A satellite image of the Gulf of Mexico and coastline.
Every summer for the past several decades, a large dead zone has threatened the economic and ecological health of the Gulf of Mexico, the nation’s largest and most productive fishery.
This dead zone occurs because of excessive nutrients entering the rivers, lakes, and estuaries that feed into or make up the Gulf of Mexico. Nitrogen and phosphorus are essential nutrients for plant growth, but too much of them can stimulate algal growth. And as algae die, they sink to the bottom of the water and decompose, all the while robbing the water body of the oxygen needed for aquatic life to thrive.
The result? Oxygen levels can drop too low to support most life in bottom and near bottom waters, creating a hypoxic or dead zone.
The size of each year’s hypoxic zone is primarily determined by the amount of nutrients flowing from the Mississippi-Atchafalaya River Basin into the northern Gulf of Mexico – particularly the nutrient flow during April and May. Agricultural inputs are the largest source of these nutrients, though inputs from atmospheric deposition, urban areas, and wastewater treatment plants also contribute.
Complete information in:
http://www.usgs.gov/blogs/features/usgs_top_story/dead-zone-the-source-of-the-gulf-of-mexicos-hypoxia/?from=textlink
- Posted using BlogPress from my iPad
Nenhum comentário:
Postar um comentário