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a
b
m/z
91+120 (from vinyl phenol derived primary from
cutin in leaves) + 124+138+150+152+164+166
(guaiacyl lignin units)
m/z
91+120 (from vinyl phenol) +60+73
(levoglucosan from cellulose)
Vp
G1
Sample 1
Sample 1
Vp
Lv
G4
G2
G3
G5
Sample 4
Sample 4
Vp
Vp
G1
G2
G3
G4
Lv
G5
Sample 5
Sample 5
Vp
G2
Vp
G1
G4
Lv
G3
G5
Sample 6
Sample 6
Vp
Vp
G4
G1
G2
Lv
G5
G3
Retention time
Retention time
Fig. 1.2
Partial ion chromatogram from Py-GC-MS analysis of modern
Metasequoia
after lipid
extraction at different stages of decay. (
a
)
m/z
91 + 120 (from vinyl phenol derived primary from
cutin in leaves) + 124 + 138 + 150 + 152 + 164 + 166 (guaiacyl lignin units) and (
b
) 91 + 120 (from
vinyl phenol) + 60 + 73 (levoglucosan from cellulose) showing the distribution of vinyl phenol vs.
lignin pyrolysis products and vinyl phenol vs. cellulose pyrolysis products, respectively. Samples
2 and 3 remained largely unaltered, as demonstrated my microscopy and macromolecular analysis
and are not fi gured. Symbols same as those used in Fig.
1.1
monitoring the decay of biopolymeric constituents of leaves (Gupta and Pancost
2004
) and changes in the chemical composition of leaves have been monitored on the
basis of the abundance of specifi c moieties relative to that of vinyl phenol (4-ethenyl
phenol) as a characteristic product of cutin (Tegelaar et al.
1989
; Mösle et al.
1998
).
Samples 1, 2, and 3 represent stages of a senescence progression while still attached
to the tree and were chemically similar. Both lignin and cellulose were degraded rela-
tive to cutin during the year long period (Fig.
1.2
). This is further supported by the
observation that in Fig.
1.1
C
16:2
fatty acid produced from the thermal breakdown of
cutin is largely undiminished in relative abundance in sample 6 when compared to
sample 1. Measurement of bulk C and N concentrations revealed a 10 wt.% loss in C
and 0.15 wt.% loss in N in sample 6 when compared to sample 1.
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