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This study compared the heavy metal bioaccumulation capacity in the epiphytic moss Scorpiurum circinatum and the epiphytic lichen Pseudevernia furfuracea, exposed in bags for 3 months in the urban area of Acerra (S Italy). The content of Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V, and Zn was measured by ICP-MS. The results showed that both species accumulated all the heavy metals assayed. The moss had the highest bioaccumulation capacity for all metals and showed a more constant and linear accumulation trend than the lichen. Intra-tissue heavy metal bioaccumulation was assessed by X-ray microanalysis applied to ESEM operated in high and low vacuum and ESEM modes.

This paper presents the results of a bioaccumulation study of trace elements in the Naples urban area based on the use of the moss Sphagnum capillifolium (Ehrh.) Hedw. and the lichen Pseudevernia furfuracea (L.) Zopf exposed in bags in 23 sites. Moss and lichen bags were exposed for 4 months starting from the beginning of July 1999. Bags gathering was carried out after 10 weeks of exposure, at the end of the dry season, and after 17 weeks, during the wet season. The elements Al, As, Ca, Cd, Cr, Co, Cu, Fe, K, Mg, Mn, Mo, Ni, Pb, Ti, V and Zn were analysed by inductively coupled plasma-mass spectrometry ICP-MS in both biomonitors. For the majority of the elements the total amounts found in S. capillifolium were higher than in P. furfuracea whether considering the whole period of exposure or the weekly uptake. It was observed that there was a much greater difference in metal accumulation by P. furfuracea between the dry and wet seasons compared with S. capillifolium. In the wet period, the lichen seems to accumulate a larger quantity of metals. With the exception of Mn, trace element concentrations did not appear to be significantly affected by the washing away of rainfall. K loss during exposure suggested cell membrane damage in both organisms. For P. furfuracea the K leakage was limited to the dry period of exposure. A clear distinction between "lithophilic" and "anthropogenic" elements was achieved by cluster analysis. Significant correlations were found among Fe-Cu-Cr-Ni, Pb-Cd-Co, V-Cr-Ni, Zn-Ni-Pb, suggesting a common source for each group of elements.