The November 2002 degassing event at Panarea Island (Italy): five months of geochemical monitoring

On 3rd November 2002, at about 3 km off-shore of Panarea Island (Aeolian Islands, Southern Italy), a series of gas vents suddenly and violently opened from the seafloor at the depth of 10-15 m, with an unusually high gas flux and superimposing on the already existing submarine fumarolic field. Starting from the 12th November 2002 a discontinuous geochemical monitoring program was carried out. The emissions consisted in an emulsion whose liquid phase derived from condensation of an uprising vapor phase occurring close to the fluid outlets without significant contamination by seawater. The whole composition of the fluids was basically H2O- and CO2-dominated, with minor amounts of typical «hydrothermal» components (such as H2S, H2, CO and light hydrocarbons), atmospheric-related compounds, and characterized by the occurrence of a significant magmatic gas fraction (mostly represented by SO2, HCl and HF). According to the observed temporal variability of the fluid compositions, between November and December 2002 the hydrothermal feeding system was controlled by oxidizing conditions due to the input of magmatic gases. The magmatic degassing phenomena showed a transient nature, as testified by the almost complete disappearance of the magmatic markers in a couple of months and by the restoration, since January 2003, of the chemical features of the existing hydrothermal system. The most striking feature of the evolution of the «Panarea degassing event» was the relatively rapid restoration of the typical reducing conditions of a stationary hydrothermal system, in which the FeO/Fe1.5O redox pair of the rock mineral phases has turned to be the dominating redox controlling system

Radiological risk from thoron, a case study: The particularly radon-prone area of Bolsena, and the lesson learned

Abstract The contribution of 220 Rn is usually negligible compared to that of 222 Rn: its very short half-life makes escape from its source site within the rock very unlikely and it never has time enough to filtrate through the ground and through cracks in the floors or cellar walls to reach living quarters. This however becomes untrue if walls built with 232 Th-rich materials are present: then sizeable amounts of thoron may be detected in the closed areas bounded by those walls. This is the case for many dwellings in central Italy, and the town of Bolsena (northern Latium) is presented as a case study. A typical building of the area, entirely constructed with tuff blocks, is investigated and the annual dose rates calculated for varying distances from the wall. Thoron concentration was found to decrease with a relaxation length of 13 cm. Thoron was found to pose a significant risk. The rate of air exchange was found to produce little effect. Wall plastering acts as a filter: thoron diffuses through it but a HVL of less than 1 cm was found to prevail

Organics in comet 67P – a first comparative analysis of mass spectra from ROSINA–DFMS, COSAC and Ptolemy

The ESA Rosetta spacecraft followed comet 67P at a close distance for more than 2 yr. In addition, it deployed the lander Philae on to the surface of the comet. The (surface) composition of the comet is of great interest to understand the origin and evolution of comets. By combining measurements made on the comet itself and in the coma, we probe the nature of this surface material and compare it to remote sensing observations. We compare data from the double focusing mass spectrometer (DFMS) of the ROSINA experiment on ESA's Rosetta mission and previously published data from the two mass spectrometers COSAC (COmetary Sampling And Composition) and Ptolemy on the lander. The mass spectra of all three instruments show very similar patterns of mainly CHO-bearing molecules that sublimate at temperatures of 275 K. The DFMS data also show a great variety of CH-, CHN-, CHS-, CHO2- and CHNO-bearing saturated and unsaturated species. Methyl isocyanate, propanal and glycol aldehyde suggested by the earlier analysis of the measured COSAC spectrum could not be confirmed. The presence of polyoxymethylene in the Ptolemy spectrum was found to be unlikely. However, the signature of the aromatic compound toluene was identified in DFMS and Ptolemy data. Comparison with remote sensing instruments confirms the complex nature of the organics on the surface of 67P, which is much more diverse than anticipated

First mineralogical maps of 4 Vesta

Before Dawn arrived at 4 Vesta only very low spatial resolution (~50 km) albedo and color maps were available from HST data. Also ground-based color and spectroscopic data were utilized as a first attempt to map Vesta’s mineralogical diversity [1-4]. The VIR spectrometer [5] onboard Dawn has ac-quired hyperspectral data while the FC camera [6] ob-tained multi-color data of the Vestan surface at very high spatial resolutions, allowing us to map complex geologic, morphologic units and features. We here re-port about the results obtained from a preliminary global mineralogical map of Vesta, based on data from the Survey orbit. This map is part of an iterative map-ping effort; the map is refined with each improvement in resolution

Mapping the mineralogical composition of the Pinaria region (Av-11) of Vesta

We present the mineralogical map of a quadrant of the southern hemisphere of Vesta spanning 0-90 degrees longitude, and -21 to -66 degrees latitude; a region named Pinaria. The region, named after the Roman vestal virgin (c. 600 B.C.), includes an approximately 37km diameter crater, also named Pinaria. Several additional large craters are in this region as is the western most region of the rim of Rhea Silvia, named Matronalia Rupes. Mineralogical maps are based on data acquired by the Visible and Infrared Mapping Spectrometer (VIR-MS) and the Framing Camera (FC) on the Dawn spacecraft that has been orbiting Vesta since July 2011. VIR-MS is sensitive to wavelengths from 0.25um to 5.1um with a spatial resolution that depends upon the mission phase: nominally from 2.5 up to 0.8 km/pixel during the approach, 0.8 km/pixel during survey, 0.2 km/pixel during the high altitude orbit (HAMO) and about 0.05 km/pixel during the low altitude orbit (LAMO). This spatial resolution does not include the effects of the spacecraft's nor Vesta's motion. FC data from Survey orbit with a spatial resolution of about 250 m/pixel have been mapped using filter band parameters selected to enhance the anticipated mineralogy of Vesta. Global color maps of Vesta's surface using these color differences and ratios are generated. VIR data show that Vesta's surface is dominated by pyroxenes, with no evidence for the presence of other minerals observed at the scale of the survey measurements. The spectral parameters of the two major pyroxene absorption bands including band centers, depths and band areas and their variation within the Pinaria region, suggest mineralogical variation representing different compositional and/or textural terrains. Matronalia Rupes has band parameters suggesting different composition or grain size possibly resulting from down slope motion of regolith revealing different material beneath. The authors gratefully acknowledge the support of the Dawn Instrument, Operations, and Science Teams. This work is supported by an Italian Space Agency (ASI) grant, the DLR, MPI and by NASA through the Dawn project and the Dawn at Vesta Participating Scientist grant

Gains and losses of coral skeletal porosity changes with ocean acidification acclimation

Ocean acidification is predicted to impact ecosystems reliant on calcifying organisms, potentially reducing the socioeconomic benefits these habitats provide. Here we investigate the acclimation potential of stony corals living along a pH gradient caused by a Mediterranean CO(2) vent that serves as a natural long-term experimental setting. We show that in response to reduced skeletal mineralization at lower pH, corals increase their skeletal macroporosity (features >10 μm) in order to maintain constant linear extension rate, an important criterion for reproductive output. At the nanoscale, the coral skeleton's structural features are not altered. However, higher skeletal porosity, and reduced bulk density and stiffness may contribute to reduce population density and increase damage susceptibility under low pH conditions. Based on these observations, the almost universally employed measure of coral biomineralization, the rate of linear extension, might not be a reliable metric for assessing coral health and resilience in a warming and acidifying ocean

Comet 67P/Churyumov-Gerasimenko preserved the pebbles that formed planetesimals

Solar System formation models predict that the building-blocks of planetesimals were mm- to cm-sized pebbles, aggregates of ices and non-volatile materials, consistent with the compact particles ejected by comet 67P/Churyumov-Gerasimenko (67P hereafter) and detected by GIADA (Grain Impact Analyzer and Dust Accumulator) on-board the Rosetta spacecraft. Planetesimals were formed by the gentle gravitational accretion of pebbles, so that they have an internal macroporosity of 40%. We measure the average dust bulk density ${\rho}D = 795 _{-65}^{+840} kg m^{-3}$ that, coupled to the 67P nucleus bulk density, provides the average dust-to-ices mass ratio δ = 8.5. We find that the measured densities of the 67P pebbles are consistent with a mixture of (15 ± 6)% of ices, (5 ± 2)% of Fe-sulfides, (28 ± 5)% of silicates, and (52 ± 12)% of hydrocarbons, in average volume abundances. This composition matches both the solar and CI-chondritic chemical abundances, thus showing that GIADA has sampled the typical non-volatile composition of the pebbles that formed all planetesimals. The GIADA data do not constrain the abundance of amorphous silicates vs. crystalline Mg,Fe- olivines and pyroxenes. We find that the pebbles have a microporosity of (52 ± 8)% (internal volume filling factor φP = 0.48±0.08), implying an average porosity for the 67P nucleus of (71 ± 8)%, lower than previously estimated

Spectral Characterization of Carboxylic Acids, Amino Acids and Ammonium Salt as the Carriers of 3.2 µm Band of Comet 67p/Churyumov-Gerasimenko

We report transmission and reflectance measurements of analogs of comet 67P in the range 0.4-4.2 µm. Ammonium ions might contribute to the 3.2 µm band revealed by the VIRTIS/Rosetta instrument

Nature, formation, and distribution of carbonates on Ceres

Different carbonates have been detected on Ceres, and their abundance and spatial distribution have been mapped using a visible and infrared mapping spectrometer (VIR), the Dawn imaging spectrometer. Carbonates are abundant and ubiquitous across the surface, but variations in the strength and position of infrared spectral absorptions indicate variations in the composition and amount of these minerals. Mg-Ca carbonates are detected all over the surface, but localized areas show Na carbonates, such as natrite (Na_2CO_3) and hydrated Na carbonates (for example, Na_2CO_3·H_2O). Their geological settings and accessory NH_4-bearing phases suggest the upwelling, excavation, and exposure of salts formed from Na-CO_3-NH_4-Cl brine solutions at multiple locations across the planet. The presence of the hydrated carbonates indicates that their formation/exposure on Ceres’ surface is geologically recent and dehydration to the anhydrous form (Na_2CO_3) is ongoing, implying a still-evolving body