Linear and non-linear relationships between soil sorption and hydrophobicity
The relationship between log K-oc and log P was examined by use of a large dataset. For most of the hydrophobic compounds (e. g. 0.5   7.5), log K-oc decreases with increasing hydrophobicity because of a lack of chemical availability due to low solubility. A linear solvation energy relationship shows that the sorption potential increases with increasing molecular size by increasing the dispersion interactions between the chemical and soil organic phase. The sorption potential decreases with increase in the basicity of hydrophobic compounds by increasing the H-bonding of chemicals with water. Principal component analysis shows that the octanol/water system is the closest system, but not an ideal surrogate, to describe the soil sorption for hydrophobic compounds as compared with other solvent/water partition systems.
soil sorption mechanism partition coefficient solvation equation