The performance of two lichen species as bioaccumulators of trace metals

The concentrations of 16 metals were measured in peripheral and central par ts of the foliose epiphytic lichens Parmelia caperata and Xanthoria parieti na collected in north-east Italy. Relevant intra- and interspecific variabi lity was shown by multivariate analysis (classification and ordination) of the matrix of metals and samples. The central, older parts of the thalli co ntained significantly higher amounts of most metals in both species. Signif icative differences were also found between peripheral parts of the two spe cies, with higher concentrations of Fe and Al in Xanthoria, and Cd and Zn i n Parmelia. An inter-species comparison of several hundred Italian measurem ents confirmed the higher affinity of Parmelia for Cd and Zn, but not that of Xanthoria for Fe and Al. In order to enhance data quality in biomonitori ng studies, it is suggested to analyse only peripheral parts of the lichens , and to avoid the joint use of Parmelia and Xanthoria when monitoring Cd a nd Zn. (C) 2001 Elsevier Science B.V. All rights reserved.