Molecular Nature of Marine Particulate Organic Iron-Carrying Moieties Revealed by Electrospray Ionization Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (ESI-FTICRMS)
| Autor: | Maureen H. Conte, Patrick G. Hatcher, Hongmei Chen, Peter H. Santschi, Manoj Kamalanathan, Luni Sun, Chen Xu, Wei Xing, Peng Lin, Antonietta Quigg |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
chemistry.chemical_classification
010504 meteorology & atmospheric sciences hydroxamate-like molecules Electrospray ionization Inorganic chemistry 010502 geochemistry & geophysics Mass spectrometry 01 natural sciences Deep sea Fourier transform ion cyclotron resonance Hydrophobic effect Alicyclic compound chemistry General Earth and Planetary Sciences Molecule Organic matter lcsh:Q lcsh:Science ESI-FTICR mass spectrometry marine particles particulate organic matter iron-carrying molecules 0105 earth and related environmental sciences |
| Zdroj: | Frontiers in Earth Science, Vol 8 (2020) |
| ISSN: | 2296-6463 |
| Popis: | Marine sinking particulate organic matter (POM), acting as a link between surface primary production and burial of organic matter in marine sediments, undergoes a variety of physical and biochemical alterations on its way to the deep ocean, resulting in an increase in its un-characterizable proportion with diagenesis. Further, the binding ligands in POM for iron, an essential nutrient to marine life and tightly coupled with organic matter, has rarely been studied. In the current study, we employed an approach combining sequential extraction with ultrahigh resolution mass spectrometry (ESI-FTICRMS), in order to explore and unravel the chemical characteristics of organic matter compounds relevant to marine particle flux within the mesopelagic and deep ocean, with a focus on the potential iron-carrying molecules. With increasing depth, POM increases in aliphaticity, and decreases in intensity-normalized O/C ratios, aromatics, and carboxylic-rich alicyclic molecules (CRAM)-like compounds. The potential iron-carrying molecules account for ∼14% of total identified molecules, and appear to have been incorporated into the marine particles via ion complexation, hydrophobic interaction, and/or interlayered “occlusion.” The relative abundance of iron-binding organic molecules in these three operationally-defined categories changes with depth: “surficially-complexed” fraction decreases with depth, the “interlayered-occluded” fraction increases to a comparable extent and “hydrophobic interaction” fraction occurs at all depths. Collectively, the potential iron-carrying organic molecules exhibit a set of unique molecular characteristics: a relatively lower average H/C ratio and a higher O/C ratio compared to bulk POM, a dominance of aromatics, black carbon-like compounds and CRAM-like compounds, and minor amounts of aliphatics. These molecules exhibit partial similar molecular features as precursors formed from photochemical reactions in the surface ocean, but they have been greatly modified by flux processes. Noticeably, a minor fraction of these iron-carrying molecules ( |
| Databáze: | OpenAIRE |
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