Presentation on Phosphorus in relation with our Environment. #environment #phosphorus #eutrophication #phosphorus_cycle #water_quality_management

1. Phosphorus
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15 30.974
Course: Water Quality Management

2. Presented by
Sabrina Shahjabeen Alam
Undergrad student
Environmental Science
University of Chittagong.
Email: sabrinaalamnisacu@gmail.com

3. Phosphorus is a nonmetal,
chemical element with the symbol P &
atomic number 15. Elemental
phosphorus exists in two major forms
white phosphorus & red phosphorus

4. Phosphorus often called as Brain Food!
Key nutrient limiting phytoplankton productivity in both aquatic and terrestrial ecosystems.
The main form of phosphorus in natural waters is orthophosphate.
Because of its highly reactivity, phosphorus is never found as a free element on Earth.
Forms the sugar-phosphate backbone of DNA and RNA.
Component of ADP and ATP responsible for energy transfer, storage, and use at cellular level.
Forms our bones and teeth!
Absorbed from environmental solutions by plants and supplied to animals and microorganisms of
decay mainly through food webs.
Phosphorus is not toxic at elevated concentration, but along with nitrogen, it can lead to
eutrophication.
Vastly used in agriculture, processing of food, manufacturing of beverages, industries and home!

5. Sources!
The largest reservoir of phosphorus on earth is sediments
and sedimentary rocks like phosphorus-bearing minerals and
calcium phosphates.
Under normal water flows, roughly 2/3 of the total phosphorus
load to lakes and rivers comes from nonpoint sources like
watershed soil runoff, dissolution of sediment phosphorus,
atmospheric deposition and stream bank erosion.
Anthropogenic sources include agricultural runoff (fertilizers),
pet and untreated human wastes and other point sources like
municipal and industrial wastewater treatment systems.

6. Figure: A qualitative model of the phosphorus cycle in an aquatic ecosystem

7. Concentrations of phosphorus in water are controlled by chemical principles of
dissolution, equilibrium, precipitation, and adsorption. These processes influence
the mass balance of phosphorus.
Inorganic phosphorus reacts with iron and aluminum in acidic sediments or waters
to form slightly soluble compounds.
Inorganic phosphorus in soils, sediment, and water usually occurs as an ionization
product of orthophosphoric acid (H3PO4) that dissociates as follows:

8. Phosphorus contained in organic matter is mineralized by
microbial activity like nitrogen. The nitrogen: phosphorus ratio in
living organisms and in decaying organic residues varies
considerably ranging from around 5:1 to 20:1.
Vertebrate animals contain 2-3%
phosphorus or more.
Crustaceans typically contain about
1% phosphorus in their dry matter.
Dry matter of plants
commonly contains 0.05–0.5%
phosphorus
Organic
Phosphorus

9. Concentrations in Water
• Phosphorus concentrations in surface waters generally are quite low.
• In highly eutrophic water or in wastewaters, more particulate phosphorus are found than
soluble reactive phosphorus.
Plant Uptake
• Major factor controlling concentrations of soluble reactive phosphorus in water.
• Phytoplankton can absorb phosphorus from water very quickly.
• Macrophyte communities stores large amounts of phosphorus in their biomass.
• Some plants can absorb more phosphorus and can store to use later.
Exchange between Water and Sediment
• If sediment is placed in a flask of distilled water and agitated until equilibrium phosphorus
concentration is attained, very little phosphorus usually will be present in the water.
• Phosphorus in sediment is not readily available to phytoplankton because of the complex
logistics of nutrient movement from sediment pore water to the illuminated zone where
phytoplankton grow.
Phosphorus Dynamics

10. Figure: Illustration of rapid uptake of phosphate by phytoplankton cells and slower
exchange of phosphate between sediment and water

11. Interaction with Nitrogen
Amounts and ratios of Nitrogen and Phosphorus vary among
species.
Marine phytoplankton contained on a weight basis about seven
times more nitrogen than phosphorus. This value is often used
as the average N:P ratio in plants.
In most ecosystems, phosphorus concentration increasing will
cause greater response in plant growth than will in nitrogen
concentration increase.
The internal recycling of nitrogen in aquatic ecosystems is much
greater than it is for phosphorus.
As a result, in order to achieve a nitrogen to phosphorus ratio of
7:1 (the Redfield ratio) in the water, it usually requires that the
addition of these two elements be at a lower N:P ratio.

12. Interesting Phosphorus
Cycle Fact!
'Once phosphorus gets lost
during runoff, it remains
lost from the cycle forever!'

13. Thank you!