Where Are All the Nitrates Coming From?

Abstract

For my project, I am trying to find out where the nitrates in Gravel Run, the stream behind our school, are coming from. I hope to accomplish finding out what runoff area gives off the most nitrates to Gravel Run. I first thought of this project because of my involvement in the schools Water Monitoring program run by Mr. Radcliffe, and observed first hand the high nitrate levels that are given off by Gravel Run each year. Knowing that Gravel Run was a groundwater fed stream and that agricultural fields and school properties surrounded it, I wondered where the nitrates came from. Before I started my project I first had to find out about the nitrogen cycle, the hydrologic cycle, ground water, the smart colorimeter, nitrates, groundwater, and Gravel Run itself.

Then I wrote a hypothesis based on my background information saying that there would be more nitrates coming off of the agricultural area because of the nitrates farmers use to feed their crops. Next I wrote up a materials list for the sampling of the well water and the testing of the well water. I had a total of four procedures to write and to follow. One was on how to gather my samples, and another was on how to pump out the water in the well each time I tested to get an accurate sample, I had learned that to test groundwater wells for the government you had to do this, so naturally I also had to figure out how to do this myself as well. My other two procedures were on how to accurately test my samples, one was how to dilute my samples, and the other was on the use of the smart colorimeter that measures nitrates in ppm, parts per million. Then I did a preliminary data session where I then rejected my hypothesis and made a new one based on the data that said that there would be more nitrates coming off of the school property.

My data concluded that there was more nitrates coming off of the schools property (wells 1 and 2) then there was coming off of the agricultural fields (wells 3 and 4). Wells 2 and 4 were at a low elevation and seem to have higher nitrate levels than wells 1 and 3 which were the higher elevated wells for each area. If you rank the wells from highest nitrate levels to lowest by their means, well 2 with 7.26ppm is first, followed by well 4 with 5.03ppm, next is well 1 with 2.03ppm, and last is well 3 with 1.88ppm. I can also see that there is a low standard deviation for each well and that the readings do not stray from a certain area.

I can hereby conclude from my data that there are more nitrates coming off of the school property then the agricultural areas. I reject my first hypothesis with the one that I got with my preliminary data. I do wish to carry on with this project to collect more data and to add some more variables that could be involved with Gravel Run's high nitrate levels like rainwater for instance. I also might want to look at the farm field across the road from the school to see if that property is some how involved.

Problem

Where do the high nitrate readings that Gravel Run receives come from? I hope to accomplish finding out what runoff area gives off the most nitrates to Gravel Run. I first thought of this project because of my involvement in the schools Water Monitoring program run by Mr. Radcliffe, and observed first hand the high nitrate levels that are given off by Gravel Run each year. Knowing that Gravel Run was a groundwater fed stream and that it was surrounded by agricultural fields and school properties, I wondered where the nitrates came from.

Background Information

The Nitrogen Cycle

Nitrogen is a component of all proteins and nucleic acids. In the nitrogen cycle, nitrogen moves in a large atmospheric cycle. Our atmosphere is about 80% nitrogen gases. Nitrogen (N2) has a very strong covalent bond which can only be broken by certain bacteria, volcanic action, and lightning. After the bond breaks, it enters the food webs.

During nitrogen fixation, nitrogen-fixing bacteria convert nitrogen to ammonia (NH3). The ammonia will then dissolve and become ammonium. Next the nitrogen becomes fixed in the water by cyanobacteria. Nitrogen becomes fixed on land by specific animals. Then plants use the fixed nitrogen in the biosynthesis of amino acids, proteins, and nucleic acid. Plant tissues are the only source of nitrogen to animals.

During decomposition and ammonification, fungi and bacteria will break down wastes containing nitrogen and the remains of organisms. The decomposers use some of the released proteins and amino acids for their metabolism. Plants absorb the rest of the nitrogen left over from the decay. Nitrifying bacteria and plants absorb the leftover ammonia or ammonium. During nitrification, they will strip the ammonium or ammonia of their electrons. As a result, nitrite develops.

Nitrates

Nitrates are a type of nutrient that is necessary for the growth and reproduction of all living organisms. They are located naturally in air, soil, water; they are also present in chemical fertilizers and animal waste. Other nitrate sources include septic systems, organic materials, industry, sewage treatment plants, and in the atmosphere.