Sources of Nitrogen and Sulfur in Precipitation in the Northern Rocky Mountains
Author Information
Author(s): Naftz David L, Schuster Paul F, Johnson Craig A
Primary Institution: U.S. Geological Survey
Hypothesis
The study aims to determine atmospheric deposition sources of nitrogen and sulfur since the late 1940s using isotopic values in ice-core samples.
Conclusion
The study found that coal-fired power plant emissions are likely a dominant source of sulfur deposition, while vehicle emissions are a significant source of nitrogen deposition in the Northern Rocky Mountains.
Supporting Evidence
- The highest δ34S value in the ice-core samples was associated with snow deposited during the 1980 eruption of Mt. St. Helens.
- The δ15N values in the ice-core samples were negative and consistent with values expected from vehicle emissions.
- Coal from southern Wyoming has a mean δ34S composition similar to the δ34S values in ice-core samples, indicating its role in sulfur deposition.
- Trends in precipitation chemistry indicated an increase in total nitrogen deposition from 1950 to the mid-1970s.
Takeaway
Scientists looked at ice from a glacier to see where the nitrogen and sulfur in rain came from over the last 50 years, finding that cars and power plants are big contributors.
Methodology
Ice cores were collected from Upper Fremont Glacier and analyzed for stable isotopes of nitrogen and sulfur to determine atmospheric deposition sources.
Limitations
The study's findings may not reflect isotopic trends due to potential post-depositional processes affecting the preservation of isotopic signatures.
Digital Object Identifier (DOI)
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