Deposition of polycyclic aromatic hydrocarbons in the North Pacific and the Arctic

Abstract

[1] Eighteen polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in surface seawater and boundary layer air from the North Pacific toward the Arctic Ocean during the Fourth Chinese National Arctic Research Expedition in the summer of 2010. Atmospheric Σ 18 PAH ranged from 910 to 7400 pg m À3 , with the highest concentrations observed in the coastal regions of East Asia. Correlations of PAHs' partial pressures versus inverse temperature were not significant, indicating the importance of ongoing primary sources on ambient PAH levels in the remote marine atmosphere. The relatively high atmospheric concentrations observed in the most northerly latitudes of the Arctic Ocean suggest the influence of regional sources. For example, higher levels of particle-bound PAHs were observed in the air of the Arctic Ocean than the North Pacific, indicating forest fire and/or within-Arctic sources. Concentrations of PAHs in surface seawater were within a range of 14-760 pg L À1 and generally decreased with increasing latitude. The observed air-sea gas exchange gradients strongly favored net deposition of PAHs along the entire cruise, with increasing deposition with increasing latitude, while the particle-bound dry deposition fluxes (particularly for the high molecular weight PAH) were highest at sample sites close to East Asia. Based on characteristic PAH ratios, atmospheric PAHs originated from the combustion of biomass or coal, while the ratios observed in seawater reflected a mixture of sources. Given the dominance of primary emissions to the atmosphere and the relatively fast removal of PAHs from the water column, then PAHs will continue to load into the surface waters of the remote marine environment via atmospheric deposition.

Tracking human footprints in Antarctica through passive sampling of polycyclic aromatic hydrocarbons in inland lakes

“…Available data from both lakes and seawater indicate higher levels of PAHs along the coast of West Antarctica than in East Antarctica. In addition, the concentrations of PAHs in the inland lakes were comparable to those (4e600 ng L À1 ) in seawater from the Fuglebekken basin in Svalbard (Norwegian Arctic) (Polkowska et al, 2011), but were several orders of magnitude higher than those found in surface seawater (0.014e0.06 ng L À1 ) from Arctic regions (71e75 N) (Ma et al, 2013) and freshwater (average values: 1.9 ± 1.9 and 2.0 ± 0.3 ng L À1 ) from high-mountain lakes at 2060e5300 m, such as lakes on Mt. Sagarmatha of Himalayas (Nepal) (Guzzella et al, 2011), Lake Redon (Pyrenees, Spain), and Lake Ladove (High Tatras, Slovakia) (Fern andez et al, 2005).…”

Sources and fate of polycyclic aromatic hydrocarbons in the Antarctic and Southern Ocean atmosphere

“…The concentrations reported in this study are generally not significantly different than those reported in the Arctic and surrounding oceans. Ma et al [2013] reported Σ 18 PAHs in the range 2.15-4.73 ng m À3 in the Arctic Ocean (latitudes > 70°N) and between 0.9 and 4.07 ng m À3 in the North Pacific Ocean (50°N-66°N). Ding et al [2007] observed concentrations Σ 15 PAHs in the range of 0.93-92.6 ng m À3 over the North Pacific Ocean and the Arctic.…”

Distribution and Sources of Dissolved Black Carbon in Surface Waters of the Chukchi Sea, Bering Sea, and the North Pacific Ocean

“…Salinity and S 275−295 (a 254 and TDLP 9 ) in surface waters of the North Pacific Ocean were higher (lower) than those of the Chukchi/Bering Seas (Figures 1, 3), which implies that riverine inputs are minor in the North Pacific Ocean compared with those in the Chukchi/Bering Seas. Although the airsea gas exchange fluxes of polycyclic aromatic hydrocarbons (PAHs) are high in the Arctic region, the PyC concentrations in aerosol particles and dry deposition of particle-bound PAHs in the North Pacific Ocean were greater than those in the Chukchi/Bering Seas (Hadley et al, 2007;Ma et al, 2013;Taketani et al, 2016). Low condensation degrees of DBC observed in surface waters of the subarctic and subtropical North Pacific thus imply that atmospheric deposition of BC and subsequent dissolution is an important source of DBC in these provinces.…”