Silica Precipitation in a Wet-Dry Cycling Hot Spring Simulation Chamber.

Terrestrial hot springs have emerged as strong contenders for sites that could have facilitated the origin of life. Cycling between wet and dry conditions is a key feature of these systems, which can produce both structural and chemical complexity within protocellular material. Silica precipitation is a common phenomenon in terrestrial hot springs and is closely associated with life in modern systems. Not only does silica preserve evidence of hot spring life, it also can help it survive during life through UV protection, a factor which would be especially relevant on the early Earth. Determining which physical and chemical components of hot springs are the result of life vs. non-life in modern hot spring systems is a difficult task, however, since life is so prevalent in these environments. Using a model hot spring simulation chamber, we demonstrate a simple yet effective way to precipitate silica with or without the presence of life. This system may be valuable in further investigating the plausible role of silica precipitation in ancient terrestrial hot spring environments even before life arose, as well as its potential role in providing protection from the high surface UV conditions which may have been present on early Earth.