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UT Researcher Takes the Measure of Life Underground

Tom Owens, Deep Carbon Observatory

The microscopic organisms that live in the Earth's crust have a total carbon mass far greater than that of the humans who live on the planet's surface, according to a new paper co-authored by a University of Tennessee researcher.

The report by biology professor Karen Lloyd and her colleagues took ten years to compile and presents the findings of the Deep Carbon Observatory, an international effort to study the "quantities, movements, forms and origins of carbon inside Earth."

Carbon is a key constituent of living things, so its presence as demonstrated by microorganisms is not surprising. What is new about the carbon observatory's findings are sheer numbers: a total carbon mass of 15 to 23 billion tons, and that more than two-thirds of known bacterial life on Earth lives underground.

Samples were drawn from mines, and holes drilled into oceanic and continental crust. Some of the samples came from five kilometers below ground level. In each, Lloyd and her colleagues discovered single- and mutli-celled organisms. In this part of the Earth, called the deep biosphere, microbes live in conditions no human could tolerate: no light, no air as we know it, temperature extremes and high pressures.

“Knowing about how carbon is distributed and how living things use it is crucial for understanding not only life cycles but also our environment,” Lloyd said in a UT press release.