The Nitrogen Cycle

Nitrogen is the main element in the air, making up nearly four-fifths of the atmosphere in the form of nitrogen molecules, each composed of two nitrogen atoms.

If Nitrogen is the main element in the air then why do we say we breathe oxygen instead of nitrogen?       

Nitrogen is not readily available for use by living organisms, as the molecules do not easily enter into chemical reactions.Breaking up nitrogen requires energy on the scale of lightning strikes, or the specialized chemical abilities of certain types of microbes. We can’t breathe Nitrogen because of the chemical reactions.

Why do We need Nitrogen and why should you care?

Ammonia factories supplement the enzymatic magic of microbial nitrogen fixation with the brute forces of temperature and pressure, extracting close to 100 million metric tons of nitrogen from the atmosphere each year. Nitrogen removed from the air by human activity adds seriously to a number of environmental problems.Nitrous oxide also remains in the air for about a century because it does not dissolve easily in water and resists reacting with other chemicals.It eventually reaches the stratosphere where sunlight breaks it into nitric oxide, which would lead to a key link in the chain of reactions that damages the Earth’s protective ozone layer.Meanwhile other fixed-nitrogen gases released from fertilizers contribute to producing ozone in the lower atmosphere becoming a pollutant and not a protector.This makes nitrogen reactive causing a production of aerosols that can induce serious respiratory illness, cancer, and cardiac disease when in the air we breathe. Yet another pollution problem, acid rain, is fueled in part by nitrogen oxides from fertilizer.

What can we do to help the nitrogen cycle

We could us engineering to help the nitrogen cycle.Engineering will maintain a sustainable food supply in the future without excessive environmental degradation and will require clever methods for remediation the human disruption of the nitrogen cycle.Engineering strategies increase denitrification that could help reduce the excess accumulation of fixed nitrogen,but the challenge is to create nitrogen molecules, not nitrous oxide.A major need for engineering innovation will be improving the efficiency of various human activities related to nitrogen.In addressing the nitrogen cycle problem, experts must remember that fertilizers and farming have played a central role in boosting worldwide food production, helping to avoid mass starvation in many areas of the world. Efforts to mitigate the agricultural disruption of the nitrogen cycle might have the effect of raising the cost of food, so such steps must be taken in concert with efforts to limit their effects on people living in poverty.

Key Terms

  • Biosphere-The part of the earth's crust, waters, and atmosphere that supports life.
  • Biochemistry-The science dealing with the chemistry of living matter.
  • Fixed Nitrogen-A process by which free nitrogen(n2) is extracted from the atmosphere and converted(fixed) into nitrogen compounds which are plant nutrients or fertilizer.
  • Organic Nitrogen-A nitrogen compound that had its origin in a living material.
  • Nitrogen-the main element in the air, making up nearly four-fifths of the atmosphere in the form of nitrogen molecules, each composed of two nitrogen atoms.
  • Biogeochemical Cycles-A pathway by which a chemical substance moves through both biotic  (biosphere) and abiotic (lithosphere, atmosphere, and hydrosphere) compartments of the Earth.


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