Hydrophobicity of peat soils: Characterization of organic compound changes associated with heat-induced water repellency

Abstract Boreal peatlands provide critical global and regional ecosystem functions including climate regulation and nutrient and water retention. Wildfire represents the largest disturbance to these ecosystems. Peatland resilience depends greatly on the extent of post-fire peat soil hydrophobicity. Climate change is altering wildfire intensity and severity and consequently impacting post-fire peat soil chemistry and structure. However, research on fire-impacted peatlands has rarely considered the influence of peat soil chemistry and structure on peatland resilience. Here we characterized the geochemical and physical properties of natural peat soils under laboratory heating conditions. The general trend observed is that hydrophilic peat soils become hydrophobic under moderate heating and then become hydrophilic again after heating for longer, or at higher, temperatures. The loss of peat soil hydrophilicity initially occurs due to evaporative water loss (250 °C and 300 °C for