In 1911, Griffith Taylor, a geologist, was in Antarctica and discovered the glacier that came to be called the Taylor Glacier, and a dry valley, the Taylor Valley. He also found a section of ice which was stained a reddish colour. Mr. Taylor guessed that the colour was caused by red algae. In the 1960’s it was found by Robert Black of the University of Wisconsin that the colour was caused by Ferric Hydroxide. Ferric Hydroxide is commonly known as rust.
There are several lakes named Lake Bonney, including 2 in South Australia, but the one in question here is a lake under the Taylor Glacier covered by about 400 metres (1300 feet) of ice. The water from this lake may be leaking slowly out to the sea, emerging at Blood Falls. The Ferrous ions in the water are being oxidised to Ferric by the Oxygen of the air.
Water in Lake Bonney
There are at least 130 lakes under the ice of Antarctica, but most of these have not been sampled directly because of the fear of contaminating the ecosystems of these lakes. Lake Bonney is different because it is not completely sealed off by the ice. The water has been sampled and bacteria found in it.
The water in Lake Bonney has practically no free Oxygen, but it does contain Ferrous Sulphate. The water is more salty than the sea, and stays liquid at its temperature of about 5 degrees C (23 degrees F.) There is also no light, so photosynthetic organisms cannot survive.
The bacteria living in Lake Bonney get their energy from the Sulphate ions of the Ferrous Sulphate in the water. Some types of bacteria in other places do this, changing the Sulphate to Sulphide, but in Lake Bonney, they do it by changing the Sulphate to Sulphite.
But studies indicate that the concentration of Sulphate ions in the water has not changed for millions of years. The cycle is completed by the Sulphite reacting with Iron in the rock underneath the lake and turning back into Sulphate.
This is very unusual behaviour for bacteria, but we cannot accurately say it is unique because it is quite possible that some other under ice lakes, either on Earth, or in other places, have similar bacteria.
There is evidence that around 700 million years ago, the whole Earth was covered with ice. One of the ways life could have survived these conditions is by living in under ice lakes like the bacteria in Lake Bonney.