Production of nitrogen oxide and dinitrogen oxide by autotrophic nitrifiers

Autotrophic nitrifiers have been shown to produce nitrogen oxide and dinitrogen oxide under oxic conditions. Dinitrogen oxide is produced mainly during nitrite reduction (i.e. aerobic denitrification) whereas nitrogen oxide is produced during both aerobic denitrification and as a result of chemodenitrification. Oxygen is the single most influential environmental factor affecting the production of nitrogen and dinitrogen oxides; a decrease in oxygen can result in a several-fold increase in nitrogen oxide and dinitrogen oxide production. Emission of nitrogen oxide and dinitrogen oxide from wastewater treatment plants and fertilized soils is well documented; however, only recently have the contributions from such environments to the global nitrogen and dinitrogen oxide budget been considered. (C) 2000 Elsevier Science Inc. All rights reserved.