Polycyclic aromatic hydrocarbons in sediments of Lake Erie, Great Lakes : spatial distribution, sources and pathways

Smirnov, Anna (1997) Polycyclic aromatic hydrocarbons in sediments of Lake Erie, Great Lakes : spatial distribution, sources and pathways. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (10MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

Polycyclic aromatic hydrocarbons (PAH) are ubiquitous organic contaminants often found in terrestrial and marine environments. Because of their hydrophobic character, they tend to be associated with fine particulates and transported to receiving basins by surface runoff and through the atmosphere. Studies of these pollutants in lacustrine sediments are important since many of them have carcinogenic and mutagenic properties, and can be harmful for higher organisms, including people. Such studies are especially important in highly urbanized and industrialized areas where tremendous anthropogenic pressure exerted upon the environment is combined with a high intensity of exploitation. Here I present a study on spatial distribution, sources and pathways of PAH in one of such settings, Lake Erie, lower Great Lakes. -- Obliteration of PAH molecular assemblages due to different decomposition processes results in difficulties in identifying their primary sources and pathways. Compound specific isotope analysis (CSIA) has recently been shown a technique that may provide independent constraints for identification of PAH origin in sediments. Therefore, analyses of both molecular and isotopic compositions of compounds have been simultaneously employed in the study in an attempt to obtain a better insight into the regional distribution pattern and original sources of these contaminants in Lake Erie. -- A cluster analysis utilizing three first principal components extracted from both molecular and isotopic data sets was performed in the first part of the study. This analysis identified three prominent areas characterized by similar molecular and isotopic composition. Portions of the lake that are immediately adjacent to the major cities comprise one such cluster. The two other clusters partitioned the lake into a southern sector and a northern sector. PAH fluvially introduced at three major cities are probably further transported and redistributed by surface and bottom circulation. This pattern of contamination superimposed on a natural background seems to be responsible for the three-cluster structure observed in the lake. In the second part of the study, the molecular and isotopic signatures of PAH were compared with those previously reported for prominent primary and secondary sources. A subtle interplay between various sources and different degree of degradation appears to account for variations in molecular and isotopic data within the previously identified zones. The research again clearly demonstrated that the isotopic signature is less subjected to weathering processes than the molecular composition and thus can greatly supplement conventional studies on PAH chemistry when source apportionment is the task. The results of both parts of the study were finally summarized in a descriptive model of sources, pathways, transport and deposition of polycyclic aromatic hydrocarbons in the sediments of Lake Erie.

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