by Rebecca Matteson

Eutrophication on the Potomac river Photo credit: Alexandr Trubetskoy

Phosphorous, a component of DNA, is essential to life on earth. However, humanity is quickly turning it into an example of what happens when you have too much of a good thing. In nature, phosphorous is cycled relatively quickly in biological systems (plants take it up from the soil, animals eat plants, excrete the phosphorus back into the soil, and so on) while on the geological level phosphorus moves slowly, entering biological systems as phosphorus-containing rocks weather. Now, however, phosphorus enters biological systems more quickly, since humans mine phosphorus from rocks in vast quantities and use it in detergents and fertilizers. Since the 1940s, the worldwide production of phosphate rock has increased by 140 million metric tonnes. While the EU has banned phosphorus-based detergent and parts of the USA have placed regulations on cleaning agent phosphate content[3] other sources of phosphorus, including agricultural runoff can cause problems as the nutrients gather in bodies of water. A 2012 summary showed that 45% of tested rivers and 76% of the tested lakes in England did not comply with phosphorus standards, though the full extent of the problem is still unknown. These excess nutrients can cause algae blooms that can deplete oxygen, limit biodiversity, and cause dead zones in a process called eutrophication. Once this eutrophication begins, it can be hard to correct, since aquatic systems recycle nutrients and even without new inputs, the phosphorus that is already there continues to impact the system. Nutrient runoff also hurts the quality of drinking water and makes bodies of water less suitable for recreational use. In addition, researchers predict that we could reach peak phosphorus before 2040, a disastrous proposition considering our current dependence on this resource. I would like to spend this semester exploring the problem of eutrophication and finding alternatives to our current unsustainable use of phosphorus.