The 2010 BP oil spill eclipsed a quieter, more persistent issue that may be more scarring to the Gulf of Mexico than even 200 million gallons of oil.
Every summer, nitrogen pollution from Midwest farms creates a so-called dead zone in the northern Gulf that in 2011 covered an area larger than Connecticut and Rhode Island combined. A study by the Environmental Working Group found 15 percent of the counties in the Mississippi River Basin are responsible for 78 percent of this pollution.
Humans turn inert atmospheric nitrogen into reactive chemicals more than all natural processes combined. Worldwide, scientists have identified more than 400 dead zones. While many governments with dead zones are considering ways to limit the pollution, the options are political and economically difficult.
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