The End of the Season

It's packing time here at McMurdo. Everyone is in from the field, and all our gear has been cleaned, and  repacked, and put away for the long Antarctic winter. The team has spent hours preparing our water and soil samples to ship north--lots of weighing and drying means hours in the lab.

But the payoff is worth it. We're already getting geochemical data back from our colleagues here from the start of the season in Garwood Valley, and have found some incredibly dense brines in the ponds at the mouth of the valley. What this all means for the evolution of water tracks and buried ice is something we're still mulling over, but the initial results are very exciting.

In the mean time, Jay Dickson sent along this little animation. It shows the Garwood Valley gang in front of the ice cliff. I think it's a good example of the lengths you sometimes have to go to to get the right sample here to answer your questions. The key to success: don't look down.

Going up....

So much snow

Snow in McMurdo, coupled with some icing conditions that make it to dangerous for the helicopters to fly, have kept the team grounded again today. Still, a flightless day can be profitably spent. Yesterday, the team dodged snowflakes and raced back to New Harbor to move some of Chris Thomas' CO2-sniffing equipment. Alex and Chris stayed overnight in our old camp so they could finish fine-tuning the station, while Brendan and I flew back to Lake Hoare with samples and lab equipment that we had left behind during our last camp move. Chris and Alex are hiking back up the valley even as I type this. It's a rather long walk, but the scenery is spectacular!

I spent the day doing much less entertaining chores than hiking home. We've been so successful sampling Taylor Valley's groundwater that a backlog of raw samples had piled up in the lab fridge. My chore today was to filter all of the muddy water we collected over the last few days so that it could be analyzed (the chemical analysis tools used by Kathy Welch and Berry Lyons--our collaborators at the other OSU) don't handle mud very well, so we have to filter out the clay and silts that hang out in the water tracks.

The water has to be filtered by hand, using syringes to push water through very fine filters (imagine a strainer with holes in it that are half the width of a human hair). We have to hand filter because one of the things we measure about the water (its isotopic composition) needs to be kept free of contamination. If we used a re-usable, automatic filtering system (like a vacuum pump), we'd have to wash it out every time we used it...and then all of our samples would look like the wash-water, and not like Antarctic groundwater!

My day's work is now neatly stacked in the fridge, awaiting analysis. Satisfying, but I'd rather be out on a mission gathering more samples in a neighboring valley.

It might not look like much, but there's a lot of water tracks represented in those bottles. You can tell it's a lab fridge because there's no old pizza in it.

Taylor Valley Variety Show

The helicopters don't fly on Sunday, so since our work in the Lake Hoare basin is done (at last!), today has been a day for rest and relaxation...and backing up data, and filtering samples, and cleaning gear (so, actually, it's been a kind of busy day).

I thought that it might be fun to post a few photos that help capture what the team has been up to here. In no particular order, here's a few snapshots of life in Taylor Valley.

The Canada Glacier and Lake Hoare (covered in ice). You can see the camp to the left. The blue dots are buildings and the yellow triangles are Scott tents.

Chris Thomas relaxing after a long climb up from the lake shore. 

Sampling snow and ice that feed the water tracks. 

Those piezometers I talked about in the last post? This is what they look like. All the polkadots are holes that will let groundwater ooze in once the piezometer is hammered in. This process is surprisingly satisfying. 

Alex Rytel and I sampling some soil on a water track. The Suess Glacier is in the background, with Lake Chad and Lake Hoare next to it. It's a rather scenic spot to do fieldwork in. 

All these photos come from Brendan Hermalyn, who was on photo-documentation duty (that's why there's no shots with him in them). 

Brine time!

It’s been a busy few weeks here in Antarctica, which is why there have been so few posts lately! I’ve been working with my team—up to 9 other outstanding scientists—which has kept me running around all day getting the junior team members trained up so they can work on the water tracks and buried ice projects, and helping the senior team members implement their own field experiments. With so many big and small projects going on up and down the whole length of Taylor Valley, it’s been hard to find a minute to post!

So, what have we been up to?

The team has been trying to figure out how much water and how much salt is moving though the ground here in Taylor Valley. Groundwater is a big part of the total water budget in the valley, but nobody knows for sure how much there is—that’s what we’re here to figure out. The organisms living in the soil in the Taylor Valley ecosystem, from the smallest microbe to the biggest nematode (okay, nematodes aren’t that big, really), rely on groundwater to survive. These organisms also rely on the groundwater to bring them food—in the form of nutrients—but are also at risk of being pickled if too much salt gets into the groundwater. The soil here is VERY salty—so much so that crusts of salt show up on the ground, looking like frost on the ground on a winter’s day at home. Because salt dissolves in water, we’ve been trying to follow the water and follow the salt. When groundwater and soil salts combine, you get a salty liquid, sometimes called a brine (if you’ve brined your Thanksgiving turkey by soaking it in salt water, you’ve experienced a piece of what it’s like to work here).

All the brown you see in these satellite images is the cold dirt of Taylor Valley. Green dots are where our camps are. 

We’ve been moving through Taylor Valley over the last few weeks, bouncing from camp to camp every few days. It feels like we’re bunch of roadies following a band on tour, except we’re following the brine (“The Brine” would actually be a pretty good name for a band). So far, we’ve visited New Harbor (a beautiful camp on the frozen coast of the Ross Sea), Lake Hoare (my old home away from home next to the Canada Glacier), and Lake Bonney (the furthest field camp from the sea).

At each camp, we’ve been trying to tap into the salty brines that flow through the ground. We track them by following the salt crusts they leave at the surface and by looking for lines of wet soil that point downhill. Water flows downhill, even when it flows through the soil, so dark lines of dirt mean water movement below! These groundwater flow lines are called “water tracks.”

A water track--can you dig it? The water flowing downhill wicks up and darkens the soil. Stolen shamelessly from Becky Ball's Polar Soils blog. 

To tap the brine, we’ve been hammering in pipes into the dirt that have lots of holes in them—like a kitchen strainer. These pipes are called piezometers. Groundwater flows into the piezometers and we can stick in a tube to suck it up into our sampling bottles. It’s like sticking a straw into the Earth. The water we get out can be analyzed by the members of our team to find out what kinds of salts are in the water (this tells us where they water came from), how long the water has been in the ground, and how much biological activity has occurred in the water).

We’ve also been trying to monitor what the water tracks have been doing using a bunch of different technologies. Chris Thomas, a team member from Oregon State University, and Becky Ball, a team member from Arizona State University, have been measuring how carbon dioxide (CO2) moves into and out of the water track, as the creates living in the ground breath. Brendan Hermalyn, a team member from the University of Hawaii has been using infrared cameras (that measure the temperature of the whole landscape) to determine how the water tracks heat up and cool down. Because the water tracks are dark in color, they absorb a lot of sunlight—but because they’re wet, they cool by evaporation (the same way sweating cools you off). We’re trying to figure out how these processes interact to make water tracks suitable for the critters that live in them. Jay Dickson has been working on recording flow in the water tracks using time lapse photography—a process similar to the one I used last year to look for water tracks on Mars! And Alex Rytel, a recent grad from Ohio State University, has been helping me measure the electrical conductivity of the landscape. Wet, salty soils are very good conductors, whereas dry soils are electrical insulators. By looking for the physical fingerprint of water tracks, we can see how they move brines through the soil.

As you can tell, we’ve been very busy! Tomorrow, it’s off to our next camp at Lake Hoare. Time to get packing!