Cycles of bioelements
See (Stolp, 1988, p. 215).
The primary reactants and reactions of the top three cycles:
- carbon (see Stolp, 1988, Fig. 8.1, p. 218)
- reactants
- CO2, carbon dioxide
- CH4, methane
- various organic compounds
- reactions
- CO2 --> organics: photosynthesis, chemosynthesis
-
Compartment diagram
- -------
- nitrogen (see Stolp, 1988, Fig. 8.8, p. 233)
- reactants
- N2, dinitrogen gas
- NH4, NH3, ammonia
- NO2 nitrate
- NO3, nitrite
- N2O, nitrous oxide
- R-NH2, reduced ammonia in protein
- reactions
- N2 --> NH4: dinitrogen fixation
- NO2 --> NH4: nitrate ammonification
- NH4 --> NO2 --> NO3: nitrification (see p. 235 for stoichiometry)
- NO3 --> N2O --> N2, NO, N2O: denitritification, bacterial nitrate respiration
- R-NH2 --> NH4: deamination
- NH4 or NO3 --> R-NH2: assimilation
- NO3 --> NH3: assimilatory nitrate reduction
-
Compartment diagram
- ----------
- sulfer (see Stolp, 1988, Fig. 8.9, p. 242)
- reactants
- S0, elemental sulfer
- R-SH, sulphydryl compounds
- H2S, hydrogen sulfide
- SO4, sulfate
- reactions
- S0 --> SO4: oxidation
- SO4 --> R-SH: assimilatory sulphate reduction
- R-SH --> H2S: desulphylation
- H2S --> S0: H2S oxidation
- S0 --> SO4: S0 oxidation
- SO4 --> R-SH: sulphate reduction (see p. 245 for stoichiometry)
Revised by Ralph 31 July 1998