It happens during the sea-ice coring when Anna Silyakova, Henry Patton and Christine Lockwood-Ireland are on the ice pack. The team has to leave coring and get quickly onboard where they can enjoy the sight of the big carnivore passing by with the rest of us.
Text and photo: Mauro Pau, researcher CAGE.
Anna Silyakova collects ice cores to investigate methane-associating processes within sea ice. Methane is a greenhouse gas, and as it rises through the water column it gets captured within the sea-ice structure during ice formation.
Although ice typically behaves as a barrier for gases to go through, sea ice is often permeable and a great mediator of gas exchange in polar regions. Being porous, adds Anna, sea ice provides paths for gases like methane to pass from the ocean surface to the atmosphere where it can make an impact on climate.
Subsequent to the sea-ice coring, we deploy the cam-pod with the aim to visually inspect the seabed for gas flares while drifting with the sea-ice at around 0.2 knots. Unfortunately, when the camera is already at 2500 m depth, or a mere 200 m from the seabed, the electrical transformer of the cam-pod system fails. Since there is no spare transformer on board, we will not be able to use the cam-pod during the cruise.
We finally are on the continental slope (water depth around 400 m). Sea-ice proved hardly predictable and forced us south of our desired study area, but as from today we are nonetheless able to study an area on the continental margin of Greenland. The acoustic team conducts a multibeam echosounder and chirp sub-bottom profiler survey, based on which they select three sites where to collect gravity cores and multi-cores, as well as to perform CTD casts. Due to tough sea-ice conditions, however, we skip the second station whilst at the third we only deploy the multi-corer. We do so through the moon pool, the port in the hull of the ship, which was previously occupied by the cam-pod system. Out of the six core liners, only two make their way back to the ship, luckily with enough material. The acoustic survey goes on for the rest of the day.