Polychlorinated Naphthalenes in Swedish Background Air

Abstract

Polychlorinated naphthalenes (PCNs) with four to eight chlorines were studied in air collected at two background stations in Sweden, one southerly and one northerly. Air was sampled with a high-volume sampler, and gas-phase adsorbents and filters were analyzed separately. The sum of TeCNs to HxCNs in the gaseous phase ranged between 1 and 10 pg/m3 with significantly higher concentrations at the southern location Hoburgen. HpCNs and OCN were below the detection limit. The highest concentrations were found in two samples from Hoburgen with the air masses coming from SW and W and during warm weather (+11 degrees C). The lowest concentration was found in a sample from the northern location Ammarnäs at cold weather (-22 degrees C) when the air came from the east. A correlation was found between logP and 1/T indicating that temperature has a larger effect than location on the concentration in the gas phase. The TeCNs constituted 50-75% in the gaseous phase. In most filter samples TeCNs and PeCNs were below the limit of quantitation. PUF samples with air trajectories from W to NE had relatively higher concentrations of late eluting TeCNs and PeCNs, while in samples with winds from SE to S the early eluting congeners dominated. Samples with early eluting congeners were mainly collected at lower temperature. TriCNs constituted the dominant homologue group both in the gaseous and particulate phase of air samples as well as in bulk deposition from a rural monitoring station south of Stockholm. The octanol-air partition coefficient described the gas/particle interaction well for samples collected at temperatures down to -8 degrees C.