Forskargruppen ombord Electras akterdäck under expedition utanför Nynäshamn.
Photo: Department of Environmental Science

The thawing of permafrost is one of the sources releasing old stored carbon and greenhouse gases. In the extensive shallow ocean of the Siberian shelf, where thawing occurs at large scale, researchers investigate how carbon, nutrients and other substances are processed and transported to the ocean and the atmosphere.

- We want to find out what is happening with permafrost on land, along the coastline and in the ocean floor, says Örjan Gustafsson, Professor in Biogeochemistry at the Department of Environmental Science. We study what happens when substances reach the ocean through coastal erosion, rivers and as gas from thawing permafrost also in the bottom sediments; how ocean acidification is affected and how large the atmospheric transport is. Parallel to this, we look at the quantities being buried in the sediment and how much that is transported to deeper layers of the interior Arctic Ocean.

RUS-SWE expedition awaits

Together with 14 other researchers at Stockholm University, Gustafsson will participate in the Russian-Swedish Arctic expedition The International Siberian Shelf Study (ISSS-2020) during 45 days in September-October. This active collaboration goes two decades back and this year’s extensive expedition include 12 different focus areas, so called work packages. Since the Swedish team is big and several methods will be used, a trial week has just been performed at R/V Electra outside Nynäshamn, Sweden, to establish the working routines.

Multicorer going into the water.
Multicorern, with a capacity of sampling several cores simultaneosly, going into the water. Photo. Thomas Strömsnäs

- We have had four full days of sampling of everything from sediments to particles and dissolved substances in the water column and also gases, Gustafsson explains. We have three different sediment sampling systems, including a newly constructed multicorer that can collect eight cores simultaneously.

The soft bottom of the ocean can reveal a lot of information about how the climate has changed historically. In deep sediment cores, researches can see how the climate warming 12 000 years ago affected the release of organic matter and greenhouse gases. By understanding the degrading processes of different organic materials, Gustafsson and his colleagues hope to be able to forecast how the climate in the future will be affected by warming-induced permafrost thawing and resulting release of old carbon and greenhouse gases.

- We need to understand the system and the processes to be able to predict the extent of emissions for the coming decade and century, he says.

Golden oldie supplements modern technology

The water column has also been sampled and in general, this field work has a distinct high-tech character. However, the team has also brought along equipment with a good bit of history from Swedish marine research.

- We have a 60 liter GoFlo water sampler that has been with us since the first modern expedition to the high Arctic Ocean, the Ymer-80. The larger volume is required for some measurements, as in our case where we perform a quite rare carbon-14 dating of methane. That is important to understand the origin of the methane, Gustafsson explains.

Potent greenhouse gas in focus

During the ISSS-2020, one working package will focus on one of the most potent but anonymous greenhouse gases nitrous oxide, commonly known as laughing gas. This is an area that has been poorly researched, especially in marine environments.

- Nitrous oxide is a very strong greenhouse gas, probably the third after carbon dioxide and methane. It has mostly been studied in the context of agricultural systems. It is also formed naturally in the environment but we don’t know how much it is to start with, says Birgit Wild, Assistant Professor in Biogeochemistry at the Department of Environmental Science and leader of the work package.

According to her, it is tricky to estimate the emission of nitrous oxide since several mechanisms are involved to form it from the nitrogen released from thawing land and subsea pemafrost. She emphasizes why we need to fill this knowledge gap.

- If we want to reduce our emissions, we have to have a good overview of the sources. We want to study these mechanisms in the fall, but first we have to set up our methods. That is what we have been doing on Electra this week, and it has been working better than expected, Wild explains.

“Great that more researchers use the infrastructure”

And her colleague, also a first-time user of the University’s research vessel, shares the opinion of a successful week in field.

- I have been doing some research in the Baltic Sea previously but never onboard Electra. It has been great fun for our different research groups. The crew is fantastic and the vessel is very well suited for sampling all parameters that we need. It is great that more different research teams use the infrastructure, Örjan Gustafsson concludes.