Icebreaker Oden, Arctic Ocean, 26 August

For a couple of days, I have had the privilege of taking part in the work of the marine geology team. The group is led by Professor Matt O’Regan from Stockholm University. He is joined by four young researchers: Albin, Jena, Miriam and Rune. All four have their own research interests within marine geology. Marine geology encompasses many different areas, but an important one is the study of the layers of clay and sand, known as sediments, that cover large parts of the world’s seafloor. These historical archives hold clues to both the past and the present.

A 12-metre-long piston corer

Bringing sediment up to Oden from depths of several thousand metres requires a bit of preparation. Three days are spent assembling the sampling equipment. Three- to four-metre-long steel pipes are joined together to form what is known as a piston corer. Weights are attached to the top of the piston corer to help drive the tube into the seafloor. This is heavy equipment, and the piston corer weighs close to two tonnes when fully assembled. A plastic tube is placed inside the 12-metre-long piston corer. This is where the sediment is collected in the form of sediment cores.

The work is physically demanding, and everyone except Matt is new to it, but the team works well together and tackles the challenges with plenty of determination and humour. It turns out that Albin is an active powerlifter, which comes in handy when the 68-kilogram lead rings have to be attached to the piston corer.

2,250 metres down to the seafloor

Then, on a fine – well, sort of – day, we reach the position for sediment sampling. Oden takes position beside a suitable ice floe, and we gather on the aft deck. There are a couple of substantial cranes there that are a great help. They are operated by the Swedish Polar Research Secretariat’s highly experienced staff, who have countless polar expeditions behind them. That is reassuring, given the considerable forces involved. A couple of crew members also assist with crane operations and safety. Yours truly has been given the honourable task of handling radio communications with the bridge. This year’s artist, author Andreas Norman, also joins us for some of the heavy work.

As the piston corer is hoisted into the air, it is partly guided by hand by two experienced marine geologists standing at the very stern of the icebreaker, on the fantail. They are also responsible for keeping the stern clear of ice floes during the sampling operation. This means several bitterly cold hours in snow and wind.

Lowering the piston corer 2,250 metres to the seafloor takes about 30 minutes. Once it reaches the bottom, a trigger corer initiates a free fall of around three metres, giving the piston corer an extra push down into the sediment. The deeper the piston corer penetrates, the greater the hope of recovering a long, intact sediment core.

On the way back up, there is plenty of speculation about how much sediment we might have recovered. I put my money on 11.2 metres, which turns out to be the winning guess.

11.5 metres of Arctic Ocean history

When the piston corer finally lies back on the aft deck, the classic call “Core on deck” comes over the radio and a flurry of activity begins. The researchers quickly gather around the piston corer to take care of the sample. The plastic tube is removed and cut into shorter, 1.5-metre sections. The sections are labelled and taken to the laboratory on the foredeck for further analysis. The result is an impressive 11.5 metres of sediment.

After more than five hours in snow and cold, the last hardy members of the team leave the aft deck and head inside for a late lunch. Any image of academics as impractical, delicate and pale from life indoors has been blown away for good.

Text: Henrik Swärd