NPS Photo
A dust cloud rises from a field being plowed in the Central Valley of California.
Nitrogen is essential for all living things. It is found in solid earth and in the atmosphere. Small amounts of nitrogen move in a dynamic cycle involving the atmosphere, oceans, lakes, streams, plants, and animals. Depending on the form and amount in the environment, nitrogen can serve as a nutrient, enhancing growth and productivity, or as a toxin, causing ecological damage or harming human health.
Human activities (emissions from vehicles, electric utilities, industrial plants and agricultural activities) have added levels of nitrogen rivaling or exceeding contributions from natural sources.
There has been a slow, continuous increase in atmospheric nitrogen deposition in park watersheds as well as around the world. However, in spite of increasing nitrogen deposition, there has been a decrease in the dissolved nitrogen that has been measured in the water flowing out of mid and high-elevation park watersheds. The consequences of increased nitrogen deposition and retention on terrestrial plant communities are unknown.
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