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

• Main Authors: Priscu, John C., Kalin, Jonas, Winans, John, Campbell, Timothy, Siegfried, Matthew R., Skidmore, Mark, Vick‐Majors, Trista J.
• Format: Text
• Language: unknown
• Published: Digital Commons @ Michigan Tech 2021
• Subjects: Antarctic glaciology; basal ice; biogeochemistry; glacial sedimentology; subglacial lakes; Department of Biological Sciences; Biology; Antarctic; Mercer; Antarc*
• Online Access: https://digitalcommons.mtu.edu/michigantech-p/15053; https://digitalcommons.mtu.edu/cgi/viewcontent.cgi?article=34355&context=michigantech-p

The 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.