Cell-membrane damage and element leaching in transplanted Parmelia sulcata lichen related to ambient SO2,...

Measurements were performed in lichen (Parmelia sulcata) transplants, to gain insight into the lichen vitality as possibly affected by both element deposition or lichen element content and further ambient atmospheric conditions (temperature, precipitation, SO2 levels). The electrical conductivity of rinsing solutions was used to assess cell-membrane damage in Parmelia sulcata in an experiment, which ran from August 2001 until August 2002. Element contents of the solutions and lichens were determined by inductively coupled plasma-optical emission spectrometry and by k0-instrumental neutron activation analysis, respectively. Factor analysis (MCATTFA) was used to determine grouping of elements of similar origin and/ or behavior. All in all, the data indicate that, apartfrom lichen Na and Cl levels, and for temperature and precipitation, no clear relationships with conductivity could be observed. Conductivity was mostly related to released Na, Cl, K, Mg, and Cs. On the basis of concentrations, Na, Cl, and K could be considered as largely determining the conductivity. The data suggest a different origin for K than that for Na and Cl: the latter two are most probably due to effects from sea salt sprays. Parmelia sulcata was sensitive enough to reflect appreciable ambient rises in air SO2 and resistant enough to recover afterward. MCATTFA on selected elements (K, Sc, Cu, V, As, and Sb) indicated the absence of any comparability between K and V, As and Sb, suggesting differences in origin and/or chemico-physical occurrence. Generally speaking, the present data suggest that the comparability of lichen vitality in large geographical areas may be limited and governed by the area's variability in temperature and precipitation rather than by variability in metal deposition rates. The leaching data on all elements and element groups, however, strongly suggest that wet deposition may also severely affect lichen elemental levels. This latter observation means that comparing outcomes for time or spatial series of lichen samples should be accompanied by a comparably careful monitoring of (preceding) ambient conditions.