Posted on 1 July 2022
Phosphates are everywhere, and they aren’t necessarily your enemy. They’re in your food, your toothpaste, and even your DNA. Phosphates are molecules composed of oxygen and phosphorus, both of which are among the five most common elements found in living organisms. Yet despite being common in nature, phosphates are capable of causing environmental havoc in our water supply, which ultimately impacts humans just as it does the organisms living in our rivers. In this article, we’ll explore the effects of phosphate pollution on nature and how it could impact our own health.
It’s normal to find some phosphates in natural bodies of water, since phosphorus occurs naturally in rocks and other mineral deposits. These rocks gradually release the phosphorus as soluble phosphates, which then enter the food chain as they are taken up by bacteria and plants. Dead organisms decay and release these phosphates back into the water, and eventually some phosphates will find their way back into sediments at the bottom of rivers and oceans.
However, there are many unnatural sources of phosphates that can and do find their way into the water supply:
Phosphate is only toxic to people and animals if present at extremely high concentrations. Unfortunately, the havoc that phosphate can wreak on the environment has nothing to do with its toxicity, but rather its status as a key nutrient.
In rivers, phosphate pollution is the main cause of eutrophication, a term that comes from the Greek eutrophos, meaning “well-nourished”. In eutrophication, an excessive supply of nutrients in the form of phosphate disrupts the balance of the ecosystem. This begins at the bottom of the food chain with the microorganisms, specifically the phytoplankton.
Phytoplankton are bacteria and protists that are capable of photosynthesis. These organisms are vital for the health of rivers and oceans because they provide a source of food for aquatic animals. They also contribute to the carbon cycle by absorbing carbon dioxide from the atmosphere, converting it into energy, and releasing oxygen back into the atmosphere. However, when phosphates accumulate in waterways, phytoplankton (as well as aquatic plants) are able to grow and multiply rapidly. This results in a phenomenon called an algal bloom, in which the water takes on the colour of algae pigments. In many cases, the entire surface of the water will become covered in a sea of algae.
Algal blooms may initially benefit larger organisms like fish by providing additional food, but this is short-lived:
Eutrophication can have a significant impact on humans living along affected rivers. That’s because phytoplankton in algal blooms can produce toxins, some of which are capable of causing severe poisoning and even death when ingested at high levels. This makes water and fish from these rivers unsuitable for human consumption, and also damages the terrestrial environment when land animals drink from the river.
It is possible to remove phosphate from water in treatment plants, usually using a chemical approach, or by using bacteria that are allowed to absorb the phosphate and are then removed from the water. However, it’s always better if we can prevent the entry of phosphate into our rivers in the first place. Here are some things that most people can do to help:
Reducing phosphorus pollution: https://www.pca.state.mn.us/water/reducing-phosphorus-pollution
What is a harmful algal bloom?: https://www.noaa.gov/what-is-harmful-algal-bloom