Friday, August 31, 2007

Moron Potassium!

Why not keep the ball rollin’ and delve deeper into the element with atomic number 19? Let’s go!

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

Potassium is pretty awsome

I had a bag of bananas baking in my car this morning. Delicious, soft bananas. All those bananas got me thinking about potassium and what an interesting element it is. So today, thanks to those bananas, we will look at a common element with some fascinating uses and behaviors.Potassium lives all the way on the left side of our periodic table in a category known as the Alkali Metals. The definition of alkali is “a hydroxide which dissolves in water to form a solution with a pH greater than 7; capable of neutralizing an acid.” A solution that is highly basic can be just as dangerous as a solution that is highly acidic. If you reach way way back into the memory of your 7th grade chemistry class (and ignore the boredom and embarrassment you probably experienced in said class) you’ll remember that acids and bases neutralize one another. I'm sorry you had to delve back to such an unpleasent time. Go to your happy place, go to your happy place.

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:

One last note about Potassium is that the compound potassium nitrate (KNO3), also known as saltpeter, has a notorious reputation for what it does and does not do to the human body. Saltpeter is one constituent of black power gunpowder, but if urban legends are correct, was also used as an anaphrodisiac everywhere from mental institutions to sailboats. I'm not aware of any studies that prove or disprove these statements, but if WW2 has any say in it, I'm a believer.

Viva Potassium!!

Friday, August 24, 2007

I <3 the Mundane!

I'm going to tell you about something incredibly mundane today: fitting your data to a line! Now before you go running off to Pink Is the New Blog, let me plead my case as to why you should care about the mundane. We often think of the mundane as being awful when really the mundane is awesome. Think of all the mundane things you spend time doing: eating, drinking, running errands, brushing your teeth, sitting around at work. I’d venture a guess that 80-95% of your day is filled with the mundane. But without the boring shit that we have to do each and every day, all the exciting shit that happens to us wouldn’t be as exciting, right? So let’s revel in the mundane as we continue today’s discussion.

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:

Concentration-------------------Arbitrary Number
0 -------------------------------0.000
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


In a perfect world, we would all have perfect data. In a perfect world, all instruments would run smoothly and do what they’re supposed to do WHEN they’re supposed to do it. In a perfect world, all spreadsheets would be organized and all precision would be less than 1% and measurements would even be repeatable. Unfortunately, we do not live in a perfect world. Instruments of analyzation break and clog and sputter, spread sheets disappear, and scientists get the shakes in the lab after a long weekend of binge drinking, resulting in imprecise pippetting. If only the public new about all the shoulder shrugging and “Meh, good enough” data out there, you’d question the BROADER GLOBAL IMPLICATIONS you heard about in the news.

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

The perils of Peru

Hey gang - bummer news out of Peru this week. If you haven’t checked the news reports there was a major earthquake in the Ica province, which is about 125 miles south of Peru. It was a magnitude 8 that occurred at 6:40pm on Wednesday. You can read about what happened here. Not really a subject to make light of. Peru is a beautiful place filled with wonderful folks just tryin’ to get by and they’ve been delt a rough hand. I would be remiss to ignore this whole situation and get back to talking about helium 3, which I was going to do today. Instead I think it would be appropriate if we learned a little bit about what’s going on in Peru’s part of the world and why they got slammed with such a huge earthquake.

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


The area I work in the North Pacific is nearby a feature called the Juan de Fuca ridge. We’ve talked a bit about plate tectonics in the past (see "The Tale of Alfred Wegener”) and up in the North Pacific is a little tectonic plate called the Juan de Fuca plate. Juan de Fuca was a 16th century Greek captain employed by Spain to chart a northern course from the Pacific Ocean to the Atlantic (thanks, Wikipedia!). He didn’t find such a passage, but what he did find was later named the Strait of Juan de Fuca which is that body of water that separates the Olympic Peninsula from Vancouver Island. Straits, plates, ridges, Lordy! What didn’t this guy get his named slapped on? When you have ridges, you have hot vents. Remember that ridges are the places where new crust is being formed as magma oozes up to the surface. Hot vents are those fun sea floor features we see on nature programs with all sorts of weird lobsters and tube worms growing around them. A sidennote here: lots of those critters (crabs, shrimps, lobsters) have no pigment because, well, what would be the advantage of having color in pitch blackness? When the submersibles get down there to take all those pretty pictures we see in magazines and on the Discovery channel, they blast the area with flood lights. All that light shocks the shit out of those critters and usually a ton of them die as a result. But before you get all worked up about this just remember that shrimps and lobsters and crabs are the bugs of the sea, so you shouldn’t feel any worse than you do squashing a cockroach. There, feel better hippy?

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

Moron Earthquakes

My new thing for Get Your Science On! is to keep a theme going throughout the week. This is easier for me ‘cause I don’t have to wrack my brain for a whole new topic, and I’ll just assume it’s easier for you because…well…it just will be. We talked a little bit about earthquakes on Tuesday and LOW AND BEHOLD what happened between now and then? AN EARTHQUAKE!

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.

A yurt.

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.

This is a good example of what goes on inside you’re new freeway columns. Lotsa rebar wrapped around more rebar. We like rebar. Rebar makes the world go round.

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

In all seriousness...

Hello Friends,

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


Coccolithophores (pronounced cock-o-lith-o-fors [keep giggling, perv]) are little guys that live in the sea. I say guys in a very casual sense since they are actually phytoplankton, which are plants, so they don’t really have any gender. What they DO have are these little plates or shields called coccoliths encircling them in what’s called a coccosphere. Just like Diatoms, these little phytoplankton are trying to not get eaten, so they build a protective coating to make themselves less tantalizing to grazing zooplankton. The coccoliths are made up of calcium carbonate, a VERY important substance for lots of folks in the marine sciences.
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!