Nitrogen Isotope Composition of Thermally Produced NOx from Various Fossil-Fuel Combustion Sources.
The nitrogen stable isotope composition of NOx (δ(15)N-NOx) may be a useful indicator for NOx source partitioning, which would help constrain NOx source contributions in nitrogen deposition studies. However, there is large uncertainty in the δ(15)N-NOx values for anthropogenic sources other than on-road vehicles and coal-fired energy generating units. To this end, this study presents a broad analysis of δ(15)N-NOx from several fossil-fuel combustion sources that includes: airplanes, gasoline-powered vehicles not equipped with a three-way catalytic converter, lawn equipment, utility vehicles, urban buses, semitrucks, residential gas furnaces, and natural-gas-fired power plants. A relatively large range of δ(15)N-NOx values was measured from -28.1‰ to 8.5‰ for individual exhaust/flue samples that generally tended to be negative due to the kinetic isotope effect associated with thermal NOx production. A negative correlation between NOx concentrations and δ(15)N-NOx for fossil-fuel combustion sources equipped with selective catalytic reducers was observed, suggesting that the catalytic reduction of NOx increases δ(15)N-NOx values relative to the NOx produced through fossil-fuel combustion processes. Combining the δ(15)N-NOx measured in this study with previous published values, a δ(15)N-NOx regional and seasonal isoscape was constructed for the contiguous U.S., which demonstrates seasonal and regional importance of various NOx sources.
Department of Earth, Atmospheric, and Planetary Sciences, Purdue University , 550 Stadium Mall Drive, West Lafayette, Indiana 47907, United States.
Wendell W
WW
Walters
Department of Chemistry, Purdue University , 560 Oval Drive, West Lafayette, Indiana 47907, United States.
Bruce D
BD
Tharp
Department of Earth, Atmospheric, and Planetary Sciences, Purdue University , 550 Stadium Mall Drive, West Lafayette, Indiana 47907, United States.
Huan
H
Fang
Department of Aviation Technology, Purdue University , 1401 Aviation Drive, West Lafayette, Indiana 47907, United States.
Brian J
BJ
Kozak
Department of Earth, Atmospheric, and Planetary Sciences, Purdue University , 550 Stadium Mall Drive, West Lafayette, Indiana 47907, United States.|Department of Chemistry, Purdue University , 560 Oval Drive, West Lafayette, Indiana 47907, United States.
Greg
G
Michalski
D000393:Air Pollutants / Q000032:analysis; D003031:Coal / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods; D005579:Fossil Fuels / Q000032:analysis*; D005742:Gasoline; D009587:Nitrogen Isotopes / Q000032:analysis*; D009589:Nitrogen Oxides / Q000032:analysis* / Q000737:chemistry; D011210:Power Plants; D012621:Seasons; D014481:United States; D001335:Vehicle Emissions / Q000032:analysis
D000393:Air Pollutants; D003031:Coal; D005579:Fossil Fuels; D005742:Gasoline; D009587:Nitrogen Isotopes; D009589:Nitrogen Oxides; D001335:Vehicle Emissions