Bioavailability of Particulate-Sorbed Polycyclic Aromatic Hydrocarbons

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Title: Bioavailability of Particulate-Sorbed Polycyclic Aromatic Hydrocarbons
Author: Thorsen, Waverly Anne
Advisors: Dr. Ross B. Leidy, Committee Member
Dr. Michael Stoskopf, Committee Member
Dr. Damian Shea, Committee Co-Chair
Dr. W. Gregory Cope, Committee Co-Chair
Abstract: Understanding the behavior of contaminants in the environment is essential for an adequate assessment of a chemicals' fate, subsequent exposure to organisms, and potential for toxic effects. However, contaminant behavior can be complex, involving multiple interactions such as sorption to, and desorption from, particles present in the water column and sediment phase, competition for binding sites, and sequestration deep within particle pores, altering the chemical and biological availability of the contaminants. Therefore, one way to understand a contaminants? behavior in the environment is to assess its bioavailability, or fraction of contaminant available for uptake by organisms. This is generally accomplished by measuring the concentration of a contaminant present in organism tissue, and comparing it to concentrations in different environmental compartments (water, sediment). In this study, numerous toxicokinetic parameters, bioconcentration factors and biota-sediment accumulation factors for 46 polycyclic aromatic hydrocarbons in freshwater mussels were measured. Elimination rates ranged from 0.04 (perylene) to 0.26/day (2,6-dimethylnapthalene), half-lives ranged from 2.6 to 16.5 days, and times to reach 95% of steady-state ranged from 11.3 to 71.3 days. The ranges and individual values compare well to available published literature values. Bioconcentration factors ranged from 1.54 (naphthalene) to 5.20 (coronene), depending on individual analyte and study conditions, but generally increased with increasing PAH hydrophobicity. Bioconcentration factors exhibited sensitivity to concentrations of dissolved and particulate organic carbon present in the water column, and to partition coefficients used to account for these parameters. Additionally, biota-sediment accumulation factors demonstrated that pyrogenic PAH (associated with incomplete-combustion) have much lower bioavailability than petrogenic PAH (associated with petroleum), with average values ranging from 0.55 +/-0.049 to 2.44 +/- 1.15, respectively. Moreover, PAH bioavailability was dependent on concentrations of soot carbon in the environment as well as the specific source of the PAH (petrogenic vs pyrogenic). This is the first study to publish these measured values for a full suite of PAH analytes.
Date: 2003-07-29
Degree: PhD
Discipline: Toxicology

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