Elucidating Dissolved Organic Sulfur in the Coastal Environment by Improved Online Liquid Chromatography Coupled to FT‐ICR Mass Spectrometry

Abstract Dissolved organic sulfur (DOS) is an important component of dissolved organic matter (DOM) and widely exists at the land‐atmosphere interface. However, the characterization of DOS at the molecular level among different environmental samples in coastal regions has not been sufficiently focused. Here, we investigated DOS in aerosol, rainwater, and river water samples in Shanghai using an improved method–online liquid chromatography coupled to Fourier transform ion cyclotron resonance mass spectrometry (LC‐FT‐ICR MS). This system is utilized to separate DOS from complicated environmental matrices. The results showed that the average relative abundance of DOS in three different environmental media (aerosol, rainwater, and river water samples) accounted for 16.8%, 21.9% and 13.1%, respectively. The common molecules of the three mediums in coastal Shanghai contain an abundance of aromatic and aliphatic DOS of anthropogenic origin in addition to the natural sources of sea spray. Notably, results from a new structural classification scheme for DOS demonstrate that anthropogenic sulfonates and their derivatives are widely spread, although their molecular diversity in different medium was recorded due to complex environmental conditions and diverse sources.