Pacific Southwest

Title: Nitrogen emissions, deposition, and monitoring in the western United States

Author: Fenn, Mark E.; Haeuber, Richard; Tonnesen, Gail S.; Baron, Jill S.; Grossman-Clarke, Susanne; Hope, Diane; Jaffe, Daniel A.; Copeland, Scott; Geiser, Linda; Rueth, Heather M.; Sickman, James O.

Date: 2003

Source: BioScience 53(4):391-403

Description: Nitrogen (N) deposition in the western United States ranges from 1 to 4 kilograms (kg) per hectare (ha) per year over much of the region to as high as 30 to 90 kg per ha per year downwind of major urban and agricultural areas. Primary N emissions sources are transportation, agriculture, and industry. Emissions of N as ammonia are about 50% as great as emissions of N as nitrogen oxides. An unknown amount of N deposition to the West Coast originates from Asia. Nitrogen deposition has increased in the West because of rapid increases in urbanization, population, distance driven, and large concentrated animal feeding operations. Studies of ecological effects suggest that emissions reductions are needed to protect sensitive ecosystem components. Deposition rates are unknown for most areas in the West, although reasonable estimates are available for sites in California, the Colorado Front Range, and central Arizona. National monitoring networks provide long-term wet deposition data and, more recently, estimated dry deposition data at remote sites. However, there is little information for many areas near emissions sources.

Keywords: Urbanization, animal feeding operations, hotspots, policy implications, regional haze

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Citation

Fenn, Mark E.; Haeuber, Richard; Tonnesen, Gail S.; Baron, Jill S.; Grossman-Clarke, Susanne; Hope, Diane; Jaffe, Daniel A.; Copeland, Scott; Geiser, Linda; Rueth, Heather M.; Sickman, James O.  2003.  Nitrogen emissions, deposition, and monitoring in the western United States.   BioScience 53(4):391-403.