Cryogenic gypsum collected during PS106-1/2 in 2017

In June-July 2017 we sampled cryogenic gypsum under pack-ice in the Nansen Basin north of Svalbard using a plankton net mounted on a Remotely Operated Vehicle (ROVnet). Cryogenic gypsum crystals were present at all sampled stations, which suggested a persisting cryogenic gypsum release from melting sea ice throughout the investigated area.

This was supported by a sea-ice backtracking model indicating that gypsum release was not related to a specific region of sea ice formation. The observed cryogenic gypsum crystals exhibited a large variability in morphology and size, with the largest crystals exceeding a length of 1 cm. Preservation, temperature and pressure laboratory studies revealed that gypsum dissolution rates accelerated with increasing temperature and pressure, ranging from 6% d-1 by mass in Polar Surface Water (-0.5 °C) to 81% d-1 by mass in Atlantic Water (2.5 °C at 65 bar).