Response of air-pollution biomonitors under three different meteorological conditions

Samples of Flavoparmelia caperata (L.) Hale thalli, from a clean area in northern Portugal (Baio), were transplanted into exposure locations at the western Atlantic coast (north, center and south) impacted by urban-industrial emissions and meteorologically different, for a ten-month long experiment split into five terms of assessment (two months each). Through the experiment, the sites were also monitored for atmospheric bulk deposition. Analytical techniques for determinations in lichens and bulk deposition were instrumental neutron activation analysis, atomic absorption spectrophotometry and inductively coupled plasma mass spectrometry. The results indicate that: (1) the biological signals of detached lichens are compatible with sources in the area; (2) there is an appreciable number of airborne elements significantly enriched in (exposed) lichen samples, including some of great environmental interest; and (3) the cumulative contents per unit area of detached-lichen material are likely to provide an acceptable estimate of the atmospheric availability of enriched elements, as measured by their cumulative contents in the dry residues of bulk deposition.