Scientists Say: Blood Falls

Blood Falls (noun, “BLUHD FAHLZ”)

Blood Falls is a five-story waterfall that flows out of Taylor Glacier in Antarctica. The water comes from a salty lake beneath the glacier that’s rich in iron. When the water reaches the glacier’s surface, the iron interacts with oxygen in the air. This reaction turns the water red. It’s the same reaction that creates reddish rust on a nail.

Scientists suspect the lake was filled by ocean water 5 million years ago. But it’s been completely cut off from other water sources for at least a million years. Over time, the water became saltier as the glacier formed above. Now, the lake is more than twice as salty as the ocean. The water can’t freeze because salt prevents water molecules from locking into the crystal structure of ice.

Because the lake is also cut off from the atmosphere, scientists call it a biological time capsule. Microbes have lived here for millions of years with no light or oxygen. Instead, these extremophiles get their energy from molecules called sulfates. This respiration strategy is similar to microbes that live in deep-sea thermal vents.

But the Blood Falls microbes are special. They extract oxygen from the sulfates and leave behind other molecules. When these leftovers interact with iron in the water, they turn back into sulfates. This means these microbes have a practically unlimited energy source.

Scientists suspect planets like Mars and Jupiter’s icy moons could be home to salty underground lakes like this one. How these microbes make a living might be a clue for how life could work on other planets, too.

In a sentence

Blood Falls is located in East Antarctica, more than 3,300 kilometers (2,000 miles) south of New Zealand.

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