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Application of Thermal Analysis to Elucidate Water‐Repellency Changes in Heated Soils
Author(s) -
Dlapa Pavel,
Simkovic Ivan,
Doerr Stefan H.,
Simkovic Ivan,
Kanka Robert,
Mataix-Solera Jorge
Publication year - 2008
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2006.0280
Subject(s) - soil water , thermogravimetric analysis , water content , volatilisation , chemistry , isothermal process , thermal decomposition , thermal , decomposition , soil science , wetting , environmental chemistry , environmental science , materials science , thermodynamics , geotechnical engineering , geology , physics , organic chemistry , composite material
It is well established that during wildfires, the volatilization and condensation of hydrophobic compounds, as well as the thermal energy input itself, can markedly change the wettability of soils. This study evaluated the effects of thermal energy input on soil water repellency of sandy forest soils from Slovakia and explored the processes underlying the changes observed using thermal analysis. Initial sample water drop penetration time values ranged from <1 to >43,200 s. Heating induced distinct increases in water repellency to >3600 s in most samples, with its elimination occurring at 175°C or higher. The thermal analysis allowed evaluation of the relationship between the destruction of soil water repellency and thermal changes affecting soil organic matter (SOM). Differences in the thermal resistance of soil water repellency correspond to the thermal stability of SOM. Kinetic analysis showed that water repellency elimination due to soil heating is linked with thermal decomposition of a more thermally labile pool of SOM. The results suggest that under nonisothermal conditions, the degree of SOM decomposition depends on both the soil temperature reached and the soil heating rate. The temperature at which a certain level of SOM decomposition is reached increases with increasing heating rate. Heating experiments and the kinetic evaluation of thermogravimetric data for isothermal conditions also demonstrated an exponential relationship between heating durations and temperature thresholds.