National Park Snow Samples Show Improved Air Quality

Montana Public Radio | By Aaron Bolton

Published September 17, 2019 at 5:14 PM MDT

National Air Pollutant Concentration Averages, 1990-2018.

Snow samples from three national parks in the Rocky Mountains reflect improved air quality in the region since the mid-1990s. That’s according to a recent publication from the National Park Service.

The Rocky Mountain Regional Snowpack Chemistry Monitoring Study has been analyzing the chemical makeup of snowpack at 57 sites. Graham Sexstone with the U.S. Geological Survey says the program was created when acid rain was the norm in the early 1990s.

"The main focus of this project in its development was trying to monitor water quality in snow packs that is associated with air pollution, particularly in these high-elevation, sensitive ecosystems."

Atmospheric pollutants can settle on snowpack, or individual snowflakes can deliver far-flung particles to these sensitive high-elevation sites.

"Small increases in a nutrient like nitrogen can really promote invasive species or contribute to algal blooms or things like that. That’s the main risk in terms of these high elevation systems."

A recent publication by the National Park Service explained that samples collected in Glacier, Great Sand Dunes and Rocky Mountain national parks between 1996 and 2018 showed a decrease in nitrate and sulfate, which is associated with vehicle and industrial emissions and can acidify water. Ammonium levels, which agriculture operations largely contribute to, have stayed flat.

Sexstone says the paper mostly reflects findings from the larger monitoring network, except for the greater Yellowstone area and other locations in Wyoming.

"That’s where we’re seeing some of the strongest increases in ammonia and ammonium in the snow. But in terms of the nitrate and sulfate trends, I’d say it’s pretty representative."

Sexstone says the network’s data mirrors improved air quality. According to the U.S. Environmental Protection Agency, most air pollutants have decreased significantly since the 1990s, but some have shown a slight uptick since 2016.