Snowfall in the Dry Valleys

I've spent the past five days in the dry valleys. As you've heard, we were weather-delayed getting out there. Then weather delayed my team from meeting me there. Then, my team got stuck there with me and couldn't get back to McMurdo. There was a lot of snow!

That snow doesn't stick around long. We don't have to wait for warm temperatures to melt the snow in order to see it disappear. In the dry valleys, the air is so dry that the snow will sublimate: turn directly from solid (snow) to gas (water vapor) and disappear from our view. On Thursday morning, there was a little over an inch of snow on the ground, but it all disappeared that day even though the air temperature never got above freezing.

These are all photos of roughly the same scene behind our hut at F6, looking north at the Kukri Hills. Here it is at 9:00 in the morning with an inch of snow, while it was still snowing a little bit. You can't even see the mountains because the clouds are so low:

And at noon:

And at 2:30 in the afternoon:

And at 6:00 pm:

And 7:30 pm:

And by midnight, it was gone:

Similarly, another group here has a camera set up in a different valley, called Wright Valley, and are taking time-lapse photos of one particular area. You can see snow come and go over the course of hours! Click here to see it on YouTube.

We think that most of the snow turns into water vapor, but some of it does melt. That extra moisture in the soil will be really important for the organisms living in the soil that are usually water-deprived. To find out how much moisture was getting added, we decided to take soil samples under the snow as it was ablating. Every few hours, we scraped away the snow and took soil samples from the surface (0-2 cm into the ground) and just below the surface (2-5 cm into the ground). We'll measure the soil moisture of those soil samples to see how much water melts into the ground from the snow and whether it ever trickles down to lower depths in the soil.

Now that we're finally all back in the lab at McMurdo (but barely, we almost got stuck at Marble Point, the helicopter fueling station, for the night!), I spent the day weighing out samples for soil moisture. Tomorrow, I will know how much the moisture was influenced by the snow, and how quickly it disappeared!

Tomorrow, I'm heading to the field with Julia, Zach, and Bishwo to sample and treat the stoichiometry plots that are at Lake Bonney. It is supposed to be a day trip, though, so there shouldn't be any getting stuck.

Stoichiometry Sampling... a Little Late!

We finally got a small enough window in the bad weather for me to get out to the field yesterday. Now I'm back at Lake Fryxell. The work that needs to be done right now is the annual treatment of our Stoichiometry Plots. These are for a long-term experiment that has been going on for several years. We hypothesize that, if the climate warms, there will be more liquid water. With that liquid water comes more nutrients in the soil. We want to know how the soil organisms respond to that nutrient and water pulses to influence nutrient cycling so that we can predict how climate change might influence the soils. So, we are adding water and nutrients to simulate this type of change. Every year we add more nutrients and every two years we take soil samples to measure the response.

To add the treatments to the plots, we have to bring a LOT of water to the field: 775 pounds of water! That means we need a lot of team members to help us carry the carboys of water solutions. Because we've had so much bad weather, our team has had to split up a lot, so only 3 of us were being sent to Fryxell to do all of the work sampling and treating the plots. It is myself, Bishwo from Brigham Young, and Zach from Colorado State. Unfortunately, the weather went sour just about as soon as I landed, so Bishwo and Zach couldn't make it to join me! I did all of the soil sampling by myself, so that the samples could be sent back to the lab for processing. They had to wait overnight, because no helicopter could come pick them up. Luckily, there was another window in the bad weather this morning, and Zach and Bishwo were able to join me for our work, and that same helicopter took our samples home to be processed while we added the treatments.

We needed to add water solutions containing carbon, nitrogen, phosphorus, carbon+nitrogen, carbon+phosphorus, or just water (as a control) to eight sets of replicate plots at Fryxell. We carry the solutions to the field in 35 ten-liter carboys, and then transfer 5.6 L at a time to pour jugs with sprinkle caps to be applied to the plots. It takes a lot of organization and communication to apply the treatments to the plots without messing up. We can't add the wrong solution to the wrong pour jug, or pour the wrong solution to the wrong plot. If we mess up and add a nutrient to a plot that's not supposed to receive nutrients, we ruin years worth of data and the future of a long-term experiment! So, it was a challenge to do the work with so few people in a short amount of time, but without rushing and messing up. We worked out a system where I filled the pour jugs for Zach and Bishwo, who were each assigned to a particular nutrient treatment. We check and double-check that I'm filling their jug with the correct solution. Then I direct them to the correct plot to apply their treatment using a map. We have to check and double-check that they're at the correct plot before applying the treatment to make absolutely sure that the wrong solution doesn't get used. They use a fiberglass cone to contain the water to the necessary area while they pour in a spiral pattern. Otherwise, the wind would blow it away from the plot! Once they've applied the nutrient solution, they come back to be refilled. We're constantly talking to each other and looking where we're going. Here's a short view of how it worked:



Unfortunately, the weather went bad again, and now Zach and Bishwo are stuck at F6 with me! It's snowing outside as I type. But, at least the work is done and the samples are at home. The rest of the Dartmouth crew is busy in the lab processing the samples, because we're planning to do the second site for the Stoichiometry Experiment on Friday!

McMurdo Weather

After 4 days at station working in the lab, we were supposed to be going back to the field today. But we have yet another bad-weather day that won't allow us to fly! So this is a good time to blog about weather in McMurdo.

We are in a polar desert. That means that there is very little precipitation, just like deserts in the U.S. But this is a polar desert, which means it is very cold, not hot like deserts in the U.S. We do get storms here, but they are mostly made up of wind and clouds and involve only a little bit of precipitation. The little bit of precipitation we get comes as snow, and most of it returns to the air before it melts into liquid water on the ground (that's called sublimation). So, it occasionally snows in the dry valleys, but when it does, it usually only looks like this for a few hours before it disappears.
Right now, we have a snow system over us. In this radar image, you can see where I am right now at McMurdo Station (at the "You Are Here" arrow). There's a big bunch of clouds right over us and the dry valleys where we're trying to go! There's not a whole lot of snow coming down. There's just a dusting on the ground, but it really restricts visibility, especially over the ice. Here is a picture looking out of our lab window across McMurdo Sound on a normal, sunny day. You can see all the way across the ice to the Trans-Antarctic Mountains and the dry valleys where we do our research.

And here's a view out of our window today.

You can't see very far! And since the ice is white and the view ahead is white, helicopter pilots can't see the difference between the ground and the sky, which makes it unsafe to fly. We've had more snow than usual this summer. I've heard from people here earlier than me this spring that at one point there were eight inches of snow on the ground in the dry valleys! That means there's more moisture on the ground from the little bit of the snow that melts, and the soils are wetter than normal. Since the soils are so water-limited, that can change a lot!

Though it's too dangerous to fly, and it's cold and there are snow flurries, it is still not truly bad weather. This area can get far worse storms that include really strong winds and white-out conditions. The strongest and most dangerous type of weather is called a "herbie". Herbies are very strong windstorms coming from the south that bring along a lot of blown snow and very cold wind chills. They can come without much warning, and people will suddenly find themselves with no visibility and dangerously low temperatures. Luckily, they are not very common, and I haven't been here for a herbie yet. I have been here for a different type of windstorm called a katabatic wind. This occurs when cold air from the south gets pushed up higher in elevation to go over a mountain (like the Trans-Antarctic Mountains). Normally, cold air sits lower on the ground and warm air rises higher, because warm air is less dense. When cold air gets forced higher due to a mountain, it'll eventually reach the top of the mountain and then rush back down to the ground on the other side. It rushes down because it gets pushed down by the warm air waiting for it on the other side and squeezed into a smaller space of a valley. This can cause huge, fast gusts of wind that rush down the valleys where we work. We've seen tents be blown away before, and at times entire buildings have been blown apart. These happen most in the winter when there is a lot of cold air coming from the south, but there are occasionally katabatics in the summers, too.

To manage safety during these different types of weather, we use a rating system that restricts activity for people on base. Condition 3 means the weather is fine, and people can move about normally. Condition 2 means stronger winds and colder temperatures, and you have to receive permission to leave the base. Condition 1 means the weather has gotten really bad, and you're not allowed to leave the building or vehicle that you're currently in. So if it turns to Condition 1, you'd better hope you're in the Galley so you can have something to eat while you wait! We can find out what Condition we're in using these electronic notices posted around station, as well as colored lights that are mounted on the outside of the buildings.Even though the weather right now is bad and it's snowing, it's still Condition 3. We can move around base, we just can't fly. Our weather service on base is predicting snow for the next several days, so it's not looking good to get back into the field!

Our Group is Complete!

Our other two group members, Ross and Julia, arrived yesterday in Antarctica. Our group is now complete! We've been very busy working in the lab, but we plan to head back to the field on Monday. That's all the news for now!

Back at the Lab

Jen and I finally made it back to McMurdo Station! We got stuck at Fryxell camp for a couple of days. The weather over McMurdo was bad, so the helicopters couldn't leave to pick us up. But, the weather in the dry valleys was very nice, so it was a nice place to be stuck. It's good to be back in town, though, because we have to process all of those samples we took to start getting some data! Since we were a day and a half behind, it's been a very busy couple of days (but at least we had a chance to shower and put on clean clothes for the first time in 8 days).

There are a lot of chemical and physical properties we measure on our soil samples. Some of them get done here at McMurdo, and some wait until we get home. One of the basic things we measure here on our soil samples is soil moisture. We want to know how much water is in the soil. Knowing how much water is in the soil tells us how much might be available for organisms living in the soil that need water. (It also helps us standardize all of the other measurements we make. If we express the amount of nutrients per gram of dry soil, it's standardized among all of the different soils we measure, rather than changing based on the amount of water in each sample if we expressed it per gram "fresh" soil.) We measure soil moisture by simply weighing a subsample of the soil, placing it in an oven at 105°C, then weighing it again after 24 hours. The weight lost was water that evaporated from the soil. Jenn and I both have weighed a lot of samples to measure moisture over the past two days.
I also started working on the moss samples I took. To measure the nutrients in the moss, I first have to rinse away all of the soil that's mixed up with the moss. I have to do that using a microscope so that I can see that all of the little pebbles have been rinsed away.

Yesterday, our colleagues from Colorado State arrived from the U.S. So, the lab has become very busy! Tomorrow, the other two group members from Dartmouth are scheduled to arrive, and then our group will be complete! So will 2009!

Getting Our Feet Wet to Sample Moss

Most people think of Antarctica as being a big, barren land with no animals or plants living on it. That is not true! In fact, there are plants growing in Antarctica, even here in the dry valleys. You just have to look very closely to be able to see them, because they are small! The only plants we have in the dry valleys are several species of moss. They grow very slowly and are generally found only in small patches.

Moss has a lot of challenges to face to grow in the dry valleys. It's very dry here, so they cannot get much water to grow. The only time water is plentiful is during the 14 weeks of the year when the meltwater streams are flowing, and that water is only available if you're right next to the stream. Sunlight is also a problem. During the winter there's no sunlight for photosynthesis, but during the summer the sun can be so intense that it can actually damage plants. So, it takes a very hardy plant to be able to grow here! Most of the time you do not find moss that is lush and green, because it's usually too cold, too dry, or there's too much sun damage. Sometimes, though, you find moss that was recently uncovered by the water or a rock, and it is green and happy.

But, moss is the only above-ground life in the dry valleys. All of the other organisms live in the soil, not on it. So, moss are in a way like the redwood forests of the Antarctic Dry Valleys! They are one of the few sources of food for soil organisms. When mosses die, they decompose in the soil, just like plants in warmer climates. The carbon and nutrients released from mosses when they decompose are probably a very important part of the soil food web.

We want to learn more about moss's role in the carbon and nutrient cycles in the dry valleys, so one of our projects is to find out where they are getting their nutrients. Mosses grow in the soil like other plants, but are always very close to water. Are their nutrients coming from the soil or the water? Do mosses take up all of the available nutrients, or just some? We're trying to find out by taking from each location a moss sample, soil sample, stream water sample, and groundwater sample. (Groundwater on the edge of a stream can be very different from the stream water, and is more likely the water being used by moss when stream flow is low, which is most of the time!) We will measure the ratio of carbon, nitrogen and phosphorus in the moss tissue and see if it reflects the ratio in the soil or the water. If the ratio (called "stoichiometry") of the moss is more like that of the water than the soil, that would suggest that the nutrient source is the water. We've visited many of the streams and wet areas around Lake Fryxell and taken moss, soil, and water samples. You can see the patch of moss at the base of the rock that my backpack is on. Jenn is in Lost Seal Stream taking a sample of stream water. She pulls the water up into a giant syringe, then snaps a filter onto the end of the syringe and sloooooowly squirts the water through the filter to remove all of the sediment. If you click on the photo to make it bigger, you can see that between my backpack and Jenn is my setup for collecting groundwater. We use a miniature well system called a piezometer. I insert a long tube into the ground using stiff wire, then attach a hand-powered vacuum pump onto the end of it to suck water out from below the stream bed into a flask. The water comes out very, very silty so I will have to filter it using a more powerful setup back at the lab. You can see a groundwater sample on the rock next to my backpack (it's the bottle with the orange label).

We've visited several streams to do sampling like this so far. Each stream that flows into Lake Fryxell has a different ratio of nutrients. If the nutrient content of moss changes the same way that the streams change, this would be a clue that nutrients are coming from the stream and that mosses use all the nutrients that are available. If the nutrient content of the moss doesn't change with the stream and soil, this would be a clue that the mosses only take up a certain amount of nutrients no matter what is available. That would suggest that their role in nutrient cycling is more stable and less likely to change if nutrient availability changes.

This is one of the projects that Jenn and I have been working on this field this past week. We are trying to return to McMurdo Station tonight to process our samples and get ready for the next field project, but the weather is bad and the helicopters can't come get us! Hopefully we will get home tonight or tomorrow morning.

Merry Christmas

Merry Christmas from Lake Hoare, Taylor Valley, Antarctica!

Before we left F6 to come to Lake Hoare, Santa and his elves came to visit us by helicopter. They brought us a giant box of "freshies": fresh vegetables, fruit, and homemade cookies and bread! We aren't normally able to get a lot of freshies down here, especially in the field, so it was a very wonderful treat!
We arrived at Lake Hoare and were set to work decorating. We decorated Christmas cookies, put up the Christmas tree, and made a gingerbread house.
Then, we had a big family dinner! There are scientists from many different projects gathered here, so there were 15 people for dinner. After dinner, we played the "gift game" by the Christmas tree. I got a cool, new water bottle! Now, in Antarctica, it is the day after Christmas, and it is time to get back to work! We'll be hiking over the glacier to Lake Fryxell camp to sample mosses along some of the streams.