Contaminants can exist in a wide range of states in aqueous environments, especially in surface waters. They can be freely dissolved or associated with dissolved or particulate organic matter depending on their chemical and physical characteristics. The freely dissolved fraction represents the most bioavailable fraction to an organism. These freely dissolved contaminants can cross biomembranes, potentially exerting toxic effects. Passive sampling devices (PSDs) have been developed to aid in sampling many of these contaminants by having the ability to distinguish between the freely dissolved and bound fraction of a contaminant. A new PSD, the Lipid-Free Tube (LFT) sampler was developed in response to some of the shortcomings of other current PSD that sample hydrophobic organic contaminants (HOCs). The device and laboratory methods were original modeled after a widely utilized PSD, the semipermeable membrane device (SPMD), and then improved upon. The effectiveness, efficiency, and sensitivity of not only the PSD itself, but also the laboratory methods were investigated. One requirement during LFT development was to ensure LFTs could be coupled with biological analyses without deleterious results. In an embryonic zebrafish developmental toxicity assay, embryos exposed to un-fortified LFT extracts did not show significant adverse biological response as compared to controls. Also, LFT technology lends itself to easy application in monitoring pesticides at remote sampling sites. LFTs were utilized during a series of training exchanges between Oregon State University and the Centre de Recherches en Ecotoxicologie pour le Sahel (CERES)/LOCUSTOX laboratory in Dakar, Senegal that sought to build "in country" analytical capacity. Application of LFTs as biological surrogates for predicting potential human health risk endpoints, such as those in a public health assessment was also investigated. LFT mass and accumulated contaminant masses were used directly, representing the amount of contaminants an organism would be exposed to through partitioning assuming steady state without metabolism. These exposure concentrations allow for calculating potential health risks in a human health risk model. LFT prove to be a robust tool not only for assessing bioavailable water concentrations of HOCs, but also potentially providing many insights into the toxicological significance of aquatic contaminants and mixtures.

Passive sampling is a popular technology for environmental monitoring, and silicone is an ideal choice for a variety of passive sampling applications. The silicone work described here encompasses laboratory and field studies that demonstrate the use of this polymer in novel environments, for new applications, and for emerging compounds. Unique attributes of silicone polymers make them advantageous for targeting semi-polar contaminants not typically targeted in environmental research. Oxygenated polycyclic hydrocarbons (OPAHs) represent an emerging class of contaminants with chemical properties well suited to silicone passive sampling. The first challenge was to create a robust OPAH analytical method to examine these compounds in silicone, and two independent methods (liquid as well as gas chromatography) were optimized and demonstrated for 24 ketone-containing aromatic hydrocarbons, more than other methods published at that time. An isotopically labeled OPAH was used as an internal standard in contrast to previous methods which used only labeled polycyclic aromatic hydrocarbons (PAHs). The efficacy of each method was further demonstrated by comparing standard addition to internal standard quantitation. Next, OPAHs, PAHs and pesticides were used to compare several silicone materials with low density polyethylene (LDPE) at Portland Harbor Superfund field sites. Target analyte detection, precision, and practical considerations in the field and laboratory were used to evaluate silicone materials. Individual differences between LDPE and the most optimal silicone polymer for OPAHs highlighted the importance of using optimized methods or polymer choice for a particular analyte class. Biggest differences were found for 9-fluorenone, benzanthrone, and 5,12-naphtacenequinone. After this successful polymer comparison, the next study involved a novel application of silicone wristbands as personal passive samplers. Commercially available silicone was modified to serve as personal samplers and tested in both an ambient and occupational settings. Silicone wristbands provided a valuable tool to monitor individual exposures that were time weighted averages of personalized exposure. The ambient study captured 49 individual compounds including PAHs, personal and consumer products, pesticides, phthalates, and as well as other industrial compounds. In the occupational study, roofers working with hot asphalt wore silicone samplers and evidence of both temporal (day versus week deployment, p

Chemicals must be bioavailable for there to be a potential for exposure and consequent risk to human or environmental health. Passive sampling devices (PSDs) are used to quantify the time-integrated concentration of bioavailable contaminants. We demonstrate that PSDs can be paired with the zebrafish developmental toxicity bioassay to produce site-specific, temporally resolved information about the toxicity of environmental samples. Furthermore, modeling associations between the chemical components of environmental mixtures and the toxic outcomes they elicit can link bioactive compounds to biological effects. This research also shows that PSDs can be used as direct biological surrogates in a risk assessment model. We were able to determine spatial and seasonal variations in exposure and risk from the consumption of polycyclic aromatic hydrocarbons (PAH) in organisms from the Portland Harbor Superfund that were not detected in the Public Health Assessment for the area. Additionally, PSDs are a tool that we were able to rapidly deploy after the Deepwater Horizon oil spill. We quantified biologically relevant PAH contamination on a large spatial scale, over a long period of time when the chemicals of concern were present at relatively low dissolved concentrations, their impact on certain areas was sporadic and their presence and toxicological significance were not easily visualized. The research presented here can be applied to improve environmental monitoring, mixture toxicity assessment and risk assessment.

The primary goal of this dissertation was to develop and evaluate an improved aquatic passive sampling device (PSD) for measurement of polar organic contaminants. Chemical uptake of current polar-PSDs (e.g., POCIS - polar organic chemical integrative sampler) is dependent on the specific environmental conditions in which the sampler is deployed (flow-rate, temperature), leading to large uncertainties when applying laboratory-derived sampling rates in-situ. A novel configuration of the diffusive gradients in thin-films (DGT) passive sampler was developed to overcome these challenges. The organic-DGT (o-DGT) configuration comprised a hydrophilic-lipophilic balance® sorbent binding phase and an outer agarose diffusive gel (thickness = 0.5-1.5 mm), notably excluding a polyethersulfone protective membrane which is used with all other polar-PSDs. Sampler calibration exhibited linear uptake and sufficient capacity for 34 pharmaceuticals and pesticides over typical environmental deployment times, with measured sampling rates ranging from 9-16 mL/d. Measured and modelled diffusion coefficients (D) through the outer agarose gel provided temperature-specific estimates of o-DGT sampling rates within 20% (measured-D) and 30% (modelled-D) compared to rates determined through full-sampler calibration. Boundary layer experiments in lab and field demonstrated that inclusion of the agarose diffusive gel negated boundary layer effects, suggesting that o-DGT uptake is largely insensitive to hydrodynamic conditions. The utility of o-DGT was evaluated under a variety of field conditions and performance was assessed in comparison to POCIS and grab samples. o-DGT was effective at measuring pharmaceuticals and pesticides in raw wastewater effluents, small creeks, large fast-flowing rivers, open-water lakes, and under ice at near-zero water temperatures. Concentrations measured by o-DGT were more accurate than POCIS when compared to grab samples, likely resulting from the influence in-situ conditions have on POCIS. Modelled sampling rates were successfully used to estimate semi-quantitative water concentrations of suspect wastewater contaminants using high-resolution mass spectrometry, demonstrating the unique utility of this o-DGT technique. This dissertation establishes o-DGT as a more accurate, user-friendly, and widely applicable passive sampler compared to current-use polar-PSDs. The o-DGT tool will help facilitate more accurate and efficient monitoring efforts and ultimately lead to more appropriate exposure data and environmental risk assessment.

Passive sampling is a novel method of analyte concentration from the environment that strives to bring greater ease to field sampling regimes than traditional liquid-solid phase extractions (SPE). It is easier to deploy than a Niskin bottle or CTD rosette, and easier to recover than hoisting up dozens of liters of water. Passive sampling also offers the opportunity for wider exploratory studies, as compounds can be selectively extracted back in lab, rather than having to select a particular phase SPE and follow phase-specific elution methods. In this study, Ethylene Vinyl Acetate copolymer (EVA) was used as a marine sorption and collection media. Its efficacy was tested in both ambient munitions sampling for TNT and RDX, and for sulfate in porewaters. For the munitions subset of samples, the interaction between salinity, temperature, and percent acetate composition of the EVA samplers was explored. It was found that salinity had a large increase on Log KEVA from 0-5 PSU, then became nonlinear from 5-34 PSU. The initial increase was present for all EVA types, and the 5-34 PSU subset’s Log KEVA was affected in similar manner between EVA types. Increasing temperature was found to decrease munitions sorption over 5-25˚C, and it was found that EVA80 was the most efficient sorption media out of the EVA subtypes. This is likely due to dipole interactions from the increase in the polar acetate group. An EVA polymer seeded with barium containing organic compounds was tested for efficacy in sulfate precipitation to the film for use in isotopic sulfur measurements. Out of the many barium containing organic compounds selected for testing, barium oxalate was chosen for its efficiency at precipitating and trapping sulfate from the marine environment, while being able to be easily purified by an acid-catalyzed hydrolysis procedure. It was also proven that the EVA sampler does not add an isotopic bias through fractionation during precipitation to the film from the environment. Overall, it was proven that the Ethylene Vinyl Acetate copolymer is an effective passive sorption media for marine systems, for both munitions compounds and inorganic sulfate.