Monitoring atmospheric levels and deposition of dioxin-like pollutants in sub-alpine Northern Italy

摘要

The objective of this work was to assess the atmospheric occurrence, seasonal variations and deposition of dioxin-like pollutants (17 PCDD/Fs + 12 DL-PCBs) in sub-alpine northern Italy. A total of 108 weekly integrated samples (aerosol + gas phases) were collected during a 1-year period (2005—2006) at the Ispra EMEP site (Northern Italy, 45°49'N, 8°38'E). Atmospheric loadings into Lake Maggiore were also estimated by implementing a deposition model. £2,3,7,8-PCDD/F atmospheric total concentrations were dominated by the aerosol-bound fraction which ranged from 50 to 3080 (1-215 WHO_(98) TEQ) fg m~(-3). In contrast DL-PCB levels were dominated by the gas phase concentrations and varied from 1800 to 14800 (1-5 WHO_(98) TEQ) fg m~(-3). The aerosol and gas phase concentrations of PCDD/Fs and DL-PCBs exhibited a similar seasonality (higher values in winter time for aerosol-bound contaminants and lower concentrations for gas phase contaminants) in spite of their different environmental sources and properties. Estimated total atmospheric (dry + wet) depositional fluxes of dioxin-like pollutants in sub-alpine northern Italy were ～0.2-～9.5 ng m~(-2) d~(-1), with wet deposition dominating. Total atmospheric inputs (2,3,7,8-PCDD/Fs + DL-PCBs) into Lake Maggiore ranged from 14 to 304 g y~(-1). Higher environmental concentrations of dioxin-like pollutants in sub-alpine northern Italy are expected in the cold season and in rainy days due to a combined effect of stagnant atmospheric conditions (low winds), household wood burning in the region and higher pollutant loads via rainfall in winter.