576 / 2024-09-18 10:23:13

Exploring dissolved organic nitrogen cycling along the river to ocean continuum: novel insights from LC-FT-ICR MS

Dissolved organic nitrogen,LC-FT-ICR MS,Pearl River Estuary

Session 45 - New Data and Technologies Driven Insights into Marine Organic Matter Cycling

Marine dissolved organic nitrogen (DON) represents one of the least understood nitrogen pools in global nitrogen cycles, comprising thousands of nitrogen-containing molecules. Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been employed to identify the molecular composition of DON across various environments. Coupling FT-ICR MS with high-performance liquid chromatography (HPLC) enables a more detailed analysis of DON's molecular compositions. This study utilizes both direct injection (DI-) and liquid chromatography (LC-) FT-ICR MS to investigate DON cycling along a river-to-ocean continuum in the Pearl River Estuary. HPLC separates DON based on polarity, providing a more comprehensive molecular analysis. The molecular composition identified by LC-FT-ICR MS was categorized into nine segments according to polarity. LC-FT-ICR MS detected a greater number of nitrogen-containing formulas compared to DI-FT-ICR MS, with many low-polarity formulas undetected by DI-FT-ICR MS. Additionally, nitrogen-containing formulas exhibited higher polarity than other formulas, suggesting that polar sorbents may more effectively in enriching DON. This study highligts the advancement of LC-FT-ICR MS in DON studes and enhance our understanding of its dynamics in marine environments.