| The design and development of an instrument system and associated methods for the detection of polycyclic aromatic hydrocarbons in the marine environment are presented. Polycyclic aromatic hydrocarbons are ubiquitous organic pollutants, several of which are proven carcinogens. The detection of these substances in the marine environment is important both because of potential carcinogenicity to humans resulting from ingestion through foodstuffs and because of proven toxicity to benthic organisms. Time-resolved, laser-induced fluorescence (TR-LIF) provides a means of achieving in situ detection of these pollutants with spatial and temporal resolution that has not been possible previously due to the expense of sample collection and laboratory processing.; Spectral and timing considerations relevant to optimal development of the instrument were explored, as were potential environmental interferences with detection and quantification. A mathematical method to allow quantification of pyrene was developed and applied to field samples, and the results compared. favorably with classical gas chromatography/mass spectroscopy analysis. From these results, and additional analyses, the instrument's limits of detection for various PAH are determined. The system's ability to detect pyrene at 5 ng l–1 is sufficient for the detection and quantification of pyrene at levels typically found in an urban estuary. The system's capability to simultaneously determine overall levels of dissolved organic carbon is also explored.; The TR-LIF system was deployed for ten cruises in Boston Harbor to study the distribution and cycling of PAH. Expected distributions of organic material resulting from freshwater inputs were confirmed, but additional point sources of material, particularly of pyrene, were identified. Statistical analyses of the data provide additional insights to the environmental sources of variation of these pollutants in the harbor, and a model for pyrene fluxes in Boston Harbor is presented.; The system was also deployed on two cruises in the Mid-Atlantic Bight. The pyrene concentrations in the Bight were generally below the system's limit of detection, but the results do provide insight to the distribution of offshore fluorophores, with both short and long lifetimes, as well as an indication of an ability to differentiate marine and terrestrial humic material sources. Extrapolation to total PAH determination and additional possible applications of the system are presented. |
