Phosphorus is a necessary element in DNA, in many molecules found in living cells, and in the bones of many animals. A smaller source of phosphorus is found in the droppings (guano) of fish-eating sea birds.Phosphorus enters the soil by the erosion of rocks. Then plant roots incorporate this phosphorus. Phosphorus is used in many biological molecules. Animals mainly through the food they eat obtain Phosphorous. Those foods that are high in phosphorus are beneficial to animals. Phosphorous is put back into the soil by decomposers. Phosphorous cycle also involves the water. However, here the phosphorous must first dissolve before entering the water. Algae and plants take in this dissolved phosphorous. When they consume it bigger water animals consume them and so on and so on. Therefore the phosphorous is transferred over and over. Eventually the phosphorous is released by decomposers and used again. A minor part of that phosphate enters land and is absorbed by plant roots where it enters the land phosphorus cycle.Humans have an effect on the phosphorous as well as the other cycles. However, in this cycle humans can speed up the long-term loss of phosphorus. This is because much of the absorbed phosphate ends up in human wastes and therefore ends up in our sewer systems. When the phosphate enters our sewer system this has a negative effect on our water systems. Since phosphate is being drained out of the land farmers must add fertilizers to the land.The water cycle, or the hydrologic cycle, is the next cycle. Water is obviously the backbone of life. It is used in our day by day lives with out even noticing sometimes. This cycle consists of few steps. The main source of energy for this cycle is the sun. First the sun heats the water. As this occurs, its molecules become energized. Then the water evaporates and rises as vapor in the atmosphere. This process is called evaporation. Next is the process called Condensation. As water vapor rises,...
