Biosignatures of in situ carbon cycling driven by physical isolation and sedimentary methanogenesis within the anoxic basin of perennially ice-covered Lake Untersee, Antarctica

Organic biomarker distribution and stable isotope composition was used to investigate biogeochemical carbon cycling in the anoxic basin of Lake Untersee, Antarctica. Phospholipid fatty acid (PLFA) concentrations indicative of microbial abundances were low in the oxic water column overlying the basin but rose in the suboxic transition zone and further increased within the underlying anoxic water, with the highest abundances near the sediment …