The Phosphorus Cycle

Chirag Tamboli Jacob Wall The Phosphorus Cycle

What is Phosphorous and Why do We need it • Phosphorus is a chemical element with symbol P and atomic number 15. • It is an essential nutrient for living organisms and also a limiting factor • It is a part of Nucleic Acids (DNA and RNA), energy molecules (ATP and ADP), and of fats • Phosphorus is a building block of certain animal and human parts • Examples of this are teeth and bones

Where is Phosphorus located • It can be found on earth in water, soil, and ocean sediments • Phosphorus is also present in bird droppings called “Guano” • Phosphorus in the environment usually exists as phosphate ions (PO43-) • Almost always, phosphorus cannot be found in the atmosphere in a gaseous state • If it is found in the atmosphere, then it is usually in very fine dust particles • It is most commonly found in rock formations and ocean sediments as phosphate salts • On the surface, phosphorus is most commonly found in apatite rock [Ca5(PO4)3OH]

Movement of the Phosphorus Cycle • The phosphorus cycle is very slow • It starts off in phosphate bearing rocks; when they are weathered or mined it gets distributed in rivers, lakes, and soil • Plants then absorb the phosphorus, then herbivorous and omnivorous animals ingest the plant, and in turn absorb the phosphorus • It is released back into the soil and ocean sediment through animal excretion and the decomposition of animals and plants

Phosphorus Bearing Rocks/Sediments • Phosphate deposits form over time into layers of sediment at the bottom of oceans and as rock formations on land • Phosphorus can be trapped in sediment for over 100 million years • Natural geological processes push the sediment layers up and expose them on the surface • Weathering, erosion, or human mining of rocks gradually release phosphorus as phosphate ions, which are soluble in water • From here, the phosphate ions enter the soil and bodies of water

Phosphorus enters Plants & Organisms • Phosphates from soils, fertilizers, and aquatic sediments are first absorbed by plants • Phosphates flow from plants to animals by consumption • Herbivores (Primary Consumers) eat the plants • Carnivores and omnivores (secondary and tertiary consumers) eat the primary consumers • This is the quickest stage when compared to the rest of them

Return into the Environment • Phosphorus is returned to the environment in different ways: • Excretion and Urination: Animal waste is broken down by decomposers which returns phosphates back into the soil • A large percentage of phosphorus is wasted through excretion • Death: • When plants and animals die, bacteria and other decomposers break down organic material and release phosphate ions back into the soil • When aquatic plants and animals die, phosphate ions bind to ocean sediments at the ocean floor, creating new deposits • Phosphates in the soil runoff or drain into different bodies of water • Over a timespan of millions of year, geological processes push sediment layers up, restarting the cycle

http://www.lenntech.com/phosphorus-cycle.htm

Credit: bhavanajagat.com

http://www.enviroliteracy.org/article.php/480.html

Video • http://www.youtube.com/watch?v=RKkC2JpjaGc

Human Impacts • Caused mainly through the use of commercial synthetic fertilizers • Plants are not able to use all of the phosphate in the soil or water, resulting in runoff into streams, rivers, lakes, etc. • The resulting runoff creates algal blooms that deprive aquatic life of oxygen • The improper application of manure as fertilizer • When manure is put down in the winter, it can be lost as runoff in the spring • Deforestation: • As forests are cut, nutrients originally stored in plants and rocks are quickly washed away by heavy rains, making the land unproductive. Unproductive land results in the extensive use of fertilizers • Wastewater and sewage treatment plants are not efficiently removing phosphorus and phosphates from water • This creates causes extra phosphate to enter water sources.

Works Cited • http://www.lenntech.com/phosphorus-cycle.htm • http://www.elmhurst.edu/~chm/vchembook/308phosphorus.html • http://www.eoearth.org/article/AP_Environmental_Science_Chapter_2-_The_Cycling_of_Matter • http://www.enviroliteracy.org/article.php/480.html • http://www.buzzle.com/articles/phosphorus-cycle.html • http://www.youtube.com/watch?v=RKkC2JpjaGc

The Phosphorus Cycle