Search results for "Vulcan"
showing 10 items of 510 documents
Volcanic CO2 flux measurement at Campi Flegrei by tunable diode laser absorption spectroscopy
2014
Near-infrared room-temperature Tunable Diode Lasers (TDL) have recently found increased usage in atmospheric chemistry and air monitoring research, but applications in volcanology are still limited to a few examples. Here, we explored the potential of a commercial infrared laser unit (GasFinder 2.0 from Boreal Laser Ltd) for measurement of volcanic CO2 mixing ratios, and ultimately for estimating the volcanic CO2 flux. Our field tests were conducted at Campi Flegrei near Pozzuoli, Southern Italy, where the GasFinder was used during three campaigns in October 2012, January 2013 and May 2013 to repeatedly measure the path-integrated mixing ratios of CO2 along cross-sections of the atmospheric…
CO2 release to the atmosphere from thermal springs of Sperchios Basin and northern Euboea (Greece): The contribution of “hidden” degassing
2020
Abstract Greece is a region characterised by intense geodynamic activity that favours the circulation of hydrothermal fluids in the crust transporting volatiles from either the deep crust or the mantle to the surface. Elevated heat flow values are detectable at Sperchios Basin and North Euboea (central Greece), two areas defined by a system of deeply rooted extensional faults and Quaternary volcanic activity. This setting contributed to the formation of numerous hydrothermal systems, which are mostly expressed as CO2-rich thermal springs with intense bubbling. The CO2 output from six bubbling pools has been determined by flux measurements with the use of the floating chamber method. The hig…
Signals and memory in tree-ring width and density data
2015
It has been suggested that maximum latewood density (MXD) should be used instead of tree-ring width (TRW) data to reconstruct post-volcanic cooling effects. A thorough assessment of high frequency signals and potentially differing memory effects in long MXD and TRW chronologies, in response to large volcanic eruptions, is still missing, however. We here present a compilation of MXD and TRW chronologies from 11 sites in the Northern Hemisphere, covering the past 750+ years, and containing significant June–August temperature signals. Basic assessment of the data using Superposed Epoch Analysis reveals a temporally extended response in TRW, by 2–3 years, to large volcanic eruptions, though pos…
The assessment of volcanic gas hazard by means of numerical models: An example from Vulcano Island (Sicily)
1999
Volcanic activity can inject large quantities of gases and aerosols into the atmosphere both during and between eruptions, creating a health risk for the local population. The paper describes how the volcanic gas concentration in the air can be computed by a flow model simulating the wind field over a digital terrain model of the volcano coupled with a Lagrangian particle model that uses the known (measured) gas emission rates to simulate gas dispersion. The coupling provides hazard maps for a number of meteorological conditions, introduced as boundary and initial conditions to the wind flow model, and permits the estimation of the risk both for actual and increased emission rates. An appli…
Active moss monitoring allows to identify and track distribution of metal(loid)s emitted from fumaroles on Vulcano Island, Italy
2014
Abstract Volatile metal(loid)s are known to be emitted from volcanoes worldwide. We tested the suitability of active moss monitoring for tracking volatile metal(loid)s released from the fumarolic field on Vulcano Island, Italy, and differentiated fumaroles from other sources of gaseous and particulate trace elements such as sea spray and soil. Metal(loid) accumulation on the mosses per day did depend neither on the state of the exposed moss (dead or living) nor exposure time (3, 6, or 9 weeks). After collection, mosses were digested with either HNO3/H2O2 or deionized water and analyzed by ICP-MS. While for most elements both extraction methods yielded similar concentrations, higher concentr…
Modelling groundwater processes in a carbonate catchment: a case study from the Madonie area (Northern Sicily)
2011
Abstract This study reports on the results of a hydrogeochemical survey carried out in the Madonie area, a carbonate massif located in Palermo Province, Northern Sicily. The large dataset (226 collected sites) is used to highlight the processes controlling the distribution of dissolved chemicals in groundwaters; and, more importantly, to develop a general model (based on reaction-path modelling, and using the EQ3/6 code) of rock–water reactions in a carbonate environment. The investigated groundwater samples have conductivity between 31.7 and 8220 μS/cm; their total dissolved solids (TDS) content is higher near the coast area, where the seawater contribution becomes important. Calcium and H…
Using the Trace Element Contents in Bronchoalveolar Lavages to Probe the Human Exposure to Inhaled Particulates
2013
Explosive volcanic eruptions eject large volumes of high surface area, metal-rich dust and ash into the atmosphere. In areas near major volcanic eruptions, humans often interact with these materials and may bioaccumulate heavy and toxic metals. To evaluate these interactions, we examine bronchoalveolar lavage samples (BAL) collected from people exposed to the paroxysmal 2001 Etna eruption. BAL samples reveal a strong enrichment of many toxic heavy metals and the capacity for trace elements released from inhaled particles to induce crystallisation of phosphatic microcryst biominerals in intraaveolar spaces. BAL rare earth element (REE) concentration patterns normalised to shale reveal a ‘V-s…
Greenhouse gas as a nutrient: methanotrophic activity in soils of hydrothermal systems
2012
Methane is the most abundant hydrocarbon in the atmosphere and a significant contributor to the radiative forcing with a global warming potential about 21 times that of CO2. Methane is released to the atmosphere by a wide number of sources, both natural and anthropogenic, with the latter being twice as large as the former. Significant amounts of geological methane, produced within the Earth’s crust (e.g. volcanic/geothermal areas), are currently released into the atmosphere (48 Tg CH4/y). Microbial oxidation in soils by methanotrophic bacteria contributes to the removal of CH4 from the atmosphere for about 3-9%. Methanotrophs belong to the Gamma- and Alpha-proteobacteria and to the recently…
Exploring methanotrophic activity in geothermal soils from Pantelleria Island (Italy)
2012
Methane is released to the atmosphere by a wide number of natural (geological and biological) and anthropogenic sources, and is the second most important greenhouse gas after CO2. Microbial oxidation in soils by methanotrophic bacteria contributes to the removal of CH4 from the atmosphere and methanotrophic activity was also detected in volcanic/geothermal areas where degassing of endogenous gases occurs. Our aim is to describe the methanotrophs at the main exhalative area of Le Favare site at Pantelleria Island, where high CH4 consumption (up to 950 ng/g/ per h) was measured. Total soil bacterial diversity was analysed by TTGE of amplified 16S rRNA genes and the diversity of proteobacteria…
Microbiology meets geochemistry: geothermal flux shapes different microbial communities at the same exhalative area
2015
Volcanic/geothermal areas are sites of complex interactions between geosphere and biosphere. Pantelleria island (Southern Mediterranean Sea) hosts a high enthalpy geothermal system characterized by high CH4 and low H2S fluxes. Two sites, FAV1 and FAV2, located a few meters apart at the main exhalative area of the island (Favara Grande), recorded similar physical conditions (soil temperature 60°C, soil gas composition enriched in CH4, H2 and CO2). However, while high methanotrophic activity (59.2 nmol g-1 h-1) and high diversity of methanotrophs was detected at FAV2, FAV1 was not active and appeared deprived of methanotrophs (1). Our aim was to investigate the main factors influencing methan…