C - Lublin
C - Lublin
C - Lublin
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According to the data of Table 1, the chemical composition of HA and FA<br />
varied considerably in the course of incubation. It is however seen that there is a<br />
relationship between the contents of M and P in HA and FA. After incubation of P-<br />
enriched soil for 3 years, the contents of M and P decreased considerably in HA but<br />
increased in FA. Consequently, the P incorporation in humus molecules resulted in<br />
the change of their reactivity in an acid medium. The P promoted reactions of M<br />
elimination.<br />
The reactivity of organic compounds is a function of the distribution of<br />
electron density in their molecules. The UV-VIS absorption spectrum reveals the<br />
excitability degree of molecular electron system. The variation of excitation state<br />
from ground state may characterize energetic state of electrons belonging to<br />
functional groups having double bonds.<br />
The difference electronic spectra (Fig. 1) show the pronounced effect of P on<br />
the electron energy state in the extractable HS. This fact suggests the P-induced<br />
structural changes in humus molecules. Bathochromic band shift observed in the<br />
region of 210-230 nm can be indicative of the appearance of additional C=C bonds<br />
in the side chains of the P-modified molecules of HS. Another P-induced spectral<br />
change is observed in the region of 250-350 nm (Fig. 1). This absorption band is<br />
Fig. 1. Electronic spectra of alkali-soluble HS<br />
and FA: 1 - initial soil; 2 – P-treated soil,<br />
incubation for 7 days; 3 – incubation for 1<br />
year; 4 – incubation for 3 years; 5 – FA from<br />
initial soil; 6 – FA from P-treated soil,<br />
incubation for 3 years.<br />
100<br />
Fig. 2. IR spectra: A – FA; B –<br />
HA; C – Fe-HA-complex; D –<br />
P-treated complex.