Session 5: What are Nitrates?

Are There Nitrates in Your Water?
Now that you've used the Internet to investigate your school's water source, you are ready to test the waters for yourself. You will be a scientist and test the quality of your school's tap water. You will do the testing in your classroom in preparation for comparing your water results with other places.

Try This!  

1 The Ups and Downs of Nitrates
2 Collect Nitrate Data



2 Ups and Downs of Nitrates? Top

Read to Learn
Sometimes, farmers and gardeners add fertilizer, manure, or compost to the soil to help plants grow. When the fertilizer mixes with the soil, it can produce nitrate. Nitrate (NO3) is a chemical compound made of nitrogen and oxygen. Plants can use the nitrogen in nitrate to grow, but too much nitrate can be dangerous. When there is more nitrate in the ground than plants can use, nitrate can pollute the water. Nitrate in water turns into a substance called nitrite, and drinking water with nitrite can make babies, pigs, and cows very sick.

Do to Learn: Computer Lab
Read The Nitrate Story and answer the questions that follow

image: The Nitrate Story
image: The Nitrate Story
image: The Nitrate Story

The Nitrate Story
Farm animals—cows, horses, chickens, and pigs—drop manure on the ground (1). When it rains, the rainwater washes substances in the manure into the soil. Nitrogen in the manure combines with oxygen in the soil to form nitrate. Trees or crops may soak up some of the nitrate, but the excess nitrate can seep into groundwater or wash into surface water.

When farmers spread fertilizer on their fields (2), some of the nitrate in that fertilizer ends up in our water too. Whatever nitrate the crops can’t use is washed into surface water or groundwater.

Nitrate also comes from lawn fertilizer (3). Many people use fertilizer because they want their lawns to grow thick and green. Most golf courses, gardens, parks, and athletic fields depend on chemical fertilizers to keep up their lush, green looks. Nitrate in lawn fertilizer can seep into the water supply just as nitrate in crop fertilizer does.

Questions:

  • What is the source of nitrate in “1”?
  • How might the nitrate move from area “1” to the tap water in the house? Trace the different paths with your pointer.
  • What is the source of nitrate in “2”?
  • How might the nitrate move from area “2” to the tap water in the house? Trace the different paths with your pointer.
  • What is the source of nitrate in “3”?
  • How might the nitrate move from area “3” to the tap water in the house? Trace the different paths with your pointer.

2 Collect Nitrate Data Top

Make sure you have a sample of your tap water before beginning. Also, remember to wear your safety goggles.
  1. Dip a nitrate strip into a sample of tap water. (Dip the end of the strip that has the squares of paper on it.)
  2. After 1 second, take the strip out of the water and shake it gently to remove any excess water.
  3. After 1 minute, examine the color of the square closest to the end of the strip. Match this color with the color on the Nitrate (NO3) Test Color Chart. The number of the color you choose is the nitrate level of the water sample (in ppm).
You can use the same procedure above to test other water sources. Gather water from home as well as school to test. Try and find water that has different sources and compare such as well water versus treated water.

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