Paola Malaspina

Temporal trends (1981-2007) of trace and rare earth elements in the lichen Cetraria islandica (L.) Ach. from Italian herbaria.

Twenty-four herbarium specimens of Cetraria islandica collected in Italy from 1981 to 2007 were used for retrospective analysis. Cd, Ce, Cu, Fe, Gd, La, Mn, Ni, Pb, Sb, V, Y, and Zn concentrations were measured. Pb showed a negative temporal trend, linked to the ban of leaded fuel for vehicles. Pb showed a negative correlation with the distance of the sampling sites from a highway in the years before 1995 and no relationship after that year, corresponding to the Pb content reduction in gasoline. A significant trend towards increasing Mn concentrations over time also emerged, which deserves further investigations due to Mn toxicity. Cluster analysis showed a group of elements of anthropogenic origin, while rare earth elements formed a separated cluster of natural origin. Lichens from herbaria proved to be a valuable tool for reconstructing historical trends in trace element deposition, highlighting variations produced by human activities.

Biomonitoring urban air pollution using transplanted lichens: element concentrations across seasons

We investigated the bioaccumulation of selected trace elements in samples of the lichen Evernia prunastri (L.) Ach. transplanted across two seasons in the urban area of Genoa (NW Italy), which is heavily affected by traffic and industrial pollution. Total concentration of most elements did not exhibit differences between seasons, exceptions being Al and Na, higher in summer, and As, Cd, and Ti, higher in winter. Differences emerged in the initial concentrations of some elements in control samples, and this was accounted for by the use of exposed-to-control (EC) ratios, which allowed interpretation of changes in element concentrations. The study area resulted highly polluted, likely by particulate matter, as suggested also by the higher concentrations of airborne PM10 during winter months. Bioaccumulation of particulate matter seems to be affected by differences in rainfall regimes across seasons, since element solubilization and leaching due to precipitation may vary considerably.

Human contribution to trace elements in urban areas as measured in holm oak ( Quercus ilex L.) bark

The effect of human activities on the presence of trace elements in the atmosphere was evaluated by analyzing samples of holm oak bark, collected in Italy in a large city, in a small town, and in a reference area, scarcely inhabited. In all cases, point sources of pollution were excluded (e.g., industries and incinerators). The concentrations of As, Cd, Co, Cu, Fe, Mn, Ni, Pb, V, and Zn were measured using inductively coupled plasma optical emission spectrometry (ICP-OES). The element concentrations in the small town are not different from the reference area, except for Pb and Cu, while the samples collected in the large city show higher concentrations of Co, Cu, Fe, Ni, Pb, V, and Zn with respect to the rural area. In particular, the Pb levels in the large city are approximately 16 times higher than in the reference site, and five times higher than in the small town. Most element concentrations are correlated in the large city, while in the reference site, only a few significant correlations between elements were found. Even in the absence of specific sources of pollution, populations living in big cities are exposed to higher concentrations of trace elements than those living in rural environments or in small urban centers.

Do tree-related factors mediate the response of lichen functional groups to eutrophication?

Abstract In the last decades, the pollution regime has been drastically changed in most industrialized countries, with a considerable decrease in sulphur dioxide (SO2) emissions and an increasing relevance of eutrophication compounds, such as nitrogen compounds and particulate matter. This situation hampers the interpretation of data in biomonitoring surveys, as high lichen diversity is not always associated with good air quality. The objective of this study was to test whether the effects of eutrophication on the abundance of different lichen functional groups varies according to some tree-related factors. We analysed the relationships between epiphytic lichen diversity, emissions of main atmospheric pollutants and tree characteristics (circumference and bark pH, light transmitted through the canopy). Hierarchical partitioning of variance and Generalized Linear Mixed Models (GLMM) confirmed that lichen functional groups with different nitrogen tolerances responded to several atmospheric pollutants, with both independent and joint effects, whereas they did not show significant differences depending on main tree-related factors. We demonstrated that, under high eutrophication levels, differences in bark pH did not significantly differentiated the composition of epiphytic lichen communities.