Chapter 19 - Nutrient Cycling

What forms of nitrogen are usable forms for plants and animals?

Ammonia & Nitrates

Why is nitrogen important?

Nitrogen is the key component of proteins, DNA, and chlorophyll. This makes it essential for the growth and development of all living organisms.

Nitrogen Cycle

Movement of nitrogen through the food chain from simple inorganic compounds into complex organic compounds.

Nitrogen cycle steps

• nitrogen fixation

• ammonification

• nitrification

• assimilation

• denitrification

Nitrogen fixation

bacteria transform atmospheric nitrogen into ammonia and lighting transforms atmospheric nitrogen intro nitrates which are absorbed by plants.

Ammonification

Bacteria transforms organic nitrogen from dead organisms or waste into ammonia.

Nitrification

Bacteria transform ammonia (NH₃) into nitrates which plants absorb

Assimilation

Process by which plats absorb ammonia (NH3) and nitrates through their roots to make proteins.

Denitrification

some bacteria convert nitrates (NO₃) in the soil to atmospheric nitrogen N₂ gas which is released into the atmosphere.

Human influence on the nitrogen cycle

• Humans have produced an excessive amount of nitrogen through our fertilizers, fossil fuel emissions, and agriculture. This excess nitrogen leads to eutrophication, air pollution, and acid rain:

  • excess nitrogen from fertilizers runs off into waterways causing rapid algal growth, and decomposers take up all of this oxygen after the algae die leading to low oxygen and dead zones.

  • Burning fossil fuels releases nitrogen oxides which end up going through the nitrogen cycle however the excess humans create overwhelms ecosystems and can harm the overall ecological balance.