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ShareMar. 28, 2009 — Nitrogen oxides in the atmosphere, which are produced by lightning, biomass burning, and soil outgassing, are converted into atmospheric nitrate through oxidation reactions. Nitrogen oxide, itself a pollutant, controls the production of ozone, which in turn is a greenhouse gas and a pollutant at ground levels. Atmospheric nitrate contributes to the load of atmospheric particulate matter and, along with sulfate, to acid rain.
Despite efforts to regulate and monitor emissions, nitrogen oxide and atmospheric nitrate burdens in the atmosphere are increasing in many regions.
To learn more, Morin et al. study the stable isotopic composition of nitrate within aerosol samples, collected along a shipborne transect, in the lower atmosphere over the Atlantic Ocean from 65 degrees South to 79 degrees North.
They find that in nonpolar regions, nitrate derived from anthropogenically emitted nitrogen oxide had isotopic properties distinct from locations influenced by natural nitrogen oxide sources.
Further, air masses exposed to snow-covered areas have low nitrogen isotopic ratios, showing that snowpack emissions of nitrogen oxide from upwind regions can have a significant effect on the local surface budget of reactive nitrogen.
The authors report their findings in the Journal of Geophysical Research-Atmospheres. They include: S. Morin, J. Savarino, and F. Domine: Institut National des Sciences de l'Univers, CNRS, Grenoble, France; also at Laboratoire de Glaciologie et Géophysique de l'Environnement, Université Josef Fourier, Grenoble, France; M. M. Frey: Institut National des Sciences de l'Univers, CNRS, Grenoble, France; also at Laboratoire de Glaciologie et Géophysique de l'Environnement, Université Josef Fourier, Grenoble, France; now at British Antarctic Survey, Natural Environment Research Council, Cambridge, U.K.; H.-W. Jacobi: Institut National des Sciences de l'Univers, CNRS, Grenoble, France; also at Laboratoire de Glaciologie et Géophysique de l'Environnement, Université Josef Fourier, Grenoble, France; Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany; L. Kaleschke; ZMAW, Institute of Oceanography, University of Hamburg, Hamburg, Germany; J. M. F. Martins: Institut National des Sciences de l'Univers, CNRS, Grenoble, France; also at Laboratoire d'Étude des Transferts en Hydrologie et Environnement, Université Josef Fourier, Grenoble, France.
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The above story is reprinted from materials provided by American Geophysical Union, via EurekAlert!, a service of AAAS.
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Journal Reference:
- Morin et al. Comprehensive isotopic composition of atmospheric nitrate in the Atlantic Ocean boundary layer from 65 degrees S to 79 degrees N. Journal of Geophysical Research, 2009; 114 (d5): D05303 DOI: 10.1029/2008JD010696
Note: If no author is given, the source is cited instead.
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