Monitoring H2S air pollution caused by the industrial exploitation of geothermal energy: The pitfall of using lichens as bioindicators

This study showed that NH₃ emitted from geothermal power plants affects the surrounding epiphytic lichen vegetation and diversity, confounding the interpretation of lichen diversity counts in terms of air pollution by H₂S. The presence of nitrophytic lichen species around geothermal installations, determined by NH₃, caused relatively high diversity values that were not related with the levels of air pollution by H₂S. It is recommended that in the presence of NH₃ emission, nitrophytic species are excluded from the calculation of lichen diversity values.     

Epiphytic lichen diversity in central European oak forests: Assessment of the effects of natural environmental factors and human influences

We investigated lichen diversity in temperate oak forests using standardized protocols. Forty-eight sites were sampled in the Czech Republic, Slovakia and Hungary. The effects of natural environmental predictors and human influences on lichen diversity (lichen diversity value, species richness) were analysed by means of correlation tests. We found that lichen diversity responded differently to environmental predictors between two regions with different human impact. In the industrial region, air pollution was the strongest factor. In the agricultural to highly forested regions, lichen diversity was strongly influenced by forest age and forest fragmentation. We found that several natural factors can in some cases obscure the effect of human influences. Thus, factors of naturality gradient must be considered (both statistically and interpretively) when studying human impact on lichen diversity.     

Is the diversity of epiphytic lichens a reliable indicator of air pollution? A case study from Italy

This work provided additional information for a better interpretation of lichen diversity values in biomonitoring studies of air pollution. The effects of 12 predictive variables were estimated for the Genova province (NW Italy) by means of a non-parametric model. The diversity of epiphytic lichens was strictly correlated with mean annual rainfall and mean annual temperature. Different variables were found to affect the lichen diversity in urban vs. forested areas. In urban areas, air pollutants, mainly SO2, are still the main limiting factor, even if under ameliorating conditions this relationship becomes less significant. In forested areas, harvesting and forest fires showed a predominant effect, suggesting the need to develop a more defined sampling protocol to estimate atmospheric pollution in such ecosystems.     

Impact of neighbourhood land-cover in epiphytic lichen diversity: analysis of multiple factors working at different spatial scales

The objective of this work was to determine the impact of neighbourhood land-cover in epiphytic lichen diversity. We used geostatistics to analyse the spatial structure of lichen-indicators (number of lichen species and Lichen Diversity Value) and correlate them to land-cover considering different distances from the observed data. The results showed that lichen diversity was influenced by different environmental factors that act in the same territory but impact lichens at different distances from the source. The differences in the distance of influence of the several land-cover types seem to be related to the size of pollutants/particles that predominantly are dispersed by each land-cover type. We also showed that a local scale of analysis gives a deeper insight into the understanding of lichen richness and abundance in the region. This work highlighted the importance of a multiple spatial scale of analysis to deeply interpret the relation between lichen diversity and the underling environmental factors.     

Epiphytic lichens as indicators of environmental quality in Rome

A synthesis of the studies on lichen diversity carried out in Rome over the period 1982-2003 is presented. In this work, the Lichen Diversity (LD) method has been applied. Besides air pollution, the most important variable affecting the epiphytic lichen flora of Rome, currently updated to 102 taxa, is the influence of the Tyrrhenian Sea. Significant changes in the lichen flora have been noted over the past 20 years, with the lowest diversity now being found in the urban centre and in the eastern and southern sectors, while the "lichen desert" area has decreased in parallel with decreasing concentrations of CO, NO(x) and SO2.     

A biological method to monitor early effects of the air pollution caused by the industrial exploitation of geothermal energy

The suitability of a set of ecophysiological parameters, to be used as early warning indicator to detect signs of a worsening environment around geothermal power plants, was tested by comparison with the diversity of epiphytic lichens, a well-established indicator of geothermal air pollution. Samples of the lichen Evernia prunastri were transplanted around a geothermal power plant at Larderello (Tuscany, Italy) and at a control site, and integrity of cell membranes, concentration of chlorophyll a, b and carotenoids, chlorophyll integrity and variations in pH of thalli were measured. The results showed that cell membrane damage, expressed by changes in electrical conductivity, could be used to detect early (exposure periods as short as 1 month) deleterious effects of geothermal air pollution.     

Diversity and sensitivity of epiphytes to oxides of nitrogen in London

This study investigated the distribution and diversity of epiphytes in London in relation to NO(x) using fine-scale atmospheric dispersion modelling. The survey recorded over 3000 epiphytes from 334 trees (Fraxinus excelsior) representing 74 lichen, 14 moss, 7 fungal and 3 algal species. There was a significant inverse relationship between diversity and NO(x). Diversity declined where NO(x) exceeded 70 microg m(-3) and NO2 exceeded 40 microg m(-3), suggesting a phytotoxic effect. However, there was a significant positive relationship between NO(x) and lichen abundance due to the ubiquitous distribution of pollution tolerant species, mainly associated with eutrophication. A scale of lichen sensitivity to NO(x) has been derived.     

Epiphytic lichen diversity on dead and dying conifers under different levels of atmospheric pollution

Based on literature data, epiphytic lichen abundance was comparably studied in montane woodlands on healthy versus dead or dying conifers of Europe and North America in areas with different levels of atmospheric pollution. Study sites comprised Picea abies forests in the Harz Mountains and in the northern Alps, Germany, Picea rubens-Abies balsamea forests on Whiteface Mountain, Adirondacks, New York, U.S.A. and Picea engelmannii-Abies lasiocarpa forests in the Salish Mountains, Montana, U.S.A. Detrended correspondence analysis showed that epiphytic lichen vegetation differed more between healthy and dead or dying trees at high- versus low-polluted sites. This is attributed to greater differences in chemical habitat conditions between trees of different vitality in highly polluted areas. Based on these results, a hypothetical model of relative importance of site factors for small-scale variation of epiphytic lichen abundance versus atmospheric pollutant load is discussed.     

The response of epiphytic lichens to air pollution and subsets of ecological predictors: a case study from the Italian Prealps

We investigated the response of epiphytic lichens to air pollution, against the background of other ecological predictors in a prealpine heterogeneous area, using Non-Parametric Multiplicative Regression (NPMR). The best NPMR model for total lichen diversity according to N environmental predictors at tree level has a cross R(2)=0.709. It includes 10 variables, belonging to three different subsets of factors: two pollution-related factors (distance in meters from the road and from the cement factory); four stand-related (habitat, heat index, LAI and elevation) and four substrate-related factors (inclination, circumference and texture and tree species). Considering separately the effects of each subset on lichen diversity, substrate- and stand-related factors produce good models with similar cross R(2) (0.490 and 0.500, respectively), whereas pollution-related factors produce a model with a lower cross R(2) (0.340). Hence, we provide information to investigate the applicability of lichen biomonitoring to complex heterogeneous areas where standardized protocols are not reliable.     

Monitoring air quality with lichens: a comparison between mapping in forest sites and in open areas

Four different methods of epiphytic lichen mapping were used for the assessment of air quality in the region under the influence of the Sostanj Thermal Power Plant (Salek Valley, Slovenia). Three methods were based on the presence of different lichen species (VDI, EU and ICP-Forest), the fourth on a frequency and coverage assessment of different growth forms of epiphytic lichens, e.g. crustose, foliose and fruticose (SI). A comparison of the results from the assessment of air quality between forest sites (ICP-Forest, SI) and open areas (VDI, EU and SI), obtained by the different methods of epiphytic lichen mapping, is presented in the contribution. Data showed that lichen species richness is worse in forest sites in comparison with open areas. From the data obtained it can be concluded that epiphytic lichen mapping in open areas is a better method for the assessment of air pollution in a given area than mapping in forest sites. The species-based methods in open areas are more powerful and useful for air quality assessment in polluted research areas than the SI and ICP-Forest methods.     

Lichen biomonitoring of ammonia emission and nitrogen deposition around a pig stockfarm

Effects of high ammonia emissions and nitrogen deposition were investigated on lichens around a pig stockfarm (ca. 7,000 animals) in central Italy. Four sites were selected along a transect at 200, 400, 1000 and 2500 m from the stockfarm, the diversity of epiphytic lichens was measured and transplanted thalli of Xanthoria parietina and Flavoparmelia caperata exposed, together with passive NH3 (diffusion tubes) samplers. Ammonia dramatically decreased from the centre of the stockfarm to the sampled sites, where it was correlated with bark pH. Total lichen diversity was not associated with either NH3 concentrations or bark pH, but the diversity of strictly nitrophytic species was highly correlated with both parameters. Physconia grisea was the best indicator species for NH3 pollution. Total N accumulated in X. parietina and F. caperata was correlated with NH3 concentrations.     

Lichens as integrating air pollution monitors

In this work an attempt to combine the results of lichen mapping with the quantitative levels of certain trace elements in Hypogymnia physodes (L.) Nyl. collected on a national scale is presented. An Index of Atmospheric Purity (IAP) was calculated using a simple method of mapping lichens based on the assessment of the cover and frequency of crustose, foliose and fruticose lichens on different tree species. For determination of trace elements in lichens k0-instrumental neutron activation analysis was used. From the IAP results it can be concluded that the epiphytic lichen flora look quite poor with more than 70% of the territory in the fourth and third classes, which represent highly polluted and moderately polluted air. By comparing IAP results with elemental levels in H. physodes using multivariate statistical methods it was found that the elemental levels do not have a direct negative effect on the diversity of lichens but can help in identification of the type of possible pollution sources and their origin.     

Lichen and moss bags as monitoring devices in urban areas. Part I: influence of exposure on sample vitality

Samples of the lichen Pseudevernia furfuracea (L.) Zopf and the moss Hypnum cupressiforme Hedw. were exposed for 6 weeks in nylon bags in two air pollution monitoring stations in Trieste and Naples (Italy) with different climates and pollution loads to evaluate influence of environmental conditions on sample vitality. This was assessed before and after exposure by transmission electron microscopy observations, K cellular location, and measurements of C, N, S and photosynthetic pigments content, CO2 gas exchange, and chlorophyll fluorescence. Almost all data sets indicate that exposures caused some damage to the species, considerably heavier in the moss, especially in Naples. The two cryptogams differed significantly in accumulation and retention of C, N, and S, the lichen clearly reflecting NO2 availability. The difference in vitality loss was related to the different ecophysiology of the species, because concentrations of phytotoxic pollutants were low during exposure. Critical notes on the analytical techniques are also given.     

Lichen and bryophyte distribution on oak in London in relation to air pollution and bark acidity

Epiphytic lichen and bryophyte distribution and frequency were investigated on the trunks of 145 young oak trees throughout London and surrounding counties, and compared with pollution levels and bark pH. Sixty-four lichen and four bryophyte species were recorded. Three major zones were identified: (i) two central regions with a few lichens, bryophytes absent; (ii) a surrounding region with a more diverse flora including a high cover of nitrophyte lichens; and (iii) an outer region, characterised by species absent from central London, including acidophytes. Nineteen species were correlated with nitrogen oxides and 16 with bark pH, suggesting that transport-related pollution and bark acidity influence lichen and bryophyte distribution in London today. Lichens and bryophytes are responding to factors that influence human and environmental health in London. Biomonitoring therefore has a practical role to assess the effects of measures to improve London's air quality.     

Susceptibility to acidic precipitation contributes to the decline of the terricolous lichens Cetraria aculeata and Cetraria islandica in central Europe

The effective quantum yield of photochemical energy conversion in photosystem II (Phi2) was shown to be reduced in the terricolous lichens Cetraria aculeata and Cetraria islandica by short-term exposure to aqueous SO2 at pH values occurring in the precipitation of areas with high SO2 pollution. Significant reduction of Phi2 was found at pH相似文献   

Relationship between epiphytic lichens, trace elements and gaseous atmospheric pollutants

A study was conducted to determine the joint effect of gaseous atmospheric pollutants and trace elements on epiphytic lichens. We used our data to test the hypothesis that lichens are generally insensitive to toxic effects of trace elements, and can therefore be used as accumulator organisms to estimate concentrations of these elements in the environment. In a field study in The Netherlands the abundance of epiphytic lichen species was estimated, and their supporting bark was collected. Concentrations of a range of trace elements were determined in the bark, and concentrations of atmospheric trace gases were estimated at the sites of collection. Multivariate statistics were used to determine the relation between the abundance of the species and pollutant concentrations. Atmospheric SO2 and NO2 appeared to be the most important factors determining lichen biodiversity. Nearly all species were sensitive to these compounds. The effect of the other trace elements was very slight; only Sb had a significantly negative effect on the abundance of a few species. It is concluded that lichens can safely be used as accumulator organisms in pollution studies, provided that concentration in lichen thalli reflect atmospheric concentrations.     

Relationships between lichen community composition and concentrations of NO2 and NH3

The relationship between different features of lichen communities in Quercus robur canopies and environmental variables, including concentrations of NO₂ and NH₃ was investigated. NO₂ concentration was the most significant variable, it was positively correlated with the proportion of lichen cover comprising nitrophytes and negatively correlated with total lichen cover. None of the lichen community features were correlated with NH₃ concentrations, which were relatively low across the site. Since nitrophytes and nitrophobes are likely to react in opposite directions to nitrogenous compounds, total lichen cover is not a suitable indicator for these pollutants. It is, therefore, suggested that the proportion of lichen cover comprising nitrophytes may be a suitable simple indicator of air quality, particularly in locations where the pollution climate is dominated by oxides of nitrogen.     

Chemical response of transplanted lichen Canomaculina pilosa to different emission sources of air pollutants

The lichen Canomaculina pilosa was transplanted to 21 sampling sites, plus two controls sites in a north-western area of Córdoba City, Argentina. The transplantation sites were set according to traffic levels, industry condition and distances from the power plant. On the transplanted lichens chlorophyll a, chlorophyll b, phaeophytin a, soluble proteins, hydroperoxy-conjugated dienes, malondialdehyde concentration and sulphur accumulation were determined. A pollution index was calculated for each sampling site. The present study provides information about chemical parameters showing variations as the response of C. pilosa to different emission sources of air pollutants. The C. pilosa chemical response was mainly associated to industries. Significant higher values were observed in phaeophytin a/chlorophyll a ratio, sulphur content and pollution index values in lichen material transplanted at sites with industry. For the distance from the power plant category, only the hydroperoxy-conjugated dienes concentration showed significant differences. For the different traffic levels no significant variations were observed for any of the chemical parameters quantified.     

Variations of sulfur isotope ratios in a single lichen thallus: A potential historical archive for sulfur pollution

Utilizing the analytical capability to measure S isotope ratios of small quantities of S in biological material without any chemical pretreatment, the variation of δ³⁴S within a lichen thallus was investigated using old and young segments of fruticose lichen thalli (Alectoria sarmentosa) from an oil refinery area in Come-By-Chance and two coastal areas, Newfoundland, Canada. Old segments of lichen samples from the oil refinery area showed significantly higher δ³⁴S values (1.0-2.5‰) than their corresponding young segments. Lichen samples from two coastal areas showed no noticeable differences in δ³⁴S values between old and young segments. These results demonstrate that lichen thalli record temporal changes in the isotopic composition of atmospheric S and hence constitute a historical archive of atmospheric S pollution.     

Effects of NO2 and NH3 from road traffic on epiphytic lichens

The results of a survey aimed at investigating whether NO2 and NH3 emitted by road traffic can influence lichen diversity, lichen vitality and the accumulation of nitrogen in lichen thalli are reported. For this purpose, distance from a highway in a rural environment of central Italy was regarded as the main parameter to check this hypothesis. The results of the present survey indicated that road traffic is not a relevant source of NH3. On the other hand, NO2 concentrations, although rather low, were negatively correlated with distance from the highway according to a typical logarithmic function. No association between NO2 concentrations and the diversity of epiphytic lichens was found, probably because of the low NO2 values measured. Also bark properties were not influenced by distance from the highway. Accumulation of nitrogen, reduction in the content of chlorophyll a, chlorophyll b and total carotenoids were found in transplanted thalli of Evernia prunastri, but NO2 was not responsible for these changes, which were probably caused by applications of N-based fertilizers.