Agriculture & Water Pollution

Water pollution comes from many sources. One of the biggest is runoff from agriculture. Runoff picks up chemicals such as pesticides and fertilizers and carries the chemicals to bodies of water. The added nutrients (particularly nitrogen and phosphorus) often cause excessive growth of algae, creating algal blooms. They algae use up oxygen in the water so that other aquatic organisms cannot survive. This has occurred over large areas of the oceans, creating dead zones, where low oxygen levels have killed all ocean life.A very large dead zone exists in the Gulf of Mexico. 


The problem begins on midwestern farms, where plants like corn, wheat and soybeans need nitrogen and phosphorus to thrive. Unfortunately, the fertilizer doesn't just stay on the farm fields. Forty-one percent of the continental US drains into the Mississippi River, and the majority of that soil is farmland. In peak growing season, 8 million pounds of nitrate flows off farms into the Mississippi River a day.  The Mississippi River then flows to the Gulf of Mexico, fueling the rapid growth of algae. When the algae die, their decay robs the water of oxygen, killing plants, fish and other marine life. 


Watch the following video:

 

Sources: USOE OER Resource Guide for Earth Systems and Agricultural Runoff and the Gulf of Mexico Dead Zone. Retrieved from http://utah.pbslearningmedia.org/resource/envh10.sci.life.eco.deadzone/agricultural-runoff-and-the-gulf-of-mexico-dead-zone/ on December 27, 2013.