Acid rain in Rocky Mountain National Park

USA

last update:

2 months ago

Problems

Causes of acid rain in Rocky Mountain National Park

Almost every region in the world, including the Rocky Mountains in Colorado, has been affected by an increase in acidic nutrients, such as nitrogen, in rain and snow over the past 200 years. Nitrogen oxides, like nitrates, are produced primarily by vehicle use and energy production. Ammonium is the main ingredient in common agricultural fertilizers. 

Nitrogen is the main nutrient needed in ecosystems. But when nitrogen levels increase too much, this change in soil and water chemistry can make it difficult for native plants to grow or even survive, leading to a cascade of negative consequences. 

In summer, the sun warms the eastern slopes of the Front Range, forcing warmer air upward, bringing with it nitrogen from cars, industry, and agriculture. As this air cools, it forms clouds over the Rocky Mountains and falls as afternoon thunderstorms, depositing pollutants.

Plant species response

Plants vary in their resistance to eutrophication and acidification. Some plant species respond to nitrogen (N) or sulfur (S) pollution by reduced growth, survival, or abundance on the landscape. Researchers used U.S. Forest Service national forest survey data to determine critical N loads and necessary S loads to prevent reduced growth or survival of sensitive tree species. They also used a database of plant community surveys to develop critical N loads and required S loads to prevent declines in sensitive herbaceous plant species. According to NPSpecies data, Rocky Mountain National Park contains:

● 4 N-sensitive tree species and 43 N-sensitive herbaceous species.
● 6 S-sensitive tree species and 38 S-sensitive herbaceous species.

Rocky Mountain National Park ecosystem has a chance to recover

The Rocky Mountains are beginning to recover from acid rain caused by traffic and industry, according to a new study by the University of California at Boulder. Researchers found that nitric and sulfuric acid levels in the Nivot Ridge Green Lakes Valley area have declined over the past 30 years.

Professor Bowman found that these ecosystems are recovering rather slowly, even after acidic elements such as nitrogen are no longer added.

Despite some bad news, the researchers generally find their results encouraging. Even if the process is slow, they say, the results show that the alpine ecosystem has a chance to recover.

Gallery

Nitrogen cycles continuously between the atmosphere, soil, and organisms. Nitrogen in the atmosphere and nitrogenous compounds in the soil are converted into substances that can be used by plants before being returned to the air and soil.

The Loch, a glacial lake in Loch Vale watershed, Rocky Mountain National Park, Colorado

Researcher cores through the ice to obtain water samples from the Loch. These samples are used to measure lake chemistry in the water

Timelines

2020

August 12

The Rocky Mountains are starting to recover from acid rain caused by traffic and industry, according to a new study from UC Boulder. The researchers found that nitric and sulfuric acid levels in the Green Lakes Valley region of Niwot Ridge have decreased over the past 30 years. 

“It looks like we’re doing the right thing. By controlling vehicle emissions, some of these really special places that make Colorado unique are going back to what they used to be,” said study co-author Jason Neff, who is the director of the Sustainability Innovation Lab at Colorado (SILC).

On the other hand, the data showed that levels of ammonium from fertilizer have more than doubled in rainfall across the area between 1984 and 2017. This indicates a need for continued monitoring and further investigation into the effects of fertilizer on mountain ecosystems.
“We used water quality modeling and statistical approaches to analyze the long-term datasets that Niwot researchers have been collecting for decades,” said study co-author Eve-Lyn Hinckley. “The data are available for anyone to download. Our modeling approaches allowed us to evaluate the patterns they hold rigorously.”

2000

November 19

The researchers discovered that levels of nitric and sulfuric acid stopped increasing in the early 2000s and started decreasing by the mid-2000s. 

Their findings were not all good news, however. Levels of ammonium from fertilizer have more than doubled in rainfall, indicating a need to continue monitoring this agricultural chemical and its effects on the mountain ecosystem.

1990

December 11

Bill Bowman is the director of the Mountain Research Station and a professor of Ecology and Evolutionary Biology has been studying how nutrients like nitrogen affect plants in mountain ecosystems. He has determined that alpine environments are unique in how they respond to these nutrients.

1984

September 28

To investigate, the UC Boulder team analyzed data since 1984 on atmospheric deposition and stream water chemistry from the Mountain Research Station located on Niwot Ridge. 

The data showed that levels of ammonium from fertilizer have more than doubled in rainfall across the area. 
This indicates a need for continued monitoring and further investigation into the effects of fertilizer on mountain ecosystems.

1970

June 15

So-called “acid rain” hit ecosystems in the Mountain West, famously wiping out fish populations and killing trees. 

Scientists began to work to understand how increased levels of acidic nutrients affect the alpine region and how long these ecosystems take to recover.

1950

January 01

USGS, CSU, and CU researchers documented changes in the species composition and concentration of algal primary producers (diatoms) in high-elevation lakes in Loch Vale. 
Diatom species indicative of nitrogen enrichment increased significantly. 

Plant and soil communities in high-elevation Rocky Mountain ecosystems were also found to be affected by slight increases in nitrogen availability. Increased nitrogen deposition corresponded to changes in tundra plant community composition, increased soil microbial activity and elevated nitrogen concentrations in the needles of old-growth spruce forests in the region. Together, these studies gave Rocky Mountain NP managers a large body of evidence on sources of nitrogen deposition to the park, the ecological effects of nitrogen on susceptible ecosystems, and pathways of nitrogen cycling.