The Effects of Nitrogen on Biodiversity at Niwot Ridge

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Graph of Nitrogen Saturation Click for larger image

Too much nitrogen can also drag calcium and magnesium out of the soil. Essentially nutrients to plant life, calcium and magnesium accumulate slowly and cannot be easily replaced. According to Gregory Lawrence (USGS Forest Hydrologist in Albany), less than 50 years' worth of auto emissions had leached more than 500 years' accumulation of calcium from some forest soils. So plants are pulled in two directions at once, causing stress. As the excess nitrogen fools them into growing faster, they have fewer other nutrients to sustain that growth. It's like drinking coffee on an empty stomach: you may feel more energetic, but you'll fall on your face when you stop.

Niwot Ridge is just one place among countless others where these effects are threatening ecosystems or are already causing harm. The world is awash in nitrogen. Industry, cars and modern agriculture are spreading over the planet and as they do, nitrogen pollution is worsening. According to biologist Peter Vitousek of Stanford University, "more commercial fertilizer was used between 1980 and 1990 than all that previous was applied in history." Fertilizer has already saturated much of the Earth's farmland.

In the United States, the Finger Lakes region of upstate New York has suffered from nitrogen pollution wafting in from the Midwest for decades. Byproducts from steel mills and other industries have drenched the area in NOx-laden acid rain, creating dangerous levels of released aluminum in the water. the Finger Lakes are so saturated with nitrates and sulfuric acid that the fish have died out completely according to Seastedt. The lakes, once some of the most popular tourist destinations of the Northeast, are sterile.

So if predictions of a nitrogen-saturated Colorado were to come true decades or centuries from now, how would the average resident be affected? Colorado doesn't suffer to the degree of the Finger Lakes, damage can still be done. In the most severe cases, human health is jeopardized when nitrogen poisons the drinking water. In some parts of the world, including the Finger Lakes, nitrate levels are so high in groundwater that the medical condition methemoglobinemia, or "blue babies," threatens infants. Concentrated in milk, nitrates oxidize the iron in red blood cells, causing infants to slowly suffocate.

Nitrates also contribute to Denver's infamous "brown cloud," which degrades visibility and, some believe, aggravates medical conditions like asthma. But although the brown cloud is worse than in the past, and some of the Front Range's groundwater is already nitrogen-polluted, the levels aren't nearly high enough to cause serious health problems, at least not yet Seastedt says.

Lastly, if Colorado's forests, tundra, and waterways become nitrogen-saturated, the nitrogen-sensitive plankton that fish depend on will die, causing serious harm to Colorado's recreational fishing industry. If plankton populations decrease, so would those of the cutthroat and rainbow trout.