Ammonia, a chemical compound with the formula NH3, is a simple form of nitrogen primarily originating from waste discharges, such as agricultural runoff, sewage, and industrial processes. This colorless gas with a pungent odor is composed of one nitrogen atom and three hydrogen atoms. Ammonia can exist in both gaseous and aqueous states, with the latter often referred to as ammonium (NH4+), depending on the pH level of the surrounding environment.

Ammonia is crucial for life on Earth as it is a fundamental building block for amino acids and nucleic acids, which are essential components of proteins and DNA, respectively. However, elevated ammonia concentrations can be toxic to aquatic life, particularly fish and other sensitive species, under certain circumstances, such as high pH levels, high temperatures, and low dissolved oxygen concentrations.

Furthermore, ammonia serves as a vital source of nitrogen for plants and algae, supporting their growth and development. However, excessive amounts can lead to eutrophication, a process characterized by an overabundance of nutrients in water bodies, which can result in harmful algal blooms and decreased oxygen levels, ultimately harming aquatic ecosystems.