Stefano Loppi

Lichens and mosses as biomonitors of trace elements in areas with thermal springs and fumarole activity (Mt. Amiata, central Italy).

The contribution of thermal springs and fumaroles to environmental levels of Al, As, B, Cd, Cu, Fe, Hg, Mo, Pb, S, Sb and Zn was evaluated by means of lichens (Parmelia sulcata) and mosses (Hypnum cupressiforme) used as bioaccumulators. Compared to the data reported for unpolluted areas, accumulation of Hg, S and Al was found, with values of Hg and S in the same range as in the vicinity of geothermal power plants. Furthermore, fumaroles turned out to be a significant source of atmospheric arsenic.

Soil contribution to the elemental composition of epiphytic lichens (Tuscany, central Italy)

Total concentrations of Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Mo, Pb, Sr, Ti, V and Zn in the epiphytic lichen Parmelia sulcata and superficial soils from 60 remote sampling sites in Tuscany (central Italy) were determined to evaluate the contribution of soil to the elemental composition of the lichen. The results showed that in the Mediterranean environment, the trace element content of unwashed lichen samples is greatly affected by soil contamination. However, despite the strong correlations between the concentrations of lithogene elements such as Al, Fe and Ti in P. sulcata, lichen levels of these elements were not at all linearly correlated with their concentrations in the soil, suggesting that dust contamination is highly variable and probably dependent on local site characteristics. All methods evaluated to minimize soil contamination indicated Cu, Pb and Zn as elements of atmospheric origin. However, while levels of Pb were similar to those reported for background areas, moderate pollution by Cu and Zn, probably from fertilizers used in agriculture, was revealed. For elements such as Cd and Mo, identified as atmophile, some uncertainty exists due to the fact that they are essential for lichen metabolism and accumulate intracellularly in lichens; they may therefore occur in soluble form in the lichen thallus.

Passive monitoring of trace elements by means of tree leaves, epiphytic lichens and bark substrate

Total concentrations of Al, Cu, Fe, Hg, Mn, Mo and Zn in theepiphytic lichen Parmelia caperata, substrate bark andleaves of oaks (Quercus cerris and Q. pubescens)from a background area in Tuscany (central Italy) werecompared. The elemental composition of unwashed samples,especially bark, was clearly affected by soil dustcontamination, thereby leading to incorrect interpretations ofbaseline concentrations and relationships between elements.The normalization of total element concentrations to thesurface soil composition (digested and analyzed by the sameprocedures), using Al as reference element, gave more reliablebaseline values and allowed comparison between differentbiomonitors. The suitability of lichens, leaves and barks forstudying the environmental distribution of trace elements interrestrial ecosystems is discussed.

Epiphytic lichens as sentinels for heavy metal pollution at forest ecosystems (central Italy).

The results of a study using epiphytic lichens (Parmelia caperata) as sentinels for heavy metal deposition at six selected forest ecosystems of central Italy are reported. The woods investigated are characterized by holm oak (Quercus ilex), turkey oak (Quercus cerris) and beech (Fagus sylvatica) and represent the typical forest ecosystems of central Italy at low, medium and high elevations, respectively. The results showed that levels of heavy metals in lichens were relatively low and consequently no risk of heavy metal air pollution is expected for the six forest ecosystems investigated. However, for two of them there are indications of a potential risk: the beech forest of Vallombrosa showed signs of contamination by Pb as a consequence of vehicle traffic due to the rather high touristic pressure in the area, and the holm oak forest of Cala Violina showed transboundary pollution by Mn, Cr and Ni originating from the steel industry in Piombino. Epiphytic lichens proved to be very effective as an early warning system to detect signs of a changing environment at forest ecosystems.

The integrity of lichen cell membrane as a suitable parameter for monitoring biological effects of acute nitrogen pollution

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.

Lichens as Bioindicators of Geothermal Air Pollution in Central Italy

The suitability of lichens as bioindicators of geothermal air pollution was evaluated in central Italy. Fifty-one sites were sampled in the Travale-Radicondoli geothermal field, an area of about 15 km{sup 2}. Lichens on 1-5 trees per station were sampled, using 30 x 50 cm grids on tree boles, where lichens were most dense. Index of Atmospheric Purity (IAP) was calculated as the sum of the frequencies of all lichen species present at the station. Using automatic mapping programs, the area was divided into four air quality zones and the lowest IAP values were found within about 500 m of geothermal power plants. No direct measurements of air pollution are available for the whole study area, however, other studies show that air pollution levels (mercury, boron) fall with distance from a geothermal source. Also no substrate parameter (height, circumference, bark pH, and buffer capacity of the trees) discriminates between IAP zones. This suggests that air pollution arising from geothermal emissions is responsible for the zonation shown, with values for species richness and IAP rising with distance from geothermal installations. It is concluded that lichens are reliable bioindicators of geothermal pollution. 64 refs., 1 fig., 3 tabs.

EFFECTS OF AGRICULTURE ON EPIPHYTIC LICHEN VEGETATION IN CENTRAL ITALY

ABSTRACT The influence of agriculture, i.e., of fertilizers and ammonia emissions from crops and sheep grazing, on epiphytic lichen vegetation, and the use of nitrophytic lichen species in bioindication of air pollution were investigated in a geothermal area in central Italy. Floristic analysis showed that the lichen vegetation is only slightly influenced by agriculture. Analysis of the lichen data and chemico-physical parameters of tree bark supporting lichen growth failed to demonstrate marked differences between agricultural and non-agricultural sites, the higher total frequency of nitrophytic species in agricultural sites being the only parameter discriminating between the two site types. Bark nitrogen and pH were not discriminant. Factors determining the higher total frequency of nitrophytic species in agricultural sites may include dust impregnation of bark and the drier microclimate of trees in these sites. It is concluded that nitrophytic lichens can be included in the calculation of the Index of ...

ANALYSIS OF THE DISTRIBUTION OF EPIPHYTIC LICHENS ON QUERCUS PUBESCENS ALONG AN ALTITUDINAL GRADIENT IN A MEDITERRANEAN AREA (TUSCANY, CENTRAL ITALY)

ABSTRACT The distribution of epiphytic lichens on Quercus pubescens in Tuscany, central Italy, was studied by means of multivariate techniques along an altitudinal gradient from 0 to 900 m. Great differences in community structure were found and the altitude of 500 m was identified as an ecotone. Epiphytic lichen vegetation on trees below the ecotone varied significantly in relation to bark pH. Climatic parameters (temperature and rainfall) were probably related to altitude. Dust was probably responsible for the rise in bark pH. The distribution of lichen species in the sampling belts fitted the core-satellite hypothesis. The use of core and satellite species as biomonitors of air pollution and bioindicators of environmental conditions is discussed.

Identifying Deviations from Naturality of Lichen Diversity for Bioindication Purposes

The results of many bioindication studies can be interpreted in terms of deviations from “normal/natural” situations (see chapter 1, this volume). The definition of “normality” or “naturality” is a very difficult one. Here, we shall consider as “natural” those areas which are free from heavy anthropization, and from long-distance transport of important pollution loads. Species richness, cover and frequency of epiphytic lichens are obviously different in different bioclimatic areas, which requires the development of different interpretation scales. The methodology presented here has been developed within the framework of a national programme sponsored by the Italian Environmental Agency (ANPA), to monitor the diversity of epiphytic lichens countrywide, following the approach proposed by Asta et al. (chapter 19, this volume).

Lichen biomonitoring of trace elements in a geothermal area (central Italy)

The epiphytic lichen Parmelia caperata was used systematically to biomonitor trace elements in the Travale-Radicondoli geothermal field (central Italy). The results showed a very low occurrence of potentially toxic heavy metals such as Cd, Hg and Pb, and relatively high values for As, B, Mo and elements associated with soil dust (Al, Co, Cr, Fe, Mn and Ni). Boron was the principal element of geothermal origin. Arsenic seems to originate both from power plants and adjacent thermal springs. It is concluded that trace element pollution in the area is low.