TMAH thermochemolysis characterization of marine sedimentary organic matter in a Newfoundland fjord

Marine sedimentary organic matter of Trinity Bay and its associated fjord, the Northwest Arm (Newfoundland), was characterized by "batch-wise" tetramethyl ammonium hydroxide (TMAH) thermochemolysis. TMAH thermochemolysis products were characterized using GC/MS, and they included aromatic and aliphatic compounds determined as methyl esters and ethers. The dominant aliphatic compounds 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 compounds are phenols, of which the most abundant is 3,4-dimethoxybenzoic acid methyl ester, an important chemical marker in evaluating the terrestrial contribution to the organic carbon pool. The spatial variation of the thermochemolysates shows expected higher abundances of fatty acids and phenols in the near-shore sediments of the Northwest Arm compared to those of the offshore sediment cores. ²¹⁰Pb dates of sediments of two near-shore cores enabled calculation of annual preserved fluxes of organic carbon, total fatty acids and phenols. The temporal and spatial input of phenols appear to be significantly influenced by saw-milling and logging activities of the local communities in the surrounding watershed.