416 research outputs found
Mount Etna the major point source of metals in the Mediterranean basin: impact on atmospheric precipitation
Mount Etna is a huge volcano in the Mediterranean basin and is located in the eastern part of
Sicily. It is considered to be, on the long-term average, the major atmospheric point source of
many environmental harmful compounds. Their emission occurs either through continuous
passive degassing from open-conduit activity or through sporadic paroxysmal eruptive
activity, in the form of gases, aerosols or particulate. Volcanic volatiles and aerosol emitted
into the atmosphere fall on the Earth’s surface as wet or dry deposition, and can influence
the environment both at local and regional scale.
To estimate the environmental impact of magma-derived trace metals and their depositions
processes, bulk deposition samples have been collected approximately fortnightly, using a
network of 5 rain gauges located at various altitudes on the upper flanks close to the summit
craters, from April 2006 to December 2007. Samples were analyzed for the main chemicalphysical
parameters (electric conductivity and pH) and for major and trace elements
concentrations.
The data obtained clearly show that the volcanic contribution is always prevailing in the
sampling site closest to the summit craters (∼1.5 km). In the distal sites (5.5-10 km from the
summit) and downwind of the summit craters, the volcanic contribution is also detectable
but often overwhelmed by anthropogenic or other natural (seawater spray, geogenic dust)
contributions. Volcanogenic contribution may derive from both dry and wet deposition of
gases and aerosols from the volcanic plume, but sometimes also from leaching of freshly
emitted volcanic ashes. In fact, in our background site (7.5 km in the upwind direction), after
an ash deposition event high concentration of lithophiles elements (Si, Al, Fe, Ti) have been
measured.
Sulphur, Chlorine and Fluorine, represent the main constituents that characterize the
volcanic contribution in the bulk deposition on Mt. Etna, although high concentrations of
many trace elements (Si, Al, Fe, Ti, Cu, As, Rb, Pb, Tl, Cd, Cr, U and Ag) display, in the site
most exposed to the volcanic emissions, average concentrations of about two orders of
magnitude higher than those measured in the background site (Mount Intraleo)
Atmospheric impact of volcanic volatiles: trace elements in snow and bulk deposition samples at Mount Etna (Italy)
Volcanoes represent an important natural source of several trace elements to the atmosphere.
For some species (e.g., As, Cd, Pb and Se) they may be the main natural source
and thereby strongly influencing geochemical cycles from the local to the global scale.
Mount Etna is one of the most actively degassing volcanoes in the world, and it is considered
to be, on the long-term average, the major atmospheric point source of many
environmental harmful compounds. Their emission occurs either through continuous
passive degassing from open-conduit activity or through sporadic paroxysmal eruptive
activity, in the form of gases, aerosols or particulate. To estimate the environmental
impact of magma-derived trace metals and their depositions processes, rainwater and
snow samples were collected at Mount Etna area. Five bulk collectors have been deployed
at various altitudes on the upper flanks around the summit craters of the volcano;
samples were collected every two week for a period of one year and analyzed
for the main chemical-physical parameters (electric conductivity and pH) and for major
and trace elements concentrations. Chemical analysis of rainwater clearly shows
that the volcanic contribution is always prevailing in the sampling site closest to the
summit crater (about 1.5 km). In the distal sites (5.5-10 km from the summit) and
downwind of the summit craters, the volcanic contribution is also detectable but often
overwhelmed by anthropogenic or other natural (seawater spray, geogenic dust) contributions.
Volcanic contribution may derive from both dry and wet deposition of gases
and aerosols from the volcanic plume, but sometimes also from leaching of freshly
emitted volcanic ashes. In fact, in our background site (7.5 km in the upwind direction)
volcanic contribution has been detected only following an ash deposition event.
About 30 samples of fresh snow were collected in the upper part of the volcano, during
the winters 2006 and 2007 to estimate deposition processes at high altitude during
cold periods. Some of the samples were collected immediately after a major explosive
event from the summit craters to understand the interaction between snow and fresh
erupted ash. Sulphur, Chlorine and Fluorine, are the major elements that prevailingly
characterize the volcanic contribution in atmospheric precipitation on Mount Etna, but
high concentrations of many trace elements are also detected in the studied samples.
In particular, bulk deposition samples display high concentration of Al, Fe, Ti, Cu,
As, Rb, Pb, Tl, Cd, Cr, U and Ag, in the site most exposed to the volcanic emissions:
median concentration values are about two orders of magnitude higher than those
measured in our background site. Also in the snow samples the volcanic signature is
clearly detectable and decreases with distance from the summit craters. Some of the
analysed elements display very high enrichment values with respect to the average
crust and, in the closest site to the summit craters, also deposition values higher than
those measured in polluted urban or industrial sites
The bridge volcanic LIdar-BILLI: A review of data collection and processing techniques in the Italian most hazardous volcanic areas
Volcanologists have demonstrated that carbon dioxide (CO2) fluxes are precursors of volcanic eruptions. Controlling volcanic gases and, in particular, the CO2 flux, is technically challenging, but we can retrieve useful information from magmatic/geological process studies for the mitigation of volcanic hazards including air traffic security. Existing techniques used to probe volcanic gas fluxes have severe limitations such as the requirement of near-vent in situ measurements, which is unsafe for operators and deleterious for equipment. In order to overcome these limitations, a novel range-resolved DIAL-Lidar (Differential Absorption Light Detection and Ranging) has been developed as part of the ERC (European Research Council) Project "BRIDGE", for sensitive, remote, and safe real-time CO2 observations. Here, we report on data collection, processing techniques, and the most significant findings of the experimental campaigns carried out at the most hazardous volcanic areas in Italy: Pozzuoli Solfatara (Phlegraen Fields), Stromboli, and Mt. Etna. The BrIdge voLcanic LIdar-BILLI has successfully obtained accurate measurements of in-plume CO2 concentration and flux. In addition, wind velocity has also been retrieved. It has been shown that the measurements of CO2 concentration performed by BILLI are comparable to those carried out by volcanologists with other standard techniques, heralding a new era in the observation of long-term volcanic gases
Unmanned aerial vehicle measurements of volcanic carbon dioxide fluxes
We report the first measurements of volcanic gases with an unmanned aerial vehicle (UAV). The data were collected at La Fossa crater, Vulcano, Italy, during April 2007, with a helicopter UAV of 3 kg payload, carrying an ultraviolet spectrometer for remotely sensing the SO2 flux (8.5 Mg d−1), and an infrared spectrometer, and electrochemical sensor assembly for measuring the plume CO2/SO2 ratio; by multiplying these data we compute a CO2 flux of 170 Mg d−1. Given the deeper exsolution of carbon dioxide from magma, and its lower solubility in hydrothermal systems, relative to SO2, the ability to remotely measure CO2 fluxes is significant, with promise to provide more profound geochemical insights, and earlier eruption forecasts, than possible with SO2 fluxes alone: the most ubiquitous current source of remotely sensed volcanic gas data
Rainwater-induced leaching of selenium, arsenic and vanadium from Etnean volcanic soils
Active volcanoes emit considerable amounts of
contaminants such as As, Se and V. Mount Etna is the biggest
volcano of Europe and an excellent geochemical site to study
water-soil processes. Due to its volcanic activity, the rainwater
has a strong compositional gradient, both in time and space.
At present, the behaviour of trace elements in the soils around
Mt Etna is poorly understood. To determine the influence of
the rainwater pH on the potential mobilization of geogenic
pollutants, batch experiments have been performed with
synthetic rainwater for 25 soils collected along the flanks of
the volcano. Our results show that:
i) The maximum concentrations in the leaching solutions are
higher for acid rain than for neutral rain (e.g. 7.7 vs 1.3
mg/L for Se).
ii) With neutral rain conditions the soils upwind from the
volcano have higher concentrations of Se than those
downwind (up to 1.3 mg/L compared to ≤0.3 mg/L for
the other samples). This trend is less clear for As and V.
iii) For soils collected from 2 to 10 km downwind of the
craters, Se concentrations in acid rain leachates decrease
one order of magnitude with increasing distance. A
similar pattern is also observed upwind from the
volcano. For As and V no clear relationship between
concentrations and location with respect to the volcanic
craters is observed.
Both i) and ii) result in a low pH dependence for samples
upwind from the volcano. The biggest difference between acid
and neutral leaching for As and V is observed for a sample 2
km downwind from the craters. The observed patterns are
influenced by potential controlling factors, such as organic
matter content, total concentrations, mineralogy, influence of
the volcanic plume, etc. Our results have implications for the
chemical composition of the Etnean aquifer, the only water
resource to the one million inhabitants around Mt Etna, as well
as for the bioavailability and potential toxicity through
agricultural activities, essential to the local economy
Vulcamera: a program for measuring volcanic SO2 using UV cameras
We report here on Vulcamera, a stand-alone program for the determination of volcanic SO2 fluxes using ultraviolet cameras. The code enables field image acquisition and all the required post-processing operations
Geogenic element behaviour in soil-rainwater interaction at Mt Etna, Sicily: preliminary results
Active volcanoes emit considerable amounts of contaminants such as As, Se and V. Previous
studies have shown that the volcanic activity at Mt Etna (Sicily) has a strong influence on local
rainwater compositions. However to date, the behaviour of trace elements in the soils around
Mt Etna is poorly understood. 4-hr batch experiments have been performed with 1:5 soil
solutions of air-dried soil (fraction <2 mm) and synthetic (acid) rainwater (using either
deionized water with a pH of ~6 or a ~500 ppm of sulphuric acid solution with a pH of ~2). In
general trace element concentrations are more enriched in soil solutions with low pH (e.g.
enrichment factor (EF) acid compared to neutral soil solution is up to 4.3x102 for V, 2.5x102
for As and 50 for Se). However, it seems that the EF especially for As and V has a correlation
with the distance to the crater. Additional, some soils located downwind of the volcano have
EFs smaller than 1 (i.e. the elements are more enriched in neutral rainwater), for several
elements like V, As and Se. For As and V the EF seems to be vary with distance to the crater.
Some possible explanations for these trends will be discussed. These results might have
important implications for the chemical composition of the Etnean aquifer, the only water
resource to the one million inhabitants around Mt Etna, as well as the bioavailability and
therefore potential toxicity through agricultural activities, essential to the local economy
Recent advances in ground-based ultraviolet remote sensing of volcanic SO2 fluxes
Measurements of volcanic SO2 emission rates have been the mainstay of remote-sensing volcanic gas geochemistry for almost four decades, and they have contributed significantly to our understanding of volcanic systems and their impact upon the atmosphere. The last ten years have brought stepchange improvements in the instrumentation applied to these observations, which began with the application of miniature ultraviolet spectrometers that were deployed in scanning and traverse configurations, with differential optical absorption spectroscopy evaluation routines. This study catalogs the
more recent empirical developments, including: ultraviolet cameras; wideangle
field-of-view differential optical absorption spectroscopy systems;
advances in scanning operations, including tomography; and improved understanding of errors, in particular concerning radiative transfer.
Furthermore, the outcomes of field deployments of sensors during the last
decade are documented, with respect to improving our understanding of volcanic dynamics and degassing into the atmosphere
UV camera measurements of fumarole field degassing (La Fossa crater, Vulcano Island)
The UV camera is becoming an important new tool in the armory of volcano geochemists to derive high time resolution SO2 flux measurements. Furthermore, the high camera spatial resolution is particularly useful for exploring multiple-source SO2 gas emissions, for instance the composite fumarolic systems topping most quiescent volcanoes. Here, we report on the first SO2 flux measurements from individual fumaroles of the fumarolic field of La Fossa crater (Vulcano Island, Aeolian Island), which we performed using a UV camera in two field campaigns: in November 12, 2009 and February 4, 2010. We derived ~ 0.5 Hz SO2 flux time-series finding fluxes from individual fumaroles, ranging from 2 to 8.7 t d−1, with a total emission from the entire system of ~ 20 t d−1 and ~ 13 t d−1, in November 2009 and February 2010 respectively. These data were augmented with molar H2S/SO2, CO2/SO2 and H2O/SO2 ratios, measured using a portable MultiGAS analyzer, for the individual fumaroles. Using the SO2 flux data in tandem with the molar ratios, we calculated the flux of volcanic species from individual fumaroles, and the crater as a whole: CO2 (684 t d−1 and 293 t d−1), H2S (8 t d−1 and 7.5 t d−1) and H2O (580 t d−1 and 225 t d−1).Published47-52JCR Journalrestricte
Mercury concentration, speciation and budget in volcanic aquifers: Italy and Guadeloupe (Lesser Antilles)
Quantifying the contribution of volcanism to global mercury (Hg) emissions is important to understand the
pathways and the mechanisms of Hg cycling through the Earth's geochemical reservoirs and to assess its
environmental impacts. While previous studies have suggested that degassing volcanoes might contribute
importantly to the atmospheric budget of mercury, little is known about the amount and behaviour of Hg in
volcanic aquifers. Here we report on detailed investigations of both the content and the speciation of
mercury in aquifers of active volcanoes in Italy and Guadeloupe Island (Lesser Antilles). In the studied
groundwaters, total Hg (THg) concentrations range from 10 to 500 ng/l and are lower than the 1000 ng/l
threshold value for human health protection fixed by the World Health Organization [WHO (1993): WHO
Guidelines for Drinking Water Quality- http://www.who.int/water_sanitation_health/GDWQ/index.htlm].
Positive co-variations of (THg) with sulphate indicate that Hg-SO4-rich acid groundwaters receive a direct
input of magmatic/hydrothermal gases carrying mercury as Hg0
(gas). Increasing THg in a volcanic aquifer could
thus be a sensitive tracer of magmatic gas input prior to an eruption. Since the complex behaviour and
toxicity of mercury in waters depend on its chemical speciation, we carefully determined the different
aqueous forms of this element in our samples.We find that dissolved elemental Hg0
(aq) and particulate-bound
Hg (HgP) widely prevail in volcanic aquifers, in proportions that highlight the efficiency of Hg adsorption onto
colloidal particles. Moreover, we observe that dissolved Hg0
aq and Hg(II) forms coexist in comparable amount
in most of the waters, in stark contrast to the results of thermodynamic equilibrium modelling. Therefore,
chemical equilibrium between dissolved mercury species in volcanic waters is either prevented by natural
kinetic effects or not preserved in collected waters due to sampling/storage artefacts. Finally, we provide a
first quantitative comparison of the relative intensity of aqueous transport and atmospheric emissions of
mercury at Mount Etna, a very active basaltic volcano
- …