13C-NMR, PAHs, WSOC and water repellence of fire-affected soils (Albic Podzols) in lichen pine forests, Russia

Postagrogenic development of Retisols in the middle taiga subzone of European Russia (Komi Republic)

“…Soil organic matter (SOM) consists of multiple pools with various stabilities and responses to land use change. Two of the most informative of these pools are the forms of organic matter released using densimetric fractionation and water-soluble organic compounds (Dymov, Gabov, & Milanovskii, 2017).…”

Natural colloid mobilization and leaching in wettable and water repellent soil under saturated condition

“…They attributed the increase of soil water repellency (i.e., CA) to the high amount of PAHs accumulated in fractions of free and occluded organic matter. Dymov et al (2017) also observed a gradual increase of the CA values in E and B horizons. They suggested that this could be associated partly with the composition of the horizon-specific SOM composition, but also partly due to the migration of hydrophobic components from upper soil layers with soil water transport.…”

“…Summarizing, at present information regarding the hydrophobity/hydrophilicity status of the suspended colloids in leachates drained to the subsurface media is scarce. Therefore, following the findings and conclusions published by Fishkis et al (2015) and Dymov et al (2015Dymov et al ( , 2017, we have the following hypothesis: i) the total amount of colloids that can be released from the soil matrix depends on soil wettability (either hydrophobic or hydrophilic), ii) colloids released from a repellent topsoil are more hydrophobic than those detached from the respective underlying wettable subsoil, because, topsoil is more influenced by higher rate of hydrophobic organic matters (Bachmann et al, 2016;Fishkis et al, 2015;Fröberg et al, 2003;Goebel et al, 2005Goebel et al, , 2011, iii) the relative amount of the hydrophobic colloids is increased by time and depended on soil carbon stock and wettability, and iv) the leached colloids may contribute differently to changes of subsoil wettability by time due to the specific hydrophilic or hydrophobic character of the colloids which is determined by the emitting soil horizon. The objectives of this study are correspondingly focused on the wetting properties of the soil and leachates: i) Comparison of the hydrophobicity status of the suspended colloids in leachates from a repellent topsoil and the respective underlying wettable subsoil under saturated conditions, ii) Evaluation of the relative amount of hydrophobic colloids from the wettable and repellent soils with leaching time, and, iii) Investigation of soil water repellency persistency in term of repellency index (RI) and contact angle (CA) changes before and after leaching.…”

“…Ritsema and Dekker (1998) found by using 3D-visualizations of water content and water repellency pattern that the dissolution of hydrophobic substances proceeded along flow paths which were formed by instability-driven fingered flow which rendered the soil within the pathways more wettable than the surrounding soil. In contrast, Dymov et al (2015Dymov et al ( , 2017 concluded that transport of hydrophobic components in water solutions might be the reason for an increase of subsoil water repellency.…”

“…This shows that probably no relevant amounts of hydrophobic colloids were mobilized after 1 PV and that an increase of total turbidity is not necessarily an evidence for a higher amount of hydrophobicity of the suspension components for the wettable soil. Dymov et al (2017) investigated the polycyclic aromatic hydrocarbons concentrations (PAHs) and water repellency (in term of CA) in burnt and unburnt soil horizons (O i -O ea -E-Bs) of lichen pine forests. They attributed the increase of soil water repellency (i.e., CA) to the high amount of PAHs accumulated in fractions of free and occluded organic matter.…”