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Abstract

This study presents four years ambient monitoring data of seventeen 2,3,7,8-chlorine substituted polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), twelve dioxin-like polychlorinated biphenyls (dl-PCBs) and sixteen polycyclic aromatic hydrocarbons (PAHs) designed by the US EPA at a background site in central Europe during 2011–2014. The concentrations expressed as toxic equivalents (TEQs) using the WHO2005-scheme for PCDD/Fs (0.2 fg m−3-61.1 fg m−3) were higher than for dl-PCBs (0.01 fg m−3-2.9 fg m−3), while the opposite was found in terms of mass concentrations. ΣPAHs ranged from 0.20 ng m−3 to 134 ng m−3. The mass concentration profile of PCDD/Fs, dl-PCBs and PAHs was similar throughout the four years. PCDD/Fs and PAHs concentrations were dominated by primary sources peaking in winter, while those of dl-PCBs were controlled by secondary sources characterized by a spring-summer peak. During 2011–2014, no significant decrease in the atmospheric levels of ΣPCDD/Fs was observed. On the other hand, the concentrations of Σdl-PCBs and ΣPAHs were decreasing, with halving times of 5.7 and 2.7 years, respectively. We estimated that 422 pg m−2 year−1-567 pg m−2 year−1 TEQ PCDD/Fs and 3.48 pg m−2 year−1-15.8 pg m−2 year−1 TEQ dl-PCBs were transferred from the air to the ground surfaces via dry particulate deposition during 2011–2014.