Chalcophile elements track the fate of sulfur at Kīlauea Volcano, Hawai'i

© 2020 Elsevier Ltd Chalcophile element concentrations in melt inclusions and matrix glasses may be used to investigate low pressure degassing processes, as well as sulfide saturation during crustal fractionation, and mantle melting. Erupted products from Kīlauea Volcano, Hawaiʻi, record three stages of sulfide saturation (in the mantle, crust, and within lava lakes), separated by episodes of sulfide resorption (i.e., sulfide undersaturation) during ascent through the thick Hawaiian lithosphere, and during syn-eruptive degassing. The presence of residual sulfides in the mantle source throughout the melting interval accounts for the high S concentrations of Kīlauean primary melts (1387–1600 ppm). Residual sulfides retain chalcophile elements during melting, decoupling the variability of these elements in high MgO melts from that of lithophile elements. Decompression associated with magma ascent through the thick Hawaiian lithosphere drives an increase in the sulfide concentration at sulfide saturation (SCSS2−), resulting in shallow storage reservoirs (∼1–5 km depth) being supplied with sulfide-undersaturated melts. A drop in temperature, coupled with major element changes during the fractionation of olivine, causes the SCSS2− to decrease. Combined with an increase in melt S contents during fractionation, this initiates a second stage of sulfide saturation at relatively high MgO contents (∼12 wt%). Syn-eruptive degassing of S drives the resorption of sulfides in contact with the carrier liquid. The covariance structure of Cu, MgO and Ni contents in melt inclusions and matrix glasses indicates that the dissolution of sulfides effectively liberates sulfide-hosted Cu and Ni back into the melt, rather than the vapour phase. The contrasting behaviour of Cu, Ni, Se and S during sulfide resorption indicates that the chalcophile element signature of the Kīlauean plume is largely controlled by silicate melt-vapour partitioning, rather than sulfide-vapour partitioning. The participation of dense sulfide liquids in shallow degassing processes may result from their direct attachment to buoyant vapour bubbles, or olivine crystals which were remobilized prior to eruption. Sulfide resorption obscures the textural and chemical record of sulfide saturation in matrix glasses, but not in melt inclusions, which are isolated from this late-stage release of chalcophile elements. The partitioning of S between the dissolving sulfide, melt and the vapour phase accounts for approximately 20% of the total S release into the atmosphere

Solar wind interaction with comet 67P: impacts of corotating interaction regions

International audienceWe present observations from the Rosetta Plasma Consortium of the effects of stormy solar wind on comet 67P/Churyumov-Gerasimenko. Four corotating interaction regions (CIRs), where the first event has possibly merged with a coronal mass ejection, are traced from Earth via Mars (using Mars Express and Mars Atmosphere and Volatile EvolutioN mission) to comet 67P from October to December 2014. When the comet is 3.1–2.7 AU from the Sun and the neutral outgassing rate ∼1025–1026 s−1, the CIRs significantly influence the cometary plasma environment at altitudes down to 10–30 km. The ionospheric low-energy (∼5 eV) plasma density increases significantly in all events, by a factor of >2 in events 1 and 2 but less in events 3 and 4. The spacecraft potential drops below −20 V upon impact when the flux of electrons increases. The increased density is likely caused by compression of the plasma environment, increased particle impact ionization, and possibly charge exchange processes and acceleration of mass-loaded plasma back to the comet ionosphere. During all events, the fluxes of suprathermal (∼10–100 eV) electrons increase significantly, suggesting that the heating mechanism of these electrons is coupled to the solar wind energy input. At impact the magnetic field strength in the coma increases by a factor of 2–5 as more interplanetary magnetic field piles up around the comet. During two CIR impact events, we observe possible plasma boundaries forming, or moving past Rosetta, as the strong solar wind compresses the cometary plasma environment. We also discuss the possibility of seeing some signatures of the ionospheric response to tail disconnection events

In-situ vitrification (ISV) organic-surrogate vapor emissions during a 1-ton pilot melt. Draft report

Pilot tests of a commercial soil vitrification process for entombing Animal/Chemical and Glass Hole area wastes were evaluated by incorporating perfluorocarbon tracers (PFTs) into aqueous and organic {open_quotes}wastes{close_quotes} within bottles of the type buried in typical Brookhaven-type holes. The objective was to add sufficient known PFT quantities of two or more types in the aqueous and organic phases while, at the same time, surrounding the test pit with known emission rate PFT sources, one type in the soil and another type in the air, such that monitoring of the air above ground and below ground would allow computation of the fugitive emission rates from the process as it occurred. Hood off-gas PFT concentrations were also to be monitored in order to verify the fraction present; claims have been made that greater than 99% of pit organics are destroyed during the melt. The output was to be the percentage escape (i.e., not captured by the hood) of pit aqueous and organic phases as the vitrification process proceeded. The actual melt commenced at 1350 on Monday 24 June 1996 and continued for just short of 48 hours. By the next day it was clear from the real-time PFT analyzer that above-ground fugitive emissions were not assessable because substantial PFT vapors were fumigating the area from the exhaust stack of the ISV hood`s soil vapor extraction (SVE) processing system. That sampling component was then switched to the stack to compare hood off-gas concentrations before and after the charcoal filtering

Study Protocol: Short Against Long Antibiotic Therapy for Infected Orthopaedic Sites - SALATIO Trials

Background: Few studies address the appropriate duration of post-surgical antibiotic therapy for orthopedic infections; with or without infected residual implants. We perform two similar randomized-clinical trials (RCT) to reduce the antibiotic use and associated adverse events. Methods: Two unblinded RCTs in adult patients (non-inferiority with a margin of 10%, a power of 80%) with the primary outcomes "remission" and "microbiologically-identical recurrences" after a combined surgical and antibiotic therapy. The main secondary outcome are antibiotic-related adverse events. The RCTs allocate the participants between 3 vs. 6 weeks of post-surgical systemic antibiotic therapy for implant-free infections; and between 6 vs. 12 weeks for residual implant-related infections. We need a total of 280 episodes (randomization schemes 1:1) with a minimal follow-up 12 months. We perform two interim analyses starting approximately after 1 and 2 years. The study approximatively lasts 3 years. Discussion: Both parellel RCT will enable to prescribe less antibiotics for future orthopedic infections in adult patients. Trial registration: ClinicalTrial.gov NCT05499481. Registered on 12 August 2022. Protocol version: 2 (19 May 2022

VESIcal Part I: An Open-Source Thermodynamic Model Engine for Mixed Volatile (H<inf>2</inf>O-CO<inf>2</inf>) Solubility in Silicate Melts

Abstract: Thermodynamics has been fundamental to the interpretation of geologic data and modeling of geologic systems for decades. However, more recent advancements in computational capabilities and a marked increase in researchers' accessibility to computing tools has outpaced the functionality and extensibility of currently available modeling tools. Here, we present VESIcal (Volatile Equilibria and Saturation Identification calculator): the first comprehensive modeling tool for H 2 O, C O 2 , and mixed ( H 2 O‐ C O 2 ) solubility in silicate melts that: (a) allows users access to seven of the most popular models, plus easy inter‐comparison between models; (b) provides universal functionality for all models (e.g., functions for calculating saturation pressures, degassing paths, etc.); (c) can process large datasets (1,000s of samples) automatically; (d) can output computed data into an Excel spreadsheet or CSV file for simple post‐modeling analysis; (e) integrates plotting capabilities directly within the tool; and (f) provides all of these within the framework of a python library, making the tool extensible by the user and allowing any of the model functions to be incorporated into any other code capable of calling python. The tool is presented within this manuscript, which may be read as a static PDF but is better experienced via the Jupyter Notebook version of this manuscript. Here, we present worked examples accessible to python users with a range of skill levels. The basic functions of VESIcal can also be accessed via a web app (https://vesical.anvil.app). The VESIcal python library is open‐source and available for download at https://github.com/kaylai/VESIcal, or it can be installed using pip. It is recommended to read and interact with this manuscript as an executable Jupyter Notebook, available at https://mybinder.org/v2/gh/kaylai/vesical-binder/HEAD?filepath=Manuscript.ipynb