Reactive Nitrogen Species Emission Trends in Three Light-/Medium-Duty United States Fleets

Authors

Gary A. Bishop, University of DenverFollow
Donald H. Stedman, University of Denver

Publication Date

2015

Document Type

Article

Organizational Units

Chemistry and Biochemistry

Keywords

Atmospheric chemistry, Emissions, Pollutants

Abstract

Repeated, fuel specific, emission measurements in Denver (2005/2013), Los Angeles (2008/2013) and Tulsa (2005/2013) provide long-term trends in on-road reactive nitrogen emissions from three light/medium duty U.S. fleets. Reductions in oxides of nitrogen (NO_x) emissions ranged from 21% in Denver (5.6 ± 1.3 to 4.4 ± 0.2 gNO_x/kg of fuel) to 43% in Tulsa (4.4 ± 0.3 to 2.5 ± 0.1 gNOx/kg of fuel) since 2005 while decreases in fleet ammonia (NH₃) emissions ranged from no change in Denver (0.45 ± 0.09 to 0.44 ± 0.02 gNH₃/kg of fuel) since 2005 to a 28% decrease in LA (0.80 ± 0.02 to 0.58 ± 0.02 gNH₃/kg of fuel) since 2008. The majority of the reduction in gasoline vehicle NO_x emissions occurred prior to the full implementation of the Tier II emission standards in 2009. High in-use NO_x emissions from small engine diesel passenger vehicles produced a significant contribution to the fleet means despite their small numbers. NH₃ emissions decreased at a slower rate than NO_x emissions due to modest NH₃ emissions reduction among the newest vehicles and increased emissions from a growing number of older vehicles with active catalytic converters. In addition, the reactive nitrogen emissions from many new model year vehicles are now dominated by NH₃.

Copyright Statement / License for Reuse

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

Publication Statement

This is an Accepted Manuscript for

Bishop, G. A.; Stedman, D. H. (2015) Reactive Nitrogen Species Emission Trends in Three Light-/Medium-Duty United States Fleets. Environ. Sci. Technol., 49(18), 11234-11240. DOI: 10.1021/acs.est.5b02392.

Copyright held by the American Chemical Society. User is responsible for all copyright compliance.

Rights Holder

Gary A. Bishop, Donald H. Stedman

Provenance

Received from author

File Format

application/pdf

Language

English (eng)

Extent

36 pgs

File Size

892 KB

Recommended Citation

Bishop, G. A.; Stedman, D. H. (2015) Reactive Nitrogen Species Emission Trends in Three Light-/Medium-Duty United States Fleets. Environ. Sci. Technol., 49(18), 11234-11240. DOI: 10.1021/acs.est.5b02392.

DOI Link

https://doi.org/10.1021/acs.est.5b02392