Search results for "LCA"
showing 10 items of 1995 documents
Estimates of mercury emission rates in active volcanic systems
2007
Mercury from volcanoes: fluxes and speciation
2008
Mercury is a toxic bio-accumulating metal that, due to its volatility has an extended atmospheric lifetime. Understanding Hg sources and sinks is therefore has importance on the global scale. We present new measurements of volcanic Hg from Mount Etna and Vulcano in Italy and Masaya volcano in Nicaragua to improve our estimates of the volcanic Hg flux. In contrast to other metals emitted from volcanoes, volcanic Hg can exist in 3 forms, namely gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and in the particle phase. These measurements also represent the first fully speciated measurements of volcanic Hg, as well as the first high time resolution measurements of gaseous Hg. Vo…
Soils as natural filters for GHG: an imbalance between the expected CH4 fluxes and the direct measurements
2018
The final composition of the atmosphere results from several processes and exchanges between all the Earth’s spheres. Some of these are widely known and others, such as the methane degassing from hydrothermal areas, are still understudied. Methane plays a key role in climate change being an efficient greenhouse gas. Although it would be crucial, the total CH4 output from geogenic sources is still not well defined; limitations in CH4 output estimations are due to many factors concerning a scarce dataset availability, difficulty in direct measurements, and interaction with methane-consuming microbiota in the soil. Often, the CH4 flux estimation was obtained indirectly, e.g. cross-correlating …
Profiling microbial communities in hyperalkaline waters of the Kizildag ophiolite complex (Turkey).
2016
It has recently been hypothesized that life on Earth could have been originated in hyperalkaline waters related to serpentinization of ophiolitic rocks, despite their extreme conditions (high pH and very low levels of nutrients). Five hyperalkaline springs of the Kizildag ophiolite complex (Turkey) were characterized. The dominant gases are either H2, CH4 or N2 . Bacterial diversity, analysed by RISA (Ribosomal Intergenic Spacer Analysis) revealed different profles for each spring. Sequencing of excised DNA bands allowed to identify the presence of Bacillus, Ralstonia, Pseudoalteromonas., Ureibacillus, Alicycliphilus, Anaerococcus. 16S ribosomal DNA sequencing by Illumina is in progress. Th…
New Inferences on Magma Dynamics in Melilitite-Carbonatite Volcanoes: The Case Study of Mt. Vulture (Southern Italy)
2022
This study provides the first micro-thermometric data of fluid inclusions (FIs) in mafic loose (disaggregated) xenocrysts and ultramafic xenoliths in explosive products of the melilitite-carbonatite Mt. Vulture volcano (southern Italy). Pure CO2 late stage FIs hosted in rock-forming minerals of wehrlite xenoliths and clinopyroxene xenocrysts were trapped at the local crust-mantle boundary (32 km). In contrast, trapping pressures within the loose olivine xenocrysts are from 3.2 to 4.5 kbar (8–13 km). Considering the ongoing degassing of mantle-derived CO2 rich gases, together with seismic evidences of the presence of low amount of melts at depth, and the tectonic control of the past volcanic…
Chemical, mineralogical and isotopic observations on hypersaline surficial deposits from Trapani evaporation ponds.
2010
Excess volatiles supplied by mingling of mafic magma at an andesite arc volcano
2010
We present the results of a study of volcanic gases at Soufriere Hills Volcano, Montserrat, which includes the first spectroscopic measurements of the major gas species CO2 and H2S at this volcano using a Multisensor Gas Analyzer System (MultiGAS) sensor. The fluxes of CO2 and H2S were 640.2750 t/d and 84.266 t/d, respectively, during July 2008, during a prolonged eruptive pause. The flux of CO2 is similar to estimates for the entire arc from previous geochemical studies, while the measured H2S flux significantly alters our interpretation of the sulphur budget for this volcano. The fluxes of both sulphur and carbon show considerable excesses over that which can be supplied by degassing of e…
Active biomonitoring (moss-bags) of volcanic emissions on Mt. Etna
2011
Biomonitoring may be defined as the use of organisms and biomaterials (biomonitors) to obtain information on certain characteristics of a particular medium (atmosphere, hydrosphere etc.). In particular, mosses accumulate large amounts of trace metals, making them good bioaccumulators to estimate atmospheric pollution. The moss-bags technique, introduced in the early 1970’, has become very popular. Such active biomonitoring technique is particularly useful in highly polluted areas and has been extensively used in industrial and/or urban areas to examine deposition patterns and to recognize point sources of pollution. The main objective of this study, which represents the first application of…
Volcanic gas and particles monitoring using moss-bags on Vulcano Island, Italy
2013
Non-stationary nature of SO2 degassing at Etna’s North-east crater (Italy).
2012
Investigating Etna’s long-term SO2 flux behaviour has led to important conclusions on the structure of the volcano’s magma feeding system, magma production (and degassing) rates, and causes for the excess degassing behaviour. Nonetheless, our knowledge of the short-term (timescales of seconds to a few hours) behaviour of magmatic volatiles (e.g., bubble coalescence, separate ascent and surface bursting of gas-rich bubbles) in the volcano’s upper feeding conduit system is still fragmentary, and based on indirect evidences (petrologic-textural data, observation of geophysical signals , physical modelling and laboratory experiments). In the past, direct gas flux measurements at Etna have been ta…