Phosphorus Cycle

Overview:

The Phosphorus Cycle is one of the slowest biogeochemical cycles.

Properties of Phosphorus:

• A non-metal element
• Atomic number is 15 – has 15 electrons and 15 protons.
• With 5 electrons in its outermost energy level, it needs 3 electrons to complete its outermost energy level.
• Found in nature with different molecular formations or chemical structure making up the matter – usually in a solid state (allotropic)
• Normally forms covalent bonds
  
• An important nutrient for plant growth & animal development
• Doesn’t naturally change into a gaseous state of matter
• Is relatively insoluble in water

The Stages of the Cycle:

Phosphorus is commonly found in rock formations and ocean sediments as phosphate salts.
These salts are a result of rocks weathering.
The salts dissolve in the water and then are assimilated by plants into organic compounds such as phospholipids, amino acids, and nucleic acids. Animals then eat plants and absorb phosphorus.
When animals/plants die, the phosphorus returns to the soil through decomposition and is available for plants again. Phosphorus also moves from the ocean to the land by birds feeding on fish or ocean plants and excreting “guano” onto land. Without the role of birds, phosphate would remain in oceans. Phosphorus then returns to sediments/rocks to rejoin the cycle and eventually will be taken up again. The cycle will then start over again.

Where Is Phosphorus Stored? Where is it found?:
Phosphorus exists in the atmosphere only in small particles of dust. Phosphorus can be found in plants, animals, humans, water, soil, in sediments. It moves from sediments, to living organisms, to soil, and then to water. Phosphorus is commonly found in rocks formations and ocean sediments as phosphate salts. in the ocean floors while waiting for upwells to bring it up, and in large quantities of sea-bird poop that harden into rock-like masses and is then harvested by humans for fertilizer

How is Phosphorus Essential for Life?:

• Phosphorus is a limiting factor in plant growth, meaning that without it, plants are unable to grow in soil. Phosphorous is a major component in fertilizer.
• Where Phosphorus is plentiful, phytoplankton (simple photosynthesizing water organism) thrives, and the fish that eat plankton can survive, and the food chain continues.
• The element is necessary in animals (including humans) due to its incorporation into ATP and nucleic acids – both necessary for cell life, animal or plant.
• ATP is a key component in intracellular energy transfer and transports chemical energy within cells for metabolism
• Nucleic Acids form up genetic material, meaning Phosphorus is essential for reproduction.

How Phosphorus Affects Each Earth System:

• Atmosphere – Phosphorus doesn’t exist in a gaseous state anytime during the cycle. It only exists as small particles of dust. The element affects the atmosphere by being a key factor for plant life. Therefore – indirectly – Phosphorus helps add oxygen into the air because it is necessary for the plants which use photosynthesis to live.
• Hydrosphere – While mostly contained in soil, water runoff causes eutrophication. The water runoff eventually ends up in the ocean in lieu to the water cycle. Phosphorus is a source of nutrition for plankton, and the plankton is able to form a food chain from the many species that eat plankton.
• Biosphere – Phosphorus is a key, or limiting factor in the existence of life. Plants need the element in order to grow (ATP) and reproduce (Nucleic Acids). Without Phosphorus, there would be no plant life, and, therefore, no animal life. Without plant life, very few animals can survive – and the lifeforms that do exist would need to find phosphorus from somewhere.
• Geosphere – The decay of dead plants returns phosphorus to sediment, where it can become compacted into sedimentary rock and enters the rock cycle. Sedimentary rock can be drawn into subduction zones to become igneous rock, and igneous rock can be changed through heat and pressure into metamorphic rock.

Human Impact on the Cycle:
Humans have had a massive influence on the Phosphorus cycle by mining phosphorus, converting it to fertilizer, and by shipping fertilizer and products (especially food from farms) around the world.

Aquatic ecosystems are being extremely affected by excess phosphorus in the water, due to run-off from farms and sewage discharge. As a result of high levels of Phosphorus in the water, *cultural/anthropogenic Eutrophication occurs. Eutrophication affects bodies of both fresh and sea water.

Human operated farms are a source of excess phosphorus.

• Liquid manure has harmful effects on the amount of phosphorus in the soil.
• In areas where waterlogging occurs, sharp increase in Phosphorus concentrations occurs and results in the draining of phosphorus.
• Disposal of agricultural wastes is already a major problem on its own, but now due to its high phosphorus content is affecting the phosphorus cycle as well.
• Overuse of phosphorus fertilizers causes a major effect on the phosphorus cycle resulting in cultural/anthropogenic eutrophication, which is harmful to aquatic ecosystems.

*Cultural/Anthropogenic Eutrophication – When excessive plant nutrients results in excessive growth in algae.

Vocab:

Covalent Bond – A bond in which the electrons are shared between two atoms. This bond is usually between two or more non-metal atoms.

Insoluble – Unable to dissolve in water

Limiting Factor – Limits the growth or development of an organism, population, or process.

ATP – Adenosine-5′-triphosphate is a nucleoside triphosphate used in cells as a coenzyme

Nucleic Acid – Complex organic substance present in living cells, esp. DNA or RNA

Photosynthesis – Process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water

Eutrophication – Can occur when erosion by water dissolves essential minerals from rock or soil and carries them into bodies of water

Please edit the following to avoid plagiarism

***Overview
Phosphorus is an element of an atomic number of 15 found on group number 15 and period 3 and is a nonmetal element with the symbol P. Phosphorus as a mineral is almost always present in an oxidized state in inorganic phosphate rocks. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but due to its high reactivity, phosphorus is never found as a free element on Earth.

Phosphorus is essential for life.
As phosphate, it is a component of DNA, RNA, ATP, and also the phospholipids that form all cell membranes.

Where it occurs?
Phosphorus is not found free in nature, but it is widely distributed in many minerals, mainly phosphates.

Inorganic phosphate rock, which is partially made of apatite (an impure tri-calcium phosphate mineral), is today the chief commercial source of this element.

About 50 percent of the global phosphorus reserves are in the Arab nations. Large deposits of apatite are located in China, from Tennessee Russia, Morocco, Florida, Idaho, Tennessee, Utah, and elsewhere. Albright and Wilson in the United Kingdom and their Niagara Falls plant, for instance, were using phosphate rock in the 1890s and 1900s, Florida, and the Îles du Connétable (guano island sources of phosphate); by 1950 they were using phosphate rock mainly from Tennessee and North Africa. In the early 1990s Albright and Wilson’s purified wet phosphoric acid business was being adversely affected by phosphate rock sales by China and the entry of their long-standing Moroccan phosphate suppliers into the purified wet phosphoric acid business. Phosphorus comprises about 0.1% by mass of the average rock, and consequently the Earth’s supply is vast, although dilute.

How it moves

Phosphorus is an important nutrient for plants and animals. Phosphorus is a limiting nutrient for aquatic organism. Phosphorus does not enter the atmosphere, remaining mostly on land and in rock and soil minerals. Eighty percent of the mined phosphorus is used to make fertilizers. Phosphates from fertilizers, sewage and detergents can cause pollution in lakes and streams. Enrichment of phosphate can lead to eutrophication of fresh and inshore marine waters, leading to algae blooms. On land most P is found in rocks and minerals. P rich deposits have generally formed in the ocean or from guano, and over time, geologic processes bring ocean sediments to land. Weathering of rocks and minerals release P in a soluble form where it is taken up by plants, and it is transformed into organic compounds. The plants may then be consumed by herbivores. After death, the animal or plant decays, and P is returned to the soil where a large part of the P is transformed into insoluble compounds. Runoff may carry a small part of the P back to the ocean. Generally with time (thousands of years) soils become deficient in P leading to ecosystem retrogression. Phosphates move quickly through plants and animals; however, the processes that move them through the soil or ocean are very slow, making the phosphorus cycle overall one of the slowest biogeochemical cycles. Initially, phosphate weathers from rocks and minerals, the most common mineral being apatite. Overall small losses occur in terrestrial environments by leaching and erosion, through the action of rain. In soil, phosphate is absorbed on iron oxides, aluminium hydroxides, clay surfaces, and organic matter particles, and becomes incorporated (immobilized or fixed). Plants and fungi can also be active in making P soluble. Unlike other cycles, P cannot be found in the air as a gas, it only occurs under highly reducing conditions as the gas phosphine PH3. An important way phosphorus returns from the ocean to land is ocean-feeding birds because fish carry phosphorous on there body. Phosphorus is usually lost from the biological cycle. Phosphorus on earth takes long to travel. Phosphorus can be deposited on the sea floor and remain there for millions of years.
Compounds found in the cycle
The availability of phosphorus in an ecosystem is restricted by the rate of release of this element during weathering. The release of phosphorus from apatite dissolution is a key control on ecosystem productivity. The primary mineral with significant phosphorus content, apatite [Ca5(PO4)3OH] undergoes carbonation. Little of this released phosphorus is taken by biota (organic form) whereas, large proportion reacts with other soil minerals leading to precipitation in unavailable forms. The later stage of weathering and soil development. Available phosphorus is found in a biogeochemical cycle in the upper soil profile, while phosphorus found at lower depths is primarily involved in geochemical reactions with secondary mineral. Low-molecular-weight (LMW) organic acids are found in soils. They originate from the activities of various microorganisms in soils or may be exuded from the roots of living plants. Several of those organic acids are capable of forming stable organo-metal complexes with various metal ions found in soil solutions. As a result, these processes may lead to the release of inorganic phosphorus associated with aluminium, iron, and calcium in soil minerals. The production and release of oxalic acid by mycorrhizal fungi explain their importance in maintaining and supplying phosphorus to plant.

The availability of organic phosphorus to support microbial, plant and animal growth depends on the rate of their degradation to generate free phosphate. There are various enzymes such as phosphatases, nucleases and phytase involved for the degradation. Some of the abiotic pathways in the environment studied are hydrolytic reactions and photolytic reactions. Enzymatic hydrolysis of organic phosphorus is an essential step in the biogeochemical phosphorus cycle, including the phosphorus nutrition of plants and microorganisms and the transfer of organic phosphorus from soil to bodies of water. Many organisms rely on the soil derived phosphorus for their phosphorus nutrition. ***