Agriculture Reference
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each year soil group and fly ash (stack gas), soils points move closer to fly ash and stack gas
with the time, especially S1 and S4 of 2010 year. It demonstrates there is a possible influence
of the MWI in neighboring soil that accumulates with year's past. By the way, the fly ash
and stack gas samples can not completely display MWI characteristic emission because
PCDD/Fs emissions change with different operation parameters. And other combustion
process like open burning, firewood usage, and vehicle might release similar PCDD/Fs. In
addition, since fly ash is a major output of PCDD/Fs in incinerators (over 50%) (UNEP
Chemicals, 2005; Huang & Buekens, 1995), a good and scientific collection and storage of fly
ash must be conducted, to avoid leaking and diffusing into the surrounding environment.
Fig. 8. PCA plot of PCDD/Fs homologue.
3.4 Analysis of HxCDFs isomer profile
PCDD/Fs from Tetra- to Octa-chlorination have ten homologues with different molecular
structure and different substituted chlorines, and these compounds have different chemical
and biological properties. PCDD/Fs are emitted from source, deposited on earth surface,
distributed and decomposed in soil and organism, lot different activities would happen in
this process, which deteriorate the relation of soil and source in PCDD/Fs homologue
pattern. In order to minimize these possible changes, further analysis focuses on isomer
profile of the same homologue. The isomer pattern is expressed as the relative percentage of
an isomer with each homologue, which is useful for source identification to compensate for
homologue-dependent difference (Ogura et al., 2001; Xu et al., 2008). HxCDF is the
