Search results for " Vulcano"

Sea level and climate forcing of the Sr isotope composition of late Miocene Mediterranean marine basins

2014

Sr isotope records from marginal marine basins track the mixing between seawater and local continental runoff, potentially recording the effects of sea level, tectonic, and climate forcing in marine fossils and sediments. Our 110 new Sr-87/Sr-86 analyses on oyster and foraminifera samples from six late Miocene stratigraphic sections in southern Turkey, Crete, and Sicily show that Sr-87/Sr-86 fell below global seawater values in the basins several million years before the Messinian Salinity Crisis, coinciding with tectonic uplift and basin shallowing. 87Sr/86Sr from more centrally located basins (away from the Mediterranean coast) drop below global seawater values only during the Messinian S…

Bioindication of volcanic mercury (Hg) deposition around Mt. Etna (Sicily)

2012

Mt. Etna is a major natural source of Hg to the Mediterranean region. Total mercury concentrations, [Hg] tot, in Castanea sativa (sweet chestnut) leaves sampled 7-13km from Etna's vents (during six campaigns in 2005-2011) were determined using atomic absorption spectroscopy. [Hg] tot in C. sativa was greatest on Etna's SE flank reflecting Hg deposition from the typically overhead volcanic plume. [Hg] tot also showed Hg accumulation over the growing season, increasing with leaf age and recent eruptive activity. [Hg] tot in C. sativa was not controlled by [Hg] tot in soils, which instead was greatest on Etna's NW flank, and was correlated with the proportion of organic matter in the soil (% O…

Surface expression of eastern Mediterranean slab dynamics: Neogene topographic and structural evolution of the southwest margin of the Central Anatol…

2012

The southwest margin of the Central Anatolian Plateau has experienced multiple phases of topographic growth, including the formation of localized highs prior to the Late Miocene that were later affected by wholesale uplift of the plateau margin. Our new biostratigraphic data limit the age of uplifted marine sediments at the southwest plateau margin at 1.5 km elevation to <7.17 Ma, and regional lithostratigraphic correlations imply that the age is <6.7 Ma. Single-grain CA-TIMS U-Pb zircon analyses from a reworked ash within the marine sediments yield dates as young as 10.6 Ma, indicating a maximum age that is consistent with the biostratigraphy. Our structural measurements within the uplifte…

Volatile contents of mafic-to-intermediate magmas at San Cristóbal volcano in Nicaragua

2017

San Cristóbal volcano in northwest Nicaragua is one of the most active basaltic–andesitic stratovolcanoes of the Central American Volcanic Arc (CAVA). Here we provide novel constraints on the volcano's magmatic plumbing system, by presenting the first direct measurements of major volatile contents in mafic-to-intermediate glass inclusions from Holocene and historic-present volcanic activity. Olivine-hosted (forsterite [Fo] &lt; 80; Fo&lt; 80) glass inclusions from Holocene tephra layers contain moderate amounts of H2O (0.1–3.3 wt%) and S and Cl up to 2500 μg/g, and define the mafic (basaltic) endmember component. Historic-present scoriae and tephra layers exhibit more-evolved olivines (Fo69…

Il Mercurio nel suolo e in ambiente terrestre

2015

Le interazioni del Hg con l'ambiente costituiscono il ciclo geochimico di questo elemento che si esplica per mezzo di complessi processi fisico-chimici differenti per ciascun comparto geochimico. Si stima che circa i due terzi del mercurio presente in ambiente sia stato prodotto durante il ventesimo secolo, e che il carico di mercurio immesso attualmente sia aumentato di circa 3 volte rispetto agli inizi del 1900 (Mason et al.. 1994). Il comparto ambientale certamente più coinvolto dalle emissioni di mercurio è quello atmosferico, da cui poi l’elemento si diffonde anche negli altri comparti, suolo e sedimenti compresi (Filzgerald &amp; Clarkson, 1991). L’Atmosfera costituisce un importante …

Mercury fluxes from volcanic and geothermal sources: an update

2014

We review the state of knowledge on global volcanogenic Hg emissions to the atmosphere and present new data from seven active volcanoes (Poás, Rincón de la Vieja, Turrialba, Aso, Mutnovsky, Gorely and Etna) and two geothermal fields (Las Pailas and Las Hornillas). The variability of Hg contents (c. 4–125 ng m−3) measured in gaseous emissions reflects the dynamic nature of volcanic plumes, where the abundances of volatiles are determined by the physical nature of degassing and variable air dilution. Based on our dataset and previous work, we propose that an average Hg/SO2 plume mass ratio of c. 7.8×10−6 (±1.5×10−6; 1 SE, n=13) is best representative of open-conduit quiescent degassing. Takin…

Measurements of Hg0 (and H2S) at the Solfatara Crater (Southern Italy): Estimating the atmospheric distribution with a real-time approach

2015

Volcanic and geothermal areas are important emitters of natural gas compounds into the atmosphere, which can be of concern when discharging close to densely, populated sites. Mercury has a strong environmental impact, its organic and inorganic complexes being toxic. The dominant form of Hg in the atmosphere is gaseous elemental mercury (GEM), which has high volatility and residence time of 1-2 years. Volcanic degassing accounts for a significant part of the natural mercury emissions. No mercury limits or target values in ambient air are present in the EU legislations, whereas US-EPA and ATSDR impose 300 and 200 ng/m3, respectively, as a limit for chronic exposure. WHO has proposed the annua…

Real-time measurements of Hg0 in volcanic, geothermal and anthropogenic systems: a multi-methodological approach using Lumex® instrumentation

2015

Mercury represents a pollutant of global concern and strong environmental impact since is highly toxic. Hg is present in air in the oxidation states of 0 and +2, the former being the dominant species with a residence time of 1-2 years due to its high volatility, relatively low solubility and chemical inertness. Both volcanic/geothermal and anthropogenic systems are crucial contributor to the release of Hg0 in the atmosphere. In this work, a Lumex® (RA-915M) was used to evaluate the environmental impact in air of Hg0 from: i) the abandoned Hg mining site and geothermal areas from Mt. Amiata (Siena, Central Italy) and ii) selected Mediterranean volcanic and geothermal systems. The Lumex® inst…

Reconstruction of the paleoenvironmental changes around the Messinian-Pliocene boundary along a W-E transect across the Mediterranean

2004

Can we consider a natural environment always of high quality and adequate to protect population from potential risks of health threats?

2013

The question posed in the title arise because the current knowledge suggests that there are important, both beneficial and adverse, relationships between natural environment and human health. The human body obtains metals and metalloids from diet, some of which are derived from local foodstuffs and municipal water supplies, and it is therefore plausible that areas characterized by various types of bedrock and superficial materials, upon which food is grown and water drained, provide different availabilities of trace elements. The present study aimed at elucidating whether the degree of human exposure to trace elements is subject to changes in local environmental factors. This hypothesis was…