What occurs during denitrification in the nitrogen cycle?

During denitrification in the nitrogen cycle, the process involves the conversion of nitrates (NO3) and nitrites (NO2) back into nitrogen gas (N2) or, to a lesser extent, nitrous oxide (N2O), which is then released into the atmosphere. This is a crucial step in the nitrogen cycle as it helps to complete the cycle by returning nitrogen to the atmosphere, thus balancing the ecosystem. Denitrification is primarily carried out by anaerobic bacteria in soil and aquatic environments, which utilize nitrates and nitrites for respiration in the absence of oxygen, releasing nitrogen gas as a byproduct.

The other processes mentioned, such as the conversion of nitrite to ammonia, nitrogen fixation, or transformation of nitrogen into nitrites, are part of different stages of the nitrogen cycle. They involve processes like ammonification or nitrogen fixation but do not characterize denitrification itself.