Nitrous oxide inside the cells, by a process catalyzed by the enzyme nitrous oxide reductase. Nitrous oxide has significant global warming potential as a greenhouse gas. On a per-molecule basis, considered over a 100-year-period, nitrous oxide has 298 times the atmospheric heat-trapping ability of carbon dioxide (), however, because of its low concentration (less than 1/1000 of that of ), its contribution to the greenhouse effect is less than one-third that of carbon dioxide, and also less than water vapour and methane. On the other hand, since 38% or more of the entering the atmosphere is the result of human activity, and
Sulfur dioxide and 2002. This improvement resulted in part from flue-gas desulfurization, a technology that enables SO to be chemically bound in power plants burning sulfur-containing coal or oil. In particular, calcium oxide (lime) reacts with sulfur dioxide to form calcium sulfite: Aerobic oxidation of the CaSO gives CaSO, anhydrite. Most gypsum sold in Europe comes from flue-gas desulfurization. Sulfur can be removed from coal during burning by using limestone as a bed material in fluidized bed combustion. Sulfur can also be removed from fuels before burning, preventing formation of SO when the fuel is burnt. The Claus process is used in