C - Lublin

of the fresh sample, segregated all the samples into four classes of secondary
transformation state. The first class of W 1 value ranging from 0,36 to 0,45
comprises moorsh formations of initial state of secondary transformations, the fifth
class of W 1 >0,90 holds for totally degraded moorshes (Gawlik J., 1992; Gawlik J.
and Harkot W. 2000).
Homoionic hydrogen forms of fresh moorsh materials containing exactly 0,4 g
of dry organic matter were treated by NaOH solutions at pH = 5, 6, 7, and 8 at
1:100 w/w solid to liquid ratio. Concentrations of the DOM in the extracts (0.45
µm filtrates) were determined spectrophotometrically at 470 nm using Jasco V-500
apparatus (MacCarthy P. and Rice J.A., 1985). A calibration curve was based on
sodium humate solutions (Aldrich H1, 675-2).
RESULTS AND DISCUSSION
The amounts of DOM which was released in the process of alkalization are
shown in Figure 1.
2.5
DOM(pH)=0.01exp(b 1 *pH)
c [mg/ml]
2
1.5
1
0.5
0
1W 1 =0,74
W 1 =0,48
4 5 6 7 8 9
pH
Fig. 1. Concentration of organic matter released at various pH’s.
The dissolution of soil organic matter was significantly affected by pH. At low,
initial pH values, the dissolved organic matter concentration was small. Changes
in pH affect the electrostatic charge that induces repulsion-attraction of negatively
charged surfaces of humic acids to other soil components. Generally the increase in
pH resulted in the increase in dissolution of organic due to negative charge increase
107