Geoscience Reference
In-Depth Information
Figure 8.1
Groundwater monitoring of SibuTown (10 July 1997 to 12 August 1997) (
after
Tai and Lee,
2003).
the plant remains is brought about by soil microflora, bacteria and fungi, which are
responsible for aerobic decay. Therefore the end products of humification are carbon
dioxide and water, the process being essentially one of biochemical oxidation. Immer-
sion in water reduces the oxygen supply, enormously which in turn reduces aerobic
microbial activity and encourages anaerobic decay, which is much less rapid. Conse-
quently, it has been said that peat shows unique geotechnical properties in comparison
with those of inorganic soils, such as clay, and sandy soils, which are made up of soil
particles only (Hashim and Islam, 2008).
In agricultural use, fens and raised bogs need to be drained to adjust the water
and air in the soil to provide suitable conditions for cultivated or pasture plants. The
removal of water from the upper peat by drainage and subsequently by oxidation leads
to compaction and hence subsidence of the surface. The release of CO
2
and N
2
Ois
increased due to the drainage of peat, but release of CH
4
decreases. The rates of release
depend on factors such as the level of groundwater and the temperature of the peat,
but gases like CH
4
and N
2
O are also released. During the process of peat extraction
the greenhouse gas (GHG) sink function of the peat land is lost.
Emissions of these gases also occur while preparing the surface for the removal of
vegetation, during ditching, during the extraction, storage and transportation of peat,
and also due to combustion and after-treatment of the cutaway area. Combustion
