An Analysis Of Using Semi-Permeable Membrane Devices To Assess Persistent Organic Pollutants In Ambient Air Of Alaska

Thesis (Ph.D.) University of Alaska Fairbanks, 2006A region of concern for persistent organic pollutants (POPS) contamination is the Arctic, because of POPs' ability to migrate long distances through the atmosphere toward cold regions, condense out of the atmosphere in those region, deposit in sensitive arctic ecosystems and bioaccumulate in Arctic species. Thus, monitoring of POP concentrations in the Arctic is necessary. However, traditional active air monitoring techniques for POPs may not be feasible in the Arctic, because of logistics and cost. While these issues may be overcome using passive air sampling devices, questions arise about the interpretation of the contaminant concentrations detected using the passive air samplers. In this dissertation semi-permeable membrane devices (SPMDs) containing triolein were characterized and evaluated for use in sampling the ambient air of Alaska for three classes of POPS (organochlorines [OCs], polychlorinated biphenyls [PCBs] and polyaromatic hydrocarbons [PAHs]). In addition, a SPMD-based sampling campaign for POPS was conducted simultaneously at five sites in Alaska during a one-year period. The POP concentrations obtained from the SPMDs were examined to determine the spatial and seasonal variability at the locations. POP concentrations detected in SPMDs were influenced by exposure to sunlight, concentrations of particulate-bound contaminants and changes in temperature. PAH concentrations in a SPMD mounted in a sunlight-blocking deployment unit were higher than in a SPMD exposed to sunlight (P = 0.007). PCB concentrations in SPMD exposed to filtered and non-filtered air were significantly different (P < 0.0001). Derived PAH air concentrations measured using SPMD were within a factor of approximately 7 of those obtained from an air sampler in Barrow, Alaska. The field study showed three distinct groups of samples. Barrow was separated from the sub-Arctic samples and a Homer sample (September-December) was distinct from the sub-Arctic samples. The separations suggest different air masses are being sampled by SPMDs. Lower concentrations of total POPs were measured at the coastal sites than the Interior sites

Occurrence and fate of semivolatile organic compounds (SVOCs) in the tropical atmosphere

Ph.DDOCTOR OF PHILOSOPH

Factors Contributing to Elevated Concentrations of Mercury and PCBs in Fish in the Inland Lakes of Michigan\u27s Upper Peninsula and Lake Superior

Mercury (Hg) pollution adversely affects ecosystems and human health. Mercury in the form of methylmercury (MeHg) bioaccumulates in aquatic ecosystems, thereby affecting fish, fish-eating wildlife and humans. The goal of this research was to clarify the effects of environmental factors on MeHg concentrations in fish in the inland lakes of the Upper Peninsula of Michigan. Of the 74 lakes for which data were available, 56 had fish mercury concentrations above the water quality guideline. Multivariate statistical analyses indicated different factors affect fish Hg concentrations in large and small lakes. Polychlorinated biphenyl (PCB) compounds are a class of persistent, bioaccumulative and toxic organic pollutants. Atmospheric deposition has been considered to be the major input of PCBs to Lake Superior. The objective of this project was to identify the source of PCBs to Lake Superior fish. Positive Matrix Factorization (PMF) identified multiple factors that contribute to the observed distribution of congeners. The congener distributions in air and fish were different from each other. Comparison of congener distributions in fish and sediments showed significant similarity, suggesting that the sediments are a source of PCBs to the fish

In Silico Prediction of Physicochemical Properties

This report provides a critical review of computational models, and in particular(quantitative) structure-property relationship (QSPR) models, that are available for the prediction of physicochemical properties. The emphasis of the review is on the usefulness of the models for the regulatory assessment of chemicals, particularly for the purposes of the new European legislation for the Registration, Evaluation, Authorisation and Restriction of CHemicals (REACH), which entered into force in the European Union (EU) on 1 June 2007. It is estimated that some 30,000 chemicals will need to be further assessed under REACH. Clearly, the cost of determining the toxicological and ecotoxicological effects, the distribution and fate of 30,000 chemicals would be enormous. However, the legislation makes it clear that testing need not be carried out if adequate data can be obtained through information exchange between manufacturers, from in vitro testing, and from in silico predictions. The effects of a chemical on a living organism or on its distribution in the environment is controlled by the physicochemical properties of the chemical. Important physicochemical properties in this respect are, for example, partition coefficient, aqueous solubility, vapour pressure and dissociation constant. Whilst all of these properties can be measured, it is much quicker and cheaper, and in many cases just as accurate, to calculate them by using dedicated software packages or by using (QSPRs). These in silico approaches are critically reviewed in this report.JRC.I.3-Toxicology and chemical substance

Development of measurement and modeling techniques to quantify atmospheric deposition of persistent, bioaccumulative and toxic chemicals in the Great Lakes

Measurement and modeling techniques were developed to improve over-water gaseous air-water exchange measurements for persistent bioaccumulative and toxic chemicals (PBTs). Analytical methods were applied to atmospheric measurements of hexachlorobenzene (HCB), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs). Additionally, the sampling and analytical methods are well suited to study semivolatile organic compounds (SOCs) in air with applications related to secondary organic aerosol formation, urban, and indoor air quality. A novel gas-phase cleanup method is described for use with thermal desorption methods for analysis of atmospheric SOCs using multicapillary denuders. The cleanup selectively removed hydrogen-bonding chemicals from samples, including much of the background matrix of oxidized organic compounds in ambient air, and thereby improved precision and method detection limits for nonpolar analytes. A model is presented that predicts gas collection efficiency and particle collection artifact for SOCs in multicapillary denuders using polydimethylsiloxane (PDMS) sorbent. An approach is presented to estimate the equilibrium PDMS-gas partition coefficient (Kpdms) from an Abraham solvation parameter model for any SOC. A high flow rate (300 L min-1) multicapillary denuder was designed for measurement of trace atmospheric SOCs. Overall method precision and detection limits were determined using field duplicates and compared to the conventional high-volume sampler method. The high-flow denuder is an alternative to high-volume or passive samplers when separation of gas and particle-associated SOCs upstream of a filter and short sample collection time are advantageous. A Lagrangian internal boundary layer transport exchange (IBLTE) Model is described. The model predicts the near-surface variation in several quantities with fetch in coastal, offshore flow: 1) modification in potential temperature and gas mixing ratio, 2) surface fluxes of sensible heat, water vapor, and trace gases using the NOAA COARE Bulk Algorithm and Gas Transfer Model, 3) vertical gradients in potential temperature and mixing ratio. The model was applied to interpret micrometeorological measurements of air-water exchange flux of HCB and several PCB congeners in Lake Superior. The IBLTE Model can be applied to any scalar, including water vapor, carbon dioxide, dimethyl sulfide, and other scalar quantities of interest with respect to hydrology, climate, and ecosystem science

PARTICLE-WATER INTERACTIONS OF HYDROPHOBIC ORGANIC MICROPOLLUTANTS IN MARINE SYSTEMS

An understanding of the reactivity of hydrophobic organic micropollutants (HOMs) is of paramount importance to water quality managers because of their toxicity, persistence, and liability to bioaccumulate. In this study, the role played by the main estuarine variables (organic matter, suspended particulate matter [SPM], particle type and salinity) on HOM behaviour was investigated by employing samples from estuaries with different geochemical signatures (Chupa, Russia, and the Dart, Plym, Beaulieu and Carnon, U K ) . A laboratory-based technique was developed for the determination of the solubility and sorptive behaviour of HOMs using 14C-labelled, beta-emitting organic compounds (2,2\5,5'-tetrachlorobiphenyl (2,2’5,5'-TCB), bis(2-ethylhexyl)phthalate ester (DEHP), and benzo[a]pyrene (BaP)) coupled with liquid scintillation counting. The results indicate that relative solubility is mainly dependent upon the type of dissolved organic carbon (DOC) present, not its concentration, and is reduced with increasing salinity. The uptake of 2,2’5,5'-TCB and BaP by particles is time dependent with a system response time (the time required to achieve 63% of the new equilibrium) of about 0.37 hours for 2,2',5,5’-TCB and 0.02 hours for BaP. The adsorption, expressed as particle-water partition coefficients, KDS, is to a varying extent dependent on DOC, salinity and particle characteristics (iron/manganese hydroxides, particulate carbon and specific surface area). Adsorption is best defined by a linear isotherm and is enhanced in sea water compared with river water owing to a reduction in charge on particle surfaces at high ionic strengths. This effect has been quantified using an adsorption salting constant, Gp, whose values are typically in the range 0.4-2 L mol-2 The inverse relationship between KD and SPM concentration, an effect well documented in the literature, has been defined by a simple power law (KD = a SPM-b where a and b are site and compound-specific constants). Typical values for a and b are approximately 4x10^ and 0.6 for 2,2',5,5'- TCB, 50x105 and 1.0 for DEHP, and 2x105 and 0.5 for BaP, respectively. Empirical parameterisation of these effects are extremely useful for encoding into numerical transport and distribution models, and their application is demonstrated in this thesis by calculating the retention of HOMs by estuaries.BMT Marine Information Systems Limited Southampto