THE PHOSPHOROS

CYCLEBY JAMES AND MELISSA

PHOSPHORUSWhat is phosphorus?

Phosphorus is found in the components of an ecosystem. It is an essential nutrient for plants and animals. Phosphorus occurs in the plasma membranes of plants and animal cells. It is an important component of the teeth and the bones of the animals.

In the non-living components of ecosystems phosphorus occurs as minerals in rocks and as dissolved phosphate in soils and rivers.

In contrast the carbon and nitrogen the phosphorus cycle does not include cycling through the atmosphere in the form of gas.

Many decades before the awareness of global warming and the prospect of rising sea levels became concerns for Pacific nations, phosphate mining wrecked havoc on numerous communities.

While the use of phosphorus is not directly responsible for global warming, it is strategically important in food production and like petroleum it is a resource of fierce international competition. Some predictions indicate that, with the current rate of consumption, the known global reserves of phosphate may be used up by the year 2060.

We use phosphorus in a lot of different places. We put it on farms to raise crops. We put it on grass to make it grow. We put it on golf courses to keep them green. It also occurs naturally in sewage.

You might think that the biggest sources of phosphorus are the obvious ones—sewage treatment plants, chemical factories, and the like. But in fact, identifiable sources such as these contribute less than 20% of the phosphorus in the river.

The rest comes from a wide array of diffuse sources. Every lawn, every farm, every golf course that uses phosphorus contributes a little bit. But add all those little bits together, and they account for 80% of the problem

Little things cause big problemsTiny plant-like organisms called algae live in river water. They use sunlight to make sugar, and serve as food for fish and other aquatic animals.Like all living things, algae needs phosphorus to grow. Normally, river water has little phosphorus, which keeps algae in check. But when large amounts of phosphorus enter the water, algae grows explosively.

Blue-green algae

PHOSPHORUS CYCLE

The major store of phosphorus is phosphorus containing rocks and sediments. Phosphorus is released from the rocks by erosion. Producer organisms, such as plants, take up phosphorus in the form of dissolved phosphates from the soil in the case of terrestrial ecosystems, or from the waters of lakes and seas in the case of aquatic ecosystems.

Phosphorus moves from plants to animals when consumers eat plants or when animals eat herbivores. Phosphorus is returned to the non-living component of an ecosystem when dead plants and animals decay through the action of decomposers. Phosphorus can also be returned to the non-living component of an ecosystem through animal wastes. The phosphorus may then be taken up again by plants or it may be washed away into rivers and seas.

Waste products of fish-eating birds are rich in phosphate. Many generations of sea-birds nesting on the same sites produces these wastes that are accumulated into a hard substance known as guano.