Which river is associated with nutrient runoff causing a well-known dead zone in the Gulf of Mexico?

Which river is associated with nutrient runoff causing a well-known dead zone in the Gulf of Mexico?

• A. Mississippi River
• B. Yangtze River
• C. Nile River
• D. Amazon River

Answer: (A)

Nutrient pollution from farming and other land uses increases nitrogen and phosphorus in rivers. Those nutrients fuel rapid algal growth when they reach coastal waters. After the blooms die, bacteria break down the organic matter, using up the dissolved oxygen and creating low-oxygen, or hypoxic, conditions. In the Gulf of Mexico, the Mississippi River system carries a huge load of these nutrients from a vast watershed into the Gulf. This nutrient influx promotes extensive algal blooms each year, and the decomposition that follows drains oxygen from the water, forming the well-known dead zone. The other rivers listed flow to different regions and cause eutrophication there, but the Gulf of Mexico’s characteristic dead zone is specifically linked to the nutrient runoff from the Mississippi River basin.

Nutrient pollution from farming and other land uses increases nitrogen and phosphorus in rivers. Those nutrients fuel rapid algal growth when they reach coastal waters. After the blooms die, bacteria break down the organic matter, using up the dissolved oxygen and creating low-oxygen, or hypoxic, conditions.

In the Gulf of Mexico, the Mississippi River system carries a huge load of these nutrients from a vast watershed into the Gulf. This nutrient influx promotes extensive algal blooms each year, and the decomposition that follows drains oxygen from the water, forming the well-known dead zone.

The other rivers listed flow to different regions and cause eutrophication there, but the Gulf of Mexico’s characteristic dead zone is specifically linked to the nutrient runoff from the Mississippi River basin.