Between December 2012 and March 2013, snow measurements were conducted at both Gourlay Snowfield and Tuva Glacier, Signy Island. Sites are denoted ''TX'' and ''GY'', where ''X'' and ''Y'' are numbers representing one of nine snowpits in a grid at Tuva and Gourlay respectively. Measurements include snow water equivalent and chemical properties. Snow thickness was measured during the surveys (and opportunistically following fresh snowfall events) at all 18 snow pits using an avalanche probe (average of 3 readings per sampling site). Snow density was also assessed at each site using a 1L pvc. snow tube. The thickness of the superimposed ice was measured at the beginning and at the end of the season after excavation using an ice axe. In order to calculate the proportion of the total winter accumulation that was transformed into superimposed ice by refreezing, its density was assumed to be 0.9 kg L-1. Three surveys at each of the 18 sites were conducted for biogeochemical conditions: ''top'' refers to the upper 20cm; ''mid'' refers to the rest of the snow; and ''ice'' is the basal ice (refrozen snowmelt on top of last summer''s surface). Key chemical properties determined include pH, dissolved organic carbon, total dissolved inorganic carbon, ammonium, chlorophyll and major ions. Funding was provided by the NERC grants NE/H014446/1 and NE/H014802/1.

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.