These data are (1) porewater extractions of cores of the permafrost and active layer of Adventdalen, Svalbard, (2) solid-phase extractions of the same cores, and (3) in-situ porewater sampling from the end of the summer, 2017. The aqueous parameters are: major ions (Ca2+, Mg2+, Na+, K+, Cl-, NO3-, SO42-), Fe(aq), Mn(aq), aqueous CH4 and CO2 concentrations, delta 13C- CH4, acetate, propionic acid, isobutyric acid, butyric acid, isovaleric acid, valeric acid, isocaproic acid, caproic acid, heptanoic acid, pH, oxidation-reduction potential, dissolved oxygen and alkalinity. The solid parameters are: organic carbon, nitrogen, acid volatile sulphur (AVS), chromium-reducible sulphur (CRS), amorphous and nanoparticulate iron (oxyhydr)oxides, crystalline iron (oxyhydr)oxides, iron bound in carbonates, and magnetite.

Funding was provided by the NERC grant NE/M019829/1.