Taking water samples from an Antarctic lake under 800 meters of ice requires days of drilling, precise equipment, a lot of patience, and a desire to understand one of the most extreme environments in the world.
More than half of the planet’s fresh water lies in Antarctica. While most of it is frozen in the ice sheet, streams of water flow beneath the ice into each other and into the Southern Ocean surrounding the continent. The understanding of the movement of this water and its dissolution into solutes shows how Carbon and terrestrial nutrients can support life in the coastal ocean.
Living with a carbon budget
Life under the ice is hard – there is no sunlight and no pressure from the ice combined with the heat emanating from the Earth’s core. Thus, the temperature of the water in the lake is just below freezing. Organic carbon, an important food source for microorganisms, is present in relatively high concentrations in Whillans Subglacial Lake. In Mercer Subglacial Lake, a neighbor of Whillans Subglacial Lake, it is dark, cold, full of soft and fluffy sediments, and the borehole is lined with bubble-filled ice. This was shown by pictures taken with cameras in the borehole.
Studying extreme environments provides insight into what extraterrestrial life might look like or how terrestrial life might survive in similar conditions. Not that humans, penguins or fish could handle it. Life in the waters beneath the ice of Antarctica is largely microbial. They still show signs of life organic carbon and other chemical byproducts of life.
Drilling for Data
While Whillans Subglacial Lake alone indicates that available nutrients may be an important factor, it is only one source of data in an ice-covered complex of subsurface lakes, streams, and estuary-like mixing zones subject to seasonal and sporadic flows.
To expand their view, researcher Vick-Majors and the rest of the team collected data at other sites. Mercer Subglacial Lake was sampled in early 2019 by the SALSA team. They make this possible with a hot water drill, a specially designed hose, a 10-liter water sampling bottle, some sediment coring equipment, and a week of summer polar weather. They also filter the drilling water, letting it pass several sources of ultraviolet light to break down microbial contaminants. The water was heated to open a borehole about 1000 meters long down to the lake.
“Some of the melted ice water now circulating through the drill bit is removed from the hole, so that when the lake is pierced, water from the lake enters the borehole,” Vick-Majors explained. “The drilling of the well takes about 24 hours and we keep it open for a few days. Collecting a single sample or lowering the cameras can take, depending on the equipment, two take two hours or longer.” And the hole is always trying to freeze.
“There is water and there is life under the ice,” Vick-Majors said. “These can teach us a lot about our planet, as this is a great place to look at look at somewhat simplified ecosystems without higher concentrations of organisms. This allows us to answer questions about life that are very are very difficult to answer.”
The Michigan Technological University is a public research university with more than 7,000 students from 54 countries. The university was founded in 1885 and offers more than 120 bachelor’s and master’s degree programs in the fields of Science and technology, engineering, forestry, Business sciences, health professions, humanities, mathematics and social sciences.
Heiner Kubny, PolarJournal