Scientific access into Mercer Subglacial Lake: scientific objectives, drilling operations and initial observations

• DOI: 10.1017/aog.2021.10
• Publication Date: 2021-06-08T09:43:40Z
• Authors: John C. Priscu; Jonas Kalin; John Winans; Timothy Campbell; Matthew R. Siegfried; Mark Skidmore; John E. Dore; Amy Leventer; David M. Harwood; Dennis Duling; Robert Zook; Justin Burnett; Dar Gibson; Edward Krula; Anatoly Mironov; Jim McManis; Graham Roberts; Brad E. Rosenheim; Brent C. Christner; Kathy Kasic; Helen A. Fricker; W. Berry Lyons; Joel Barker; Mark Bowling; Billy Collins; Christina Davis; Al Gagnon; Christopher Gardner; Chloe Gustafson; Ok-Sun Kim; Wei Li; Alex Michaud; Molly O. Patterson; Martyn Tranter; Ryan Venturelli; Trista Vick-Majors; Cooper Elsworth
• Keywords: 550; glacial sedimentology; Biogeochemistry; 15. Life on land; basal ice; 01 natural sciences; 6. Clean water; Glacial sedimentology; Antarctic glaciology; biogeochemistry; 13. Climate action; Meteorology. Climatology; subglacial lakes; 14. Life underwater; QC851-999; Subglacial lakes; Basal ice; 0105 earth and related environmental sciences

AbstractThe Subglacial Antarctic Lakes Scientific Access (SALSA) Project accessed Mercer Subglacial Lake using environmentally clean hot-water drilling to examine interactions among ice, water, sediment, rock, microbes and carbon reservoirs within the lake water column and underlying sediments. A ~0.4 m diameter borehole was melted through 1087 m of ice and maintained over ~10 days, allowing observation of ice properties and collection of water and sediment with various tools. Over this period, SALSA collected: 60 L of lake water and 10 L of deep borehole water; microbes >0.2 μm in diameter from in situ filtration of ~100 L of lake water; 10 multicores 0.32–0.49 m long; 1.0 and 1.76 m long gravity cores; three conductivity–temperature–depth profiles of borehole and lake water; five discrete depth current meter measurements in the lake and images of ice, the lake water–ice interface and lake sediments. Temperature and conductivity data showed the hydrodynamic character of water mixing between the borehole and lake after entry. Models simulating melting of the ~6 m thick basal accreted ice layer imply that debris fall-out through the ~15 m water column to the lake sediments from borehole melting had little effect on the stratigraphy of surficial sediment cores.