Explore the vast range of titles available.

Experimental clinopyroxenes synthesized at 850-1500 degC and 0-60 kbar in the CMS and CMAS-Cr systems and in more complex lherzolitic systems have been used to calibrate a Cr-in-Cpx barometer and an enstatite-in-Cpx thermometer for Cr-diopsides derived from garnet peridotites. The experiments cover a wide range of possible natural peridotitic compositions, from fertile pyrolite to refractory, high-Cr lherzolite.

Crystal-structure modeling of experimental Ca-rich clinopyroxenes [Ca + Na > 0.5 apfu; Mg/(Mg + Fe super(2+)) > 0.7] coexisting with basic and ultrabasic melts was utilized for calibration of geobarometers based on unit-cell volume (V sub(cell)) vs M1-site volume (V sub(M1)). The clinopyroxene database includes over one hundred experiments from literature and sixteen previously unpublished experiments on basanite and picrobasalt starting materials. The coexisting melts span a wide range of petrologically relevant anhydrous and hydrous compositions (from quartz-normative basalt to nephelinite, excluding high-Al basalts and melts coexisting with garnet or melilite) at pressure conditions pertinent to the earth's crust and uppermost mantle (P= 0-24 kbar) in a variety of fO 2 conditions (from CCO-buffered to air-buffered) and mineral assemblages (Cpx plus or minus Opx plus or minus Pig plus or minus Ol plus or minus Plag plus or minus Lc plus or minus Ne plus or minus Spl plus or minus Amp plus or minus Ilm). As previously found for near-liquidus products of basaltic melts, the experimental clinopyroxenes follow two distinct trends: (i) at a given P, V sub(cell) is linearly and negatively correlated with V sub(M1). This corresponds with the extent of Tschermak-type substitutions, which depends strongly on aSiO and a sub(CaO); (ii) for a fixed melt composition, V sub(cell) and V sub(M1) decrease linearly as P increases, due to a combination of M sub(1), M sub(2) and T site exchanges. Despite the chemical complexity of these relationships, P could be modeled as a linear function of V sub(cell) and V sub(M1). A simplified solution for anhydrous magmas reproduced the experimental pressures with an uncertainty of 1.75 kbar (=1; max. dev. = 5.5 kbar; N = 135). An expanded T-dependent solution capable of recovering the measured pressures of both anhydrous and hydrous experiments with an uncertainty of 1.70 kbar (=1; max. dev. = 5.4 kbar; N = 157) was obtained by correcting unit-cell and M1-site volumes for thermal expansivity and compressibility. The corrected formulation is more resistant to the effects of temperature variations and is therefore recommended. Nevertheless, it requires an independent, accurate estimate of crystallization T. Underestimating T by 20 degree C propagates into a 1-kbar increase of calculated P. The applicability of the T-dependent formulation was tested on hydrous ultramafic to gabbroic rocks of the southern Adamello batholith for which P-T evolution could independently be constrained by field observation, petrography and experimentally determined phase relations. The pressure estimates obtained by clinopyroxene structural geobarometry closely matched those predicted by phase equilibria of a picrobasaltic melt parental to the investigated magmatic rocks. To facilitate application of the present geobarometers, both anhydrous and corrected solutions were implemented as MS-DOS super( registered ) and UNIX super( registered ) software programs (CpxBar) designed to permit retrieval of the pressure of crystallization directly from a chemical analysis or from uncorrected unit-cell and M1-site volume X-ray data.

Work is in progress for the completion of a computer-aided key to all lichens known to occur in Italy, which will be freely available online, and as a free application for mobile devices. A first example, concerning the lichens of Northern Italy (2.339 infrageneric taxa), is already available online for testing. A computer-generated but manually edited dichotomous key is invoked for all species previously filtered via a multi-entry interface, where several selected characters can be specified in a single step. To optimize the two query interfaces, two different datasets are used, one for the dichotomous, the other for the multi-entry interface.

Biomonitoring programs enable researchers to evaluate the impacts of pollution over widely distributed geographic areas. Results are presented from a project conducted to compare the biodiversity distributions of pollution-sensitive lichens with lung-cancer mortality patterns in the Veneto region, located in norhtern Italy. Results from this comparison suggest strong links between air pollution and lung cancer. The study of lichen biodiversity included 2425 measurements of epiphytic lichen biodiversity at 662 sites scattered throughout the region of interest. Mortality data at the municipal level were obtained from studies conducted by the Italian National Institute of Statistics. The highest correlation was observed between lichen biodiversity and cancer in young native male residents of the region.

In Europe, epiphytic lichens are incorporated in forest diversity monitoring projects in which sampling at the tree level is carried out on 4 grids on the 4 cardinal points (N, S, E, W) of the trunk. Our results, based on the analysis of a dataset referring to six forest sites in NE-Italy and including 264 trees, indicate that a lichen assessment based on sampling at the tree level less than four cardinal points might be effective in estimating species richness across different forest types, showing very high rates of species capture. Similar results were achieved if the reduction of sampling effort is applied to the number of trees sampled within each area. This effect can be explained taking into account the redundant information collected on the same tree. In the framework of forest monitoring programs, the main perspective of our results is related to the possibility of investing saved resources for improving lichen inventories by including in the surveys currently neglected microhabitats. Further studies would be welcome to identify an optimal balance between sampling effort and information gathered, as economic resources are often a constraint to activate and maintain large-scale and long-term monitoring projects.

Moss bags of Rhynchostegium riparioides were exposed to different water concentrations of 11 trace elements under laboratory conditions, according to a saturated fractional factorial design (67 treated combinations), with the aim of measuring (1) element uptake and (2) the main effects and first-order interactions of influent factors. Bioaccumulation was directly proportional to water concentration, but the uptake ratio (ranging from 10² to 10⁵) also depended on the concentration of other metals. The highest uptake ratios were observed for Al, Cu, Cr, Hg, and Pb. The multiple regression model showed that interactions among elements exist and induce both antagonism (Fe is the most frequent competitor) and synergism (Cr exerts a great influence on Pb and Zn uptake). Interactions might be relatively strong (as for As, Cr, and Pb) or weak (Cd and Hg). This evidence should be taken into consideration in biomonitoring surveys of industrial sites, where effluents release more than one contaminant.

Aim The mountain biodiversity is highly threatened by climate change, with many species facing habitat reduction and/or local extinction. Poikilohydric organisms like lichens are extremely sensitive to environmental conditions and changes. A comprehensive overview of the impact of climate change on the future distribution of lichens is still missing. Thus, we quantified the range shift, loss in suitable areas and potential climatic refugia for more than 250 lichens, exploring these trends for each species and grouping them by their ecological needs and functional traits. Location Alps chain and surrounding areas (Europe). Methods We performed species distribution models to investigate the range shifts of 272 lichens under different climate change scenarios. Range shift was investigated by modelling gain and loss in suitability score along the elevational gradient, for each species separately and grouping them based on growth forms and temperature‐affinities. Based on the ‘high suitability score stability’ index we developed maps of potential refuge areas. Results We predicted a huge loss of habitat suitability over time, especially under the SSP5‐5.8. Fruticose lichens and cryophilous species will be the most impacted. Moreover, contrary to the assumption of an upward range shift, most species showed no significant relationship between altitude and increase in habitat suitability, suggesting different redistribution patterns for lichens. In the same way, climatic refugia are not only identified at high elevations but also in deep valleys and cold exposure. Main Conclusions The response of lichens to climate change is extremely heterogeneous, and an upper‐range shift is less common than expected. Spatial redistribution is highly distinct among functional groups. The identified climatic refugia confirm this pattern, underlining the urgent need to improve the conservation effort, especially for fruticose and cryophilic species.

The crystal structures of 212 experimentally synthesized, igneous clinopyroxenes were modeled from electronprobe chemical data. The coexisting melts span a wide range of petrologically relevant, dry and hydrous compositions, characterized by variable enrichment in silica and alkalis. Experimental conditions pertain to Earth's crust and uppermost mantle (P = 0-24 kbar; garnet absent) and a variety of fO2 values (from CCO-buffered to air-buffered) and mineral assemblages (Cpx ± Opx ± Pig ± Ol ± Plag ± Spl ± Mt ± Amp ± Ilm). Unit-cell volume (Vcell) versus M1-polyhedron volume (VM1) relations were investigated over a range of pressures and temperatures using data derived from structure modeling and corrected for thermal expansivity and compressibility. The relationships between pressure and clinopyroxene structural parameters were found to be dependent on the nature of the coexisting melt. To reduce compositional effects, only clinopyroxenes belonging to mildly alkaline (MA) and tholeiitic (TH) series were considered. Pressure was modeled as a linear function of Vcell, VM1, and Mg/(Mg + Fe2+)Cpx ratio. A calibration based on the whole data set (MA + TH) reproduced the experimental pressures within 1.4 kbar at the 1-σ level. The maximum residuals were 3.5 kbar and 3.9 kbar for MA- and TH-clinopyroxenes, respectively. Better statistics were obtained by considering MA- and TH-clinopyroxenes separately. A calibration based on the 69 MA-clinopyroxenes reproduced the experimental pressures within 1.1 kbar (1σ) and with a maximum residual of 2.7 kbar. A calibration based on the 143 TH-clinopyroxenes reproduced the experimental pressures within 1.0 kbar (1σ) and with a maximum residual of 3.4 kbar. When these geobarometers are applied to natural samples for which P is unknown, the correction for compressibility is necessarily made through a trial-and-error procedure. This expedient propagates an additional error that increases the above uncertainties and residuals by a factor of about 2. Applications to natural, igneous rocks for which the pressures of crystallization could be constrained based on experimental, petrological or geological evidence yielded pressure estimates that reproduced the expected values to within ca. 2 kbar. Compared to the MA-formulation, the TH-formulation appears to be less robust to variations in magma composition. When applied to high-pressure (>10 kbar) clinopyroxenes synthesized from very low Na (Na2O < 1.5%) melts, the latter geobarometer can underestimate P by as much as 6 kbar. Calculation of P through the present geobarometers requires clinopyroxene major-element composition and an independent, accurate estimate of crystallization T. Underestimating T by 20 °C propagates into a 1-kbar increase in calculated P. The proposed geobarometers are incorporated in the CpxBar software program, which is designed to retrieve the pressure of crystallization from a clinopyroxene chemical analysis.

QUESTION: Poikilohydric organisms can survive desiccation without damage and recover soon after re‐wetting. In this work we explore the realized niches of epilithic, poikilohydric organisms, i.e. lichenized and lichenicolous fungi and bryophytes, grouped into 15 functional guilds based on growth form, reproductive strategy and photosynthetic traits. We hypothesize that in Mediterranean ecosystems, the distribution of these guilds is controlled by water availability and solar radiation, together with characteristics of the substrate. LOCATION: Western Sardinia (Italy). The area hosts Mediterranean Quercus ilex forests on basaltic substrata within an agroforestry landscape. METHODS: The presence or absence of species from each guild was recorded in 1025 small quadrats (10 × 10 cm). Four environmental variables were measured: solar radiation, microtopography (potential water run‐off), substrate roughness and number of cracks. The occurrence of each guild was related to environmental variables using non‐parametric multiplicative regression, and ecological niches of the guilds were derived from those models. RESULTS: The occurrence of all functional guilds varied significantly according to the selected environmental variables. In most cases, solar radiation was the most important variable; TI was included first in the model of two sorediate guilds, whereas four sexually reproducing functional guilds had surface relief as first variable. The growth forms were separated along a gradient of increasing solar radiation, whereas water run‐off and surface roughness mainly discriminated reproductive strategies and photobionts. Vegetatively reproducing guilds with other photobionts than Euphyta‐like pigments were confined to the border of the ecological space, defined by gradients of environmental factors, which was largely occupied by more competitive, sexually reproducing organisms. CONCLUSIONS: Functional traits of epilithic poikilohydric organisms were associated with ecological adaptations to the stressful environment of Mediterranean outcrops. We showed that their response in terms of probability of occurrence is coherent with quantitative gradients of solar radiation and water availability at the micro‐scale.

Several trace elements discharged by the petrochemical industry are toxic to humans and the ecosystem. In this study, we assessed airborne trace elements in the vicinity of the Map Ta Phut petrochemical industrial complex in Thailand by transplanting the lichen Parmotrema tinctorum to eight industrial, two rural, and one clean air sites between October 2013 and June 2014. After 242 days, the concentrations of As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Sb, Ti, V, and Zn in lichens at most industrial sites were higher than those at the rural and the control sites; in particular, As, Cu, Mo, Sb, V, and Zn were significantly higher than at the control site ( p  < 0.05). Contamination factors (CFs) indicated that Cd, Cu, Mo, and Sb, which have severe health impacts, heavily contaminated at most industrial sites. Principal component analysis (PCA) showed that most elements were associated with industry, with lesser contributions from traffic and agriculture. Based on the pollution load indexes (PLIs), two industrial sites were highly polluted, five were moderately polluted, and one had a low pollution level, whereas the pollution load at the rural sites was comparable to background levels. This study reinforces the utility of lichens as cost-effective biomonitors of airborne elements, suitable for use in developing countries, where adequate numbers of air monitoring instruments are unavailable due to financial, technical, and policy constraints.