Nitrous atmospheric lifetime

Recovery from a large input of atmospheric CO2 from burning fossil fuels will result in an effective lifetime of tens of thousands of years (Archer, 2005). Methane has an atmospheric lifetime of 12 to 15 years. The methane is degraded to water and CO2 by chemical reactions in the atmosphere. Nitrous oxide has an atmospheric lifetime of 120 years, while CFC-12 has an atmospheric lifetime of 100 years. HCFC-22 has an atmospheric lifetime of 12.1 years, and tetrafluoromethane has an atmospheric lifetime of 50,000 years. Sulfur hexafluoride has an atmospheric lifetime of 3200 years. 

The atmospheric lifetime of nitrous acid with respect to OH radicals is about 2 days. However, photolysis is the most important loss process of HONO during the daytime with an overhead Sun, its lifetime from photodecomposition is only about 10 min. see table IX-M-1. The reaction with OH can play a significant role during nighttime if the OH radical is produced. HONO can be an important source of OH radicals in the troposphere see section IX-H-1. 

Nitrous oxide (N2O) is an important greenhonse gas with a radiative forcing effect 310 times that of CO2 and a lifetime in the troposphere of approximately 120 years. Part of the N2O is converted to NO in the stratosphere, and so contributes to depletion of ozone. Nitric oxide (NO) is very reactive in the atmosphere and has a lifetime of only 1-10 days. It contribntes to acidification and to reactions leading to the formation of ozone in the troposphere, and so also to global warming. 

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