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RoMANS - Rocky Mountain Atmospheric
Nitrogen & Sulfur Study

RoMANS Report (October 2009):

report cover
RoMANS report cover

Rocky Mountain NP is negatively impacted by the atmospheric deposition of nitrogen and sulfur compounds. Airborne nitrate and sulfate particles contribute to degraded visibility in the park and nitrogen deposition changes ecosystem functions and surface water chemistry. The National Park Service has a legal obligation to protect these and other natural resources unimpaired for future generations. To learn more about the impacts of Nitrogen and Sulfur on Rocky Mountian NP, the Rocky Mountain Airborne Nitrogen and Sulfur (RoMANS) study was conducted during two representative sampling periods in 2006 with the following objectives:

  • Identify the overall mix of oxidized and reduced nitrogen in the air and precipitation on the east and west sides of the Continental Divide
  • Identify the relative contributions of nitrogen at Rocky Mountain National Park from emissions originating within the state of Colorado and outside the state, as well as relative contributions of in-state regions, and
  • Identify the relative contributions of differing source types including mobile, agricultural, other area sources, and large and small point sources.

Key findings indicate that:

  1. Nitrogen and sulfur concentration and deposition rates were about a factor of 2 higher in the summer than in the spring and resulted from very different meteorological processes.  In the summer, elevated concentrations and deposition occurred almost daily, as a result of convective activity. In the spring, virtually all of the wet deposition resulted from a single synoptic-scale event associated with sustained upslope transport. 
  2. In both the spring and summer sampling periods, average concentrations for most oxidized and reduced species were highest in northeastern Colorado, with a sharply decreasing, east-to-west gradient. During the spring, the split between sources of in- versus out-of-state nitrogen was about 67:33; during the summer, the split between sources of in- versus out-of-state nitrogen was about 53:47.
  3. The source attribution results indicate that roughly half of the nitrogen deposition in Rocky Mountain NP originates from sources east of the park and half from sources west of the park.  However, the mechanisms causing deposition from eastern and western sources are quite different.  In general, emissions of nitrogen compounds west of Rocky Mountain NP are low or distant from the park.  These low level emissions impact the park because airmass transport is persistently from the west.  To the east of Rocky Mountain NP are a number of high nitrogen emission regions, including the nearby Front Range and agriculturally intensive areas in northeastern Colorado.  Upslope, easterly airmass transport from these areas is relatively infrequent; however, when it does occur, Rocky Mountain NP often experiences its highest ambient nitrogen concentrations.
updated on 05/17/2010  I   http://www.nature.nps.gov/air/studies/romans.cfm   I  Email: Webmaster