24-hour mission

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.