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| Titel |
Impact of drainage on wettability of fen peat-moorsh soils |
| VerfasserIn |
L. Szajdak, J. Szatyłowicz, T. Brandyk |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250021992
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| Zusammenfassung |
| High water retention in peat is attributed to structural voids (macro-pores) due to the partial
degradation of the structure of peat-forming plants, and molecular absorption sites
(micro-pores) associated with the formation of humic substances. Water retention by the
heterogeneously-structured system in peat organic matter depends on the chemical structure
of solid surfaces. These naturally wet solids, if dried sufficiently, lose the ability to rewet
quickly when immersed in water. The ability of peat surfaces to attract and hold water is
attributed to hydrophilic functional groups which characterize the organic substances of peat.
The investigations of chemical and physical properties were performed for three different
peat-moorsh soils located in the Biebrza River Valley in Poland. All examined soils were
used as meadow. Soil samples were taken from two depths: 5-10 cm (moorsh) and 50-80 cm
(peat). Total organic carbon (TOC), dissolved organic carbon (DOC) and humic acids
(HA) extracted from these samples were analysed. Also basic physical properties
such as ash content and bulk density were measured. Wetting behavior of soils was
quantified using water drop penetration time test (WDPT) and measured values of
the soil-water contact angle using sessile drop method. The measurements were
conducted on air-dry soil samples which volumetric moisture content was not exceeding
7%.
The significant differences in the concentrations of TOC, DOC and properties of HA
between two investigated depth of among peat and moorsh samples were observed. The
measured concentrations of total organic carbon in the considered soils ranged from 37.2 to
45.6%. Generally, the decrease of total organic carbon concentration with depth of profiles
was observed. The contents of dissolved organic carbon in the soils ranged from 5.3 to
19.4%. The quantities of dissolved organic carbon decreased simultaneously with
E4/E6 values and with the depth of the soil profiles. For the investigated peat’s, an
increase of the depth is accompanied by the decrease in the degree of humification
or an increase in chemical maturity of HA. The measured values of the contact
angle for investigated soils were in the range from 81.4˚ to 114.3˚ what indicates
their high water repellency. The WDPT was positively correlated with total organic
carbon, organic matter and humic acids content while ash content, soil bulk density,
pH and absorbance were correlated negatively. The highest value of correlation
coefficient (statistically significant) was obtained for relation between WDPT and ash
content. The soil water contact angle was less correlated with peat-moorsh soil
properties in comparison with WDPT with one exception pH. The pH against the
contact angle indicates tendency of increasing the contact angle with decreasing pH. |
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