Using Passive Samplers to Assess Bioavailability, Toxicity, and Reactivity of Hydrophobic Organic Chemicals (HOCS)
Alexandra Patricia Tcaciuc, Ph.D., 2015
Philip Gschwend, Advisor
This thesis presents a methodology for estimating the bioaccumulation potential of hydrophobic organic chemicals (HOCs) using polyethylene (PE) passive samplers and comprehensive two-dimensional gas chromatography (GC × GC). First, we show that lipid-water and sampler-water partition coefficients can be estimated within a factor of 2 and 3, respectively, from GC × GC retention times. Body burdens of HOCs estimated using this method are then compared to measurements of accumulation in the Nereis virens polychaete The estimated total body burdens of HOCs were also in good agreement with measured toxicity measurements using the water flea Daphnia magna, with toxicity occurring at body burdens larger than 30 mg/glipid. In contrast, the toxicity estimated based on priority pollutants alone underestimated the observed toxicity, emphasizing the importance of cumulative effects. Lastly, mass transfer models describing (1) the transfer between water and PE and (2) transfer of reactive chemicals between sediment beds and PE were developed to advance our understanding of the processes that affect passive sampling results in situ (operating away from equilibrium). In addition, the reaction diffusion model was used to infer in situ degradation rates of dichlorodiphenyltrichloroethane (DDT) in the sediments of a freshwater lake (0.09 and 0.9 d-1).