High-Resolution Molecular-Level Characterization of a Blanket Bog Peat Profile

Area of Science:

• Geochemistry
• Environmental Science
• Analytical Chemistry

Background:

• Peatlands are critical global carbon sinks, but understanding their carbon cycling at a molecular level remains challenging.
• Tracking molecular-level changes is essential for assessing peatland health and function.

Purpose of the Study:

• To profile a peat core from Flow Country, Scotland, using multiple analytical techniques to understand molecular-level carbon cycling.
• To evaluate the strengths of various physicochemical and spectroscopic methods for peat analysis.
• To identify molecular signatures related to peat depth, water table, and microbial activity.

Main Methods:

• Analysis of air-dried peat, labile and recalcitrant peat extracts, and pore water dissolved organic matter (PW-DOM).
• Techniques employed include Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR), Nuclear Magnetic Resonance (NMR) spectroscopy (solid/liquid-state), and Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS).

Main Results:

• Solid-state NMR revealed changes in compound class distribution with core depth and water table.
• Liquid-state NMR and FT-ICR-MS showed variations in molecular composition along the core depth across all analyzed phases.
• Previously unreported compounds were identified throughout the core, suggesting localized microbial activity hotspots.

Conclusions:

• The study provides complementary insights into molecular-level peat changes, revealing gradual changes with age, zonation influenced by the water table, and hotspots of microbial activity.
• These findings offer a foundation for future research into peatland function and health at the molecular scale.
• The composition of PW-DOM was found to vary with depth, contrary to some previous reports.