Polychlorinated naphthalenes and coplanar polychlorinated biphenyls in arctic air

Concentrations of polychlorinated naphthalenes (PCNs) are reported for the first time in arctic air. The data represent combined air samples from the Barents Sea (n = 2), eastern Arctic Ocean (n = 10), Norwegian Sea (n = 2), and two land-based monitoring stations at Alert, Canada (n = 5), and Dunai Island in eastern Siberia, Russia (n = 3). Values for Sigma PCN (pg m(-3)) were 6-49 for shipboard samples and 0.3-8 for land-based stations and were dominated by the 3-Cl and 4-Cl homologues, which accounted for 90-95% of the total mass. Average values for Sigma PCB (pg m(-3)) for the shipboard samples were 126, 24, and 75 for the Barents Sea, eastern Arctic, and Norwegian Sea, respectively. Three-dimensional 5-day air parcel back-trajectories arriving at the ship at 850 and 925 hPa suggested that elevated PCB and PCN concentrations for shipboard samples originated in Europe. Concentrations (fg m(-3)) of coplanar PCBs in artic air were 3-40 (PCB 77) and 0.3-8 (PCB 126)-about an order of magnitude lower than in urban air. Higher concentrations of PCB 77 and PCB 126, 347 and 5.0 (fg m(-3)), respectively, were found in the Barents Sea for two samples with elevated Sigma PCBs. The proportion of coplanar PCBs to Sigma PCBs was within the range of values reported for Aroclor and Clophen mixtures. The 2,3,7,8-TCDD toxicity of the air samples was assessed in terms of the TEQ (dioxin toxic equivalents) contribution of mono-ortho PCBs (congeners 105, 114, 118, 156), non-ortho (coplanar) PCBs (congeners 77 and 126), and dioxin-like PCNs for which toxic equivalent factors have been determined. The results show a 13-67% TEQ contribution of PCNs in arctic air, and it is concluded that further investigation of this compound class is merited.