Inoculating soil with an adapted microbial community is a more effective bioaugmentation approach than inoculation with pure strains in bioremediation.However,information on the potential of different inocula from sites with varying contamination levels and pollution histories in soil remediation is lacking.The objective of the study was to investigate the potential of adapted microorganisms in soil inocula,with different contamination levels and pollution histories,to degrade 1,2,4-trichlorobenzene (1,2,4-TCB).Three different soils from chlorobenzene-contaminated sites were inoculated into agricultural soils and soil suspension cultures spiked with 1,2,4-TCB.The results showed that 36.52% of the initially applied 1,2,4-TCB was present in the non-inoculated soil,whereas about 19.00% of 1,2,4-TCB was present in the agricultural soils inoculated with contaminated soils after 28 days of incubation.The soils inoculated with adapted microbial biomass (in the soil inocula) showed higher respiration and lower 1,2,4-TCB volatilization than the non-inoculated soils,suggesting the existence of 1,2,4-TCB adapted degraders in the contaminated soils used for inoculation.It was further confirmed in the contaminated soil suspension cultures that the concentration of inorganic chloride ions increased continuously over the entire experimental period.Higher contamination of the inocula led not only to higher degradation potential but also to higher residue formation.However,even inocula of low-level contamination were effective in enhancing the degradation of 1,2,4-TCB.Therefore,applying adapted microorganisms in the form of soil inocula,especially with lower contamination levels,could be an effective and environment-friendly strategy for soil remediation.
SONG YangWANG FangF. O. KENGARABIAN Yong-RongYANG Xing-LunLIU Cui-YingJIANG Xin
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 hydrocaxbons （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）anthracene） were recorded over 113 days of incubation. No microorganisms were detected in the HgC12-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 biodegradiation 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 ℃ for 45 rain.
WANG Cong-YingWANG FangWANG TaoYANG Xing-LunBIAN Yong-RongF. O. KENGARALI Zeng-BoJIANG Xin
