Date of Award
Master of Science (MS)
Chemistry & Biochemistry
Patrick G. Hatcher
Marine organic matter is mainly believed to originate from autochthonous organic matter, while terrigenous organic matter is assumed to be largely degraded prior to reaching the open ocean or more recently replaced by marine organic matter via a stripping process. Sediment samples along a transect extending from the Mississippi River Birdsfoot Delta to the Mississippi Canyon on the Louisiana continental shelf were examined by advanced analytical techniques, electrospray ionization coupled to a 12T Fourier transform ion cyclotron resonance mass spectrometer (ESI-FTICR-MS) and quantitative solid-state multiple cross polarization magic angle spinning (multi-CPMAS) 13C NMR in an effort to understand the source and export of terrigenous organic matter to the Gulf of Mexico. Both NMR and mass spectral data indicate that condensed aromatics (CA) and carboxyl-containing aliphatic molecules (CCAM) are present at the mouth of the river, we suggest a high contribution from terrigenous soil-like organic matter. With seaward progression, CA mass spectral peak magnitudes diminish by 15% and, correspondingly, 30% of integrated NMR peak areas. In contrast, mass spectral and NMR CCAM peaks grow by 7 and 13% respectively. These trends suggest that data collected from this investigation using humic acid extracts shows molecular evidence of terrigenous organic matter deposited in offshore sediments.
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Ware, Sarah A..
"Molecular Evidence for the Export of Terrigenous Organic Matter to the North Gulf of Mexico by Solid-State 13C NMR and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry of Humic Acids"
(2023). Master of Science (MS), Thesis, Chemistry & Biochemistry, Old Dominion University, DOI: 10.25777/a8xa-q953