Thursday, November 21, 2019

Science 6..11-12 Assignment Example | Topics and Well Written Essays - 750 words

Science 6..11-12 - Assignment Example Dead zones represent low-oxygen areas (hypoxic areas) in the world’s coastline and lakes. All organisms need oxygen to survive. The absence or low oxygen levels in these areas make it impossible for organisms to survive hence the term dead zone. The Gulf of Mexico gives a quintessential example of one such area. According to National Geographic, in 2010, the Gulf of Mexico Dead Zone was approximately 20,140 square kilometers. It has a seasonal hypoxic zone that forms every year in late summer. Its size varies from less than 5,000 square kilometers to approximately 22,000 square kilometers. The primary cause of dead zone formation is human activities. The upsurge in population has led to an increase in intensive agricultural and industrial activities. These activities lead to the emission of nitrogen and phosphorus into the environment i.e. soil, water and air. These are washed off into water basins such as oceans and lakes. These nutrients increase the fertility of the marine ecosystem; organisms like phytoplankton, algae and seaweed grow rapidly (algal bloom). This prevents the penetration of sunlight and absorption of oxygen by organisms living beneath the water surface leading to the reduction of the organisms immensely through death. Due to low-oxygen and available nutrients, the organisms (phytoplankton, algae and seaweed) eventually die and sink to the bottom of the sea where they are decomposed by bacteria. Oxygen can flow freely but is eventually used up by the process of decomposition leading to low-oxygen (hypoxia). Organisms that live beneath die or wither and others like the fish flee and a dead zone is formed. Several methods can be embraced to reduce the occurrence of dead zones. The use of synthetic fertilizers can be discontinued or reduced as they contain large quantities of nitrogen and phosphorus. Farmers can also use natural sources like compost and manure and adopt farming methods like contour cropping and no-till to reduce

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