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. [Display omitted] • PAH concentrations in Arctic surface snow change at seasonal scale. • Long-range deposition of PAHs occurs mainly during winter. • The strong seasonality detected for retene reflects local coal inputs. • The signal obtainable from snow deposition is detached from atmospheric trends. [ABSTRACT FROM AUTHOR]