Nautanen field work

Nautanen field work:
Confessions of a new PhD student

Sandra Fischer, PhD student in Physical Geography, Stockholm University

Nautanen is an old mining community in northern Sweden that bears witness to many of the questions in focus for REXSAC. In early September, a group of REXSAC PhD students and senior researchers traveled there for an amazing fieldwork campaign.

I am a PhD student within REXSAC and my adventure started a week earlier than the rest of the REXSAC group, when Jerker Jarsjö, my supervisor, and I went to our study site in Gällivare. Our research topic during this field campaign concerned the environmental impacts of mining and pollutant pathways, specifically from the closed mining site Nautanen, where copper mining took place from 1903 to 1908.

So how do you do this? How do you plan a field campaign, decide what to measure, how to measure it, what equipment to take (including spares if something breaks), and then figure out how to transport everything to and from the field? Wow, so many small details that are crucial for a good field campaign. I usually brag about my organizational skills but this was a completely new level!

Our goal was to try to capture how contaminants behave in Arctic environments and to understand what geochemical and hydro-climatic processes are involved in the transport pathways around Nautanen. So, we could just take some water samples and then send them back to the lab, easy-peasy, right? Nope. I realized it is far from easy. For example, water samples need to be prepared with highly concentrated nitric acid as soon as possible after the sample has been taken. But you cannot bring acid on an airplane and PostNord or DHL are not too eager to transport it. Therefore, I would have to take the train with the acid (not sure though about their regulations…) and Jerker the plane with all the heavy equipment. Ok, good.

All pre-planning arranged, we arrived at Gällivare, had a rental car to reach the site, and found our hotel. From the hotel, the drive out to the field site takes about 20 minutes. On the first trip to the site we learned that this 20 minutes can’t be rushed; a fast drive with a city car on an extremely bumpy forest road is not going to end well for the car. Our car had to be towed away after a gouge in the oil tank. Ehem. The next day we had a new car and everything was fine but now we had learned our lesson.

In the field, we collected water and sediment samples, measured some parameters directly (e.g. pH, water temperature) and measured streamflow at each sampling point. We estimated streamflow by standing in the middle of the river with a small propeller attached to a stick. The water is freezing cold even in wading pants. We then counted how fast the propeller rotates in the flowing water, and from this calculated river discharge. This allowed us to relate discharge to metal concentrations in the water, and therefore the total mass of metal transported in the system.

After a day taking samples, we spent the evening preparing them for transport and analysis. This mainly involves transferring and redistribution samples to small test tubes, which are sent back to Stockholm University. In practice, it meant many late nights wearing white gloves, filtering water samples, and adding nitric acid for preservation (which was scary, it has a concentration of 70%, so you do not want that on your skin). At the same time, you should keep track of the samples and not mix up sample N13-M-uf-b with sample N13-M-f-a, even if it’s in the middle of the night.

Later, the rest of the REXSAC team met up at the Nautanen site for some thorough interdisciplinary fieldwork. We had a tight schedule with different teams going back and forth between Nautanen and Gällivare for interviews, sampling, documentation and mine visits. For the environmental sampling, we wanted one last sample from Nautanen: lake sediment. In lake sediments, we could potentially get a historical record of the activities in the lake and an understanding of what kind of water and sediment that has been passing through the system. Since bringing a boat from Stockholm University all the way to Nautanen was impossible, even for my organizational skills, we rented two large canoes outside Gällivare to get out on the lake. To find a good sampling point in the lake we first needed to locate the lake’s deepest part (presumably where most sediments would accumulate).

With sonar equipment in hand, we paddled across the lake a few times to get a feeling for the bottom conditions. Most places had a depth of about 4-7m but suddenly the bottom dropped from 6m to 18m… 30m… 40m! And then 6m again. We found several of these very deep holes and I started to imagine a Nessie monster hiding in deep, dark caves. Maybe these samples were not that important after all. But my other supervisor, Ninis Rosqvist, didn’t give up and went out again on the lake to map these deep submarine shafts. Ten minutes later she was back and said something was wrong with the sonar equipment and the deepest part was only gradually getting to 15m. All normal. No Nessie monsters. We can take samples. Phew. Still a bit uneasy (just me) we went back on the water. Now the tricky part began. Ninis, with sediment sampler in hand, me with the sonar equipment and a team of excellent paddlers: PhD colleagues Chris, Jasmiini and Jean-Sébastien in turns. Ninis lowers the sampler carefully into the water. When pulled up just below the water surface I put a piston at the bottom to prevent the sediment sample from pouring out. We did it! We have a sediment core from the lake bottom! Then back to the shore and by a cheese-slide technique (not the technical term) to divide the core into 0.5cm samples in small plastic bags. Phew. We managed.

A lot more was going on at Nautanen at the same time. We all helped with documenting old house foundations and prepared drone flights to take aerial photos. There could be material for a whole novel about all our experiences this week, but this is a snapshot on what I am doing with my research. As always when meeting the REXSAC team, it is inspiring, on a tight schedule, full of laughter and a lot of new thoughts. I am so grateful to be part of this project and to learn about interviewing techniques, how moose behave in the winter, see the gigantic Aitik mine, and to get to know all these amazing people! During the fall, I will analyze and start interpreting all the results from this field campaign. I will keep you updated!

Image: Lake sediment sampling at Nautanen mining area, northern Sweden. Sandra Fischer (left) and Jasmiini Pylkkänen (right) are dividing up the sediment core into smaller plastic bags for analysis. Photo: Christian Fohringer