Saturday, December 17, 2011

The Hengill region became blanketed in snow much earlier this year than last. The snow has greatly limited our access to our sites. We've tried walking (3 hours one way), skiing (2 hours one way), and earlier we described what happened the last time we used a truck. On Friday, the University of Iceland's Geology department allowed us to rent a couple of snowmobiles and borrow Sveinbjörn, a technician who helped out with the equipment and our reconstruction of our heat exchanger. We were able to get to our sites in 20 minutes on the snow mobiles (pics 1, 2, & 3).

The dam feeding water from stream 7 into the heat exchanger was breached in late November. Before we could return and fix the system the water left in the pipes froze. The heat exchanger was fine.

Friday, we traveled in by snow mobile, rebuilt the dam, and excavated three different sections of iced up pipe. One section of pipe was covered in a meter of snow in places (pic 6). After excavating the pipes we let them thaw in stream 8 (20˚C) and then reattached all the piping (pics 4 & 5). Everything was running smoothly when we left Friday evening.

After we finished up with the heat exchanger we went over to our reference stream to retrieve some dissolved oxygen probes before the holiday break. Normally this is a 45 minute drive in the summer, but it only takes 20 minutes on snow mobiles. I know what I was for Christmas. About 70% of OH2 was covered in a layer of hard packed, wind blown snow (1 to 3 meters worth). Here is Jim trying to pull a probe out of the lower section of OH2. There's really a stream down there. I swear.

Wednesday, December 7, 2011


Hengill has gotten a lot of snow recently. So, for our December sampling we got help accessing our streams from the Hveragerði Rescue Squad. Most Icelandic towns have Rescue Squads. These are all volunteer organizations which help people lost, hurt, or stranded at sea, on land, and on top of glaciers. In their off time, they generously help us get to our field sites. The Hveragerði Rescue Squad has a truck with very wide tires. When the tires are slightly deflated the truck "floats" on the snow like its wearing snowshoes.

Last week we ran into some problems trying to drive into Hengill. While driving across a field we ran into a snow covered trench. The truck's front tires were hopelessly stuck. We had to call some people from the Selfoss Rescue Squad to pull the truck out.

The snow is just to deep for trucks. We'll have to ski or hike into our sites until the snow melts. Hopefully that will happen before May.

Tuesday, December 6, 2011

November Showers

After a fairly sunny summer, there has been a lot of rain this fall. In November, discharge in many of our streams was approximately 10 times higher than during the summer, although the discharge in some streams has hardly changed. These differences in flow arise because some of our streams drain large watersheds (like stream 14, shown above in Nov and below in July) while others have tiny watersheds and appear to derive almost all of their water from springs (e.g., stream 8). These differences in discharge variability among streams likely translates into large differences in disturbance. Disturbance is known to play an important role in shaping stream food webs and ecosystems.

Below, Wyatt dances while he measures nutrient uptake in stream 14 sometime in July.

Since the summer, we’ve been measuring the magnitude of disturbance in each of our landscape streams. We use super glue to attach tiny pieces of flagging tape to 50 randomly selected rocks in each stream. The photo below shows a transect of flagged rocks in stream 7. The flagged rock at the bottom of the photo has been moved downstream away from the transect.

After three months, we return to each streams and determine whether each rock has moved. In sum, these rock movement measurements give us a metric of the degree of disturbance in each stream.

Wednesday, October 26, 2011

Heat exchanger goes online!

What began as a pipe-dream (pardon the pun) more than two years ago has finally come to fruition. Five members of the University of Alabama team (Alex Huryn, Jon Benstead, Dan Nelson, Vija Pelekis and Philip Johnson) left on 19 October to install the heat exchanger at Hengill. Here we are unloading 750 lbs of gear at Birmingham airport. Those 14 bags came to $950 in excess baggage charges. Not bad for overnighting all that stuff to Iceland.

We were joined in Iceland by our stalwart postdoc Jim Hood and Ryan McClure, an undergraduate from Wyatt Cross's lab at Montana State University. With limited time, we had to hit the ground running. So the red-eye flight was followed only by a change of clothes, lots of coffee and obligatory hot-dogs. Then the rather groggy team headed out to Hengill for a long day's work, starting with some punishing sand-bag detail (Dr. Wyatt Cross's absence was more than conspicuous at this point :-) :). With the sandbags filled and carried to the site, we could begin constructing the heat exchanger. Here's a couple of shots of Alex Huryn and our intrepid engineer Philip Johnson joining the stainless steel pipes and starting to attach them to the PVC manifolds.

By mid-morning the next day, the heat exchanger was complete and the flexible 2" tubing for moving water through it was in place on the hillside. Here's a shot of the completed exchanger, with Alex, Philip and Gisli Gislason in the background.

It was soon lifted into place in the pool at the head of the warm stream and hooked up to the flexible tubing.

All that was left was to submerge the heat exchanger by damming the warm stream. Here's a shot of the completed set-up.

We could finally begin the warming manipulation, with immediate and impressive results! Here's a plot from four temperature loggers spaced along the experimental warming reach. All showed an increase of 3 degrees C (the upper logger [A] showed some variability as we adjusted the position of the diffuser at the outlet). This is good news, given that discharge in the cold stream is high at the moment, with only 40% of its flow going through the heat exchanger. Our potential warming will increase as discharge declines.

Here's a final shot from the opposite hillside, showing the position of all the components of the heat exchanger (including the vital engineer!). The whole set-up creates a ~30-m reach of the right-hand (cold) stream that will be warmed at 3 to 5 degrees C above ambient, hopefully for the next three years. We've already been studying this reach (and a reference cold stream) for a year. Every month we collect microbial, algal and invertebrate samples, as well as measuring nutrient uptake and whole-stream metabolism.

All in all, a fantastically successful trip and the result of many months of preparation by a large group of people. Special mention should go to our engineer, Dr. Philip Johnson, and Chau Tran, who helped Jon Benstead test the heat exchanger over the summer and then packed all of its components for shipping from Alabama.

Watch this space!

Tuesday, August 16, 2011

Looking back at a great summer

Hello! I am Brooke Weigel, the REU student on the project this summer. I was in Iceland from the 15th of June until the 6th of August. This summer was a fantastic learning experience – from both living in another country, far away in the middle of the Atlantic, and through the invaluable research experience that I gained working with many inspiring grad students and mentors. It was very exciting to be part of the first summer of the project, since we had to creatively adapt our sampling equipment and procedures, among other things, as the streams required . For example, during the July landscape sampling we did “nutrient slugs” on all of the streams (and almost all in one day!). During one slug on Stream 5, Wyatt and I discovered that the salt was traveling downstream at a much slower rate than was calculated previously. In the photo you can see Jim coming to the rescue with his computer; we quickly adapted to the new travel time and modified our timing of the water samples in order to capture all of the NaCl breakthrough curve. One of the most valuable things I learned this summer is that science is always a work in progress!

In addition to helping out with the July landscape sampling, Adam and I conducted an experiment to examine the influence of temperature on the processes of benthic nutrient uptake and metabolism (see previous blog post). It was fun and challenging to come up with the procedure for sampling these chambers, since they are usually only used for metabolism. At the very end of the summer, Adam and I worked hard analyzing the data for six of the streams that we sampled. I hope to be able to continue analyzing and interpreting at the data in preparation for the NABS science conference next year.

In addition to acquiring tons of great data, we had some time to explore the beautiful country of Iceland. Here is a photo of me scuba diving in a part of the mid-Atlantic rift, which runs through Lake Þingvellir and divides the North American and Eurasian plates. The water was even colder than stream 13 – it was only 3 °C! After the project was completed, our group had a wonderful time up at Lake Myvatn. From there, I traveled around the East Fjords and down along the south coast of the island. This summer was fantastic! Thanks to everyone who made it happen.

Thursday, August 4, 2011

Toom-Toom and Weigs

This summer we were lucky to have Adam Toomey and Brooke Weigel join our research team. Both are undergraduate scholars who conducted independent projects at Hengill. A Howard Hughes Fellowship supported Adam Toomey who will be a senior at Washington-Jefferson College (Washington, PA). Brooke Weigel was an REU Fellow. Brooke will be a junior this year at Saint Olaf College (Northfield, MN).

Adam and Brooke collaborated on a project examining patterns of epilithic metabolism and nutrient uptake across a temperature gradient. They incubated tiles in six streams varying in temperature from about 7 ˚C to 22 ˚C. After about month, Adam and Brooke used chambers to measure metabolism and nutrient uptake. Toom-Toom and Weigs (as they are fondly known in Hengill) used YSI probes to measure changes in dissolved oxygen (DO) during a “light” incubation (first picture) and then during a “dark” incubation (second picture). In the third picture Brooke is showing off our improvised battery pack.

Changes in DO during the “light” incubation reflect the balance of primary production and respiration. Dissolved oxygen changes during the “dark” incubation provide a measure of respiration (we assume primary production doesn’t occur in the dark). After the light and dark incubations, Adam and Brooke added stream water spiked with a small amount of nitrogen and phosphorus. They took several water samples over the next few hours to measure the uptake of nutrients by the epilithon. The forth picture shows Adam taking nutrient samples and the last picture shows epilithon from a cold stream greedily sucking up nutrients.

Toom-Toom and Weigs recently completed their projects. They hope to present their results at next summer’s North American Benthological Society meetings.

A very busy July for the team

July has been quiet with regard to blog posts, mostly because the team in Iceland has been slaving in the field. Now we're trying to catch up and post some news.

The landscape study kicked into full gear in July, helped by our two intrepid undergraduates, Brooke and Adam. Here we are unpacking the trucks for a full day of slug additions across the landscape gradient. These additions required a huge amount of planning and preparation, but went off without a hitch.

This shot gives some idea of how the team was spread out across the landscape during many days in July. I took this photo while doing slug additions in stream 9. In the foreground are Jim, Adam and Dan doing the same in stream 7. Further back, Junks is doing a slug in stream 6, while in the distance one can just see Brooke and Wyatt doing their slugs in stream 5. Beautiful! The question now is: can this be done in winter? We'll have to wait and see.

Rope sampler party

Our 'epirope-on' sampler. .  creative and nice. . .

Adam and Brooke show off the end result. These samplers have now been deployed across all the landscape study streams.

Thursday, July 28, 2011


July was a busy month in Hengill. Here are just a few highlights as we move into August.
Brooke sampling chambers during a nutrient uptake experiment

The beginning of the month marked the arrival of a few fresh faces as Adam and Brooke, two REU students working with us this summer, arrived and jumped right into field work.

<--- Brooke sampling benthic chambers during a nutrient uptake experiment.---

We also started sampling on the landscape gradient portion of the project, getting a helping hand from Wyatt and Jon. We had a lot of work to do across the 13 streams, but many hands make for light work –and good times. The landscape sampling flew by without a hitch, leaving us with samples to run and data to analyze. ---Wyatt preparing for a 'slug' addition--->

As the landscape sampling drew to a close so was July. As a break, we made a trip up to the north to explore the area around Mývatn and meet with fellow scientists from the University of Wisconsin-Madison studying aquatic-terrestrial linkages between Mývatn and the surrounding landscape. We had the pleasure of seeing some of their field sites and hearing about some of the awesome work they are doing up there. We very much enjoyed their hospitality and look forward to sharing many more good times together.

<---Dan 'stoic-ing' out---

Keep posted for more photos from July soon.

Wednesday, June 29, 2011

Shake-down for the heat exchanger

We've tested the heat exchanger and it passed with flying colors.

Alex was on the roof of the Bevill Building here at UA, which gave us a drop of about 7 m (a little less than the drop we have at Hengill). The hose could only get 0.3 L per second through the exchanger. Our flow at the field site will be higher than that, but the exchanger should be able to handle it. Now we have to take it apart and figure out the cheapest way to get it to Iceland.

Tuesday, June 28, 2011

Heat exchanger assembled (almost)!

Check it out! In a flurry of activity this afternoon, Chau and Benstead assembled the heat exchanger in two halves. It's all ready to carry outside - 12 connections and it will be in one piece and ready for flow and pressure testing. That will happen in the morning - watch out for a video.

Heat exchanger under construction

Here are some shots of the heat exchanger starting to come together in the Benstead lab. Here, Jon and Chau are getting ready to link up the 72 steel tubes to the manifolds. Note that Philip the Engineer is conspicuously absent for the construction phase...

We should be ready for a flow test in the next 24 hours. Watch this space. Then it will all have to be taken apart and shipped out to Iceland for the planned October deployment.

Tuesday, June 14, 2011

June Fieldwork

What do you get if you put two engineers and a stream together? A dam, of course!

We were joined in June by Drs. Pauline and Philip Johnson from the University of Alabama's Department of Civil, Construction and Environmental Engineering. Here they are busy doing some geomorphic work at the top of our warm stream (Stream 8). This is the eventual site for the heat exchanger that will warm water for the thermal manipulation of the adjacent cold stream.

The engineers are joined in this picture by Alex Huryn and Dan Nelson, the Ph.D. student who is working on the warming experiment. Philip is holding one of the manifolds for the heat exchanger. The whole thing will need to be submerged eventually. Hence, the need for some kind of dam.

In addition to planning for the construction and installation of the heat exchanger (set for September 2011), we also did a lot of fieldwork in Streams 7 and OH2, the two streams under intensive study as part of the warming experiment. Here's a shot of some benthic metabolism measurements under way at OH2.

Another task was to continue collecting reaeration data from Streams 7 and OH2. Here's a shot of our set-up for delivering a solution of rhodamine and SF6 to the streams using a gas bag and metering pump.

All in all, the June trip was a great success. We brought 500 lbs of gear to Iceland (for $110!), got a lot of fieldwork done and brought several months-worth of samples home safely. We even managed to get the dry shipper all the way home on the plane - quite a victory after some miserable failures.

Now we're gearing up for the very busy summer ahead. The undergraduate assistants arrive on 15 June and work on the landscape temperature gradient will start soon after. Let's hope for some pleasant weather!

Wednesday, May 18, 2011

The tubing for the heat exchanger arrives from Texas

This morning we took delivery of 800' of shiny stainless steel tubing. This means we're gearing up to put the heat exchanger together for installation into Hengill streams 7 and 8 in September (with help from Dr. Philip Johnson of UA's Department of Civil, Construction and Environmental Engineering). Watch this space!

Tuesday, March 1, 2011

February Trip

Back from another successful trip.  The weather cooperated for the most part, and we ate lamb testicles!  What more could you ask for?
Kid in the candy store.
Where is Stream 7?
Jim and Gisli sampling from 'the hole' in OH2
In the rescue team vehicle. .. .good stuff.
Rescue team leader from Hveragerdi

Jon in the midst of a nutrient slug.
A nice view of Hengladalir
Lamb testicles, whale blubber, fermented skate, smoked lamb, blood sausage, sheep head. . and more. . .thank you Gisli!
Jim looks scared as the lamb testicles arrive. . .