The seasonal change of PAHs in Svalbard surface snow

The Arctic region is threatened by contamination deriving from both long-range pollution and local human activities. Polycyclic Aromatic Hydrocarbons (PAHs) are environmental tracers of emission, transport and deposition processes. A first campaign has been conducted at Ny-Ålesund, Svalbard, from October 2018 to May 2019, monitoring weekly concentrations of PAHs in Arctic surface snow. The trend of the 16 high priority PAH compounds showed that long-range inputs occurred mainly in the winter, with concentrations ranging from 0.8 ng L^-1 to 37 ng L^-1. In contrast to this, the most abundant analyte retene, showed an opposite seasonal trend with highest values in autumn and late spring (up to 97 ng L^-1), while in winter this compound remained below 3 ng L^-1. This is most likely due to local contributions from outcropping coal deposits and stockpiles. Our results show a general agreement with the atmospheric signal, although significant skews can be attributed to post-depositional processes, wind erosion, melting episodes and redistribution.