The soil organic carbon-water partitioning coefficient is the ratio of the mass of a chemical that is adsorbed in the soil per unit mass of organic carbon in the soil per the equilibrium chemical concentration in solution. It is the "distribution coefficient" (Kd) normalized to total organic carbon content. KOC values are useful in predicting the mobility of organic soil contaminants; higher KOC values correlate to less mobile organic chemicals while lower KOC values correlate to more mobile organic chemicals.
Water partition coefficient, is simply a measure of the hydrophobicity (water repulsing) of an organic compound. The more hydrophobic a compound, the less soluble it is, therefore the more likely it will adsorb to soil particles(Bedient 1994).