Sequential microbial/chemical reactions

A valuable review (Hamby 1996) has been given that summarizes chemical and physical treatments of soils, and contaminated ground and surface waters. Some procedures for chemical destruction of selected xenobiotics have been given in Chapter 4, Section 4.1.1 and 4.1.3, comments on sequential microbial and chemical reactions in Chapter 4, Section 4.2.3, and an example of combined biological and chemical remediation is given in Section 8.2.1. 

In the absence of oxygen, the complete remineralization of complex organic molecules to CO2 is a chemically difficult problem that cannot be accomplished by a single microbial metabolism. Instead, such substrates are degraded into successively smaller pieces via the activities of multiple groups of microorganisms ([19], Fig. 1). Most of these sequential steps are oxidation-reduction reactions... 

Thermal Controls. Sediment deposition and consolidation does not, however, lead to a cessation of chemical activity. The zone of microbial alteration of sedimentary organic matter is followed by series of systematic and sequential chemical transformations as thermal processes become the dominant controls on the molecular composition of sediments. Initially these processes consist of a diverse range of reactions that involve defunctionalization (e.g. decarboxylation, dehydration, dehydrogenation) structural rearrangements, stereochemical isomerizations, and both oxidations and r uctions (55,45). These transformations occur within the shallow. 

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