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Geologist Finds Rocks Contribute Carbon Dioxide to Atmosphere
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A geologist at the University of Massachusetts, Amherst has published a study showing how quickly sedimentary rocks can release carbon into the atmosphere.

In nature, carbon is stored in a number of places including trees, plankton and rocks. U Mass Geosciences Professor Steven Petsch wanted to figure out how carbon from rocks could get into the atmosphere. In the lab he pulverized sedimentary rocks that are rich in organic carbon and slowly poured water through them, for an entire year. The idea was to mimic rainwater percolating through the earth.

The rock samples slowly released a small percentage of their carbon. Petsch then fed that organic matter to natural bacteria found in river water. The aquatic bacteria released the carbon. Petsch says it was surprising how quickly the carbon could be biodegraded and restored to carbon dioxide in the atmosphere.

“Most scientists, prior to the work that people like me have been doing, we kind of thought that once carbon got into rocks it was inert. It’s not part of earths carbon cycle any longer. It’s not bio-available any longer. It just sits there.”

Petsch says by better understanding the part rocks play in the natural carbon-cycle, scientists can better estimate the human contribution to climate change.

“Until we know what the background cycling of carbon is we can’t really assess how severe human impacts are going to be.”

Petsch says that although sedimentary rocks may only release a small amount of carbon, it should still be factored into the bigger picture