Characterizing marine atmospheric VOC diversity and fluxes using PTR-TOF-MS measurements in the Baltic Sea

We present continuous measurements of volatile organic compounds (VOCs) and their fluxes in the marine atmospheric boundary layer using proton‐transfer‐reaction time‐of‐flight mass spectrometry (PTR-TOF-MS) coupled with a sonic anemometer for direct eddy covariance measurements at the Utö Atmospheric and Marine Research Station in the Baltic Sea. The measurements, conducted from July to September 2024, identified over 200 distinct masses corresponding to a diverse array of volatile compounds, representing a comprehensive characterization of marine VOC composition. Our experimental setup combines VOC mixing ratio and flux measurements with concurrent monitoring of physical and biogeochemical parameters, providing a unique dataset for understanding air-sea gas exchange processes. Preliminary principal component analysis reveals strong correlations between VOC mixing ratio variability and key parameters including water-side pCO2, dissolved oxygen concentration, and air temperature, suggesting complex biogeochemical controls on VOC emissions. The high temporal resolution and sensitivity of the PTR-TOF-MS, combined with direct flux measurements, enables detailed investigation of both abundant and trace VOC species, their diurnal patterns, and their response to varying environmental conditions. This comprehensive dataset will provide valuable insights into the complexity of VOC emissions in marine environments and their coupling with biological and physical processes in the Baltic Sea region.