Emerging contaminants during arctic rain-on-snow events: A case study from the 2023-24 Ny-Ålesund campaign

The Svalbard Archipelago has undergone rapid warming in recent decades, increasing the frequency and intensity of Rain-on-Snow (ROS) events. While the physical and ecological consequences of ROS in the Arctic have been extensively documented, their role in modulating the atmospheric fate of emerging contaminants remains poorly understood. This study investigates the chemical signature of four ROS events during the 2023-24 field campaign in Ny-Ålesund (Kongsfjorden, Svalbard, Norway), focusing on the behaviour of emerging pollutants across pre-, during-, and post-event phases. By combining aerosol and wet deposition data with meteorological variables and air mass back-trajectories, we explore the potential of ROS to act as removal mechanisms for benzothiazole derivatives, tris(2-carboxyethyl) phosphine (TCEP) as flame retardant, pesticides, and haloacetic acids. The results highlight a substantial variability in contaminant patterns across events and suggest the influence of synoptic-scale air mass origin and local meteorological conditions. Diagnostic ratios and inorganic ion proxies provide insight into possible atmospheric transformation pathways and transport processes. This study provides the first detailed chemical characterisation of aerosol and depositions during Rain-On-Snow events, establishing a preliminary framework to better understand the complex interactions between ROS and contaminant cycling in a warming Arctic. This work contributes to ongoing efforts to clarify the mechanisms of atmospheric scavenging under changing climate conditions.