In our lakes and rivers all over the U.S, we have an issue with pollution, but not the type that we would expect or can even see. Nitrogen and phosphorus are needed for every plant and animal to grow, they give us the energy we need to make food, but when they exceed their natural levels they can be the catalyst that brings it all down. S.R. Carpenter, a professor of limnology (fish studies) at Wisconsin says that “nutrient enrichment seriously degrades aquatic ecosystems and impairs the use of water for drinking, industry, agriculture, recreation, and other purposes.” That is pretty much everything we use water for, so maybe it is time we take a look at what we are actually doing.
There are a few main ways that nitrogen and phosphorus get artificially added to the environment. The number one addition is through fertilizers either on industrial farms or in our backyard gardens. The second way and one that surprised me is the addition through sewage pipes and septic tanks that are not operating properly or using a “safety feature” what the EPA calls “combined sewage overflow.” The last major cause of pollution is cities in general. They are massive plots of concrete and pavement that cause an unusual amount of run of, carrying pet and other animal waste along with lawn fertilizers into the city drains during rain events. Cleaning products and detergents also contain phosphorus that cannot be fully removed from water treatment facilities.
The reason nitrogen and phosphorus pollution is a big problem is that they can cause algae blooms. These blooms are huge, the largest bloom to date is in Qingdao, China and measured 7,500 square miles. The blooms in the U.S. tend to be smaller (around 400-800 square miles) because they occur in our freshwater lakes and rivers that have a smaller surface area than the ocean blooms in China. Algae by itself are usually not harmful, but when it dies in such a large patch the decomposers in the water use up all the available oxygen feeding on the algae. Any other organism under the algae blanket suffocates and dies (known as a fish kill). On top of that, some strains of algae that bloom can be toxic, killing humans (especially infants) and animals that drink it.
If you want to learn more about nitrogen and phosphorus pollution, algae blooms, their causes, and some solutions please head over to my Articles page or click the link!