Polycyclic aromatic hydrocarbons (PAHs) and their nitrated and oxygenated derivatives in the Arctic boundary layer: seasonal trends and local anthropogenic influence
Résumé
A total of 22 polycyclic aromatic hydrocarbons (PAHs), 29 oxy-PAHs, and 35 nitro-PAHs (polycyclic aromatic compounds, PACs) were measured in gaseous and particulate phases in the ambient air of Longyearbyen, the most populated settlement in Svalbard, the European Arctic. The sampling campaign started in the polar night in November 2017 and lasted for 8 months until June 2018, when a light cycle reached a sunlit period with no night. The transport regimes of the near-surface, potentially polluted air masses from midlatitudes to the Arctic and the polar boundary layer meteorology were studied. The data analysis showed the observed winter PAC levels were mainly influenced by the lower-latitude sources in northwestern Eurasia, while local emissions dominated in spring and summer. The highest PAC concentrations observed in spring, with PAH concentrations a factor of 30 higher compared to the measurements at the closest background station in Svalbard (Zeppelin, 115 km distance from Longyearbyen), were attributed to local snowmobile-driving emissions. The lowest PAC concentrations were expected in summer due to enhanced photochemical degradation under the 24 h midnight sun conditions and inhibited long-range atmospheric transport. In contrast, the measured summer concentrations were notably higher than those in winter due to the harbour (ship) emissions.