[Effect of nonionic surfactant Tween80 and DOM on the behaviors of desorption of phenanthrene and pyrene in soil-water systems].

Batch experiments were conducted to study the effects of dissolved organic matter (DOM) and nonionic surfactant (Tween80) on the desorption of phenanthrene and pyrene in soil-water systems. The results showed that DOM derived from pig manure and pig manure compost increased the desorption of phenanthrene and pyrene in soil-water systems, and the effect of pig manure compost DOM was better than that of pig manure DOM; with the increase of Tween80, the desorption rate of phenanthrene and pyrene also increased compared with the control, especially at high concentration of Tween80 (150 mg x L(-)). And at this concentration, the desorption rates were increased by 1.7 times for phenanthrene and 6.2 times for pyrene than that of the control. The combined effects of Tween80 and DOM on the desorption of phenanthrene and pyrene were influenced by the concentration of Tween80. When Tween80 at low concentration, the combined effects were not significant. Howerver, with 150 mg x L(-1) Tween80 in soil-water systems, the desorption rates of phenanthrene and pyrene were drastically higher than the sum of DOM and Tween80. The results also indicated that DOMs with high molecular-size fraction ( > 25 000 could attain a higher desorption of both phenanthrene and pyrene in soil-water systems than their lowmolecular-size counterpart (< 1000) under the same experiments conditions.