Basics on Phosphorous Cycle. for earth sciences

1. Presented by
Anish Kumar S
Roll No: 22270060
Central University Of Tamilnadu

2.  Biogeochemical Cycle
 Importance of Phosphorous
 Global cycling of Phosphorous
 Human Impacts on Phosphorous cycle
 Eutrophication

3.  Energy flow through an ecosystem and is dissipated as heat, but chemical
elements are recycled.
 The ways in which an element or compound such as water moves between its
various living and non-living forms and locations in the biosphere is called a
biogeochemical cycle
 Biogeochemical cycles important to living organisms includes –
Water, Carbon, Nitrogen, Sulphur and Phosphorus

4. Which Biochemical Cycle can be considered as a key to life ?

5. Is Phosphorous important ?

6.  Phosphorous contributes about 0.1% weight percent and Cosmic
abundance of about 1 atom per 100 silicon atom;
 Phosphorus is an essential nutrient for living organisms
 It’s a key part of nucleic acid, like DNA and of phospholipids that
form our cell membranes.
 As calcium phosphate , it also makes up the supportive components
of our bones

7.  In nature , Phosphorus is often the Limiting nutrient- in other words, the
nutrient that’s in shortest supply and puts a limit on growth –and this is
particularly true for aquatic and fresh water ecosystem.

8.  The phosphorus cycle is slow compared to other biogeochemical cycles such as the
water, carbon, and nitrogen cycles.
 In nature, phosphorus is found mostly in the form of phosphate ions PO43-

10.  Phosphate compounds are found in sedimentary rocks, and as the rocks
weather—wear down over long time periods—the phosphorus they contain slowly
leaches into surface water and soils. Volcanic ash, aerosols, and mineral dust can
also be significant phosphate sources, though phosphorus has no real gas phase,
unlike other elements such as carbon, nitrogen, and sulfur.
 Phosphate compounds in the soil can be taken up by plants and, from there,
transferred to animals that eat the plants. When plants and animals excrete
wastes or die, phosphates may be taken up by detritivores or returned to the soil.
Phosphorus-containing compounds may also be carried in surface runoff to rivers,
lakes, and oceans, where they are taken up by aquatic organisms.
 When phosphorus-containing compounds from the bodies or wastes of marine
organisms sink to the floor of the ocean, they form new sedimentary layers. Over
long periods of time, phosphorus-containing sedimentary rock may be moved
from the ocean to the land by a geological process called uplift. However, this
process is very slow, and the average phosphate ion has an oceanic residence
time—time in the ocean—of 20,000 to 100,000 years.

11.  Initially, phosphate weathers from rocks. The small losses in a terrestrial system
caused by leaching through the action of rain are balanced in the gains from
weathering rocks.
 In soil, phosphate is absorbed on clay surfaces and organic matter particles and
becomes incorporated (immobilized). Plants dissolve ionized forms of phosphate.
 The dead remains of plants get decayed and supplies Phosphate back to the soil

12.  The ecosystem phase of the phosphorus cycle moves faster than the sediment
phase.
 All organisms require phosphorus for synthesizing phospholipids, NADPH, ATP,
nucleic acids, and other compounds. Plants absorb phosphorus very quickly, and
then herbivores get phosphorus by eat plants. Then carnivores get phosphorus by
eating herbivores.
 Eventually both of these organisms will excrete phosphorus as a waste. This
decomposition will release phosphorus into the soil. Plants absorb the phosphorus
from the soil and they recycle it within the ecosystem.

13.  Unlike the other cycles, there is no volatile phosphorus-containing product to
return phosphorus to the atmosphere in the way carbon dioxide, nitrogen gas, and
sulfur dioxide are returned.
 Therefore, phosphorus tends to accumulate in the seas. It can be retrieved by
mining the above-ground sediments of ancient seas, mostly as deposits of calcium
phosphate.
 Seabirds also mine phosphorus from the sea by eating phosphorus-containing fish
and depositing it as guano (bird droppings).
 Certain small islands inhabited by such birds have long been mined for these
deposits as a source of phosphorus for fertilizers.

14.  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.

16.  Humans have greatly influenced the Phosphorus cycle by mining Phosphorous,
converting it to fertilizer, and by shipping fertilizer and products around the globe.
 Transporting Phosphorus rich food from farms to cities has made a major change
in the global Phosphorous cycle.
 Waters are enriched in Phosphorous from farms run off, and from effluents that
are inadequately treated before get discharged into water bodies.
 Like nitrogen, increased use of fertilizers increases phosphorus runoff into our
waterways .Which contributes to eutrophication

17.  Natural eutrophication is a process by which lakes gradually age and become
more productive and may take thousands of years to progress.
 Cultural or anthropogenic eutrophication, however, is water pollution caused by
excessive plant nutrients, which results in excessive growth in algae population..

18.  Some algae make water taste or smell bad or produce toxic compounds. Also, when all of
those algae die and are decomposed by microbes, large amounts of oxygen are used up as
their bodies are broken down. This spike in oxygen usage can sharply lower dissolved
oxygen levels in the water and may lead to death by hypoxia—lack of oxygen—for other
aquatic organisms, such as shellfish and finfish.
 Regions of lakes and oceans that are depleted of oxygen due to a nutrient influx are called
dead zones. The number of dead zones has increased for several years, and more than 400
of these zones existed in 2008. One of the worst dead zones is off the coast of the United
States in the Gulf of Mexico. Fertilizer runoff from the Mississippi River Basin created a
dead zone of over 8,463 square miles. As you can see in the figure below, dead zones are
found in areas of high industrialization and population density around the world.

19.  "Biogeochemical cycles" by Robert Bear, David Rintoul, Bruce Snyder, Martha
Smith-Caldas, Christopher Herren, and Eva Horne
Biogeochemical Cycles by Robert Bear
 https://www.khanacademy.org/science/biology/ecology/biogeochemical-cycles/a/the-
phosphorous-cycle
 https://www.slideshare.net/redbloodcelz/phosphorus-cycle?from_m_app=android