Nitrogen Cycle

Nitrogen Cycle

1. The importance

   • Nitrogen is an important component of DNA and proteins which are essential for life processes. For animals proteins are essential for muscle function and for plants it is mostly used for growth

2. Stores

   • Ocean
     • major stores of include oceans and soil
     • Excess nitrate and ammonium that are not used by plants mix with rain water and are washed from the soil into the ground water and streams. Unused nitrogen can settle in the ocean or river bottoms in sediments. Sediments will form rocks and nitrogen will not be available till weathering over time will allow nitrogen to be realsead into the ocean
   • Land
     • On land nitrogen is stored in much smaller amounts and is stored in living organisms, lakes and marshes
     • Nitrification coverts ammonium to nitrate. Nitrification takes place in two stages and involves nitrifying bacteria. In the first stage of nitrification, certain species of nitrifying bacteria converts ammonium into nitrite in the second stage different species of nitrifying bacteria converts nitrite into nitrate
   • Atmosphere
     • The atmosphere has the largest store of nitrogen where it exits a gas (N2)
     • Nitrogen is returned to the atmosphere in a process called denitrification which involves a bacteria known as denitrifying bacteria. In a series of chemical reactions, denitrifying bacteria converts nitrate back into nitrogen gas it can also be returned into the atmosphere by ammonia from volcanic ash

3. How it’s cycled

   • although a large percentage of the earths atmosphere is nitrogen gas , most organisms can't uses that form of nitrogen so the nitrogen cycle involves the processes nitrogen fixation, nitrification and uptake
   • nitrification is the process in which ammonium is converted into nitrate by using nitrifying bacteria the uptake of nitrates is important not only to plants but also other organisms when they eat plants they incorporate nitrogen into the proteins in their tissues
   • nitrogen fixation is the process in which nitrogen gas is converted into compounds that contain nitrate or ammonium is can occur in the atmosphere in the ocean or on land

4. Human activities that affect the flow

   • clearing forests by burning releases trapped nitrogen into the atmosphere which eventually turns into acid rain
   • fossil fuel combustion in power plants has contributated to doubling the available nitrogen in the biosphere
   • plants don't use all of the chemical fertilizer as a result excess nitrogen in the form of nitrate and ammonium can escape back into the atmosphere or can be washed from the soil by rain and can enter streams