Antarctica's Dry Valleys may not be so dry. A helicopter-borne sensor that penetrates below the surface of large swathes of terrain has found compelling evidence that ice-free McMurdo Dry Valleys may be hiding a salty aquifer.
Brines, or salty water, form extensive aquifers below glaciers, lakes and within permanently frozen soils. If they are present, it might provide answers about the biological adaptations of previously unknown ecosystems that persist in the extreme cold and dark of the Antarctic winter.
"Over billions of years of evolution, microbes seem to have adapted to conditions in almost all surface and near-surface environments on Earth. Tiny pore spaces filled with hyper-saline brine staying liquid down to -15 Celsius, or 5 degrees Fahrenheit, may pose one of the greatest challenges to microbes," said Slawek Tulacyzk, a glaciologist at the University of California, Santa Cruz and co-author of the Nature Communications paper. "Our electromagnetic data indicates that margins of Antarctica may shelter a vast microbial habitat, in which limits of life are tested by difficult physical and chemical conditions."
The team also found evidence that brines flow towards the Antarctic coast from roughly 11 miles inland, eventually discharging into the Southern Ocean. It is possible that nutrients from microbial weathering in these deep brines are released, effecting near-shore biological productivity. However, the vast majority of Antarctica's coastal margins remain unexplored. This new survey highlights the importance of these sensitive interfaces.
The researchers used a transient electromagnetic AEM sensor called SkyTEM, mounted to a helicopter, to produce extensive imagery of the subsurface of the coldest, driest desert on our planet, the McMurdo Dry Valleys. Using a helicopter to make the observations allowed large areas of rugged terrain to be efficiently surveyed. The results shed new light on the history and evolution of the dry valley landscape, which, uniquely in the Antarctic is ice-free and which during the height of the southern summer has free-flowing rivers and streams. The dry valleys are also home to briny lakes at the surface and beneath at least one of the glaciers that intrude into the Valleys.
Overall, the dry valleys ecosystem -- cold, vegetation-free and home only to microscopic animal and plant life -- resembles, during the Antarctic summer, conditions on the surface on Mars. In addition to many other studies, the dry valleys are home to projects that are investigating how climate has changed over geologic time.