Scientists Discover Unexpected Pollutant While Monitoring Fragile Mountain Habitats

Too much of a good thing could prove hazardous to an ecosystem's health - at least as far as nitrogen is concerned. Because it enhances plant growth, one might assume there can never be too much nitrogen in the environment. However, scientists from the Mountain Ecosystems Section of the Fort Collins Science Center (FORT) are discovering limits to how much nitrogen an ecosystem can accumulate.

For fourteen years, FORT scientists have been monitoring the air, water, and soil of mountain habitats within Rocky Mountain National Park , Colorado, and results have revealed high concentrations of nitrate (a form of nitrogen) in some lakes and streams. The impacts of these high nitrate concentrations on plants and animals are just beginning to be understood.

The process by which nitrate forms and accumulates in the environment is complex. Nitrogen oxides and ammonia are released into the atmosphere from automobile, power plant, and agricultural emissions. These emissions build up and transform in the atmosphere to produce smog. Eventually, nitrogen (in the form of nitrate and ammonium) collects in water droplets and falls back to earth as rain and snow. When the nitrogen can no longer be used by plants and microbes, the excess is leached into streams and lakes, affecting water quality.

Studies conducted by FORT scientists have revealed that concentrations of nitrogen in lakes and streams in Rocky Mountain National Park are an order of magnitude greater than expected levels and equal to regions where acid rain is a problem. High concentrations of nitrogen could have major impacts on the biodiversity of mountain habitats by bringing about shifts in plant and animal communities, decreases in soil fertility, acidification in lakes (which affects fish and other aquatic life), increases in algae growth, and increases in the vulnerability of plants to stresses such as insects, cold, and drought.
FORT scientists plan to further investigate how extensive the nitrogen pollution problem is in the Park and how close Rocky Mountain forests are to nitrogen saturation. Their future work will explore the pathways by which nitrogen moves through high elevation ecosystems.

This study is part of the Watershed Ecosystem Studies at FORT. The findings were made at the Loch Vale Watershed Research Project in cooperation with the Natural Resource Ecology Laboratory.

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For more information, please contact:

Jill Baron, Research Ecologist
(970) 491-1968
jill@nrel.colostate.edu