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Biogeochemical cycles& Mineralisation

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Elemental cycles: C, N, S, P, Fe, Mn

Biomass substitute for oil

Fig. 27.1 Macrobiogeochemistry

Fig. 27.2 Carbon cycle

Fig. 27.3Influence of oxygen on degradation of organic matter.

Fig. 27.4 Nitrogen cycle

Nodules on the roots of Legume plant

Rhizobium species live in the nodules to fix N2. Dead rhizobia are N-source for plant to synthesize amino acids.

N2 + 3H2 → 2 NH3

Nitrogenase, ATP, Mo, Fe165 · 106 ton N/yr

Haber-Bosch process:40 · 106 ton N/yr

Biological nitrogen fixation• Symbiotic kg N/ha·yrRhizobium 20 – 500

clover, sojabeans, pea, luzern

Actinomyceter 40 – 500alder, buckthorn, myrtle, avens

• Non-symbioticAzotobacter, Clostridium 0.2Bluegreen algae 10 - 20

Fig. 27.6 Sulfur cycle

Fig. 27.5 Phosphorus cycle

Fig. 27.7 Fe cycle

Fig. 27.8 Manganese cycle

Fig. 27.9 The Mercury cycle

Fig. 27.10 Microenvironments

Role of microorganisms in flow of organic carbon and CO2