The Ammonia Nitrogen Cycle

Ammonia is one of the most commonly produced industrial chemicals in the United States. It is a naturally occurring compound and it is not considered to be a contributor to ozone depletion, greenhouse effect or global warming. It is a key intermediate in the nitrogen cycle, a process by which nitrogen is converted into various chemicals forms, and carried out through both a biological and physical processes.

Understanding the role of ammonia in the nitrogen cycle is important.

The Process

There are four key processes in the nitrogen cycle that result in the transformation of ammonia. These processes are; Nitrogen Fixation, Ammonification, Nitrification, and Denitrification. As part of this cycle, nitrogen gas and oxidized forms of nitrogen are transformed and returned to the biological world.

The process begins with Nitrogen Fixation, this is the process by which nitrogen gas, in our atmosphere, is converted into organic nitrogen. This occurs naturally in free living soil bacteria as well as other bacteria that forms symbioses with legumes and other plant life.

Organic nitrogen then goes through a process called Ammonification also known as nitrogen mineralization and is the conversion of organic nitrogen into ammonia.

Next, is the biological oxidation of ammonia nitrogen to nitrate, with nitrite serving as the intermediate (NH4) - (NO2) - (NO3) this is referred to as Nitrification.

Finally, there is denitrification a process whereby the nitrogen oxides (i.e., nitrate and nitrite) are reduced under anaerobic conditions to (N2) and (N2O) which are colorless odorless gasses that are safe to be released back into the atmosphere and environment.

The diagram below take from The Ammonia Data Book gives a simplified visual of the Nitrogen Cycle.

Other common ways ammonia is released into the atmosphere.

There are also several other ways in which ammonia is released into the environment. Daily life cycle occurrences play a vital role in the release of ammonia into our water, soil and atmosphere as well.

Decaying matter, livestock excreta, burning of coal wood and other natural products are contributors to ammonia releases in the atmosphere and soil (more or less becoming part of the nitrogen cycle).

Ammonia can also be released into our water through effluent from sewage treatment plants, effluent from the industrial process, and runoff from fertilized fields and over populated areas containing livestock.

The industrial refrigeration industry has a very small effect on the overall environment in terms of ammonia. We contribute less than 1% of ammonia into the atmosphere. Ammonia is a natural part of our environment and imperative, not only to the nitrogen cycle, but to many other biological processes as well. As a natural gas (and refrigerant) in most cases it is hazardless.

For more information on the effects of ammonia as a natural refrigerant check out The Ammonia Data Book or visit our elibrary for related material