The Impacts of Phosphorus- and Nitrogen-Containing Pollutants on Dissolved Oxygen Levels

Mariah Nacke, Alex Kirkpatrick, Jillian Wormington


Increased human impact on the environment has led to a number of adverse global effects, such as eutrophication. This process provides excess nutrients to algae in aquatic ecosystems, resulting in later decomposition of these organisms. The process of decomposition results in a decline in overall dissolved oxygen (DO) levels in the water. This decline is adverse, due to its reducing available DO required by other aquatic organisms in a given ecosystem. Phosphorus (P) and nitrogen (N) are two common elements in sewage waste, which causes eutrophication through pollution. We hypothesized that nitrogen- and phosphorus-treated groups would have different DO levels than the untreated group, because nitrogen and phosphorus support the growth of algae. We recorded the DO levels in groups containing untreated water, fertilizer-treated water, and detergent-treated water to test how nitrogen and phosphorus levels may impact eutrophication over time. We found an overall increase in algal growth in all of our samples across time, with the largest amounts of algae being present in our polluted samples. Of the polluted samples, the P and N treated samples contained sufficiently more algae than the sample solely treated with P. This indicates that the amount or variety of pollutants present in a water source greatly impact the degree of algal growth that occur, resulting in expedited eutrophication in more heavily polluted areas. 

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