Ph.D. Dissertation Defense: Huan Xia
Tuesday, May 23, 2017 · 1 - 3 PM
Ph.D. Dissertation Defense Announcement
Abstract:
Polycyclic aromatic hydrocarbons (PAHs) are a group of organic
contaminants that are widely distributed in soils, some of which are
potent human carcinogens. When PAHs are released into soils, they are
often emitted within a certain source matrix (e.g. soot, coal tar or
oils). In addition to the diversity of the PAH source matrix, soils are
also very heterogeneous mixtures containing many different components,
such as sand, clay, organic matter and black carbon which can have
varying capacity and affinity for sorbing hydrophobic organic
contaminants. Together, these different matrices in soil control the PAH
bioavailability to different receptors such as soil invertebrates and
human beings via various exposure pathways. In terms of soil
remediation, numerous recent studies have demonstrated the prominent
effectiveness of condensed, black carbon particles, such as biochar or
activated carbon (AC), in reducing the bioavailability of hydrophobic
contaminants in ecological receptors.
The primary objective of this research was to investigate how different PAH source materials and geochemical soil components interact with each other and affect the overall sorption capacity for PAHs and the freely dissolved concentrations measured by passive samplers. Subsequently how these interactions can affect the PAH exposure to both ecological receptor, such as soil invertebrates, as well as human beings through dermal contact and incidental ingestion of contaminated soils are investigated. For each of these exposure pathways, equilibrium and kinetic models have been developed to explain and predict PAH bioavailability to different receptors. The performance of the models has been evaluated under different source materials. In general, these models can give adequate predictions of PAH bioavailability with deviation falling within one log unit when evaluated across a very large range of concentrations. In terms of soil remediation, biochar amendment has exhibited promising and varying effectiveness in reducing PAH bioavailability from soils to different receptors. The effectiveness also varies with different source materials.
Candidate: Huan Xia
Tuesday, May 23rd at 1:00 pm in TRC Room 206
Dissertation Title: Measuring and Reducing Bioavailability of PAHs in Soils
The primary objective of this research was to investigate how different PAH source materials and geochemical soil components interact with each other and affect the overall sorption capacity for PAHs and the freely dissolved concentrations measured by passive samplers. Subsequently how these interactions can affect the PAH exposure to both ecological receptor, such as soil invertebrates, as well as human beings through dermal contact and incidental ingestion of contaminated soils are investigated. For each of these exposure pathways, equilibrium and kinetic models have been developed to explain and predict PAH bioavailability to different receptors. The performance of the models has been evaluated under different source materials. In general, these models can give adequate predictions of PAH bioavailability with deviation falling within one log unit when evaluated across a very large range of concentrations. In terms of soil remediation, biochar amendment has exhibited promising and varying effectiveness in reducing PAH bioavailability from soils to different receptors. The effectiveness also varies with different source materials.
