Dead zones are low oxygen areas in the world’s oceans and lakes. A combination of physical, chemical and biological factors creates dead zones, with nutrient pollution being the major culprit. These nutrients come from the run-off of chemical fertilizers and wastewater.
Hypoxic zones can occur naturally, but scientists are concerned about the areas created or enhanced by human activity. Excess nutrients that run off land or are piped as wastewater into rivers and coasts can stimulate an overgrowth of algae, which then sinks and decomposes in the water. The decomposition process consumes oxygen and depletes the supply available to healthy marine life.
Dead zones occur in many areas of the country, particularly along the East Coast, the Gulf of Mexico, and the Great Lakes, but there is no part of the country or the world that is immune. The second largest dead zone in the world is located in the U.S., in the northern Gulf of Mexico.
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