Urban snow indicates pollution originating from road traffic

• This study revealed traffic-derived pollutants in urban snow.
• Most metals, PAHs and nutrients showed the same pattern of deposition.
• Consistent increase of pollutants with low, intermediate and high intensity traffic.
• Significantly more pollution next to roads than at 5 m from the road bank.
• This study provides useful information for managing pollution in cold climates.

Traffic is a major source of pollutants in cities. In this well-replicated study we analysed a broad array of contaminants in snowpacks along roads of different traffic intensities. The majority of pollutants showed a similar pattern with respect to traffic intensity: pH and conductivity as well as concentrations of PAHs, total suspended solids, phosphorus and most heavy metals were higher next to high intensity roads compared to low intensity roads. These pollutant levels also decreased considerably up to 5 m distance from the roads. Furthermore, apart from nitrogen, these variables increased in concentration from control sites in urban forest patches to road bank sites next to roads of low, intermediate and high traffic intensities. The deposition pattern of various traffic-derived pollutants – whether gaseous or particle-bound – was the same. Such information can be useful for the purposes of managing pollutants in urban areas.