POLYCHLORINATED NAPHTHALENES IN URBAN AIR

Air samples were collected at an urban site (Chicago,IL) and a semi-ur ban location (Downsview, Ontario) in February and March 1995 to measur e atmospheric concentrations and particle/gas partitioning of polychlo rinated naphthalenes (PCN). PCNs were quantified by gas chromatography -negative-ion mass spectrometry (GC-NIMS) against Halowax 1014, a comm ercial mixture of PCN compounds. GC-flame ionization responses were us ed to assign mass percent contributions to congeners in Halowax 1014. The reliability of this method was checked using pure compounds and wa s within +/-20% of the true value for 5 out of 6 congeners tested. Mea n atmospheric concentrations (Sigma PCN) at the urban and semi-urban s ite were 68 pg m(-3) (n=14) and 17 pg m(-3) (n=2), respectively. Sever al bioaccumulating PCNs which have ''dioxin-like'' toxicity similar to coplanar PCBs were quantified. The tetrachlorodibenzodioxin (TCDD) to xicity contribution of one of these PCNs in Chicago air was estimated to outweigh the contributions of some of the coplanar PCBs. The fracti on of PCNs on particles exhibited a stepwise increase with homolog gro up. A need for relevant physicochemical data for this group of compoun ds was identified. (C) 1997 Elsevier Science Ltd.