Atmospheric Dioxin and Furan Deposition in Relation to Land-Use and Other Pollutants: A Survey with Lichens

Polychlorodibenzeno-dioxins and polychlorodibenzeno-furans (PCDD\Fs) are considered among the most toxic compounds on earth. The aim of the present study was to evaluate atmospheric PCDD\F deposition and identify the areas with greater deposition of these compounds in an important industrialized and urbanized region of Portugal, using lichens as biomonitors. For this purpose, samples of the lichen Xanthoria parietina were collected at 60 sampling sites, covering urban, industrial, forestry and agriculture areas, and analyzed for PCDD\Fs, sulfur, nitrogen, zinc, iron, chromium, lead, cobalt, nickel, copper, calcium, manganese, magnesium and potassium. The concentrations of PCDD\Fs in lichens were compared with the other elements and related to land-use and population density. The results obtained through the geostatistical interpolations and after principal component analysis have shown that PCDD\F deposition estimated by lichens is greater near industrial and highly populated urban areas. We found that lichens are suitable biomonitors of PCDD\F atmospheric deposition and can contribute to a better knowledge of air quality in a region, enabling identification of critical pollutant deposition areas.