Classification of frozen cores from Ilulissat, Greenland: Boreholes drilled in 2018 and 2021

DTU Sustain has conducted soil classification experiments on permafrost cores, extracted during summer 2018 and spring 2021, from boreholes located in Ilulissat. These laboratory investigations included frozen state description of the cores, determination of bulk properties, ice saturation, pore water salinity, organic content and grain density, and grain size distribution analyses.

In early spring 2021, cores were retrieved in the field when the active layer was still frozen. Results from the laboratory experiments show that samples from the active layer generally have a lower water content. The top of permafrost is characterized by very ice rich material, while the ice content decreases at greater depths. Pore water salinity is very low or negligible within the active layer and oppositely increases with depth.

In comparison, cores were retrieved when the active layer was unfrozen in summer 2018. Samples from the active layer have a higher water content than frozen samples collected in 2021 at comparable depths. Similarly to the borehole profiles from 2021, ice rich layers are observed at the permafrost table, and the ground ice content decreases with depth in conjunction with rising pore water salinity.