Phosphate is a very general term referring to any salt or anion derived from phosphoric acid but most commonly means orthophosphate. This is the ion left after the removal of three protons from phosphoric acid to give PO43-. Orthophosphates are particularly important due to their roles in nature, as well as to industries such as agriculture. They also have a key role within chemical reactions in human cells, and organic phosphates are often found as nucleotides in DNA in the form of esters.
Due to being a highly reactive element, phosphorus is never found freely in nature, but is instead found as phosphates which are naturally occurring in rock and are mined around the world for use in agriculture as fertilisers and in other industry. It is used as a fertiliser because phosphorus is a constituent of plant cells and essential for the development of plants in ways such as root growth, cell division, and water efficiency.
Besides forming nucleotides in DNA as previously mentioned, phosphates have several roles within the function of the body. For example, the addition and removal (phosphorylation and dephosphorylation) of phosphate ions are the source and storage of energy for metabolic processes within cells. The structures of bones and teeth are made up of calcium phosphate in the form of hydroxyapatite. In the case of the hard enamel on the outside of teeth, some of the hydroxyl groups are replaced with fluoride ions to give fluorapatite. Phosphates can also be medicinal, such as making the urine more acidic to help cure urinary tract infections or to prevent calcium stones in the urinary tract.
High blood level of phosphate is called hyperphosphatemia and is most commonly caused by kidney failure when the kidneys fail to remove as much phosphate as necessary from the bloodstream. When this occurs, it is advised to avoid phosphate rich foods such as soft drinks, fast food, processed foods, and condiments. Hyperphosphatemia can cause calcium deposits to build up in soft tissue and was found to be an indicator of cardiovascular problems.
Many phosphates are soluble in water at normal conditions which is very useful in terms of crop fertilisation, but less so for drinking water as agricultural run-off can contaminate surface water sources. Some phosphate sources are known to be made up of significant quantities of radioactive uranium isotopes. This creates a concern for radioactivity being released into drinking water when this phosphate is used as a fertiliser. One such area known for this is Mulberry in Florida, US.
Despite this, phosphate is often added to drinking water during the treatment process as a 'corrosion inhibitor'. The leaching of lead into water is highly dependent on a number of water conditions such as the hardness and pH ‐ the added phosphate reacts with lead and copper to form compounds that remain in solid form, preventing dissolution into the water.
Phosphate in your drinking water can be detected by the following tests.
Phosphate can be reduced or removed from your drinking water using the following methods.
