Effects of Bioremediation on Bioavailability and Genotoxicity of Contaminants in PAH-contaminated Soil Public Deposited

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  • March 22, 2019
Creator
  • Hu, Jing
    • Affiliation: Gillings School of Global Public Health, Department of Environmental Sciences and Engineering
Abstract
  • Polycyclic aromatic hydrocarbons (PAHs) are a major pollutant class at thousands of contaminated sites. They are of great concern due to their genotoxicity, mutagenicity and carcinogenicity. Bioremediation is one of the commonly applied remediation strategies to clean up PAHs from the soils and the sediments. However, remediation goals are typically based on removal of the target PAHs rather than on broader measures related to health risks. To better understand the risks addressed by remedial action and the risks caused by remedial action, the bioavailability and genotoxicity of contaminants in a PAH-contaminated soil from a former manufactured-gas plant site were investigated for two bioremediation processes simulated in the laboratory: an ex situ bioreactor system and an in situ column system. Potential dermal bioavailability of PAHs was investigated via PAH desorption from both untreated soil and treated soil to a two-dimensional hydrophobic surface as a function of soil loading, temperature, soil moisture content and contact time. This study demonstrated that dermal exposure assessment from soil should consider site-specific conditions that influence the bioavailability of hydrophobic contaminants to skin. Moreover, the effects of remediation on potential dermal exposure should consider not only the reduction in contaminant concentration but also the reduction in contaminant bioavailability. Effects of bioremediation on toxicity and genotoxicity of PAH-contaminated soil were evaluated by the DT40 DNA damage response analysis. This study demonstrated that different bioremediation strategies could lead to different outcomes of toxicity and genotoxicity for PAH-contaminated soil. Toxicity and genotoxicity bioassays can be an effective supplement to chemical analysis-based risk assessment for contaminated soil. Bioavailability of genotoxins in the soil was investigated throughout the bioreactor treatment cycle. This study demonstrated that although bioreactor treatment could increase the genotoxicity of the whole soil, any genotoxic constituents that may have formed during treatment were primarily associated with less accessible domains in the soil. Bioavailability should be incorporated into the evaluation of bioremediation as a treatment strategy of contaminated soils to reduce the extent of cleanup required to that which is necessary to be protective of humans as well as ecosystems.
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  • In Copyright
Advisor
  • Aitken, Michael
Degree
  • Doctor of Philosophy
Graduation year
  • 2012
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