Poo water? Nah, it’s just Fertilizer. A study of the effects of fertilizer on dissolved oxygen in water.

Abstract

In this experiment, we tested the effects fertilizer had on the dissolved oxygen content of three different sources of water collected throughout Oklahoma. We wanted to see if agricultural wastes, such as fertilizer, in fact affected the quality of water if introduced to a water ecosystem. We hypothesized that adding fertilizer would cause eutrophication in the water samples, and initially cause a decrease in the amount of dissolved oxygen present. To test this, we took 100mL samples from each source of water, and tested their dissolved oxygen levels before our pollutant was added. We then added 10mL of fertilizer to each of these, and allowed them to sit for one week. Our results from the first week showed an increase in the amount of dissolved oxygen. To test if this was an error, we took another 100mL sample from each water source and added 10mL of fertilizer to these and allowed them to sit for a week, in order to repeat our first experiment. We found that in this second test, overall our dissolved oxygen levels were higher, save for one of the samples that showed a decrease in dissolved oxygen. We concluded that the initial rise in dissolved oxygen could be a result of increased photosynthesis in algae, which would indicate an increase in algal growth. In the long run, the dissolved oxygen levels could potentially decrease if the algae deplete the resources present in the water.