A laboratory experiment was conducted to evaluate the role of sedimentary organic matter on the removal of alkylbenzenesulfonates (ABS) from water to sediment. Kerogen-like materials (an organic fraction which is soluble neither in any organic nor inorganic solvents) were isolated from river (The Tamagawa river) and lake (Lake Haruna) sediments. The kerogen was mixed with ABS with C₁₀ to C₁₃ alkyl chains in aqueous solutions. Obtained results were as follows.
(1) The incorporation of ABS into kerogens followed Freundlich adsorption isotherm equation.
(2) The amount of incorporation of ABS into kerogens increased with the increased of pH. When pH of the solution was 7 and the concentration of ABS and kerogen were 1 mg and 20 mg in 5 ml respectively. The ABS incorporated into kerogen amounted to 42-47 μg/mg-kerogen.
(3) ABS having longer alkyl chains were more likely to incorporated into kerogens than those with shorter chains. This result suggests that the incorporation of ABS is due to hydrophobic-bonding.
(4) When ABS which had been incorporated into kerogens was extracted with methanol, approximately 100% of ABS was recovered from Lake Haruna kerogen, whereas only 30-50% was recovered from the Tamagawa river kerogens.
(5) In the light of the present study, the amount and the relative abundance of ABS with C₁₀ to C₁₃ which were observed for the Tamagawa river sediment can be explained by the mechanism where major sedimentary organic mater plays the important role in the incorporation of ABS from water to the sediment.