What gas is produced as a byproduct of denitrification?

During the denitrification process, nitrate (NO3-) is reduced to nitrogen gas (N2) by specific bacteria in the absence of oxygen. This microbial process serves as an essential part of the nitrogen cycle and helps to return nitrogen to the atmosphere, effectively reducing the nitrogen levels in the water, which can help control pollution.

The production of nitrogen gas is crucial because it is a stable component of the atmosphere, making up about 78% of it. Denitrification thus plays a vital role in maintaining the balance of nitrogen in ecosystems. The bacteria involved in this process typically utilize the nitrate as an electron acceptor instead of oxygen, driving the transformation to nitrogen gas, which is then released back into the atmosphere.

In contrast, other byproducts like carbon dioxide, ammonia, and methane are associated with different biochemical processes such as aerobic respiration and organic matter decomposition, but they do not directly relate to denitrification. For instance, carbon dioxide is mainly produced in aerobic respiration, while ammonia can be a product of ammonification or nitrification, not denitrification. Methane is primarily produced by anaerobic digestion in different environmental contexts. Thus, nitrogen gas is specifically the correct answer associated with denitrification.