Nitrates

Background Information
Nitrogen is an element needed by all living plants and animals to build protein. In aquatic ecosystems, nitrogen is present in many forms. It can combine with oxygen to form a compound called nitrate. Nitrates may come from fertilizers, sewage, and industrial waste. They can cause eutrophication of lakes or ponds. Eutrophication occurs when nutrients (such as nitrates and phosphates) are added to a body of water. These nutrients usually come from runoff from farmlands and lawns, sewage, detergents, animal wastes, and leaking septic systems. High levels of nutrients in a body of water may cause plant life and algae to flourish. As the plants grow, they can choke out other organisms. Algae blooms may eventually cover the water's surface. These large plant populations produce oxygen in the upper layers of the water but when the plants die and fall to the bottom, they are decomposed by bacteria which use a lot of the dissolved oxygen in the lower layers. Bodies of water with high levels of nitrates usually have high BOD levels due to the bacteria consuming the organic plant waste and subsequent low DO levels.

Test Procedure
Perform the nitrate test using a nitrate-nitrogen test kit. Follow the instructions provided with the kit. Concentrations of nitrates are usually expressed as nitrate-nitrogen (NO₃-N) and not as nitrate (NO₃). For this project, nitrate measurements should be reported as nitrate-nitrogen (ppm).

What To Expect
A nitrate-nitrogen reading of less than 1.0 ppm is considered to be excellent. A reading between 1.1-3 ppm is considered to be good. A reading between 3.1-5ppm is fair, and a reading greater than 5 ppm is considered to be poor.

This project is developed and managed by the Center for Improved Engineering and Science Education (CIESE)