Skip to Main Content
Spatial patterns of atmospheric deposition of nitrogen and sulfur using ion-exchange resin collectors in Rocky Mountain National Park, USAAuthor(s): David W. Clow; Heidi A. Roop; Leora Nanus; Mark E. Fenn; Graham A. Sexstone
Source: Atmospheric Environment. 101: 149-157
Publication Series: Scientific Journal (JRNL)
Station: Pacific Southwest Research Station
Download Publication (2.0 MB)
DescriptionLakes and streams in Class 1 wilderness areas in the western United States (U.S.) are at risk from atmospheric deposition of nitrogen (N) and sulfur (S), and protection of these resources is mandated under the Federal Clean Air Act and amendments. Assessment of critical loads, which are the maximum exposure to pollution an area can receive without adverse effects on sensitive ecosystems, requires accurate deposition estimates. However, deposition is difficult and expensive to measure in high-elevation wilderness, and spatial patterns in N and S deposition in these areas remain poorly quantified. In this study, ion-exchange resin (IER) collectors were used to measure dissolved inorganic N (DIN) and S deposition during June 2006–September 2007 at approximately 20 alpine/subalpine sites spanning the Continental Divide in Rocky Mountain National Park. Results indicated good agreement between deposition estimated from IER collectors and commonly used wet + dry methods during summer, but poor agreement during winter. Snowpack sampling was found to be a more accurate way of quantifying DIN and S deposition during winter. Summer DIN deposition was significantly greater on the east side of the park than on the west side (25–50%; p ≤ 0.03), consistent with transport of pollutants to the park from urban and agricultural areas to the east. Sources of atmospheric nitrate (NO3−) were examined using N isotopes. The average δ15N of NO3− from IER collectors was 3.5‰ higher during winter than during summer (p < 0.001), indicating a seasonal shift in the relative importance of regional NOx sources, such as coal combustion and vehicular sources of atmospheric NO3−. There were no significant differences in δ15N of NO3− between east and west sides of the park during summer or winter (p = 0.83), indicating that the two areas may have similar sources of atmospheric NO3−. Results from this study indicate that a combination of IER collectors and snowpack sampling can be used to characterize spatial variability in DIN and S deposition in high-elevation wilderness areas. These data can improve our ability to model critical loads by filling gaps in geographic coverage of deposition monitoring/modeling programs and thus may enable policy makers to better protect sensitive natural resources in Class 1 Wilderness areas.
- You may send email to firstname.lastname@example.org to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationClow, David W.; Roop, Heidi A.; Nanus, Leora; Fenn, Mark E.; Sexstone, Graham A. 2015. Spatial patterns of atmospheric deposition of nitrogen and sulfur using ion-exchange resin collectors in Rocky Mountain National Park, USA. Atmospheric Environment. 101: 149-157.
KeywordsNitrogen, Sulfur, Deposition, Isotopes, Ion-exchange, Park
- Atmospheric deposition of nitrogen and sulfur and preferential canopy consumption of nitrate in forests of the Pacific Northwest, USA
- Wet and dry deposition in the AOSR collected by ion exchange resin samplers
- Potential canopy interception of nitrogen in the Pacific Northwest, USA
XML: View XML