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Sources of Nitrogen
If nitrogen has always been in the environment, why is it such a
problem now?
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Student Worksheet
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As mentioned in the previous lesson, nitrogen is essential for life on Earth. In addition
to the natural sources of nitrogen, there are many human created sources of nitrogen. As the
human population increases, we are increasingly impacting the environment.
Procedure
1. Read the information below about four different sources of nitrogen. As a class,
discuss the questions about the sources.
| Sources |
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Questions |
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Agriculture (The Haber Process) - The two natural ways to change nitrogen gas
into a compound that is usable by living organisms (nitrogen fixation) are lightening
strikes and special bacteria that live on the roots of certain plants. Around 1900, it
was realized that the fixed nitrogen naturally available was not enough to supply the amount
of food needed by a rapidly growing human population. Fritz Haber, a German chemist, developed
an artificial process to fix nitrogen gas into nitrogen fertilizer. Today, fertilizer factories
produce approximately 100 million tons of fertilizer each year, close to double the amount of
nitrogen produced by natural processes. About 20 percent of the fertilizer applied (farms,
lawns, golf courses, etc.) in North America runs off into the water.
Approximately 70% of crops harvested are fed to farm animals. |
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How might nitrogen fertilizer have any impact on the ocean?
What do you think happens to the farm animal waste? |
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| Run-off - As water flows over paved roads, parking lots, fertilized lawns,
etc., the water dissolves and carries along many pollutants including sediment, nutrients
(including nitrogen), pesticides, herbicides and petroleum to list a few. If the land is
covered by an impervious surface, the water will run directly off the surface into a local
storm drain carrying all the pollutants along. Most storm drains connect directly to a
local water body (river, ocean, etc). If the land is pervious, the pollutants have a
chance to be filtered or reabsorbed into the soil.
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How can run-off impact the ocean? |
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| Sewage - In many areas, human waste is either treated at a sewage
treatment plant or in a septic tank. The waste is treated to remove harmful bacteria,
but is still very rich in nitrogen, phosphorous and other nutrients. An average person
eating meat, fish and vegetables excretes about 10-15 grams of nitrogen per day. |
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Do you think the amount of human sewage created impacts the ocean? |
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| Fossil fuel burning - Burning fossil fuel releases nitrous oxide
(NO2) and nitric oxide (NO). Nitrous oxide plays a role in depleting the ozone
layer and is a greenhouse gas that traps more than 200 times more heat than carbon dioxide.
Nitric oxide causes smog and acid rain. |
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How can nitrogen in the atmosphere impact the ocean? |
2. Create a working group of 4 - 6 students. Select one of the environmental issues listed below.
Use the links to begin research on the issue and create a poster to share with your class.
Each poster should:
- Define the environmental issue.
- Explain why and how the environment can be impacted by the environmental issue.
- How is nitrogen involved with the environmental issue?
- How do humans add to or cause the environmental issue?
- How can humans change or improve the environmental issue?
Assessment
As a class, discuss the following questions:
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After reviewing all of the class posters, what common issues can be identified? |
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Are any of the environmental issues related or interrelated? Explain. |
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Nitrogen is a very important nutrient to monitor/measure.
How do you think scientists test for or monitor nitrogen? |
Optional Activity
A suggested optional activity - Understanding Water Run-off - will help students
understand the difference between pervious and impervious surfaces.
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