Production time series of H2, CO2, CH4 and C2H4 production after comminution of Subglacial Lake Whillans sediments and solute composition of water.

Four depths within a sediment core collected in Subglacial Whillans were used to investigate the potential contributions from crushing to the gas and nutrient pool in subglacial environments. These depths were used to produce three samples: SLW Top (0-4 cm), SLW Mid (an amalgamation of 14- 16 and 28-30 cm depths) and SLW Bot (36-38 cm). Sediment samples were dried and disaggregated/crushed under low energy (LE), and then further crushed anoxically using a ball mill for 30 mins at 500 rpm (HE). Headspace gases were analysed immediately after high energy crushing. Subsamples of HE and LE crushed sediments were analysed to determine surface Si radicals produced and H2O2 produced after two minutes reacting with anoxic H2O2. Approximately 3g of HE and LE sediments were transferred to serum bottles, where they were incubated with 4ml of anoxic water. A dry control of HE sediment was kept for SLW Mid. Headspace gases were analysed before the addition of water and then again after 2 mins of reaction, with further headspace gas analysis taken after 1, 2, 5, 21 and 41 days. At the end of the incubation period, the slurry was filtered and analysed for concentrations of Na+, Mg2+, K+, Ca2+, F-, CH3COO-, Cl-, Br-, NO3-, SO42-, NH4+, NO2-, dissolved Si, PO43-, Fe2+ and total Fe.