[Prediction of PAHs Bioavailability in Spiked Soil by Composite Extraction with Hydroxypropyl--cyclodextrin and Rhamnolipid].

In this study, composite extraction of hydroxypropyl--cyclodextrin (HPCD) with rhamnolipid (RL) was selected to assess the bioavailability of polycyclic aromatic hydrocarbons (PAHs) to earthworms in red soil from Hainan, China, spiked with phenanthrene (Phe), pyrene (Pyr) and benzo (a) pyrene (BaP). The results showed that when RL was more than the critical micelle concentration, apparent solubility of PAHs increased due to micellar solubilization of RL. So more PAHs were desorbed from solid phase of soil. Real biological experiments showed that there was a good linear relationship between earthworm-accumulated PAHs and HPCD/RL-extracted PAHs (=0.98, =15). However, earthworm-accumulated PAHs was 2.04 times higher than HPCD-extracted PAHs, but only 1.15 times higher than HPCD/RL-extracted PAHs. This indicated that HPCD/RL was more actual and reliable than HPCD in the assessment of PAHs bioavailability to earthworms. Therefore, the addition of RL, to some extent, enhanced the prediction ability of HPCD in PAHs bioavailability, which might provide a new direction and implications in risk assessment and bioremediation of organic contaminants.