Abstract:

Polycyclic aromatic hydrocarbons(PAHs) are a kind of organic pollutants which chronically remain in environments, and they are particularly concerned because some of them are potent toxic and can pose a carcinogenics risk to humans, and some can be highly persistent in the environment. The aim of this study was to investigate changes of PAHs contents in diesel-contaminated soils and to conduct a preliminary evaluation on the potential risk of residual PAHs after phytoremediation. The results showed that after one year PAHs concentration in the planted soils was reduced by 50.6%, 61.4%, 43.9% compared with the control and PAHs in the soils declined mostly rapidly from the third month to the sixth month regardless afforested land or not. BaA, ANT, PYR were mostly decreased in the planted soils. Four tested tree species all enhanced degradation of the chemicals. Sediment quality guidelines (SQGs), developed for many potentially toxic substances, can be used to classify sediment samples with regard to their potential for toxicity, to identify contaminants of concern, and to prioritize areas of concern based on the frequency and degree to which the guidelines are exceeded. The calculated averages of the mean effect range median (MERM) were used to preliminarily evaluate the potential ecological risk of residual PAHs in the diesel-contaminated soils after one-year phytoremediation. The FLO, PHE, PYR in the planted soils in L3 exceeded 1.5 times of the values, indicating there existed the high ecological risk. Therefore, it is important to control PAHs pollution release.

Key words: soil, PAHs, risk evaluation, afforestation species