The dissolved oxygen protocol is the last in a series of eight hydrology protocols:

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Junior High and Up Estimated Time: 15 Minutes

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Nitrogen exists in water in many forms and is important for the growth of plants in water. Two forms of nitrogen are nitrate-nitrogen (NO3-) and nitrite (NO2-) and of the two nitrates is usually the most important. Nitrate-nitrogen comes from the atmosphere and more specifically from snow, fog, or through the decay of material in soil and sediments. When nitrate is added to a body of water, the water then becomes enriched and causes the growth of plants and algae. The process of enriching water is called eutrophication. This process can adversely affect aquatic life and can contaminate drinking water. Thus, the knowledge of a body of water’s nitrate content is important to know. Nitrate-nitrogen is always expressed in milligrams per liter, (mg/L). Calibration Test the accuracy of the Nitrate kit by using a standard nitrate solution and performing the nitrate protocol with the standard solution in place of the sample water. How to Measure Nitrate Students will first create nitrite by mixing nitrate with a Mixed Acid Reagent (composed of Acetic Acid, Copper Sulfate and Ammonium Chloride). Students will then add a Nitrate Reducing Powder (composed of Manganous Sulfate monohydrate, Cadmium Powder, Ammonium Chloride and Sulfanilamide) to create a color. The intensity of the color is proportional to the amount of nitrate in the sample. The amount of nitrate is determined by comparing this color to a color comparator included in the kit. At least three students should read the color comparator so as to make sure that the results are as accurate as possible.

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50 mL beaker Nitrate Test Kit 100 mL graduated cylinder 500 mL graduated cylinder 3 500-mL bottles or jars Distilled water

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Students should wear the appropriate safety equipment listed and follow carefully all safety instructions specified by your test kit.

1)Students carefully read the instructions in their Nitrate Test Kit 2) The students add the Nitrate Reducing Powder to create a colored solution.

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