Nitrogen Isotopes In Ice Cores Record Human Activity | June 8, 2009 Issue - Vol. 87 Issue 23 | Chemical & Engineering News
Volume 87 Issue 23 | p. 52 | Concentrates
Issue Date: June 8, 2009

Nitrogen Isotopes In Ice Cores Record Human Activity

A study of ice cores from Greenland reveals that the nitrogen isotope ratio in nitrates has undergone a marked change in the past 300 years
Department: Science & Technology
Keywords: ice core, nitrogen isotope, nitrogen isotope
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Hastings (left) and professional driller Bella Bergeron drilled ice cores in Greenland for the nitrogen isotope studies.
Credit: Courtesy of Meredith Hastings
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Hastings (left) and professional driller Bella Bergeron drilled ice cores in Greenland for the nitrogen isotope studies.
Credit: Courtesy of Meredith Hastings
Core Evidence
Nitrogen isotope ratios in Greenland ice reflect industry-age activity.
Credit: Courtesy of Medredith Hastings
8723icecore
 
Core Evidence
Nitrogen isotope ratios in Greenland ice reflect industry-age activity.
Credit: Courtesy of Medredith Hastings

A study of ice cores from Greenland reveals that the nitrogen isotope ratio in nitrates has undergone a marked change during the past 300 years—ever since humans began generating nitrogen oxides (NOx) by burning large quantities of fossil fuels and fixing nitrogen from the atmosphere to make synthetic fertilizers (Science 2009, 324, 1288). It's known that NOx readily converts to nitrates in the atmosphere. And scientists have suggested in the past that the 15N/14N makeup of nitrates should hold information about where the nitrogen came from, says geological scientist Meredith G. Hastings of Brown University, who led the research team. The new ice core study provided "a unique opportunity to look at whether isotopes of nitrate have changed with the sources," Hastings says. And they have: The researchers found that the percentage of 15N in the nitrates began a dramatic decline in the mid-1800s. With this temporal association with the onset of anthropogenic NOx emissions, scientists can now begin to "quantitatively reconstruct the influence of different NOx sources on preserved nitrate" in ice cores and other nitrate-containing samples, Hastings and coworkers write.

 
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