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| Titel |
Compatibility assessment of methods used for soil hydrophobicity determination |
| VerfasserIn |
Ewa Papierowska, Jan Szatylowicz, Barbara Kalisz, Andrzej Łachacz, Wojciech Matysiak, Guillaume Debaene |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250135129
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| Publikation (Nr.) |
 EGU/EGU2016-15952.pdf |
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| Zusammenfassung |
| Soil hydrophobicity is a global problem. Effect of hydrophobicity on the soil environment is
very important, because it can cause irreversible changes in ecosystems, leading to their
complete degradation. The choice of method used to determine soil hydrophobicity is not
simple because there is no obvious criteria for their selection. The results obtained by various
methods may not be coherent and may indicate different degrees of hydrophobicity within the
same soil sample. The objective of the study was to assess the compatibility between
methods used to determine the hydrophobicity of selected organic and mineral-organic
soils.
Two groups of soil materials were examined: hydrogenic (87 soil samples) and autogenic
soils (19 soil samples) collected from 41 soil profiles located in north-eastern Poland. Air-dry
soil samples were used. Hydrophobicity was determined using two different methods i.e. on
the basis of wetting contact angle measurements between water and solid phase of soils and
with water drop penetration time tests. The value of the wetting contact angle was measured
using the sessile drop method with optical goniometer CAM 100 (KSV Instruments). The
wetting contact angles were determined at room temperature (20˚ C) within 10 min after
sample preparation using standard procedure. In addition, water drop penetration time was
measured.
In order to compare the methods used for the assessment of soil hydrophobicity, the
agreement between observers model was applied. In this model five categories of soil
hydrophobicity were proposed according to the class used in the soil hydrofobicity
classification based on water drop penetration time test. Based on this classification the
values of the weighted kappa coefficients were calculated using SAS 9.4 (SAS
Institute, 2013, Cary NC) for evaluating relationships between between the different
investigated methods. The results of agreement were presented in forms of agreement
charts.
Research results indicated good agreement between two compared methods (the wetting
contact angle and the water drop penetration time. This agreement makes it possible to
estimate the value of the contact angle based on the measured water drop penetration time.
For instance, in hydrophilic samples, for which the measured penetration time was less than
5 seconds, it can be assumed that the average value of the contact angle was less than 40˚ .
In the case of extremely hydrophobic soil samples, for which the water drop penetration
time was longer than 3600 seconds, the contact angles were higher than 130˚ C. |
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