Biogeocmemical Applications

Figure 49 shows the pyrolysis mass spectra of two different types of peat. Whereas the Sphagnum peat exhibits an almost strictly polysaccharide pattern, the bog peat spectrum exhibits additional strong phenolic ion series typical of lignins (see lignin spectrum in Figure 10). This agrees with the absence of true lignins in Sphagnum moss. The only lignin-like constituent of Sphagnum moss - sphagnol (ref. 85) - probably gives rise to the non-methoxylated phenolic series at m/z 94, 108, 120 and 134. Also note the absence of pyrolytic methane formation from methoxyl groups in Sphagnum peat. Bog peat, however, is composed to a large extent of wool grass and other higher plant residues (ref. 184). Therefore it contains grass lignins characterised by the presence of methoxylated phenolic series derived from guaiacylic (m/z 124, 138, 150 and 164), and syringylic (weak signals at m/z 154, 168, and 180) building blocks in addition to the non-methoxylated series found in sphagnol (ref. 97).


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