Characterization of crude oil-associated hydrophobic soil sites in Alberta

Decades after a crude oil contamination event, soils may become hydrophobic. We characterized landscape and soil conditions at 27 hydrophobic soil sites in Alberta, Canada. Unlike natural hydrophobicity, the generation of crude oil-associated hydrophobicity is not restricted to any particular soil textural class or topographical position. We found that residual oil contamination, powdery surface structure, and absence of vegetation can indicate the presence of hydrophobic soil, however, these conditions are not present at all sites. We conducted a detailed soil profile examination at 12 sites and determined a positive correlation between hydrophobicity and dichloromethane extractable organic concentration. This relationship may be modified by soil conditions related to pH as the addition of sodium sulfate to samples reduced hydrophobicity. However, the removal of carbonates or salts from hydrophobic soil samples and the addition of calcium carbonate did not alter hydrophobicity.