Effects of Autoclaving and Mercuric Chloride Sterilization on PAHs Dissipation in a Two-Liquid-Phase Soil Slurry

A two-liquid-phase (TLP) soil slurry system was employed to quantify the efficiencies of autoclaving and mercuric chloride sterilization in the dissipation of polycyclic aromatic hydrocarbons (PAHs). The fates of 11 PAHs (naphthalene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, dibenzo(a, h)anth-racene) were recorded over 113 days of incubation. No microorganisms were detected in the HgCl2-sterilized soil slurries during the whole incubation period, indicating very effective sterilization. However, about 2%–36% losses of PAHs were observed in the HgCl2-sterilized slurry. In contrast to the HgCl2-sterilized soil slurry, some microorganisms survived in the autoclaved soil slurries. Moreover, significant biodegradation of 6 PAHs (naphthalene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene) was observed in the autoclaved soil slurries. This indicated that biodegradation results of PAHs in the soil slurries, calculated on basis of the autoclaved control, would be underestimated. It could be concluded that the sterilization efficiency and effectiveness of HgCl2 on soil slurry was much higher than those of autoclaving at 121 °C for 45 min.