The Effect of Partitioned vs. Compounded Nitrogen and Phosphorus Additives on Algal Cell Abundance

Samantha Shafer, Erin Yen, Joshua Spiers, Cody Barnes


Nitrogen and Phosphorous are two of the most common elements used in fertilizers. The runoff of these fertilizers into water sources is a significant source of water eutrophication, which results in harmfully excessive algal growth on the surface of the water. We studied the effects of nitrogen, phosphorus, and combined nitrogen-phosphorus additives on the growth of algae in a sample of water. We hypothesized that the water with the compounded nitrogen and phosphorous additive will produce more algae cells than the water with the partitioned or no additives because the addition of nitrogen and phosphorous will both enable the algae to produce more sugar, thereby increasing growth. In order to test this hypothesis, we collected samples of water from various locations around Theta Pond, determined the initial algal cell density, and treated them with either a nitrogen source, a phosphorus source, a combined nitrogen-phosphorus source, or nothing. After nine days, we determined the final algal cell density, and determined the percent difference between the initial and final samples. The results of this experiment did not support our hypothesis. There was a significant decrease in the density of algal cells in each of our samples, which was likely due to some experimental error, such as waiting too long between algal cell counts, or using less effective forms of nitrogen and phosphorus. In the future, a daily algal count and different forms of the elemental additives could be beneficial additions to this experimental design. 

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