By: Abbi White, Bree Vculek, and Hilary Madinger
Last night
we spent the night under the Icelandic midnight sun camping at our Hengill
sampling sites. It was an unbelievably beautiful night! Sunday afternoon was a
rare Icelandic sunny day and the night was a continuous sunset. We were even
visited by Jill and Jon who delivered pizza, falafel, and chocolate (Sirius
chocolate, an Islandic treat). Perhaps our experience wasn’t quite rustic…
The
mission for our trip was to try collecting diel (24 hour - hence the overnight
camping) water samples to calculate net nitrogen fixation. Every hour we
collected water samples, temperature, and air pressure from the stream in two
different places. When we are all done sampling, the water samples will fly
back to Wyoming with Hilary to be analyzed on a membrane inlet mass
spectrometer (MIMS). Then we will run the data through a model to estimate net nitrogen fixation. The basic idea of how the model works is that using the
temperature and air pressure measurements we can calculate what the expected
dissolved gas concentrations of the stream would be if it was in equilibrium
with the atmosphere. But streams are not at equilibrium because there are
biological processes changing the dissolved gas concentration. So we will
compare the dissolved gas concentration in our water samples with the
concentration we expect due to temperature and pressure alone and the
difference in the dissolved nitrogen = net nitrogen fixation!
Since we collected
hourly samples, we also had time to do a bit of exploring in the valley. We
went for a midnight hike up one of the mountains, kept our feet warm with mud
from a hotpot, drank water from a spring head, and embraced nature for a night.
We also squeezed in some additional stream measurements to help with our
analysis. Overall, we had a great time together sampling and camping and highly
recommend the experience. Now we are anxious to see how the results look.