TABLE 1.

Standard free-energy changes for the reactions of denitrification^a

Reaction	Substrates	Products	ΔG° (KJ per reaction)	ΔG° (KJ per mol of electron acceptor)	ΔG° (KJ per mol of H2)
1	2H2 + 2H+ + 2NO2−	N2O + 3H2O	−454	−226.5	−226.5
2	4H2 + 2H+ + 2NO3−	N2O + 5H2O	−779.5	−389.7	−194.8
3	3H2 + 2H+ + 2NO2−	N2 + 4H2O	−795	−397.5	−265
4	5H2 + 2H+ + 2NO3−	N2 + 6 H2O	−1,120.5	−560.3	−224.1
5	H2 + NO3−	NO2− + H2O	−163.2	−163.2	−163.2
6	H2 + 2H+ + 2NO2−	2NO + 2H2O	−147	−73.5	−147
7	H2 + 2NO	N2O + H2O	−306.1	−153	−306.1
8	H2 + N2O	N2 + H2O	−341.1	−341.1	−341.1

^aData derived from reference 46.