area around the Big Bend. This convergent zone includes the Los Angeles region. Lucky us!
Along with the Transverse Ranges, we get the Garlock Fault out of all this Big Bend business. The Garlock is one of the larger lateral faults in California. If you’re ever flying north from Southern California, you can actually tell where this fault runs visually if you look out your airplane window. Pretty neat, huh? Make sure to point it out to the person sleeping next to you by saying “Hey, look look! That’s the Garlock fault! It’s a left-lateral strike slip fault that defines the boundary between the Mojave block and the Sierra Nevada/Basin and Range province!” I advise to also make sure to spit a lot when you talk and maybe sneeze on them once or twice because you are a nerd and should behave thusly.
Tuesday, July 24, 2007
Remember back when we talked about plate boundaries? The places where those big tectonic plates crash into and move along with one another? No. Well, let’s remind ourselves before we move on.
There are three types of plate boundaries: divergent (pulling apart), convergent (crashing together) and conservative (rubbin’ against one another). An example of a divergent plate boundary is the East African Rift, of a convergent boundary we’ve got the Himalayas, and for our conservative boundary we’ve got the good ole’ San Andreas Fault.
For most of the last 600 million years, the western part of North America was a convergent plate boundary. An old old plate that doesn’t exist anymore called the Farallon plate was happily subducting underneath North America (see Figure). What happened was that there was a pointy bit of the Pacific/Farallon plate boundary that rammed into the North American subduction zone about 30 million years ago and everything went apeshit. When that pointy bit hit North America, the subduction zone along the western margin started swallowing up a divergent zone (where new crust is being made). Instead of one outdoing the other, the whole thing just fell into a new regime altogether and we got a conservative plate boundary. Why, you ask? I don't think we have a good explination as to why we got the San Andreas out of this mess. Or at least I don’t know anybody that knows why. It’s like taking a hot dog and smashing it together with a hamburger and ending up with sushi. Crazy!
The sushi that we ended up with is the San Andreas, the big mother of all faults in California. Unless you’ve been living in a cave or on the East Coast or are totally oblivious to all that surrounds you, you probably know that this is the fault that gives everybody the jitters. And rightly so, it’s a big fuckin’ fault that has caused a lot of problems in the past. The San Andreas Fault serves as the boundary for the North American plate to the East (what the rest of America is attached to) and the Pacific plate to the West. Yes, that means in a few million years Los Angeles will be sittin’ pretty right next to San Francisco. Don’t frown, San Francisco. Surely by then we will have engaged Iran in nuclear conflict so you won’t have to put up with anything more than the mutated remains of model/actress zombies looking for temp jobs.
Zing! It’s good to be back!
Friday, July 20, 2007
In the meantime, head on over to www.chiefmag.com for a fancy article about zombies and physics written by yours truely.
Tabitha and Paris Killton
Wednesday, June 27, 2007
SILICA --> DIATOMS --> CO2 UPTAKE --> BROAD GLOBAL IMPLICATIONS!
I am running samples for Silica today. And I ran samples for Silica yesterday. And I will probably be running Silica samples tomorrow. How do you run Silica samples, you ask? Well, I’ll tell you!
We use a technique called colorimetry. In a nutshell, we add a little bit of our water sample, add a cocktail of hazardous chemicals, pump the mixture into a machine called a Spectrophotometer and presto-chango we get an absorbance reading! Absorbance is a number that makes no sense until it’s put in the context of a standard. Here, let me explain.
Imagine that you are a fancy-pants scientist with a very expensive and very sensitive Spectrophotometer. Your Spectrophotometer has a beam of light built somewhere in its complicated interior. When you stick something in front of that light, the little reader inside the Spectrophotometer says “Hey, that asshole put something in front of me. This is how much my beam of light has changed.” You record this number. Please dismiss any disparaging comments made by your scientific instruments because this senario imaginary and scientific instruments don’t talk. But if they did, they would be grumpy.
Now about this standard business – a standard is just a sample with a concentration that you know precisely. You want to use a couple of standards with different concentrations so you can get a good range of values. In your imaginary lab, you’ll run your standards and say to yourself “A standard with concentration X gave me an absorbance reading of Y”. When you do this for all of your standards you’ll end up with a nice linear relationship between absorbance and concentration. You’ll get yourself a simple equation that you can pop all of your meaningless absorbance readings into and get out very useful concentrations and then make lots of charts and tables and powerpoint presentations with your data.
What we’re dealing with here is described by Beer’s Law. This is a serious scientific law with important implications and has nothing to do you with you doing a keg stand at your frat brother’s 23rd birthday party last year so quit snickering. Beer’s Law relates Absorbance (what your little spectrophotometer reads out) and Concentration (what you are trying to get). Beer’s law says:
I1 / Io = 10^-A. where A = l*c*k (the little ^ tells you that -A is an exponent)
Break it down!
Io is the intensity of the light you start with, I1 is the intensity of the light after it has passed thru your sample (see figure), A is the absorbance (what your instrument reads out), l is the path length of the beam, k is your “absorbance coefficient” (whatever that means), and c is the concentration in your sample (what you want).
In a perfect world you would know all these things. You would know your beam path length and your initial intensity and all that shit. But the big secret is that science is imperfect. Your spectrophotometer is gonna get bumped around and glassware is going to get dropped on it or samples spilled on it or cheeto crumbs mashed into it somewhere. This is why you use the ole’ standards trick 'cause now you can avoid having to use Beer’s Law. See, scientists aren’t perfect either. We just plan ahead because we know how sloppy and clumsy we really are.
Wednesday, June 6, 2007
* Never throw up in the bathroom. Only throw up overboard. I don’t know why, but if you toss your cookies in the bathroom everyone gets mad at you.
* Front of the boat is the bow, back of the boat is the stern.
* If you’re facing the bow, starboard is on your right, port is on your left. You can remember this because “port” and “left” both have four letters in them.
* Let the captain talk to you. Some are friendly, most are not. Feel out the situation for yourself before you start gabbing about how early it is or how cold you are or how choppy the water is. He’s gonna think you’re a pussy if you start in with the complaints. And he’d be right.
* Anything that looks like a hose is typically important.
* No sandals on deck, hippie.
* No farting on deck. Wait till you’re someplace enclosed and in close proximity to the most annoying member of the science party. Preferable the cold storage room.
* Scientists, as a rule, are more annoying than crew members. Shocking, I know.
* Someone will always know what you’ve been looking at on the community computers. Always
* Don’t press any buttons, especially not if they’re flashing. Tell someone else about it.
* Do answer a phone if it is ringing nearby.
* Don’t talk too much.
* Do get your work done and show up for your watch shift on time.
* Do bring your own alcohol supply IF you are working on a US research vessel.
* Do take advantage of the open bar when working on Canadian, German, or Russian boats (for reals!)
* Don’t eat anything out of ANY refrigerator EVER!
* Don’t accept any compliments/favors/candy from members of the crew unless you intend on sleeping with them.
* Two movies to never put on in the community movie room: Apocalypse Now and Maid in Manhattan. Both will make you extremely unpopular.
* Don’t roll up to the chief engineer with a bunch of bolts in your hand and ask him if they are important. Even as a prank.
* Do get some exercise while you’re at sea. Just look at the crew.
* Don’t eat Doritos while working on the computer.
* Don’t eat Doritos while working with any scientific equipment.
* You know what? Give the Doritos a rest, why don’t you.
* The ocean is a beautiful place and deserves your respect. No peeing off the stern.
There, that should get you through a few days. Let your common sense guide you the rest of the way.