Excess nitrogen is particularly harmful for marine ecosystems, and can be linked to everything from increased outbreaks of red tides to the deaths of marine mammals and the loss of biodiversity. What's more, many scientists predict that the problem will worsen in the coming decades unless action is taken now to reduce nutrient excesses in U.S. waters. State and local governments often are responsible for identifying and dealing with nutrient pollution, and their efforts can significantly improve coastal environmental quality. But state and local agencies can't do it all, and they certainly can't do it alone. To truly protect our coasts, rivers, and lakes, our nation needs a comprehensive strategy to prevent excessive amounts of nitrogen and phosphorus from entering our waterways.
Nutrient pollution is a complex problem that is taking on ever-larger proportions.
For example, human activities have more than doubled the amount of nitrogen globally from 1960 to 1990, with the use of synthetic fertilizers accounting for the majority of that growth. More than half of all synthetic fertilizers ever produced has been used in the past 15 years. In the United States, approximately 20 percent of the nitrogen in these fertilizers seeps into ground water, rivers, and streams, gradually making its way into coastal waters. Other sources of nitrogen include animal wastes, waste-water treatment plants, and the combustion of fossil fuels. When these fuels burn, nitrogen compounds are released into the atmosphere, and then fall in acid rain, adding significant amounts of nitrogen to some coastal waters.