Chemical and ecotoxicity assessment of PAH-contaminated soils remediated by enhanced soil flushing

Development of remediative techniques for PAH-contaminated soils and evaluation of residual toxicity after remediation are important issues in the assessment of soil quality. To investigate the efficiency of soil remediation technology using biomonitoring assay, soil flushing experiments with surfactant and ecotoxicity tests with Eisenia fetida were carried out for artificially phenanthrene-contaminated soils. Mortality and growth of the earthworms were significantly influenced by phenanthrene concentration and exposure time to the contaminant. Sublethal toxicity effects such as weight variation of the organisms appeared to be more reliable factors than acute effects (e.g., mortality) to represent soil toxicity when compared with chemical determination of remaining phenanthrene. The contaminated soils remediated with more than 15 pore volumes of the surfactant were not significantly toxic to the earthworms with respect to average weight development, which was clearly confirmed by the results of chemical assessment for remaining phenanthrene in the soils. According to this, optimum amount of surfactant solution for effective remediation was estimated as 15 pore volumes. These results showed that the improvement of PAH remediation technology can be complemented by employing ecotoxicological assessment of remediated soils.