Bioaccumulation behaviour of transplants of the lichen Flavoparmelia caperata in relation to total deposition at a polluted location in Portugal

This experiment compares the short and long time element accumulation behaviour of transplants of Flavoparmelia caperata lichen thalli and total deposition in an atmospheric polluted area. It was found that lichens exposed for a short time behaved differently from lichens in cumulative exposition suggesting the presence of acclimatization behaviour. The lichen transplant elemental content does not unequivocally represent the average or cumulative environmental availability of the exposure period. Reflection characteristics depend on the element and the lichen physiological conditions. Good correlations between lichen elemental contents and total deposition were obtained when a physiological lichen parameter was introduced in a mathematical model, suggesting that metabolically mediated accumulation is important.     

High acidity tolerance in lichens with fumarprotocetraric, perlatolic or thamnolic acids is correlated with low pKa1 values of these lichen substances

The depsidone fumarprotocetraric acid as well as the depsides perlatolic and thamnolic acids are lichen secondary metabolites. Their first dissociation constants (pK_a1) in methanol were determined to be 2.7 for perlatolic acid and 2.8 for fumarprotocetraric and thamnolic acids by UV spectroscopy. Lower pK_a1 values are, so far, not known from lichen substances. Several lichens producing at least one of these compounds are known for their outstanding tolerance to acidic air pollution. This is demonstrated by evaluating published pH preferences for central European lichens. The low pK_a1 values suggest that strong dissociation of the studied lichen substances is a prerequisite for the occurrence of lichens with these compounds on very acidic substrata, as protonated lichen substances of different chemical groups, but not their conjugated bases, are known to shuttle protons into the cytoplasm and thereby apparently damage lichens.     

Bags with oven-dried moss for the active monitoring of airborne trace elements in urban areas

To define a harmonized methodology for the use of moss and lichen bags as active monitoring devices of airborne trace elements in urban areas, we evaluated the element accumulation in bags exposed in Naples in different spring weather conditions for 6- and 12-weeks. Three different pre-exposure treatments were applied to moss and lichen materials: water-washing, acid-washing and oven-drying. During the different exposure periods in the Naples urban environment the moss accumulated always higher amounts of elements (except Hg) than lichens and the element accumulation increased during wetter weather and higher PM₁₀ conditions. The oven pre-treatment did not substantially modify the morphology and element composition of moss and the exposure in bags of this material for 6-weeks was sufficient to detect the pattern of airborne trace elements.     

Copper tolerance in the macrolichens Cladonia furcata and Cladina arbuscula subsp. mitis is constitutive rather than inducible

In this study we assessed the degree of copper (Cu) tolerance in two common lichen species (Cladonia furcata and Cladina arbuscula subsp. mitis) that grow on both uncontaminated substrata and the surface of waste heaps from abandoned old Cu-mines. Regardless of their locality, populations of these lichens contain identical strains of photobionts (Asterochloris clade A in C. arbuscula subsp. mitis and clade D in C. furcata). Therefore, it was expected that if there were differences in Cu toxicity or tolerance between populations, that the photobiont could not be a key element of Cu tolerance in these two lichen species. In laboratory experiments samples of both lichen species (from contaminated and control sites) were incubated in Cu solutions (500 μM) for 24 h. We attempted to determine whether Cu tolerance in these lichens was constitutive, or inducible form. Based on measurements of Cu accumulation, chlorophyll a integrity, chlorophyll a fluorescence, photosynthesis, respiration, measurements of the content of thiobarbituric acid reactive substances (TBARS), the content of soluble proteins, reactive oxygen species (ROS) and the amount of extracellular secondary metabolites of both lichens we found that there were no significant differences in the response of all selected populations of both lichen species to short-term exposure to these high levels of Cu. As a result, we conclude that Cu tolerance in these two lichen species is the constitutive rather than the inducible.     

Lichen and moss bags as monitoring devices in urban areas. Part II: trace element content in living and dead biomonitors and comparison with synthetic materials

Lobes of the lichen Pseudevernia furfuracea (L.) Zopf and shoots of the moss Hypnum cupressiforme Hedw. were subjected to different treatments (water washing, oven drying, HNO3 washing, NH4-oxalate extraction) to assess the influence of vitality on accumulation efficiency, during a 6-week exposure in bags in two Italian cities, Trieste and Naples. No trend emerged between treatments, in terms of accumulation ability, for major and trace elements. Only water-washed lichens showed an increased C and N content after exposure in both cities. Element concentrations generally reached higher values in mosses than in lichens, especially for Al, Fe, and Zn (both cities), and for Cu, Mg and Na (Naples). Surface development strongly influenced accumulation capacity of the biomonitors. Quartzose and cation exchange filters revealed, on a weight basis, a poor performance. In urban environments, surface interception of atmospheric particulate seems to play a major role in accumulation, irrespective of organism vitality.     

Biomonitoring spatial and temporal impact of atmospheric dust from a cement industry

The objective of this work was to evaluate the spatial and temporal impact of dust-pollution in the vicinity of a cement industry, located in an area with dry climate. The spatial impact integrated over time was evaluated from the concentrations of Ca, Fe and Mg in in-situ Xanthoria parietina. The temporal pattern was assessed through one-month transplants of the lichen Ramalina canariensis. Four potential sources of atmospheric dust were evaluated: the limestone-quarry; the unpaved roads, the deposit area and the cement mill. Calcium concentration in lichens was considered the best cement-dust indicator. Different types of dust (clinker and grinded-limestone-dust) resulted in different time-patterns of Ca accumulation, which was also related with the different influence that wet and dry periods have in the lichen accumulation process. The dust pollution was found to be deposited locally and dependent on: the nature of dust particles and the volume and frequency of precipitation.     

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   

Influence of angular exposure and proximity to vehicular traffic on the diversity of epiphytic lichens and the bioaccumulation of traffic-related elements

This study investigated the influence of angular exposure and distance from vehicular traffic on the diversity of epiphytic lichens and the bioaccumulation of traffic-related elements in a town of central Italy. An Index of Lichen Diversity (ILD) was calculated on the street-facing and the opposite side of road-lining trees and in a urban park 250 m away, and the content of selected trace elements (Al, Ba, Ce, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, V, and Zn) was determined in samples of the lichen Punctelia borreri (Sm.) Krog growing on tree bark, both on the exposed and opposite sides. ILD increases with distance from traffic emissions. However, at the site with vehicle traffic, non-nitrophilous lichens decreased while nitrophilous ones increased. The concentration of the traffic-related elements Ba, Cr, Cu, Mn, Sb, and Zn accumulated in thalli of P. borreri was higher on roadside trees than in trees from the urban park. ILD was not affected by the angular exposure to the road and the bioaccumulation of traffic-related elements was similar in lichens from the side of the bole exposed to traffic emissions and particulate resuspension and from the opposite side. The angular exposure in respect to the traffic source does not influence trace element accumulation. These results are important when using lichens for biomonitoring purposes, both for planning future studies and for the reliability of the interpretation of past surveys that do not report information about the angular exposure of the collected lichen material.     

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.     

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.     

Air pollution and climate gradients in western Oregon and Washington indicated by epiphytic macrolichens

Human activity is changing air quality and climate in the US Pacific Northwest. In a first application of non-metric multidimensional scaling to a large-scale, framework dataset, we modeled lichen community response to air quality and climate gradients at 1416 forested 0.4 ha plots. Model development balanced polluted plots across elevation, forest type and precipitation ranges to isolate pollution response. Air and climate scores were fitted for remaining plots, classed by lichen bioeffects, and mapped. Projected 2040 temperatures would create climate zones with no current analogue. Worst air scores occurred in urban-industrial and agricultural valleys and represented 24% of the landscape. They were correlated with: absence of sensitive lichens, enhancement of nitrophilous lichens, mean wet deposition of ammonium >0.06 mg l(-1), lichen nitrogen and sulfur concentrations >0.6% and 0.07%, and SO(2) levels harmful to sensitive lichens. The model can detect changes in air quality and climate by scoring re-measurements.     

Lichens as an integrating tool for monitoring PAH atmospheric deposition: A comparison with soil, air and pine needles

The aim of this study was to validate lichens as biomonitors of PAH atmospheric deposition; for that, an inter-comparison between the PAH profile and concentrations intercepted in lichens with those of air, soil and pine needles was performed. The study was conducted in a petro-industrial area and the results showed that PAH profiles in lichens were similar to those of the air and pine needles, but completely different from those of soils. Lichens accumulated higher PAH concentrations when compared to the other environmental compartments and its concentrations were significantly and linearly correlated with concentrations of PAHs in soil; we showed that a translation of the lichen PAHs concentrations into regulatory standards is possible, fulfilling one of the most important requirements of using lichens as biomonitors. With lichens we were then able to characterize the air PAHs profile of urban, petro-industrial and background areas.     

Ammonium and nitrate tolerance in lichens

Since lichens lack roots and take up water, solutes and gases over the entire thallus surface, these organisms respond more sensitively to changes in atmospheric purity than vascular plants. After centuries where effects of sulphur dioxide and acidity were in the focus of research on atmospheric chemistry and lichens, recently the globally increased levels of ammonia and nitrate increasingly affect lichen vegetation and gave rise to intense research on the tolerance of lichens to nitrogen pollution. The present paper discusses the main findings on the uptake of ammonia and nitrate in the lichen symbiosis and to the tolerance of lichens to eutrophication. Ammonia and nitrate are both efficiently taken up under ambient conditions. The tolerance to high nitrogen levels depends, among others, on the capability of the photobiont to provide sufficient amounts of carbon skeletons for ammonia assimilation. Lowly productive lichens are apparently predisposed to be sensitive to excess nitrogen.     

Epiphytic Algae and Lichen Cover in Boreal Forests—A Long-Term Study Along a N and S Deposition Gradient in Sweden

The aim was to describe spatiotemporal patterns of colonization of spruce branches by algae and lichens and the relationship with decreasing deposition of N and S. Coverage was estimated annually over 10 years for four Swedish Integrated Monitoring catchments with varying deposition levels. Initial hypotheses were that algal coverage would be positively correlated with deposition and that lichen coverage would be negatively correlated with S and positively with N deposition. Data were analyzed using regression, ANOVA, and partial least square regression. The results showed a temporal decrease in the coverage of algae but an increase in colonization rates, while lichens showed less uniform patterns. Within catchments, algae and lichen coverages were positively correlated with mainly S deposition. Across catchments, coverage of algae increased, while the coverage of lichens decreased with increasing N and S deposition. Colonization rates of both algae and lichens showed weak correlations with both spatial and temporal trends in N and S deposition. Thus, while N and S deposition had an effect on the colonization and coverage of algae and lichens, other factors are also important.     

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.     

Influence of growth form on the accumulation of airborne copper by lichens

Lichens are known to accumulate airborne elements. This characteristic makes them useful as biomonitors of air quality. However, direct correlations of element concentrations in the air with element concentrations in lichen thalli are generally unavailable. The purpose of this study was to quantitatively examine the relationship between concentrations of copper in ambient air samples and thalli of foliose and fruticose lichens. Lichen samples from four sites along an air copper gradient were collected and analyzed. Foliose specimens consistently accumulated more than twice as much copper as fruticose specimens at all four sites. The relationship between copper concentrations in foliose and fruticose lichens and ambient air samples along an airborne copper gradient was examined using a stepwise regression model. An R² value of (0.84) and an F-statistic of (182.5, p<0.001) for the model indicate that variability in lichen copper concentrations between sites is explained by airborne copper concentrations. Based on the regression analysis both foliose and fruticose growth forms appear to accurately predict airborne copper concentrations. A significant interaction between the airborne copper and growth form variables and large differences in the calculated slopes suggests that foliose lichens more efficiently accumulate airborne copper than fruticose lichens.     

Comparative study of the suitability of three lichen species to trace-element air monitoring

To investigate the suitability of three lichen species (Cetraria islandica, Evernia prunastri, and Ramalina farinacea) as transplants to trace-element air biomonitoring, they were exposed on substratum-free supports, from July 1996 until July 1997, in three European countries with different climates (Germany, Italy, Romania), at six sites with different types of air pollutants (two in each country). After 2, 4, 6, and 12 months of exposure, some portions of thallus were collected, prepared, and measured by instrumental neutron activation analysis (INAA) at the Institute of Physics and Nuclear Engineering in Bucharest and by energy dispersive X-ray fluorescence analysis (EDXRFA) at the University of Hohenheim in Stuttgart. Fifteen environmentally relevant elements: As, Br, Ca, Co, Cr, Cu, Fe, K, Mn, Ni, Pb, S, Sb, V, and Zn were determined. The analytical results were compared statistically. To study the distribution of the trace-elements between the lichens and the lichen throughfall water inside a virtual column, the throughfall water was collected under the lichen transplants during 6 and 12 months. The dried residues were analysed by INAA at Bucharest. The accumulating capacity for all investigated species is evident. For a comparative evaluation, the initial element contents, the "accumulation factors" relative to the bulk deposition, the interspecies "calibration factors", and the "retention efficiencies", defined as ratios of the lichen enrichment to the sum of this enrichment and the content in the lichen throughfall water, were considered. These criteria attest the best suitability for Evernia prunastri, followed by Ramalina farinacea and Cetraria islandica.     

Biological effects of ammonia released from a composting plant assessed with lichens

In this study, we investigated whether ammonia emissions from industrial composting of organic waste may influence the surrounding environment, using lichens as bioindicators. To this purpose, samples of N-tolerant and N-sensitive lichens, namely Xanthoria parietina and Evernia prunastri, were transplanted for 1–3 months along transects at increasing distance (0–400 m) from a composting facility in Tuscany, Italy. Atmospheric concentrations of ammonia were measured using passive samplers. The physiological response of lichen transplants was investigated by means of the photosynthetic efficiency (measured as chlorophyll a fluorescence emission), the integrity of cell membranes (measured as electrolyte leakage), and sample viability (measured as enzymatic activity of dehydrogenase). Epiphytic lichen communities were investigated using biodiversity indices. The results showed decreasing concentrations of ammonia, from 48.7 μg/m³ at the composting facility to 2.7 μg/m³ at 400 m. The N-tolerant X. parietina was not affected and some physiological parameters even showed a higher performance, while the N-sensitive E. prunastri showed a reduced performance with increasing atmospheric concentrations approaching the source. A shift from lichen communities composed by meso-acidophilous species (actual condition) to more nitrophilous communities in the near future, approaching the composting facility is suggested. It is concluded that lichens can provide useful data for decision-makers to establish correct science-based environmentally sustainable waste management policies.     

Lichens as sentinels for air pollution at remote alpine areas (Italy)

The present study was undertaken with the aim of using epiphytic lichens as sentinels for air pollution at two remote alpine sites (1,400 and 1,800 m above sea level (asl)) of NW Italy. The results indicated that the site at 1,800 m prompted for early warning indications of biological changes. Although levels of the many elements assayed in samples of the lichen Pseudevernia furfuracea (L.) Zopf, ranging from minor elements (e.g., Al) to ultra-trace (e.g., Pt), were at normal levels, indications of a slowly worsening environment were given by the lichen biodiversity and by damage to cell membranes. The analysis of Pb isotopic ratios suggested that the origin of Pb accumulated in lichens is not local, but linked to the long-range transport by air masses. It was concluded that the origin of pollutants is from air mass coming from the Po plain of Italy and from densely populated areas of Switzerland and France.     

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.