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ES2206  How is the Size of the Dead Zone Affected by the Flow of Nitrates Into the Gulf?

The size of the dead zone in the Gulf of Mexico changes from year to year. One way to explore a possible link between nitrates and the dead zone is to observe the size of the dead zone compared to the amount of nitrates that flow into the Gulf from the Mississippi River each year.

The Mississippi River Basin includes the Mississippi River and all its tributaries. The basin encompasses 41% of the land of the continental United States, including much of the country's farmland. The nitrates that enter the Mississippi River come from organic or inorganic sources. Organic nitrates occur naturally. Sources include manure from animals, human sewage, and nitrogen products produced by certain types of plants. Inorganic sources include fertilizers and industrial waste.

  !   Compare the two charts below. Look for any patterns between the area of the dead zone and the amount of nitrate flux into the Gulf.

NOAA
Area of the dead zone in the Gulf of Mexico
NOAA
Amount of nitrate flux (flow) into the Gulf of Mexico

3. Describe how the size of the dead zone in the Gulf changed from 1985 to 1998.

4. How does the area of the dead zone compare with nitrate flux over the same period? Describe the relationship.


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