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====2010 Duke study====A 2010 study by Duke University scientists, [http://www.precaution.org/lib/co2_into_drinking_water.101111.pdf "Potential Impacts of Leakage from Deep CO2 Geosequestration on Overlying Freshwater Aquifers"] found that leaks from [[carbon dioxide]] injected deep underground could bubble up into drinking water aquifers near the surface, driving up levels of contaminants in the water tenfold or more in some places. The study was based on a year-long analysis of core samples from four drinking water aquifers. The researchers, Mark Little and Robert Jackson, found "the potential for contamination is real, but there are ways to avoid or reduce the risk," said Jackson, saying some sites are more susceptible than others.<ref name=pg>[http://www.powergenworldwide.com/index/display/articledisplay/4047169887/articles/powergenworldwide/emissions-and-environment/air-pollution-control-equipment-and-services/2010/11/duke-carbon.html "Carbon dioxide contamination possible even with sequestration: Duke Univ. research"] Power-Gen, Nov. 12, 2010.</ref>
Duke researchers Researchers Mark Little and Robert B. Jackson collected core samples from four freshwater aquifers around the nation that overlie potential CCS sites and incubated the samples in their university lab for a year, with CO2 bubbling through them. After a year's exposure to the CO2, analysis showed a number he scientists found that tiny amounts of potential sites where CO2 leaks drive contaminants drove up levels of [[heavy metals]], including [[manganese]], [[cobalt]], [[nickel]], and [[iron]] in the water tenfold or more, "in some cases to levels above places. Some of these metals moved into the maximum contaminant loads set by the EPA for potable waterquickly," Jackson saidwithin one week or two. Three key factors – solidThey also observed potentially dangerous [[uranium]] and [[barium]] moving into the water over the entire year-phase metal mobilitylong experiment. Further, carbonate buffering capacity and electron exchanges in when the overlying freshwater aquifer – were found CO2 buried deep underground escapes into groundwater, it forms carbonic acid, a chemical reaction very similar to influence the risk of drinking process that occurs when the oceans absorb CO2. The increased acidity caused by CO2 dissolved in water contamination from underground carbon leakscan cause metals to leach out of surrounding sand and rock.<ref name=pg>Catherine M. Cooney, [http://solveclimatenews.com/news/20101207/study-charts-how-underground-co2-can-leach-metals-water "Study Charts How Underground CO2 Can Leach Metals into Water"] Solve Climate News, Dec. 7, 2010.</ref>
====2010 Environment Science Technology study====
A 2010 study in Environment Science Technology, [http://pubs.acs.org/doi/abs/10.1021/es102235w "Potential Impacts of Leakage from Deep CO2 Geosequestration on Overlying Freshwater Aquifers"] by Mark Little and Robert Jackson found that if CO2 stored deep underground were to leak in even small amounts, it could cause metals to be released in shallow groundwater aquifers at concentrations that would pose a health risk. Little and Jackson studied samples of sand and rock taken from four freshwater aquifers located around the country that overlie potential carbon capture and sequestration (CCS) sites over a period of a year. The scientists found that tiny amounts of CO2 drove up levels of [[heavy metals]], including [[manganese]], [[cobalt]], [[nickel]], and [[iron]] in the water tenfold or more in some places. Some of these metals moved into the water quickly, within one week or two. They also observed potentially dangerous [[uranium]] and [[barium]] moving into the water over the entire year-long experiment. Further, when the CO2 buried deep underground escapes into groundwater, it forms carbonic acid, a chemical reaction very similar to the process that occurs when the oceans absorb CO2. The increased acidity caused by CO2 dissolved in water underground can cause metals to leach out of surrounding sand and rock.<ref>Catherine M. Cooney, [http://solveclimatenews.com/news/20101207/study-charts-how-underground-co2-can-leach-metals-water "Study Charts How Underground CO2 Can Leach Metals into Water"] Solve Climate News, Dec. 7, 2010.</ref>
SW: →Potential for contamination of drinking water: - add section
===Potential for contamination of drinking water===
The study also identified four markers that scientists can use to test for early warnings of potential carbon dioxide leaks. "Along with changes in carbonate concentration and acidity of the water, concentrations of manganese, iron and calcium could all be used as geochemical markers of a leak, as their concentration increase within two weeks of exposure to CO2," Jackson said.<ref name=pg/>
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