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The lichen Evernia prunastri (L.) Ach. has been exposed for 3 months in and around an industrial area of Mediterranean Italy for monitoring physiological (photosynthetic efficiency, membrane lipids peroxidation and cell membrane integrity) and chemical (bioaccumulation of the heavy metals Cr, Ni, Pb, V and Zn) effects and investigate the consistency with the environmental quality status depicted by the diversity of epiphytic lichens (index of lichen diversity (ILD)). The results showed that thalli transplanted close to the industrial area exhibited early stress symptoms, as revealed by the increase in electrical conductivity indicating a damage endured by lichen cell membranes. The electrical conductivity was inversely correlated with the diversity of epiphytic lichens recorded at the same sites. The ILD negatively correlated also with membrane lipid peroxidation and the rate of accumulation of Pb, V and Zn. Reciprocal correlations found among trace elements pinpointed vehicular traffic and metal processing in the industrial area as main sources. The damage endured by cell membranes was the best physiological indicator consistent with the air quality status depicted by the diversity of epiphytic lichens.

This study aimed at investigating the cellular distribution of Hg in the lichens Cladonia arbuscula subsp. mitis and Peltigera rufescens treated with Hg²(+) and at testing if Hg treatment affects selected physiological parameters. In both species, increasing Hg accumulation under increasing Hg supply in the treatment solutions was found. P. rufescens showed a higher intracellular accumulation. Photosynthetic parameters were negatively affected in both species, as indicated by the decrease in photosynthetic pigments content, photosynthetic efficiency and chlorophyll integrity. Cell membranes of both species endured damage as indicated by the increase in the concentration of products of lipid peroxidation and decrease in ergosterol content. Nevertheless, differences between the two species were found, suggesting a differential sensitivity to Hg.

The present work aims at testing if exposure time and dose play a role in the response of lichen species to nitrogen (N) pollution. To this purpose, samples of the N-sensitive Evernia prunastri and the N-tolerant Xanthoria parietina were treated for 5 weeks either with solutions of NH 4 NO 3 0.05 and 1 M, or (NH 4 ) 2 SO 4 0.025 and 0.5 M. Photosynthetic efficiency was measured as an indicator of sample vitality. The results showed that the lowest concentrations were ineffective at the beginning, but after several supplies both compounds inhibited photosynthetic activity of E. prunastri . The highest concentrations had a deleterious effect, but with a temporal trend. For X. parietina no effect was found for the lowest concentrations, while the same trend shown by E. prunastri was instead observed following treatments with the highest concentrations. It was concluded that the response of lichens to N supply is not only species-specific, but also time- and dose-dependent. The results give a clue on field studies on the relationships between lichens and N pollution.

In this study, a biomonitoring project using the moss Scorpiurum circinatum was carried out to evaluate the deposition and biological effects of heavy metals in the area of Acerra (Naples, S Italy), one of the vertices of the sadly called ‘‘Italian triangle of death’’ owing to the dramatic increase in tumours. The results clearly indicated that the study area is heavily polluted by heavy metals, a large proportion of which is likely present in the atmosphere in particulate form. The ultrastructural organization of exposed samples was essentially preserved, but cell membrane pits, cytoplasm vesicles and concentric multilamellar/ multivesicular bodies, probably induced by pollution, were found, which may be involved in the tolerance mechanisms to metal pollution in this moss species. Although severe biological effects were not found at the ultrastructural level in the exposed moss, effects on humans, especially after long-term exposure, are to be expected

This paper tested if culturing the moss Scorpiurum circinatum (Brid.) Fleisch. & Loeske with metal solutions (Cd, Cu, Pb and Zn) for 30 days causes metal bioaccumulation and ultrastructural changes. The results showed that despite the high heavy metal concentrations in treatment solutions, treated samples did not show severe ultrastructural changes and cells were still alive and generally well preserved. Bioaccumulation highlighted that moss cells survived to heavy metal toxicity by immobilizing most toxic ions extracellularly, likely in binding sites of the cell wall, which is the main site of metal detoxification.

The aim of this study was to test in a short term laboratory experiment the accumulation and physiological effects of As in the epiphytic lichen Xanthoria parietina. Arsenic content in treated samples increased progressively with increasing concentration in treatment solutions. Treatment of X. parietina thalli with 0.1, 1, 10 ppm As solutions caused significant decrease of viability, measured as intensity of respiratory activity, and damages to cell membranes, assessed by increase of electric conductivity of rinsing water and lipid peroxidation products. Soluble proteins content decreased and H₂O₂ content increased already at the lowest As concentration tested (0.01 ppm). Photosynthetic efficiency, measured in terms of F(V)/F(M) ratio, decreased significantly only at the highest As concentration (10 ppm). It was concluded that As exposure causes physiological stress both on the mycobiont and the photobiont and that cell membrane damage, expressed in terms of electric conductivity of rinsing water, is the parameter most affected by As treatment.

This study investigated if atmospheric ammonia (NH3) pollution around a sheep farm influences the photosynthetic performance of the lichens Evernia prunastri and Pseudevernia furfuracea. Thalli of both species were transplanted for up to 30 days in a semi-arid region (Crete, Greece), at sites with concentrations of atmospheric ammonia of ca. 60 microg/m3 (at a sheep farm), ca. 15 microg/m3 (60 m from the sheep farm) and ca. 2 microg/m3 (a remote area 5 km away). Lichen photosynthesis was analysed by the chlorophyll a fluorescence emission to identify targets of ammonia pollution. The results indicated that the photosystem II of the two lichens exposed to NH(3) is susceptible to this pollutant in the gas-phase. The parameter PI(ABS), a global index of photosynthetic performance that combines in a single expression the three functional steps of the photosynthetic activity (light absorption, excitation energy trapping, and conversion of excitation energy to electron transport) was much more sensitive to NH3 than the FV/FM ratio, one of the most commonly used stress indicators.

The results of a study aimed at investigating the effects of boron excess on a set of ecophysiological parameters in the lichen Xanthoria parietina , to set up a monitoring system to trace early biological effects of boron pollution in geothermal areas, are reported. To this purpose, lichen thalli have been incubated for 24 h in solutions at boron concentrations of 0.1, 1, 10 and 100 ppm, which were within the range in bulk deposition and geothermal fluids. The results showed a general trend of decreasing sample viability and increasing cell membrane damage and membrane lipid peroxidation under increasing boron concentrations, while photosynthetic efficiency, chlorophyll degradation and the contents of H 2 O 2 and water-soluble proteins were not affected. It was argued that the fungal partner, that represents the large majority of the lichen biomass, is more sensitive to boron excess than the algal partner.

This study aimed at testing the suitability of cell membrane integrity in the lichen Evernia prunastri (L.) Ach. as sensitive indicator of nitrogen (N) stress, to set up a rapid and effective method for monitoring biological effects of acute N pollution. Lichen samples were incubated in solutions of potassium nitrate, ammonium nitrate and ammonium sulphate at different concentrations, and cell membrane damage, expressed in terms of increased electrolyte leakage, was measured after 0, 24, 48 and 96 h. Cell membrane damage was observed in E. prunastri in the presence of high or very high N concentrations, irrespective of the compound supplied. Since the mycobiont represents the large majority of a lichen biomass, it is reasonable to assume that ion leakage mainly occurred from fungal cells. Although in biomonitoring studies the photobiont is usually regarded as the most sensitive partner of the lichen symbiosis, our findings suggest that the mycobiont is most affected in the case of N-excess, and that this feature can be used as suitable indicator of acute N stress episodes.