A World in a Grain of Snow

To see a world in a grain of sand,

and a heaven in a wild flower,

Hold infinity in the palm of your hand,

And eternity in an hour.

- William Blake, excerpt from “Auguries of Innocence”

While at Summit, we keep ourselves very busy trying to accomplish science goals – making measurements, collecting samples, running tests and troubleshooting robot performance. It’s hectic and fun and exhilarating, and it all moves so quickly. Every day, right after eating a delicious lunch and filling up on perfectly scrumptious cookies, I tow my sled of instruments down to the south end of the station. With the last building out of view, I unpack my gear and set out to make a long series of measurements. Before I get started, I remind myself to take a look out over the seemingly infinite expanse of ice and let it sink in. I have the incredible opportunity to be in such a special place doing exactly what I want to be doing.  The beauty and calm of the place can be experienced by immersing yourself in the surroundings, or just by taking a look down at the delicate snowflakes that coat the vast ice surface.

Fresh dendrite snow flakes from the morning of June 14th, as seen through a microscope. (Photo: Elena Willmot)

The Quest for Buried Ice Layers!

Last summer, just before IGERT cohort 3 journeyed up to Summit Camp, the Greenland ice sheet experienced extensive surface melting. Much of the top layer of snow melted and dripped through the snow near the surface. But of course in the cold weather, it didn’t remain as water for very long! This water refroze in the snow, forming flat layers of ice which are connected to one another by vertical columns of ice (see the picture below for an idea of what this looks like). Since last summer, it has snowed quite a bit at Summit, so now the ice layers and the columns that connect them are buried. We would like to know what this ice layer looks like and how many of these ice columns formed in areas around Summit Camp. Now don’t get me wrong, I love digging a good snow pit, but unfortunately, we can’t dig up miles of snow. What we would like is to see what’s under the snow without having to break our backs.

A view inside of our snow pit. I am pointing to the vertical ice column which is right beneath an ice layer that extends all the way across the snow pit. (Photo: Jim Lever)

Using ground penetrating radar (GPR), we can look down below us and “see” the layers of snow upon which we stand. We can also see when there is something different in the snow, like ice which is visible because it has a much higher density.  In our first week, we have spent some time getting the radar system running and testing it out by setting it in a sled and pulling it behind as we walk. One question lingered – is the radar “seeing” what we would see in real life? For that, we had to dig! We dug up a snow pit to see just how prominent the ice layer actually is and to determine if we could see any vertical ice columns. Sure enough, both the ice layer and even a vertical column were easy to find in the snow pit!

Walking off into the distance with the ground penetrating radar in tow. (Photo: Jim Lever)

Though pulling sleds wasn’t so bad, I would sometimes sink nearly to my knees in snow drifts which made keeping a constant walking pace tough. Enter Cool Robot – an autonomous robot (designed right at Dartmouth’s Thayer School of Engineering and wired up by IGERTeer Ben Walker!) that can follow preset directions and drive itself in nice, well-paced patterns across the snow while towing the radar system. We set up a square grid for the robot to follow that was 50 meters on each side. The robot is light and reliable – not sinking into the snow, keeping a constant pace and following our directions within about a meter of the set path. So I’ll admit, Cool Robot has me beat by far in the ability to run a GPR survey. But hey, at least I know not to run straight into the flag markers all around camp! : )

Cool Robot crushing the competition in quality of GPR surveys! (Photo: Jim Lever)

Cargo Chaos!

Although the 2013 Field Seminar doesn’t start for another month (and the Kangerlussuaq early season crew doesn’t head out for another two weeks), packing and preparation have been in full swing these past few days.  While fancy graduation receptions took place all across campus, we gathered cargo and food in the Arctic Library, packed it all into boxes, coolers, and crates, and entered each piece into the Polar Services online cargo tracking system.

Food planning for the field is a lot of fun.  At the supermarket, we filled two enormous carts past overflowing.  At checkout, our cashier told us it was the largest single purchase she had ever seen!  To ensure breakfast enjoyment, I baked two enormous batches of granola. 

Once all of the food was in the Arctic Library, chaotic food organization ensued.  Hopefully we won’t go hungry…

After food planning, we moved on to packing science cargo.  All of our field gear has to be packed up safely so it is intact when we arrive in Kangerlussuaq.  Each package must be weighed, measured, and entered into the cargo tracking system with a description of its contents and value.  With 28 separate packages, this is no small task!  Each package gets its own manifest slipped inside and its own label taped on the outside.  After almost an entire roll of duct tape, those labels aren’t going anywhere!

Yesterday, Zach and I loaded everything into a huge cargo van (including two bubble-wrapped modular kayaks) and headed over to Scotia, NY. 

We handed off the cargo to our friends at the 109^th Airlift Wing; we are ever thankful for all the work they do to make our field seasons successful.  The next time we see them will be June 25^th, when we board the plane to Greenland!

IGERTs Greenland Field Season Begins!

The first of the IGERTs are up in Greenland as the 2013 field season begins. Ben Walker and I (IGERT cohort 4s) are up at Summit Station in Greenland for the next three and a half weeks with Dr. Jim Lever from CRREL and Alison Morlock (a recent Thayer MS graduate – congrats!). We will be working with the Cool Robot – a solar powered robot that is designed to carry instruments across polar ice sheets for scientific research. I have a few different projects that I’ll be working on up here, and the science is just getting started!

Spectacular view out of the window of the LC-130 cargo plane! My best guess at a location is Northern Canada!

We had a great trip from Scotia up to Kangerlussuaq on Monday, and only a night in Kanger before heading up to Summit. We still took the time to take a walk around Kanger and up to Lake Ferguson. After the unfortunate washout of the bridge last summer, construction of the bridge across the river in town is moving along, but it is still not complete. We were able to take a route around and over to the lake. We were surprised to find that there was still ice on the lake!

There was still ice covering most of Lake Ferguson!

We received a very warm welcome from the crews at Kanger and at Summit, and we are so thankful of all they have done for us already! The rest of the week has been spent acclimatizing to the altitude, unpacking and testing out gear and making plans for the rest of our trip. More updates to come!

View of Summit Camp at bedtime

Greenland Climate of the Past & Present

Last summer, several IGERT fellows had the serendipitous and rare opportunity to witness a warming climate’s effect on Greenland first-hand. Julia Bradley-Cook was stationed in Kangerlussuaq collecting data on carbon cycling in soil when the bridge over the Watson river collapsed from anomalously high flows of meltwater (see http://dartmouthigert.wordpress.com/2012/07/11/glacial-melt-threatens-town-water-supply and http://dartmouthigert.wordpress.com/2012/07/11/update-the-river-powers-on). Days later, the 3rd cohort of Dartmouth IGERT students flew up to Summit Camp, Greenland’s highest point, and observed features of the ice sheet-wide surface melt. Fellow Kaitlin Keegan, Thayer Professor Mary Albert, and their collaborators study the frequency of such melt events; their work at the North Greenland Eemian Ice Drilling (NEEM) sight has suggested that such an event last transpired in 1889 and, therefore, is unprecedented in the satellite record. (See http://dartmouthigert.wordpress.com/2012/07/21/new-summit-melt-layer).

A new Nature publication on Greenland climate authored by the NEEM community, which includes Albert and Keegan, prompted an entry on the scientific blog site RealClimate.org. RealClimate was started and is maintained by “working climate scientists” who “aim to provide a quick response to developing stories and provide the context sometimes missing in mainstream commentary.” Check out the discussion on Greenland’s 2012 summer conditions, how they compare to those 125,000 years ago, and what we can learn about past temperatures and sea level rise from an ice core! I was particularly excited about the conclusion of the entry since author Dr. Steig mentioned the significance of a new ice core from West Antarctica. I just returned from a field season on Roosevelt Island assisting with the drilling of this core, which will help scientists understand the sensitivity of the Ross Ice Shelf and, thus, of the West Antarctic ice sheet to changes in climate. http://www.realclimate.org/index.php/archives/2013/01/the-greenland-melt/

The Promised Phosphorus Blog

I’ve been promising a blog post about phosphorus in Taylor Valley, so here goes.  At this point in the season, we’re a little frantic processing samples, packaging up boxes of soil and rock to send home, returning all of our gear, and cleaning the lab.  But I’ll find the time to write this post, since it’s something I’m invested in.

So why are we interested in phosphorus in the first place?  Phosphorus is a limiting nutrient in many ecosystems, but the Taylor Valley lake basins are some of the most phosphorus deficient systems in the world.  Understanding how phosphorus enters the Taylor Valley system and becomes available to organisms is thus critical to understanding the controls on life in this extreme environment.

In addition to general phosphorus deficiency throughout most of the valley, there is also an interesting and well-established phosphorus gradient up the valley.  Down in the lowest-elevation Fryxell basin, there is a relative abundance of phosphorus compared to the higher elevation Hoare and Bonney basins.  Why does this gradient exist?  Multiple ideas have been proposed: perhaps it is due differences in climate, age of the soils, or till type from which the soil has formed.  This last explanation – that the composition of the till determines the amount of phosphorus available – is one that seems to fit best with the data.  And it is this claim that I hope to address with the samples that I have collected this season.

Even within the Fryxell basin there are different colors of till. How do different till types impact the soil geochemistry?

If the till type results in such a strong phosphorus gradient, then the till in the Fryxell basin must be significantly different from the till covering the rest of the valley.  Indeed, the Ross Sea till that covers the Fryxell basin contains kenyte, an unusual phosphorus-rich volcanic rock originating from Mt. Erebus, the volcano that dominates Ross Island.  The Taylor till found throughout the rest of the valley, on the other hand, contains no kenyte. Is Mt. Erebus responsible for providing the Fryxell basin with its higher levels of phosphorus?  Using the rock and soil samples I’ve collected, we hope to use isotopic signatures to differentiate apatite (the most common phosphorus-bearing mineral) that stems directly from Mt. Erebus from apatite stemming from other rock types.

A kenyte boulder found near Lake Fryxell. The boulder likely comes from Mt. Erebus, on Ross Island.

We are not only interested in how apatite gets into the Taylor Valley system; we are also curious about its fate.  How do microorganisms interact with the apatite in the soil?  Are microorganisms responsible for releasing phosphorus from the apatite?  As a start, we’ve set up a little experiment (involving soil sausages) that will stay out in the field until next season.  The sausages are tubes full of soil, apatite grains, and glass beads (used as controls), cleverly held together with red clips.  The semi-permeable tubing we used will allow the environment to interact with what’s inside the sausages while keeping everything nicely contained for retrieval next year.  When we collect the apatite grains next year, we hope to be able to see evidence of how the grains have been altered by microorganisms.  We’ll look for organisms on the grains themselves, as well as signs that the microbes have been eating away at the mineral.

Ross and I put together the apatite soil incubations.

On Friday, Eric and I went out to F6 camp to bury the sausages.  We picked a location near Von Guerard stream – a wet soil but a stable location.  We buried the soil incubations five centimeters below the surface, marking them with tags and recording the exact location.  Next year we’ll return to dig them up.  I hope both that they are intact, and that they give us more insight into the ways in which phosphorus moves throughout the Taylor Valley system.

An apatite soil incubation buried in the ground.

Next step?  Packaging up my samples to be shipped back to Dartmouth, and figuring out how to process them once we’re all back in Hanover.

Nematodes, Rotifers, and Tardigrades (Oh My!)

While I’ve been spending the past few days rinsing dishes, measuring soil pH, and rinsing more dishes, my lab mates have been glued to the microscopes, counting nematodes, rotifers, and tardigrades (oh my!).  As I mentioned in my previous post, the Soils Team of the Dry Valleys LTER is interested in the invertebrate diversity and productivity in varying soil types.  Collecting these data requires a lot of counting; my lab mates may be going slightly crazy after spending so many days staring through a microscope, clicking their counters.

Martijn and Ashley have been tied to the microscopes all day!

For me, since I don’t actually have to count the samples, it has been exciting to get to know the different characters of the Dry Valleys soils.  The nematodes are the major players: Scottnema lindsayae, Eudorylaimus, and Plectus.  Of the three nematode genera, Scottnema (named after explorer Robert F. Scott) is the most abundant in typical Dry Valley soil.  Scottnema, unlike the other two genera, is endemic to the Dry Valleys, meaning that it is found nowhere else in the world.

Scottnema is the most abundant land animal on the Antarctic continent!

In more moist soils, along stream banks and next to ponds, Eudorylaimus and Plectus are abundant.  Rotifers and tardigrades are not as plentiful as the nematodes, and are quite exciting to spot in the scope.  Tardigrades, affectionately known as water bears, are especially cute.

So what are my lab mates looking for through the microscope?  Nematodes are identified by size, the morphology of the mouth region and tail, and the general shape of the body.  For instance, Eudorylaimus is much bigger than the other two genera, while Scottnema is distinguished by a crown-like mouth region.

Eudorylaimus is much larger than Scottnema.

After they identify the genera, the next step is to identify the type of individual: live or dead, male or female, juvenile or adult.  In a split second, a click is made and the tally of individuals goes up.  (As I type this, I’m listening to a pleasant background clicking noise of Sabrina counting a sample.)  So far the record is 1423 nematodes in one sample – and that’s just from 100 grams of soil!

Ashley uses a counter to keep track of the genus, gender, and life stage of each individual.

These little critters, so abundant in a seemingly lifeless environment, are incredibly tough.  They have to be, to survive some of the harshest conditions on the planet.  Not only do these microscopic organisms have to survive extreme cold, but they also have to contend with extreme aridity.  Indeed, some of the most closely related species to the Dry Valleys nematodes are found in hot deserts, where they use the same coping strategy to deal with the lack of water: anhydrobiosis.  In an anhydrobiotic state, a nematode’s entire metabolic system has shut down; the organism can wait indefinitely for more favorable environmental conditions.  Without such an effective strategy for dealing with the lack of liquid water, these organisms would be unable to survive in the Dry Valleys.

As the Wormherders continue to count the samples, I’ll be sure to post pictures of any interesting finds!  Many thanks to Ashley Shaw and Dr. Martijn Vandegehuchte (both from Colorado State University) for sharing their nematode knowledge and helping me to take the photos!