The bio- and thermal lability of dissolved organic matter as revealed by high-resolution mass spectrometry and thermal chemical analyses

Details

• Journal Title:
  Marine Chemistry
• Personal Author:
  Lu, Kaijun ; Xue, Jianhong ; Guo, Laodong ; Liu, Zhanfei
• NOAA Program & Office:
  Sea Grant
• Sea Grant Program:
  TAMU (Texas Sea Grant)
• Description:
  It is critical to understand the chemical structures and lability of dissolved organic matter (DOM) in aquatic environments, as DOM represents one of the largest reduced carbon pools on earth. To achieve a comprehensive view of its composition and reactivity, DOM from both riverine and coastal waters were concurrently extracted via both ultrafiltration and modified styrene divinyl benzene polymer (PPL) based solid-phase-extraction (SPE), and further compared through multi-dimensional angles, including elemental analysis, total hydrolyzable amino acid composition, high-resolution liquid chromatography mass spectrometry (under both electrospray ionization modes), and thermochemical analysis. With a very low percentage (< 5%) of shared molecules, ultrafiltered-DOM (UDOM) and SPE-extracted DOM (SPEDOM) showed distinct differences in their bio- and thermal labilities. SPEDOM not only contained more “degraded” biomarkers, such as glycine, β-alanine, and γ-aminobutyric acid, but was also dominated by a higher abundance of more bio-recalcitrant lignin-like structures. Furthermore, thermogravimetric analysis revealed a higher activation energy of SPEDOM (138.8 ± 0.5 kJ·mol−1) than that of UDOM (125.4 ± 2.8 kJ·mol−1), suggesting that SPEDOM is more thermally recalcitrant than UDOM. Consistently, thermal slicing ramped pyrolysis showed a lower percentage of recalcitrant pyrolyzates (e.g., aromatic and phenol structures), but a higher contribution of labile compound classes (e.g., aliphatic structures) in UDOM, as well as a higher diversity of pyrolyzates from UDOM than SPEDOM. Taken together, our results demonstrated a highly heterogeneous nature in DOM composition and distinctly different bio- and thermal labilities between UDOM and SPEDOM, indicating that characterization of different fractions of DOM is needed for a comprehensive evaluation of natural DOM.
• Source:
  Marine Chemistry, 250, 104184
• DOI:
  https://doi.org/10.1016/j.marchem.2022.104184
• ISSN:
  0304-4203
• Format:
  PDF
• Publisher:
  Elsevier BV
• Document Type:
  Journal Article
• Rights Information:
  Accepted Manuscript
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha256:88e6a8ac01472b561f7439c82b1445eb94f1ff135640e50b37117cfb01cccb14
• Download URL:
  https://repository.library.noaa.gov/view/noaa/61197/noaa_61197_DS1.pdf
• File Type:
  [PDF - 7.25 MB ]