Element-Enrichment Factors in Lichens from Terceira, Santa Maria and Madeira Islands (Azores and Madeira Archipelagoes)

Abstract

In this study, more than 20 minor and trace elements have been determined by INAA (instrumental neutron activation analysis), in different species of lichens in three Portuguese islands of the Central North Atlantic (Santa Maria, Terceira, and Madeira Islands). The foliose species Parmotrema bangii, Parmotrema robustum, Parmotrema crinitum, Flavoparmelia caperata, Platismatia glauca, and the fruiticose species Ramalina canariensis, Ramalina farinacea, Ramalina implectens, Ramalina pusilla, Cladonia furcata, Cladonia coniocraea, Usnea dasaea, Usnea esperantiana, were the collected species. Samples of superficial soils were also collected and the fraction below 64 μ m was analysed. The enrichment factors relative to this fraction using Al as the normalising element were calculated. Fruiticose and foliose lichens displayed different EF values concerning bromine and potassium. The first was more enriched in the foliose species while the latter was more enriched in the fruiticose species and was assigned to the physiological response. Enrichment was found for Mg, Cs, As, Hg, Na, Zn, and Cl, in all the species. Lichen-based concentration patterns were shown for Na, Al, Cl, Br, Sb, Ce, and Hg and compared to similar patterns in Portugal mainland. In general, the patterns compared well except for Cl, Na, and Br. Background levels of the epiphytic lichens collected in the islands were obtained.