Sources and environmental fate of pyrogenic polycyclic aromatic hydrocarbons (PAHs) in the Arctic

Polycyclic aromatic hydrocarbons (PAHs) are large class of hydrophobic, semi-volatile organic contaminants that may enter the environment from both natural sources and anthropogenic activities. Pyrogenic PAHs arise from the incomplete combustion of fossil fuels and organic matter and following dispersal via long-range transport and may subsequently deposit in surface waters, soils and sediments of remote regions, including the Arctic. The current review summarizes and discusses Arctic data that is available for combustion-derived PAHs between 2004 and early 2018, focusing largely on data collected from remote, unexploited Arctic regions and from studies that provide some evidence of a pyrogenic origin. The increasing use of attribution ratios, which aid in discriminating PAHs from petrogenic or pyrogenic sources, suggest PAHs found in Arctic marine waters and sediment predominantly originate from natural underwater seeps, while those measured in air, freshwater, and terrestrial environments are likely to have originated from atmospheric and combustion-derived sources. Modeling efforts indicate that atmospheric PAHs in the Canadian and Norwegian Arctic are likely to have originated in the northern hemisphere – predominantly from Western Russia, northern Europe, and North America. East Asia appears to be a minor source of PAHs to the Arctic, despite contributing more than 50% of global PAH emissions. In comparison to the growing data for atmospheric PAHs, environmental data for these compounds in terrestria