title: Characterization of AhR agonist compounds in roadside snow.
abstract: Aryl hydrocarbon receptor (AhR) agonistic contaminants were identified in roadside snow samples. Snow was collected in Oslo, Norway, and compared to a background sample collected from a mountain area. The water and particulate fractions were analysed for AhR agonists using a dioxin-responsive, chemically activated luciferase expression (CALUX) cell assay and by gas chromatography coupled to high-resolution time-of-flight mass spectrometry with targeted analysis for polycyclic aromatic hydrocarbons (PAHs) and broad-spectrum non-target analysis. The AhR agonist levels in the dissolved fractions in the roadside samples were between 15 and 387 pg/L CALUX toxic equivalents (TEQ(CALUX)). An elevated AhR activity of 221 pg TEQ(CALUX) per litre was detected in the mountain sample. In the particle-bound fractions, the TEQ(CALUX) was between 1,350 and 7,390 pg/L. One possible explanation for the elevated levels in the dissolved fraction of the mountain sample could be the presence of black carbon in the roadside samples, potentially adsorbing dioxin-like compounds and rendering them unavailable for AhR interaction. No polychlorinated dibenzodioxins and dibenzofurans or polychlorinated biphenyls were detected in the samples; the occurrence of PAHs, however, explained up to 9 % of the AhR agonist activity in the samples, whilst comprehensive two-dimensional gas chromatography coupled to mass spectrometry GCxGC-ToF-Ms identified PAH derivatives such as polycyclic aromatic ketones and alkylated, nitrogen sulphur and oxygen PAHs in the particle fractions. The (large) discrepancy between the total and explained activity highlights the fact that there are other as yet unidentified AhR agonists present in the environment.
authors.affiliation: Norwegian Institute for Water Research (NIVA), Gaustadalleen 21, 0349 Oslo, Norway. Martine.Muusse@niva.no
authors.forename: Martine
authors.initials: M
authors.lastname: Muusse
authors.forename: Katherine
authors.initials: K
authors.lastname: Langford
authors.forename: Knut Erik
authors.initials: KE
authors.lastname: Tollefsen
authors.forename: Gerard
authors.initials: G
authors.lastname: Cornelissen
authors.forename: Peter
authors.initials: P
authors.lastname: Haglund
authors.forename: Ketil
authors.initials: K
authors.lastname: Hylland
authors.forename: Kevin V
authors.initials: KV
authors.lastname: Thomas
mesh_terms: D008401:Gas Chromatography-Mass Spectrometry; D009664:Norway; D010316:Particle Size; D011083:Polycyclic Compounds / Q000032:analysis* / Q000494:pharmacology; D018336:Receptors, Aryl Hydrocarbon / Q000819:agonists*; D012914:Snow / Q000737:chemistry*
chemical_list: D011083:Polycyclic Compounds; D018336:Receptors, Aryl Hydrocarbon