The legendary Blood Falls are nestled among Antarctica's huge stretches of gleaming white snow and mystical blue glacier ice. Blood Falls, an iron-rich, hypersaline discharge located near the terminal of Taylor Glacier in the McMurdo Dry Valleys, spews bold streaks of bright-red brine from within the glacier out onto the ice-covered surface of Lake Bonney.
Griffith Taylor, an Australian geologist, was the first to discover Blood Falls in 1911, while on one of the first Antarctic missions. Taylor wrongly attributed the color to the presence of red algae at the time. For nearly a century, the source of this color was unknown, but we now know that the iron-rich liquid turns red when it breaches the surface and oxidizes––the same process that causes iron to rust.
Taylor Glacier was once considered to be solidly frozen from its surface to its bed, according to researchers. However, as monitoring techniques have improved over time, scientists have been able to discover massive amounts of hypersaline liquid water beneath the glacier at temperatures below freezing. The high salt content of hypersaline water allows it to remain liquid even at temperatures below zero degrees Celsius.
They discovered that the chemical makeup of the brine was very different from that of present seawater. This suggested that weathering contributed to major changes in the chemical composition of the water as the brine was moved throughout the glacier environment over time.
The subsurface water zones appear to extend from the coast of Antarctica to at least 7.5 miles (12 kilometers) inland. It's thought that the water is twice as salty as saltwater.
What Micro-organisms inhabit this glacier?
The samples revealed a subglacial brine that was cold (-7 °C) and iron-rich (3.4 mM) (8 percent NaCl). Scientists isolated and characterized a type of bacteria that can grow in salty water (halophilic), thrives in the cold (psychrophile), and is heterotrophic from these samples, and assigned it to the genus Marinobacter. At least four gene clusters involved in secondary metabolism were discovered by DNA bioinformatics analysis. The creation of aryl polyenes, which act as antioxidants and protect bacteria from reactive oxygen species, is linked to two gene clusters. A different gene cluster appears to be involved in terpene biosynthesis, most likely for color production. Thiomicrospira sp. and Desulfocapsa sp. are two other bacteria found.
How is it related to our Solar system?
This research has implications not only for Earth's subglacial conditions but also for other worlds in our solar system. Sub-cryospheric oceans are expected to exist on seven worlds, including Titan and Enceladus (two of Saturn's moons), Europa (one of Jupiter's moons), Pluto, and Mars.
Lyons and his colleagues came to the conclusion that the subglacial brine environment is likely to be life-friendly. The potential of sub-cryospheric conditions like this one to support life on Earth suggests that similar environments could support life elsewhere in our solar system.