Seen from above, the Mississippi River carries sediment into the Gulf of Mexico. That sediment often contains pollutants from fertilizers that cause a spike in algal blooms.
大量降水携带数吨肥料和生活污水随着密西西比河汇入大海，完成了蜿蜒8000迈的死亡地带。
Record-breaking Midwest rainfall washed tons of fertilizer and sewage water out to sea, contributing to a devastatingly large patch of polluted water, scientists say.
JUST OFF THE coast of Louisiana and Texas where the Mississippi River empties, the ocean is dying. The cyclical event known as the dead zone occurs every year, but scientists predict that this year's could be one of the largest in recorded history.
Annual spring rains wash the nutrients used in fertilizers and sewage into the Mississippi. That fresh water, less dense than ocean water, sits on top of the ocean, preventing oxygen from mixing through the water column. Eventually those freshwater nutrients can spur a burst of algal growth, which consumes oxygen as the plants decompose.
The resulting patch of low-oxygen waters leads to a condition called hypoxia, where animals in the area suffocate and die. Scientists estimate that this year the dead zone in the Gulf of Mexico will spread for just over or just under8,000 square miles across the continental shelf situated off the coast.
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