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

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 similar to 0.4m diameter borehole was melted through 1087m of ice and maintained over similar to 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 mu m in diameter from in situ filtration of similar to 100 L of lake water; 10 multicores 0.32-0.49m long; 1.0 and 1.76m 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 similar to 6m thick basal accreted ice layer imply that debris fall-out through the similar to 15m water column to the lake sediments from borehole melting had little effect on the stratigraphy of surficial sediment cores.

Automated summary

The SALSA Project used environmentally clean hot-water drilling to access Mercer Subglacial Lake in Antarctica, collecting various samples and observing the interactions among ice, water, sediment, rock, microbes, and carbon reservoirs. Data showed hydrodynamic water mixing between the borehole and lake, with little effect on the stratigraphy of surficial sediment cores from debris fall-out.