The role of organic matter components in soil on partitioning of Chlorohydrocarbons

Triolein, farnesol, humic acid, methyl salicylate, lignin and cellulose were selected as representative soil organic matter components. Equilibrium partition coefficients between these materials and water were experimentally determined for lindane, aldrin and a series of chlorobenzenes. Theoretical values for the chlorobenzenes were also determined using a Regular Solution Theory approach. The molecular size and polarity of the sorbent or organic matter components were identified as factors influencing the magnitude of the partition coefficient. Both experimental and theoretical partition coefficients were compared with soil/water values expressed on an organic matter basis. For the chlorobenzenes considered, experimental values for humic acid agreed most closely with those from soil, although triolein and lignin were also similar. Theoretical partition coefficients were in general lower than experimental values, but within a factor of 10 . Closest agreement was noted with triolein. Soil/water partition coefficients were consistent with partitioning between humic acid and water.