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. (15th January 2022)

• Record Type: Journal Article
• Authors: Ware, Sarah A.; Hartman, Blaine E.; Waggoner, Derek C.; Vaughn, Derrick R.; Bianchi, Thomas S.; Hatcher, Patrick G.
• Is Part Of: Geochimica et cosmochimica acta. Volume 317(2022)
• Page Start: 39
• Page End: 52
• Publication Date: 2022-01-15
• Subjects: FTICR -- Solid state 13C NMR -- Humic acid -- organic matter -- Mississippi River delta -- Gulf of Mexico -- fate of terrigenous organic matter -- van Krevlen; Geochemistry -- Periodicals; Meteorites -- Periodicals; Géochimie -- Périodiques; Météorites -- Périodiques; Geochemie; Astrochemie; Electronic journals; 551.905
• DOI: 10.1016/j.gca.2021.10.018
• Languages: English
• ISSNs: 0016-7037

Abstract

Abstract: 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) 13 C 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, reflective of high contributions from terrigenous soil-like organic matter. Mass spectral peak magnitudes of CA diminish by 15%, with increasing distance offshore, and represent 30% of integrated NMR peak areas. In contrast, mass spectral and NMR CCAM peaks increase by 7 and 13%, respectively. These trends in humic acid extracts, provide novel molecular evidence of terrigenous organic matter deposition in offshore sediments.