Response of air-pollution biomonitors under three different meteorological conditions
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Response of air-pollution biomonitors under three different meteorological conditions N. Canha • M. C. Freitas • A. M. G. Pacheco
Received: 4 April 2012 / Published online: 17 August 2012 Ó Akade´miai Kiado´, Budapest, Hungary 2012
Abstract Samples of Flavoparmelia caperata (L.) Hale thalli, from a clean area in northern Portugal (Baia˜o), were transplanted into exposure locations at the western Atlantic coast (north, center and south) impacted by urban-industrial emissions and meteorologically different, for a tenmonth 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. Keywords Biomonitoring Transplanted lichens k0-INAA Bulk deposition
N. Canha (&) M. C. Freitas URSN, IST/ITN, Instituto Superior Te´cnico, Universidade Te´cnica de Lisboa, Polo de Loures—Campus Tecnolo´gico e Nuclear, E.N. 10, 2686-953 Sacave´m, Portugal e-mail: [email protected] A. M. G. Pacheco CERENA-IST, Technical University of Lisbon, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
Introduction Lichens were early considered as sentinel plants for atmospheric contamination [1, 2] and, since then, dose– response relationships in stressed habitats have been searched. In fact, comparing to other types of biota used for biomonitoring purposes (vascular plants, non-lichenised fungi or mosses), lichens gather several features that give them a higher monitoring potential than all the others [3, 4]. In particular, epiphytic lichens are considered to be more adequate for such a purpose than saxicolous and terricolous species, as the variability inherent in rocks and soils is far greater than in vegetable substrata (due to the genetic control acting on the latter). Still, living organisms are not physical–chemical, measuring devices, therefore no single plant biomonitor will ever account quantitatively—or even just qualitatively— for every attribute of interest. For instance, preferential element accumulation has been extensively documented, and differential uptake/retention efficiency has been reported for biomonitoring studies involving lower epiphytes, higher epiphytes and vascular plants, per se or combined [5, 6]. An inherently high biovariability plus an array of biotic and abiotic factors contribute to the overall perfor
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