Where+are+the+world's+dead+zones+and+what+is+the+trend+of+where+they+occur?

__Where are the world's dead zones?__

Dead zones can be found off the east coast of the United States and in the seas of Europe. Some are found off the coasts of China, Japan, Brazil, Australia and New Zealand. The world's largest dead zone, however is found in the Baltic Sea. Other areas include the northern Adiatic Sea, the Yellow Sea, and the Gulf of Thailand. Forty-three of the world's known dead zones occur in United States coastal waters. The world's second largest, is in the Gulf of Mexico.

__What is the trend of where they occur?__

Most occur in temperate waters. They tend to occur in a combination of agricultural runoff, deposition of nitrogen from burning fossil fuels and human waste discharge. These all over-fertilize the sea. Another source of nutrient buildup in coastal waters is offshore fish farming.

Worldwide, fertilizer is used annually 145 million tons, that is ten times larger than the last half-century. This compares with the amount of increase in the number of dead zones around the world today, as shown by the graph.



Excess nutrients from fertilizer runoff are transported by the Mississippi River into the Gulf of Mexico. Thus, this is believed to be the primary cause of the Gulf of Mexico's dead zone.

__Famous Examples of Where Dead Zones Occur around the World-__ Chesapeake Bay · Largest estuary in the US Baltic Sea · 1/4th is a dead zone · Inland Sea surrounded by nearly all land Kattegat Strait (Scandinavia) · The connection between the Baltic and North Seas Black Sea · Inland Sea, completely surrounded by land · Receives lots of river water Adriatic Sea · Separating the Italian Peninsula from the Balkan Peninsula, surrounded by land on three sides

Common Trends from the Examples
 * 1) Found near lots of land
 * 2) Where lots of water meets
 * 3) Lots of land drainage reaches the rivers which all leads to the dead zone

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