A Study of the Human Impact on the Carbon, Phosphorus, and Nitrogen Cycles

563 Words2 Pages
Human Impact on the Carbon, Phosphorus, and Nitrogen Cycles Introduction Except for small amount of cosmic debris that enters the Earth's atmosphere, the Earth is a closed system for matter. All the elements needed for the structure and chemical processes of life come from the elements that were present in the Earth's crust when it was formed billions of years ago. This matter is continually cycling the atmosphere, hydrosphere, biosphere, and lithosphere, from periods of a few days to millions of years. These cycles are called biogeochemical cycles, because they include a variety of biological, geological, and chemical processes (Biogeochemical Cycles," 2008). This paper will look at the impact humans have had on the carbon, nitrogen and phosphorus cycles. Discussion Carbon Cycle The carbon cycle has been significantly altered by extracting and combusting billions of tons of hydrocarbons in fossils that were buried deep in the Earth's crust. In addition, clearing vegetation that stores carbon has also impacted the carbon cycle. Global release of carbon through human activities has increased from 1 billion tons per year in 1940 to 6.5 billion tons per year in 2000. About half of this extra carbon is taken up by plants and the oceans, while the other half remains in the atmosphere. Nitrogen Cycle The major human activities that today influence the global nitrogen cycle are fossil fuel combustion, the production and use of chemical fertilizer, and the growing of
Open Document