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Mercury (Hg) is a global environmental concern due to its toxicity (especially high in methylated form) and the long-range distribution of its gaseous elemental form (GEM). Hg-contaminated areas, such as abandoned mining sites, pose intrinsic difficulties for their management and heavy monitoring costs. In these environments, plant-based solutions may play a key role in the ecosystem quality assessment and support remediation strategies, combining reliability and costeffectiveness. In this study, we adopted a biomonitoring approach by using tree rings of four different species collected in the proximity of the miningmetallurgical area of Abbadia San Salvatore, central Italy, a major former Hg mining district whose reclamation is currently in progress. Our dendrochemical analysis was aimed at identifying the historical changes of local atmospheric Hg contamination and at singling out, for the first time in the study area, other potentially toxic elements (PTEs) associated with the past mining activity. Collected cores dated back to early as 1940 and provided the temporal patterns of atmospheric Hg emission vs the produced liquid quantities, so reconstructing the historical impact of the mining site on nearby terrestrial ecosystems and resident human population. Current GEM contamination was found about twenty times lower than that of the fully operational mine periods. From a first survey on other PTEs, thallium (Tl) and lead (Pb) appeared to be potentially associated with the mining activity, thus suggesting new working assumptions for further dendrochemical analyses and for the inclusion of Pb in human biomonitoring surveys of the Mt. Amiata area, actually not present in the control list. The results prompt a more thorough assessment by tracking for a longer time span a critical site that is an ideal open-field lab to study the ecophysiology of different tree species in relation to environmental behavior of PTEs for better-assessing wildlife and human exposures. [ABSTRACT FROM AUTHOR]

In this study, leaves of the evergreen holm oak Quercus ilex were used to assess airborne contamination of potentially toxic elements (PTEs) at five towns located on the slopes of the Mt. Amiata (central Italy), an area with a long history of mining and, more recently, an important district for the industrial exploitation of geothermal energy. PTE composition and covariance of washed and unwashed Q. ilex leaves of three different ages (6, 12 and 24 month-old) were used to identify atmospheric inputs of PTEs at residential areas, evaluate long-term adsorption and retention of PTEs by the leaves, thus providing an indication of potential human exposure. Moreover, the determination of foliar concentrations of major elements (C, N, S and P) allowed an assessment of the nutritional status of the investigated urban tree stands which excluded the existence of stress condition caused by air pollution or other disturbances. Results indicated that overall Pb, Cu, and Cd concentration were low in the investigated urban sites, if compared with similar studies conducted in larger Italian cities, denoting a low contribution of vehicular traffic to the atmospheric pathway. The five urban settlements were characterized by a specific profile of elements (Al, Ba, Hg and Sb) enriched in unwashed leaves, resulting from the distinct geochemical characteristics of the area and from diffuse (i.e., urban activity) and point sources of PTEs emission (i.e., brownfields, geothermal power plants). The latter sources primarily govern the distribution of Hg, whose contamination was found to be very localized close to a major abandoned mining area. Our data provided quantitative evidence of the spectrum of PTEs potentially impacting resident population and may prove useful in support of follow-up instrumental monitoring campaigns of air quality, as well as for human health and ecological risk assessments. [ABSTRACT FROM AUTHOR]

Leaf nutrient composition and stoichiometry reflect complex interactions of the plant with its environment and are useful traits to explore ecological processes and relationships. In the present study, the foliar elemental compositions of two common Mediterranean woody species, the evergreen broad-leaved Quercus ilex and the coniferous Pinus pinaster growing in an area of Central Italy known for geochemical and geothermal anomalies, were investigated. To assess the site-specific and age-dependent pattern of foliar composition and stoichiometry, macronutrients (C, N, P, K, Mg, S) and trace elements (Al, As, Ba, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Sb, V, Zn) were determined in leaves and needles of three different ages (6-, 12- and 24-month-old) collected from metalliferous (geothermal, mining) and rural areas. Leaves of Q. ilex showed comparatively high concentrations of micronutrients (i.e., Cu, Fe and Zn), while needles of P. pinaster accumulated significantly high concentrations of potentially toxic elements (i.e., As, Pb and S). No significant trend was found in elemental concentrations in relation to the age of leaves and needles. Multi-element stoichiometry of P. pinaster was driven by the geochemical heterogeneity of the sites, suggesting plastic adaptation at the sites with the most selective edaphoclimatic conditions (i.e., patches with nutrient poor and metalliferous soils). On the other hand, the content of both nutrients and potentially toxic elements in Q. ilex leaves varied little across the study area, reflecting stoichiometric stability; this is consistent with the ecophysiological features of Q. ilex as a late-successional species with a dominant role in the ecosystems of the Mediterranean area. Our findings demonstrate the value of foliar stoichiometric traits for understanding plant adaptation in a heterogeneous environment and also the consequences of biotic interactions during succession. [Display omitted] • Needles of P. pinaster accumulate potentially toxic elements, such as As, Pb and S. • Nutritional plasticity distinguishes P. pinaster colonizing mining and geothermal sites. • Invariant nutritional status (homeostasis) characterizes the late-successional Q. ilex. • Multi-elemental foliar composition reveals pine-ecosystem interactions. [ABSTRACT FROM AUTHOR]