Polycyclic aromatic hydrocarbons in rainwater and surface waters of Lake Maggiore, a subalpine lake in Northern Italy

Abstract

Fourteen polycyclic aromatic hydrocarbons (PAHs) were measured in surface waters and precipitation inputs to Lake Maggiore, a subalpine lake in Northern Italy, from July 2003 to January 2004. Particulate and dissolved phases in surface water and rain samples were determined. Analyses of PAHs were performed using XAD-2 resin to isolate the dissolved PAHs and subsequent extraction by accelerated solvent extraction (ASE). Both the dissolved and particulate phase PAH patterns in surface water and rainwater samples were dominated by the low molecular weight compounds (e.g., phenanthrene, fluoranthene and pyrene). More than 85% of PAHs in surface waters and 72% of PAHs in rainwater were associated to the dissolved phase. The ΣPAH concentrations in surface waters (particulate and dissolved phases) were 0.584 ± 0.033 ng l −1, 2.9 ± 0.312 ng l −1 and in rainwater (particulate and dissolved phases) 27.5 ± 2 ng l −1, 75.4 ± 9 ng l −1, respectively. Temporal variability of PAH concentrations in rain and surface water samples were observed, with higher concentrations in November and December, coinciding with the largest precipitation amounts. The comparison of PAH signatures in rainwater and surface waters seems to indicate that wet deposition (2.5–41 μg m −2 month −1) is the main source of PAH contamination into surface waters of Lake Maggiore.