Humification in peatlands

Keppler F, Biester H, Putschew A, Silk PJ, Schdler F1F, Muller G (2004) Organoiodine Formation during Humification in Peatlands. Environ Chem Lett 1 219... 

Peatlands, or organic soils, are water-logged deposits of partly decomposed plant debris. Ecological variation and diversity in extent of domination by water influence the degree of humification in peatlands. Humification in peatlands does not coincide with decomposition as well as in mineral soils. Measurement and extraction of peatland humus are hampered by the presence of large proportions of unhumified material. Therefore, most studies on the characterization of peatland humus have focused on humic acids, or on pyrophosphate extracts of the organic soils. Pyrophosphate extracts contain less unhumified materials than alkali extracts but are far less effective in extracting the peat humic substances. 

It is desirable to have at least a semiquantitative estimate of the extent of humification, or degree of decomposition of a peat material, since this is a prominent feature of all aspects of natural and economic roles of peatlands. Many avenues are available for achieving this objective because humification involves numerous reactions and results in various products and effects as discussed by Stevenson in Chapter 2. 

As discussed in the above section, humification and decomposition of drained and cultivated peatlands cause subsidence. Up to 70% of the continual loss in surface elevation by 1-70 mm/yr is due to biochemical processes (Stephens and Speir, 1970 Mathur, 1982c). Subsidence threatens to phase... 

The formation of humic substances in a peatland environment is a complex humification process which is principally due to certain enzymatic and microbial activities. These organic matter transformation processes are influenced by the nature of the peat-forming plants and certain physical and chemical properties within a particular peatland. In very acidic or low nutrient peatlands a very different microflora may exist than in a more eutrophic and less wet situation. In the former situation humification may be retarded and the peatland plants will be preserved and thus accumulate. On the other hand, in less acid environments with moderate amounts of nutrients and periodic water-table fluctuations humification proceeds relatively rapidly and leads to decomposed organic soils such is the case in drained and cultivated organic soils. 

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