Trace element, rare earth element and trace carbon compounds in Subglacial Lake Whillans, West Antarctica

Whillans Subglacial Lake (SLW) lies beneath 801 m of ice in the lower portion of the Whillans Ice Stream (WIS)in West Antarctica and is part of an extensive and active subglacial drainage network. Here, the geochemicalcharacterization of SLW rare earth elements (REE), trace elements (TE), free amino acids (FAA), and phenoliccompounds (PC) measured in lakewater and sediment porewater are reported. The results show, on average,higher values of REEs in the lakewater than in the porewater, and clear changes in all REE concentrations and selectredox sensitive trace element concentrations in porewaters at a depth of ~15 cm in the 38 cm lake sedimentcore. This is consistent with prior results on the lake sediment redox conditions based on gas chemistry and microbiologicaldata. Low concentrations of vanillyl phenols were measured in the SLW water column with higherconcentrations in porewater samples and their concentration profiles in the sediments may also reflect changingredox conditions in the sediments. Vanillin concentrations increased with depth in the sediments as oxygenationdecreases, while the concentrations of vanillic acid, the more oxidized component, were higher in the more oxygenatedsurface sediments. Collectively these results indicate redox changes occurring with the upper 38 cm ofsediment in SLW and provide support for the existence of a seawater source, already hypothesized, in the sedimentsbelow the lowest measured depth, and of a complex and dynamic geochemical system beneath the WestAntarctic Ice Sheet.Our results are the first to detail geochemical properties from an Antarctic subglacial environment using directsampling technology. Due to their isolation from the wider environment, subglacial lakes represent one of ourplanets last pristine environments that provide habitats for microbial