Nitrogen Cycling and Nitrous oxide (N2O)
Until recently, nitrous oxide (N2O) had not been as well recognized as carbon dioxide (CO2) as a greenhouse gas. Although present in much smaller concentration in the atmosphere than CO2 (~320 ppb), the greenhouse gas potential of N2O is ~300 times greater than CO2 and N2O accounts for ~6 percent of the total greenhouse gas emissions. Furthermore, N2O is also currently the largest contributor to ozone depletion in the stratosphere and will remain so in the foreseeable future. Therefore, the sources and sinks of N2O in the biological nitrogen cycle, which determine the fate of N2O in the environment, deserve more attention.
Some of the largest sources of N2O emissions are agricultural soils, adipic acid/nitric acid production plants, and management of manure in livestock farming. Activated sludge processes in wastewater treatment plants are also known to be significant contributors of N2O emissions to the atmosphere. Previous approaches to the reduction of N2O emission relied on chemical processes for highly concentrated N2O from industrial processes, and source identification and control for lowly concentrated N2O from non-point agricultural sources. The discovery of the novel types of denitrification-independent N2O-reducing organisms allows for an innovative method to control the N2O emission: an active biological removal of N2O from both point and non-point sources.
The Environmental Microbiology Laboratory at KAIST is investigating the potential of utilizing these N2O-reducers as the N2O sink and are planning various experiments that will lead to the design of the biological N2O removal system.