Compound-specific carbon isotope geochemistry of polycyclic aromatic hydrocarbons in eastern Newfoundland estuaries

• Main Author: O'Malley, Vincent Patrick
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 1994
• Subjects: St. John's Harbour; Newfoundland
• Online Access: https://research.library.mun.ca/6849/; https://research.library.mun.ca/6849/1/VincentPatrickOMalley.pdf; https://research.library.mun.ca/6849/3/VincentPatrickOMalley.pdf

Compound-specific carbon isotope analysis (CSIA) was performed on individual polycyclic (or polynuclear) aromatic hydrocarbons (PAH) isolated from a diverse range of environmental samples. These measurements were undertaken to determine whether CSIA could provide additional or complementary information to molecular signatures for quantitatively apportioning inputs of PAH to depositional environments. PAH extraction and purification methods suitable for CSIA were developed, and the isotopic integrity of the δ¹³C values of standard PAH taken through these work-up procedures and when exposed to a range of weathering reactions was assessed. The molecular and isotopic signatures of prominent primary and secondary sources of PAH were then characterized and quantitatively compared to the corresponding signatures isolated from St. John's Harbour and Conception Bay sediment samples. -- No significant isotopic fractionations were observed in a range of 3, 4 and 5- ring PAH taken through the sample work-up procedures. The δ¹³C values of a similar range of standard compounds was also unaffected when exposed to a series of .volatilization, photolytic and microbial degradation studies. -- The molecular signatures of the prominent primary combustion sources in eastern Newfoundland (fire and car soots) were characterized by the presence of 3, 4 and 5-ring parental PAH, whereas petroleum-related sources including crankcase oil were dominated by 2 and 3-ring parental and methylated PAH. The trend observed in the δ¹³C values of the 3, 4 and 5-ring PAH in the two combustion sources was postulated to be jointly controlled by precursor compounds in the original source material and a series of secondary reactions that occur during pyrolysis and pyrosynthesis (e.g., wood burning and car engine combustion). The significantly δ¹³C-depleted compounds observed in crankcase oil compared to the combustion sources, particularly phenanthrene and pyrene, was attributed to thermally-induced aromatization reactions of natural compounds in the ...