DENITRIFICATION: A CRITICAL PROCESS IN THE GLOBAL NITROGEN CYCLE

Denitrification is a microbial process in which nitrate (NO₃⁻) is sequentially reduced to nitrogen gas (N₂) via intermediate forms such as nitrite (NO₂⁻), nitric oxide (NO), and nitrous oxide (N₂O). It plays a pivotal role in the global nitrogen cycle by removing bioavailable nitrogen from soils and aquatic systems, thus regulating nutrient dynamics and mitigating nitrate pollution. Denitrification also produces nitrous oxide — a potent greenhouse gas and ozone‑depleting substance — making its study vital for both environmental quality and climate change research. This article reviews the biochemical mechanisms, environmental controls, ecological significance, and implications of denitrification for ecosystem management and greenhouse gas mitigation.