Land treatment of PAH contaminated soil: Performance measured by chemical and toxicity assays

The performance of a soil remediation process can be determined by measurin g the reduction in target soil contaminant concentrations and by assessing the treatment's ability to lower soil toxicity. Land treatment of polycycli c a romantic hydrocarbon (PAH)-contaminated soil from a farmer wood-treatin g site was simulated at pilot scale in temperature-controlled soil pans. Ni neteen two- through six-ring PAHs were monitored with rime (initial total P AHs = 2800 mg/kg). Twenty-five weeks of treatment yielded a final total PAH level of 1160 mg/kg. Statistically significant decreases in concentrations were seen in total, two-, three-, and four-ring PAHs. Carcinogenic and fiv e-and six-ring PAHs showed no significant change in concentration. Land tre atment resulted in significant toxicity reduction based on root elongation, Allium chromosomal aberration, and solid-phase Microtox bioassays. Acute t oxicity, as measured by the earthworm survival assay, was significantly red uced and completely removed. The Ames spiral plate mutagenicity assay revea led that the untreated soil was slightly mutagenic and that treatment may h ave reduced murtagenicity. The variety of results generated from the chemic al and toxicity assays emphasize the need for conducting a battery of such tests to fully understand soil remediation processes.