Effects of Phosphate and Nitrate on Pond Water
By Claudia Phillips
September 6, 2014
This lab was designed to study and observe the effects of phosphate and nitrate applied to pond water (1). Phosphorous, commonly used in fertilizers, is a necessary and vital element for life but can enhance the effects of eutrophication (the over-enrichment of nutrients in water) (2). Nitrate is a common source of food for most algae, but too much can make living conditions in water harsh (3). They are both common pollutants found in fresh water systems throughout the world.
The lab’s main objective was to analyze how the two compounds physically affect fresh water. Through a daily detailed analysis and recording of data, my group and I modeled the large-scale effects that pollutants such as phosphate and nitrate can have on fresh water systems.
The lab was designed to test the hypothesis that if nitrate and phosphate were applied to pond water repetitiously over the course of 10 days, then the phosphate would kill off any algae or bacteria growing and the nitrate would enhance and feed it. Recalling that phosphorous is used in fertilizers and manure, and knowing that it is a pollutant, I surmised that the compound would have a negative effect on the pond water. Nitrate, also used in fertilizers, is also found in private and public water and is regulated by the EPA (4). Drawing from this, and knowing that algae feed on nitrate, I predicted that the algae would grow due to its excess in food supply. METHODOLOGY
The methods followed in this lab are outlined in Lab-Aids™ #20 Pollutant Effects of Phosphates and Nitrates (5). My group and I filled 7 containers with pond water and throughout the course of 8 days, applied a consistent amount of phosphate, nitrate, and phosphate and nitrate solution to the cups (Table 1). Cup #
None - Control
9 drops phosphate solution
18 drops phosphate solution
9 drops nitrate solution
18 drops nitrate solution
9 drops phosphate and nitrate solution
18 drops phosphate and nitrate solution
Table 1 Drops of each solution added per day per cup
Every day after adding the drops, we monitored the cups and recorded our observations into a data table. After we were finished each day, we placed a white paper towel across all cups and placed it under a heating lamp to be turned on until it was time again the next day to monitor the investigation. RESULTS
Overall, we found that the nitrate and phosphate solution produced more algal growth than any other solution. The first day, each cup of water had a similar green-tinted appearance (Figure 1). The sample of water was taken from West Lake in Apex, North Carolina. This day, all we did was record its appearance and administer the drops.
Fig. 1 Water containers at day one. Cups were a greenish-brownish tint and contained few particles of dirt, algae, and other miscellaneous material found in ponds. Photo courtesy of Adrian Pavone. As time went on, a very clear pattern began to show itself. Cup 6 promptly began to grow more algae than the others (Figure 2). Cup 6 contained 9 drops of phosphate and nitrate solution.
Fig. 2 Cup 6 at day two. Some algae growth at the bottom around the edges. Photo courtesy of Adrian Pavone.
The only other cup to show growth from days 2 to 3 was Cup 3, which contained 18 drops of phosphate solution (Figure 3). Day three showed the same results. Only until day four did the other cups begin to show signs of algae growth (Figure 4). Cups 3, 6, and 7 showed the most algae growth at this point in time (Figures 5-7).
Fig. 3 Cup 3 at day two. Some algae growth at bottom, few particles around edge of bottom. The effects of the solutions began to show in most cups around this day. Photo courtesy of Adrian Pavone.
Fig. 4 All cups on day four. Green color and particles can be seen at the bottoms of all cups. Cup 6 (second row, far...
Citations: 1. Perlman, Howard. "Phosphorus and Water." Phosphorus and Water: The USGS Water Science School. USGS Water Science School, 17 Mar. 2014. Web. 04 Sept. 2014.
2. "Eutrophication and Hypoxia." Eutrophication and Hypoxia. World Resources Institute, n.d. Web. 04 Sept. 2014.
3. "Nitrates and Their Effect on Water Quality." Wheatley River Improvement Group, n.d. Web. 4 Sept. 2014. .
4. "Nitrate in Drinking Water." EPA, 5 Feb. 2014. Web. 04 Sept. 2014.
5. "Lab Aids." Pollutant Effects of Phosphates and Nitrates. Course Handout. Aug 29 2014.
6. "Water What-ifs." Science Junction. North Carolina State University, 24 Feb. 2000. Web. 04 Sept. 2014. .
7. "Nutrient Pollution." The Problem. EPA, 16 Mar. 2014. Web. 03 Sept. 2014. .
8. Khan, Fareed A., and Abid Ali Ansari. "Eutrophication: An Ecological Vision."The Botanical Review 71.4 (2005): 449-82. Web. 6 Sept. 2014.
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