Transport of urban-derived organic contaminants into a boreal lake: a case study with passive samplers

The aim of this study was to evaluate the sources, transport and distribution of hydrophobic organic contaminants produced in an urban area. Passive sampling devices (PSDs) were employed in the storm-water drainage of the city of Lahti, in an adjacent boreal lake (Vesijärvi) and along its shore. Samples were analysed for 16 polycyclic aromatic hydrocarbons (PAHs) and 28 polychlorinated biphenyls (PCBs) with a gas chromatograph–mass spectrometer. Concentrations of contaminants were elevated in the stormwater drainage and in the vicinity of the stormwater outlets in Vesijärvi, but declined as a function of distance from the shore. Atmospheric PAH concentrations were significantly higher in the autumn than in the summer. Petrogenic PAHs contributed significantly to stormwater contamination, while pyrogenic pollutants mainly appeared to be carried to Vesijärvi by atmospheric transport.