Ammonia, nitrite transformations and their fixation by different biological and chemical agents.

Nitrogen compounds like ammonia and nitrite can antagonistically affect the environment and human health in many ways. The high rise in demand for food has led to excessive use of fertilisers eventually causing increased losses of reactive nitrogen to the environment. Ammonia and nitrite can be introduced into the environment through agricultural runoff, wastewater discharges and other anthropogenic activities. The over-accumulation of different forms of nitrogen (ammonia and nitrite) in the ecosystem can be noxious to many life forms including humans and aquatic life. High concentrations of both nitrogenous forms led to nutrient pollution, decreased oxygen levels in the water bodies ultimately resulting in dead zones and eutrophication. In humans elevated nitrite levels can cause methemoglobinemia. Remediation of these contaminants has become a crucial environmental concern in the recent past. To prevent nutrient pollution and reduce their harmful effects several mechanisms including physical and chemical treatments have been introduced and it is also required to fix the remaining of the pollutants by these biological and chemical agents. Current review deals with the mechanism, organisms, enzymes involved in the transformation and their fixation by various mechanisms (fixation using chemicals, using modified biochar, solidification, phytostabilisation, nano material-related compounds, etc.) [ABSTRACT FROM AUTHOR]