Search results for "Thermal"

Helium and CO2 soil gas emission from Santorini (Greece)

1994

Soil gas investigation is a useful tool to detect active faults. The sudden appearance of soil gas anomalies in zones of deep-reaching faults represents a promising potential precursor of earthquakes and volcanic eruptions. In volcanic areas the development of soil gas monitoring techniques is particularly important, as they can represent, together with remote sensing techniques, the only geochemical methods that can be safely applied during volcanic unrest, when it becomes impossible or too dangerous to sample crater fumaroles. A soil gas survey was carried out in June 1993 at the main island of Thera, in the Santorini volcanic complex. CO2 flux and CO2 and helium concentrations were measu…

Gas emissions and crustal deformation from the Krýsuvík high temperature geothermal system, Iceland

2020

Abstract The Krýsuvik volcanic system is located on the oblique spreading Reykjanes Peninsula, SW Iceland. Since early 2009 the region has been undergoing episodes of localized ground uplift and subsidence. From April–November 2013, we operated near-real time monitoring of gas emissions in Krýsuvik, using a Multi-component Gas Analyzer System (Multi-GAS), collecting data on gas composition from a fumarole (H2O, CO2, SO2, H2S). The dataset in this study, comprises a near-continuous gas composition time series, the quantification of diffuse CO2 gas flux, analytical results for direct samples of dry gas, seismic records, and GPS data. Gas emissions from the Krýsuvik geothermal system were exam…

Microbial Biofilms Along a Geochemical Gradient at the Shallow-Water Hydrothermal System of Vulcano Island, Mediterranean Sea

2022

Shallow water hydrothermal vents represent highly dynamic environments where strong geochemical gradients can shape microbial communities. Recently, these systems are being widely used for investigating the effects of ocean acidification on biota as vent emissions can release high CO2 concentrations causing local pH reduction. However, other gas species, as well as trace elements and metals, are often released in association with CO2 and can potentially act as confounding factors. In this study, we evaluated the composition, diversity and inferred functional profiles of microbial biofilms in Levante Bay (Vulcano Island, Italy, Mediterranean Sea), a well-studied shallow-water hydrothermal ve…

EFFECTS OF SHALLOW WATER HYDROTHERMAL VENTS ON PHYTOBENTHIC COMMUNITIES

2012

Metallic nanoparticle enrichment at low temperature, shallow CO2 seeps in Southern Italy

2012

We report on metal enrichment along a natural pH gradient owing to increased CO2 degassing at cold, shallow seeps of Vulcano Island in the Mediterranean Sea, off Sicily. We assessed composition of unfiltered and filtered seawater (<100 nm) along acidic zones ranging between ambient and pH 5, and showed that most seep derived elements are present as nanoclusters which then aggregate into larger colloids while mixing with ambient seawater along a pH gradient. Size and elemental composition of such naturally occurring nanoparticles assessed by modern characterisation methods were in good agreement with the results from conventional analytical methods. We provide analytical evidence for the pre…

Innovative Compact Solar Air Conditioner based on Fixed and Cooled Adsorption Beds and Wet Heat Exchangers

2014

Abstract In this work, a new all-in-one compact solar air conditioner concept is presented. The system is mainly based on a new DEC process which utilises fixed and cooled adsorption beds operating in a batch process and two wet heat exchangers. The proposed innovative adsorption bed is a fin and tube heat exchanger commonly used in the air conditioning sector, wherein the spaces between the fins are filled with silica gel grains. The main feature of this component is to allow simultaneous dehumidification and cooling of air. Furthermore, since the component hosts a considerable amount of adsorption material, solar energy can be efficiently stored in the desiccant media in terms of accumula…

A FTIR study on low hydration saccharide amorphous matrices: Thermal behaviour of the Water Association Band

2011

Abstract We report a study on the thermal behaviour of the infrared Water Association Band (WAB) in dry binary saccharide–water systems (containing trehalose, sucrose, maltose, and raffinose). This is a follow-up of preceding studies on analogous carboxymyoglobin-saccharide–water ternary systems, which pointed out a mutual protein-matrix influence (coupling). A comparison between binary and ternary systems, for all the saccharides studied, evidences a reduction in the residual water content in the latter and, except for trehalose, a sizable modification in the thermal behaviour, which is discussed in terms of structure and hydrogen bonding properties of the sugars. The study allowed us also…

Groundwater radon measurements in the Mt. Etna area.

2003

Radon levels were measured in 119 groundwater samples collected throughout the active volcanic area of Mt. Etna by means of a portable Lucas-type scintillation chamber. The measured activity values range from 1.8 to 52.7 Bq l(-1). About 40% of the samples exceed the maximum contaminant level of 11 Bq l(-1) proposed by the USEPA in 1991. The highest radon levels are measured in the eastern sector of the volcano, which is the seismically most active zone of the volcano. On the contrary the south-western sector, which is both seismically active and a site of intense magmatic degassing, display lower radon levels. This is probably due to the formation of a free gas phase (oversaturation of CO(2…

Critical analysis of thermal inertia approaches for surface soil water content retrieval

2013

The “thermal inertia” method to retrieve surface soil water content maps on bare or sparsely-vegetated soils is analysed. The study area is a small experimental watershed, where optical and thermal images (in day and night time) and in situ data were simultaneously acquired. The sensitivity of thermal inertia to the phase difference between incoming radiation and soil temperature is demonstrated. Thus, to obtain an accurate value of the phase difference, the temporal distance between thermographs using a three-temperature approach is evaluated. We highlight when a cosine correction of the temperature needs to be applied, depending on whether the thermal inertia formulation includes two gene…

Characterizing weld pool surfaces from polarization state of thermal emissions

2013

International audience; In this Letter, a vision-based remote sensing methodology is proposed to measure the topography of weld pool surfaces from one single view. Thermal radiations emitted by the hot liquid metal at a wavelength within the arc plasma blind spectral window are acquired by a wavefront division polarimetric system. The refractive index of the liquid metal and the topography of the weld pool surface are inferred from the polarimetric state of the thermal radiations.