Discuss how humans impact each of the following cycles, providing specific examples of each. The nitrogen cycle, the phosphorus cycle, and the carbon cycle.

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The nitrogen cycle is impacted by humans whenever fertilizer is applied to farmland to help crops grow. This adds nitrates to the soil. If soil erodes, the nitrates are transported and deposited in the nearest body of water. This can cause algae to overgrow in a process called eutrophication. The lake will run out of oxygen as the algae die off and bacteria begin their decomposition.Sessile organisms are greatly affected. Later, it can result in fish kills and smelly water. The phosphorus cycle occurs between the land and the sea. The atmosphere is not involved in this cycle at all. Phosphorus usually weathers from rocks and is incorporated into plants, which are in turn eaten by herbivores which are consumed by carnivores. In urine and feces, phosphorus is excreted and when organisms decompose, phosphorus is returned to the ecosystem. When humans add additional phosphates to the environment, just as with nitrogen, eutrophication can occur in fresh water ecosystems. By adding manure to farmlands, this can add phosphates to the environment. The carbon cycle is influenced by humans because they have been adding more carbon to the atmosphere since the industrial revolution due to the combustion of fossil fuels. When coal, oil and gas are burned, carbon dixoide is added to the atmosphere as well as carbon monoxide. Plants need carbon dioxide for photosynthesis, but due to air pollution which kills plants, and clearing land by cutting down forests, there is excess carbon dioxide in the atmosphere because the plants cannot keep up. It has been shown that carbon dioxide in the atmosphere leads to global warming due to the greenhouse effect. Sunlight can enter the earth's atmosphere but the heat energy becomes trapped near the surface, leading to higher temperatures. This in turn, can melt the polar ice caps and may lead to flooding when the sea level rises. It can change the earth's climate and possibly spread dangerous disease-carrying organisms like mosquitoes, which thrive in higher temperatures.

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Give specific examples of each cycle and how humans impact Nitrogen cycle, Phosphorus cycle, and Carbon cycle?    

When one speaks of a cycle of any type, we are referring to how an element of that cycle is recycled along in many forms, never being used up, but continually changing forms.

The nitrogen cycle involves plants removing nitrogen gas from the atmosphere, fixing it into their plant cell structure.  Humans can not absorb nitrogen from the air, so they either eat the plants that pull it from the air, or they eat other animals that have nitrogen as part of their body's chemical makeup.

The phosphorous cycle is similar, plants absorb phosphorous as a nutrient from the soil.  Humans eat the plants or eat other animals that have phosphorous as a part of the chemical makeup of their bodies.  Elemental phosphorous was first identified in the sediment of human urine, and bone ash was used as an early fertilizer to replace phosphorous in the soil.

Carbon in the carbon cyle is an interactive process between plants and humans.  Humans take in oxygen and give off carbon dioxide as a waste product.  Plants take in carbon dioxide and give off oxygen as a waste product.

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