Thriving on the ocean floor

Anne M Stark, LLNL, (925) 422-9799, stark8@llnl.gov

Laboratory and UC Santa Cruz researchers have found that there is an extensive biological community living in porous rock beneath the deep ocean floor.

The microbes appear to be an important source of dissolved organic matter in deep ocean water, a finding that could dramatically change ideas about the ocean carbon cycle.

LLNL's Tom Guilderson and UC Santa Cruz' Matthew McCarthy found evidence of the hidden microbial ecosystem beneath the seafloor by analyzing carbon isotopes in the organic molecules in their samples. Of the three naturally occurring isotopes of carbon, carbon-12 is the most abundant, and both carbon-12 and the slightly heavier carbon-13 are stable. Carbon-14 is an unstable isotope formed in the upper atmosphere through the action of cosmic rays, and its steady decay is the basis for carbon-dating of organic material.

Guilderson used the Lab's Center for Accelerator Mass Spectrometry to analyze the samples.

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Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy's National Nuclear Security Administration.