Phosphorus Cycle

Phosphorus is another chemical element that is common in the structure of living organisms (see Figure 8.20); however, the phosphorus cycle is different from the hydrologic, carbon, and nitrogen cycles because phosphorus is found in sedimentary rock. These massive deposits are gradually eroding and providing phosphorus to ecosystems. A large amount of eroded phosphorus ends up in deep sediments in the oceans and in lesser amounts in shallow sediments. Part of the phosphorus comes to land when marine animals surface. Decomposing plant or animal tissue and animal droppings return organic forms of phosphorus to the water and soil. Fish-eating birds, for example, play a role in the recovery of phosphorus. Guano deposits (bird excreta) on the Peruvian coast are an example. Humans have hastened the rate of phosphorus loss through mining and the production of fertilizers, which are washed away and the phosphorus lost. Odum (1983) suggested, however, that there was no immediate cause for concern, as the known reserves of phosphate are quite large.

Phosphorus has become very important in water quality studies, because it is often found to be a limiting factor. Controlling phosphorus compounds that enter surface waters and contribute to the growth of algae blooms is of considerable interest and has generated much study (Metcalf & Eddy, 2003). Upon entering a stream, phosphorus acts as a fertilizer, promoting the growth of undesirable algae populations or algae blooms. As the organic matter decays, dissolved oxygen levels decrease and fish and other aquatic species die.

Although it is true that phosphorus discharged into streams is a contributing factor to stream pollution, it is also true that phosphorus is not the lone factor. Odum (1975) warned against what he called the one-factor control hypothesis (i.e., one-problem/one-solution syndrome). He observed that environmentalists in the past had focused on one of two items, such as phosphorus contamination, and failed to understand that the strategy for pollution control must involve reducing the input of all enriching and toxic materials

Guide to Alternative Fuels

Guide to Alternative Fuels

Your Alternative Fuel Solution for Saving Money, Reducing Oil Dependency, and Helping the Planet. Ethanol is an alternative to gasoline. The use of ethanol has been demonstrated to reduce greenhouse emissions slightly as compared to gasoline. Through this ebook, you are going to learn what you will need to know why choosing an alternative fuel may benefit you and your future.

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