The nitrogen cycle
What are the three ways that nitrogen fixation can occur?
1. In the atmosphere. Lightning gives the N2 gas enough energy to react with the O2 gas to form nitrate and ammonium. These newly formed compounds then enter the soil through precipitation. This process only creates a small amount of nitrogen fixation. 2. In the soil. Nitrogen-fixing bacteria such as Rhizobium convert N2 gas into ammonium ions. 3. In the water. Some species of cyanobacteria also convert N2 into NH4+ during the process of photosynthesis.
What is nitrification?
A process using certain soil bacteria which involves two stages. In the first stage, ammonium is converted to nitrite. In the second stage, a different bacteria nitrite is converted to nitrate.
How much of the earth's atmosphere is nitrogen?
Approximately 78%
Nitrogen is very important in the structure of what?
DNA and proteins
Where is excess nitrogen dissolved?
In waterways
How has the amount of nitrogen in the ecosystem changed in the past 50 years and why?
It has doubled due to human activities.
What does burning release as well?
It increases acid precipitation in the form of nitric acid (HNO3)
If nitrogen enters the ocean through being dissolved in water, what will happen to it?
It will eventually be trapped in sedimentary rocks and will not be released until the rocks weather.
Nitrogen in the atmosphere is in what form?
N2 gas
What is nitrogen fixation?
Nitrogen fixation is the conversion of N2 gas into compounds containing nitrate (NO3-) and ammonium (NH4+)
What do burning fossil fuels and treating sewage release?
Nitrogen oxide (NO) and nitrogen dioxide (NO2)
What are some nitrogen stores?
Oceans, terrestrial ecosystems, waterways, and as organic matter in soil
What happens to the excess nitrogen created by the fertilizer used by farmers.
The excess nitrogen is leeched into the waterways. This promotes huge growth in aquatic algae (algae blooms). These algae blooms use up all the CO2 and O2 and block the sunlight, killing many aquatic organisms. The algae blooms also produce neurotoxins that poison animals.
What do agriculture practices use for their crops?
They use large amounts of nitrogen-containing fertilizer.
How is nitrogen returned to the atmosphere?
Through denitrification. Nitrates are converted back to N2 gas by denitrifying bacteria. N2 gas is also returned to the atmosphere through volcanos.
