Effect of Fertilizer on Water Quality of Creeks over Time

(1) Saratoga High School, Saratoga, California, USA

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Many people use fertilizer for commercial use, but are unaware of its harmful impacts. The main two ingredients in fertilizer are phosphorus and nitrogen, which are present in fertilizers through compounds such as ammonium phosphate and nitrate. Excess nitrates are dangerous as high nitrate levels in drinking water can cause infants to develop illnesses. In this experiment, we studied the effects of fertilizer on the water quality of Saratoga Creek over time. For 4 days, we measured the total dissolved solids (TDS), pH, and nitrate levels of eight creekwater samples after three fertilizer treatments of 0.5 tsp, 1 tsp, and 1.5 tsp were added. Results showed that fertilizer had a significant effect on all 3 indicators, with TDS levels substantially exceeding the 500 ppm level suggested in the “U.S. Secondary Maximum Contaminant Levels” (SMCLs) and nitrate concentrations surpassing the 10 ppm standard in drinking water set by the EPA. TDS concentrations for the 3 fertilizer treatments at 4 days exceeded the standard by around 6, 12, and 20 times respectively, while pH levels dropped below the acceptable range of 6.5-8.5. Nitrate levels spiked at two days, then gradually returned to their original levels. Although TDS does not pose as great a health risk, high nitrate levels in water can have damaging effects on people’s health if consumed, and low pH levels can contaminate the habitats of aquatic species. Therefore, we suggest that people limit their fertilizer use to protect the environment and their peers.

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