Emerging contaminants during Arctic Rain-On-Snow events: insights from the 2023-24 Ny-Ålesund campaign

The Svalbard Archipelago has experienced rapid warming in recent decades, leading to an increased frequency and intensity of Rain-on-Snow (ROS) events. While the physical and ecological impacts of ROS in the Arctic are well documented, their potential role in influencing the atmospheric fate of emerging contaminants remains largely unexplored. This study examines the chemical signature of four ROS events observed during the 2023–24 field campaign in Ny-Ålesund (Kongsfjorden, Svalbard, Norway), with particular attention to the behaviour of emerging pollutants before, during, and after each event. By integrating aerosol and wet deposition measurements with meteorological parameters and air-mass back-trajectory analyses, we assess the capacity of ROS events to act as removal processes for benzothiazole derivatives, tris(2-carboxyethyl)phosphine (TCEP) used as a flame retardant, pesticides, and haloacetic acids. Our results reveal marked variability in contaminant patterns across events, indicating a strong influence of synoptic-scale air mass origins and local meteorological conditions. Diagnostic ratios and inorganic ion tracers further provide insights into potential atmospheric transformation pathways and transport mechanisms. This study presents the first detailed chemical characterisation of aerosols and depositions associated with Rain-on-Snow events, offering a preliminary framework to better understand the interactions between ROS processes and contaminant cycling in a rapidly warming Arctic. This work contributes to ongoing efforts to elucidate atmospheric scavenging mechanisms under changing climate conditions.