Hello guest! [ Log In ]
View Geologic Publication Information

Geologic Publications for Mount Rainier

Precipitation chemistry and deposition at a high-elevation site in the Pacific Northwest United States (1989-2015)

[ back to previous page ]

Author(s): Anne M. Johansen, Clint Duncan, Ashleen Reddy, Naomi Swain, Mari Sorey, Annika Nieber, James Agren, Matt Lenington, David Bolstad, Barbara A. Samora, Rebecca A. Lofgren

Document Type:
Publisher: Atmospheric Environment
Published Year: 2019
Volume: 212
Pages: 221 to 230
DOI Identifier: 10.1016/j.atmosenv.2019.05.021
ISBN Identifier:
Keywords: Acid deposition Nitrate Ammonium High-elevation Long-term Mount rainier national park

Emissions from fuel combustion and agricultural activities contribute significantly to the continuous atmospheric entrainment of pollutants into protected and vulnerable ecosystems where long-term monitoring is often a challenge. Here, results are presented from a 26-year study (1989–2015) of wet precipitation collected at Paradise Station (1654 m above sea level), Mount Rainier National Park, Washington, USA. Weekly samples were analyzed for pH, conductivity and major anions and cations. While precipitation concentrations for sulfate, nitrate, protons and conductivity peaked in the early 2000s, overall trends decreased by 54%, 46%, 41%, and 37%, respectively. Associated pH values increased from 5.2 to 5.6, and were largely controlled by non-sea-salt contributions of sulfate and neutralizing calcium, potassium and magnesium. Between 1999 and 2015, nitrogen (N) deposition rates from ammonium increased by a factor of 3.6, from 0.27 to 0.96 kg N ha−1 yr−1 (p = 0.02), while nitrate deposition did not change statistically (0.91–0.74 kg N ha−1 yr−1, p = 0.30). Combined, these N sources are reaching reported critical loads of 2.0 kg N ha−1 yr−1. Results indicate that emission regulations focused on stationary sources have effectively decreased apparent acid precipitation, however, increased nitrogen deposition from ammonium may lead to further fertilization and acidification of delicate soils and waters. Continued long-term monitoring is thus imperative to track continued anthropogenic inputs to vulnerable ecosystems.

View Report:
View Report (1.64M)

Suggested Citations:
In Text Citation:
Johansen and others (2019) or (Johansen et al., 2019)

References Citation:
Johansen, A.M., C. Duncan, A. Reddy, N. Swain, M. Sorey, A. Nieber, J. Agren, M. Lenington, D. Bolstad, B.A. Samora, and R.A. Lofgren, 2019, Precipitation chemistry and deposition at a high-elevation site in the Pacific Northwest United States (1989-2015): Atmospheric Environment, Vol. 212, pp. 221-230, doi: 10.1016/j.atmosenv.2019.05.021.