Reactive oxygen species (ROS) are chemically reactive molecules that can cause damage to cells and tissues, leading to oxidative stress. Mitochondria are the main source of ROS production in cells, and enzymes can regulate ROS levels. ROS can also act as signaling molecules in cellular processes and have been implicated in various diseases. Detecting and measuring ROS levels is crucial in understanding their role in cellular function and dysfunction.

The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms in the environment. It involves several steps, including nitrogen fixation, nitrification, denitrification, and ammonification.