Carbon geosequestration will contaminate water supply, study says

What goes down must come up: Duke researchers say carbon geosequestration will eventually contaminate the nation's drinking water supply.
Written by Andrew Nusca, Contributor

To invert the old saying: "What goes down must come up."

New research indicates that one proposed solution to combat climate change, geosequestration, may come back to bite us in the you-know-what.

Scientists say the suggestion, which involves injecting carbon dioxide deep below the Earth's surface for storage, will eventually backfire and contaminate our water supply.

Geosequestration is part of a series of new carbon capture and storage technologies under development by governments and industries worldwide -- including the U.S. Department of Energy -- to reduce the amount of greenhouse gas emissions entering the Earth’s atmosphere.

But according to Duke University researchers, the carbon dioxide will eventually bubble up into drinking water aquifers near the Earth's surface, driving up levels of contaminants in the water more than 10 times over.

Professors Robert Jackson and Mark Little took core samples from four drinking water aquifers near potential CCS sites, and incubated them for a year in the lab, with CO2 bubbling through them.

At the end of the incubation period, the samples showed greatly elevated contamination levels -- in some cases, above the maximum loads set by the EPA for potable water.

They found three key influences on the degree of contamination:

  • Solid-phase metal mobility
  • Carbonate buffering capacity
  • Redox state in the overlying freshwater aquifer

The good news? There are ways to avoid or reduce the risk, they said.

Simply test for the following markers:

  • Changes in carbonate concentration
  • Changes in acidity of the water
  • Changes in concentrations of manganese, iron and calcium

For the last marker, the scientists said that increased levels could be seen within two weeks of exposure to carbon dioxide.

They write:

After exposure to CO2, water pH declines of 1−2 units were apparent in all aquifer samples. CO2 caused concentrations of the alkali and alkaline earths and manganese, cobalt, nickel, and iron to increase by more than 2 orders of magnitude. Potentially dangerous uranium and barium increased throughout the entire experiment in some samples.

Their research was published in the journal Environmental Science & Technology.

Illustration: LeJean Hardin and Jaime Payne/Wikipedia

This post was originally published on Smartplanet.com

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