Environmental biogeochemistry of the Northwest Arm and the Trinity Bay, Newfoundland : novel molecular and carbon isotopic approaches

• Main Author: Pulchan, K. Jerry
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2001
• Subjects: Northwest Arm; Newfoundland
• Online Access: https://research.library.mun.ca/6580/; https://research.library.mun.ca/6580/1/KJerryPulchan.pdf; https://research.library.mun.ca/6580/3/KJerryPulchan.pdf

In this study, marine sedimentary organic matter of Trinity Bay and the Northwest Arm in spatial and temporal terms) was analyzed by pyrolysis and tetramethylammonium hydroxide chemolysis - techniques that degrade complex organic materials into moieties that are amenable to analysis. In addition, chemolysates were analyzed for their molecular isotopic signatures. The goal was to interpret the variation in the pyrolysate and chemolysate compositions in the context of sources and fates of organic matter and the influence of the surrounding communities on the distribution of terrestrially-derived material in the bay. -- Pyrolysis products of organic matter present in near-shore sediments (Trinity Bay, Newfoundland) were characterized using GC/MS. The major products observed by "on-line" pyrolysis/GC/MS were nonadecene, phenol, methyl phenol, indole, and methylindole giving limited structural information about the sources of sedimentary organic matter. Spatial variation of the pyrolysates of the sediment were interpreted in the context of sources of organic matter, that were related to the historical economic activities of the study area. -- A "batch-wise" TMAH thermochemolysis (in-situ methylation) technique was developed for the analysis of marine sediments. Standard phenolic aldehyde and acids and fatty acids were quantitatively methylated while triacylglycerol were converted to fatty acid methyl esters. Thermochemolysis of carbohydrates produced 1,2,4-trimethoxybenzene as an interesting chemolysate marker. Polyunsaturated fatty acids could be analyzed using the thermochemolysis conditions employed. -- TMAH thermochemolysis products of sediments and model compounds were characterized using GC/MS and GC/C/IRMS. Thermochemolysates of sediments included aromatic and aliphatic compounds determined as methyl esters and ethers. The dominant aliphatics are fatty acids that ranged from C₁₄ to C₂₈, with a predominance of even carbon numbered species, and are either saturated, mono-unsaturated or branched. The aromatic ...