What are the chemical reactions involved in the Nitrogen Cycle?

Nitric Oxide (NO) is released into the atmosphere when any type

of fuel is burned. This includes byproducts of internal combustion
engines.

- Nitrous Oxide (N2O) is released into the atmosphere through
bacteria in livestock waste and commercial fertilizers applied to
the soil.

- Removing nitrogen from the Earth’s crust and soil when we mine
nitrogen-rich mineral deposits.

- Discharge of municipal sewage adds nitrogen compounds to
aquatic ecosystems which disrupts the ecosystem and kills fish.
 
 
- Many organic molecules in the bodies of plants, animals and humans include nitrogen compounds (for example amino-acids, proteins and DNA)