Search results for "LCA"
showing 10 items of 1995 documents
Sea level rise in the Mediterranean Sea: High resolution constraints from vermetid reefs
2009
The Mediterranean Sea (MS), is extremely sensitive to rising sea-levels (SL) as attested by drowned archeological remains from the Roman Period [2]. Due to the absence of coral reefs, evidence for recent and Holocene SL change has so far mainly been restricted to coastal cores [1] archeological remains [2] and submerged speleothem deposits. Vermetid reefs are an extremely sensitive high resolution carbonate archive [3,4] and they are mainly formed in the lower intertidal zone by gregarious and sessile gastropods belonging to the genus Dendropoma (family Vermetidae). Since their interval of growth is restricted to the tidal zone, they can be used as precise SL proxies (about ±0.1 m in low ra…
La Union Europea y el patio trasero americano
2002
Pasajes de París / 5; Urbanismo
2006
THE BIOGEOCHEMICAL BEHAVIOUR OF RARE EARTH ELEMENTS AS A CONSEQUENCE OF PROCESSES OCCURING IN THE VITIS VINIFERA L. – SOIL SYSTEM
2014
The geochemical behaviour of lanthanides and yttrium (Rare Earth Elements, REE) has been investigated mainly in geological systems as the REE exploitation in industrial and agricultural practices is progressively growing in the last years, to such an extent to become strategic materials. Extensive researches evidenced that REE capability to investigate processes occurring at the interface between different media such as the in depth investigation of REE behaviour is a matter of fact in many geochemical studies. These capabilities are a consequence of the chemical characters of REE that are exploited to investigate processes occurring during migrations of chemical elements in the soil-to-pla…
Volcanic signature of volatile trace elements on atmospheric deposition at Mt. Etna, Italy
2009
Volcanic volatiles and aerosol emitted into the atmosphere ultimately fall on the Earth’s surface as wet or dry deposition, and they can influence the environment and the ecosystems at local and regional scales. Therefore, atmospheric deposition plays a key-role in the geochemical cycles, redistributing volcanogenic elements to the ground. For this reason, estimating the volcanogenic trace element fluxes from the atmosphere to the surface is necessary for a better knowledge of the environmental impact of the volcanic emissions. Nevertheless, from a literature review, we have recognized the scarcity of investigation on trace element deposition in the surroundings of active volcanoes. Here, w…
Generation of CO2-rich melts during basalt magma ascent and degassing
2013
International audience; To test mechanisms of basaltic ma gma degassing, continuous decompressions of volatile-bearing (2.7-3.8 wt% H2O, 600-1300 ppm CO2) Stromboli melts were performed from 250-200 to 50-25 MPa at 1180-1140°C. Ascent rates were varied from 0.25 to ~ 1.5 m/s. Glasses after decompression show a wide range of textures, from totally bubble-free to bubble-rich, the latter with bubble number densities from 104 to 106/cm3, similar to Stromboli pumices. Vesicularities range from 0 to ~ 20 vol%. Final melt H2O concentrations are homogeneous and always close to solubilities. In contrast, the rate of vesiculation controls the final melt CO2 concentration. High vesicularity charges ha…
A golden era for volcanic gas geochemistry?
2022
The exsolution, rise, expansion, and separation of volatiles from magma provide the driving force behind both effusive and explosive volcanic eruptions. The field of volcanic gas geochemistry therefore plays a key role in understanding volcanism. In this article, we summarize the most important findings of the past few decades and how these shape today’s understanding of volcanic degassing. We argue that the recent advent of automated, continuous geochemical monitoring at volcanoes now allows us to track activity from unrest to eruption, thus providing valuable insights into the behavior of volatiles throughout the entire sequence. In the next 10 years, the volcanological community stands t…
THE NATURE AND SOURCE OF MAJOR MAGMATIC VOLATILES: OPEN-VENT DEGASSING VOLCANOES IN THE CENTRAL AMERICAN VOLCANIC ARC
Major volatiles play an important role in subduction zone magmatism, from magma generation in the mantle, to crustal ascent and evolution, until its dramatic expression during a volcanic eruption. In the attempt to add a piece of information on source and behavior of major volatiles in arc volcanism, I here report on the geochemistry of H2O, CO2, S and Cl in two volcanic systems in NW Nicaragua (Central America), San Cristóbal and Telica. The observational approach is based upon combination of some of the most recent techniques in volcanic gas monitoring and petrology. I here explore quiescent and eruptive degassing processes by combining both volcanic gas and melt inclusion approaches. Fie…
The geochemical cycle of Tellurium in volcanic environments
This research is focused on the geochemistry of Tellurium (Te) in active volcanic environments. To this end concentrations of Te have been measured on different matrices (plume, ashes, soils, atmospheric depositions and plants). Samples were collected from different volcanoes around the world: volcanic aerosols from Etna and Vulcano (Italy), Turrialba (Costa Rica), Myakejima, Asama and Aso (Japan), Mutnovsky and Gorely (Kamchatka, Russia), Copahue (Argentina), Nyamuragira and Nyiragongo (D.R. Congo); atmospheric depositions from Etna and Vulcano (Italy), Nyiragongo (D.R. Congo); ash from Etna (Italy), Copahue (Argentina), San Miguel (El Salvador). Among with plume and rain samples, several …