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Human Impact on Biogeochemical Cycles


Humans are one of the largest consumers on Earth and hands down use and impact more of the world’s supply of natural resources than any other species. Maybe it is due to the sheer size of the species, or maybe it is due to over-consumption. There are three biogeochemical cycles that humans impact daily: The Carbon Cycle, The Phosphorus Cycle and The Nitrogen Cycle. As learned by the Law of Conservation of Matter, atoms cannot be destroyed or created, instead they recycle themselves, so these cycles show how the different types of atoms are transformed and used by consumption.

Carbon can be found in the World’s atmosphere, as well as emitted from the burning of fossil fuels and even breathed out of many species’ mouth, including humans. In this cycle you could start with the large amounts of carbon that is in the atmosphere and which is then pulled in from plant life and turned into organic matter (oxygen) that helps animals breath. In eating the plant, the animal then picks up the transformed atom and in turn, turns it back into carbon as they breathe. In death their bodies are consumed by scavengers which will release the carbon back into the air or stay deposited in the earth, which can then turn into coal or another fossil fuel that will be burned, releasing the carbon back into the air to finish its cycle. Humans are cutting down forests for an ever-growing population which is lessening the amount of CO2 transferred to oxygen, lowering our air quality. To make matters worse, over consumption of fossil fuels are putting large amounts of carbon into the atmosphere causes a loss of a natural protector from the sun, the ozone layer.

Phosphorus is an important mineral nutrient needed in all ecosystems, it is used as fertilizer to hasten plant blooming as well as used in plant production, which in turn is a key element needed for animals and humans. The cycle begins with rain runoff that breaks down rocks which release phosphorus into the ground and eventually into the water supply. From there, the phosphorus is drawn in from plants and then turned into an organic phosphate that is eaten by consumers. Like carbon most of the recycling at this point occurs when the animal excrete the phosphorus back into the land via sweat, urine and then eventual death. Humans are affecting this cycle with the over use of fertilizers rich in phosphorus that are finding their way into the ocean, where the excess is wreaking havoc on the ecosystems. With most phosphorus getting trapped essentially in the ocean, ocean life becomes tainted with over fertilization that can lead to death of plant and animal life.

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Nitrogen is found in large amounts in our atmosphere and like phosphorus, is needed by most organic material to survive. Like the cycles before, the Nitrogen cycle can begin by the many producers absorbing and then incorporating the nitrogen into useable organic material. And like previous cycles, consumers come in and consume the plants and the nitrogen is released through excreting and inevitable death of the animals, putting the nitrogen back into the earth’s soil. Where this cycle is unique is how the nitrogen is then turned useable again by bacteria called nitrifying bacteria. There are several other processes that will “fix” nitrogen and make it useable to plant life that will suck it back into the cycle to complete it. Humans impact this cycle dramatically through industrialization and over consumption, resulting in more than double the natural amount of nitrogen from the atmosphere into the soil. Excess nitrogen is finding its way into the soil where it sucks surrounding land dry of minerals that lead to mineral deficiencies. It also is becoming in excess in the water supply, wreaking havoc on the plant life and animal life.


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