Effect of mantle oxidation state and escape upon the evolution of Earth's magma ocean atmosphere

The magma ocean period was a critical phase determining how Earth atmosphere developed into habitability. However there are major uncertainties in the role of key processes such as outgassing from the planetary interior and escape of species to space that play a major role in determining the atmosphere of early Earth. We investigate the influence of outgassing of various species and escape of H$_2$ for different mantle redox states upon the composition and evolution of the atmosphere for the magma ocean period. We include an important new atmosphere-interior coupling mechanism namely the redox evolution of the mantle which strongly affects the outgassing of species. We simulate the volatile outgassing and chemical speciation at the surface for various redox states of the mantle by employing a C-H-O based chemical speciation model combined with an interior outgassing model. We then apply a line-by-line radiative transfer model to study the remote appearance of the planet in terms of the infrared emission and transmission. Finally, we use a parameterized diffusion-limited and XUV energy-driven atmospheric escape model to calculate the loss of H$_2$ to space. We have simulated the thermal emission and transmission spectra for reduced or oxidized atmospheres present during the magma ocean period of Earth. Reduced or thin atmospheres consisting of H$_2$ in abundance emit more radiation to space and have larger effective height as compared to oxidized or thick atmospheres which are abundant in H$_2$O and CO$_2$. We obtain the outgassing rates of H2 from the mantle into the atmosphere to be a factor of ten times larger than the rates of diffusion-limited escape to space. Our work presents useful insight into the development of Earth atmosphere during the magma ocean period as well as input to guide future studies discussing exoplanetary interior compositions.Comment: 26 pages, 15 figures, accepted for publicatio

Infected pancreatic necrosis: outcomes and clinical predictors of mortality. A post hoc analysis of the MANCTRA-1 international study

: The identification of high-risk patients in the early stages of infected pancreatic necrosis (IPN) is critical, because it could help the clinicians to adopt more effective management strategies. We conducted a post hoc analysis of the MANCTRA-1 international study to assess the association between clinical risk factors and mortality among adult patients with IPN. Univariable and multivariable logistic regression models were used to identify prognostic factors of mortality. We identified 247 consecutive patients with IPN hospitalised between January 2019 and December 2020. History of uncontrolled arterial hypertension (p = 0.032; 95% CI 1.135-15.882; aOR 4.245), qSOFA (p = 0.005; 95% CI 1.359-5.879; aOR 2.828), renal failure (p = 0.022; 95% CI 1.138-5.442; aOR 2.489), and haemodynamic failure (p = 0.018; 95% CI 1.184-5.978; aOR 2.661), were identified as independent predictors of mortality in IPN patients. Cholangitis (p = 0.003; 95% CI 1.598-9.930; aOR 3.983), abdominal compartment syndrome (p = 0.032; 95% CI 1.090-6.967; aOR 2.735), and gastrointestinal/intra-abdominal bleeding (p = 0.009; 95% CI 1.286-5.712; aOR 2.710) were independently associated with the risk of mortality. Upfront open surgical necrosectomy was strongly associated with the risk of mortality (p < 0.001; 95% CI 1.912-7.442; aOR 3.772), whereas endoscopic drainage of pancreatic necrosis (p = 0.018; 95% CI 0.138-0.834; aOR 0.339) and enteral nutrition (p = 0.003; 95% CI 0.143-0.716; aOR 0.320) were found as protective factors. Organ failure, acute cholangitis, and upfront open surgical necrosectomy were the most significant predictors of mortality. Our study confirmed that, even in a subgroup of particularly ill patients such as those with IPN, upfront open surgery should be avoided as much as possible. Study protocol registered in ClinicalTrials.Gov (I.D. Number NCT04747990)

Interior-surface-atmosphere interactions of rocky planets: simulation of volcanic outgassing and volatile chemical speciation in the C-O-H system

The characterization of the volcanic volatile outgassing is central for investigating the composition and the development of rocky planet atmospheres. I have analysed the volcanic gas release via numerical simulations of the volatile pathway from the mantle to the atmosphere of a planet. The thesis has been carried out as a subproject within the Transregional Collaborative Research Center TRR 170 ”Late accretion onto terrestrial planets” which gave the opportunity to collaborate with other subprojects and research institutions. The aim of the thesis was to develop a numerical model for characterising the volcanic outgassed composition during the early Earth evolution. The core of this research is the volatile chemical speciation model which simulates the volcanic outgassing considering the C-O-H system. I designed the model following the ”Mass balance and equilibrium” method (French, 1966; Holloway, 1981; Holland, 1984; Huizenga, 2005; Fegley, 2013; Gaillard and Scaillet, 2014; Schaefer and Fegley, 2017) taking into consideration the principal factors that define the outgassed composition of a silicate melt namely: pressure, temperature and redox state. The volatile chemical speciation is calculated considering that the volatile species are in chemical equilibrium with the silicate melt and an ideal gas behaviour. The redox state of the system was reproduced by using some of the most common petrological mineral buffers (Holloway et al., 1992), for both reducing or oxidising conditions. The collected results demonstrate how the magma redox state is the driving parameter that affects the final outgassed composition. In reducing conditions (QIF and IW buffers) the principal outgassed species are H2 and CO whereas, in oxidising states (NiNiO and QFM buffers) the dominant volatile species are H2O and CO2. In order to investigate the volatile outgassing at a global scale, the volatile chemical speciation model was coupled with different models that reproduce the mantle convection regime (Noack and Breuer, 2013; Noack et al., 2014, 2017) and the corresponding outgassed atmospheres (Dorn et al., 2018). The coupling of the models is employed to investigate the volatile outgassing at different conditions. In Guimond et al. (2021), we investigated the early Earth evolution outgassing during the magma ocean stage. Still considering a global Earth magma ocean, in Katyal et al. (2020) we simulated the degassed atmospheric composition, H2 escape and the infrared emission/transmission. Ortenzi et al. (2020) analyses the degassing for rocky planets considering a stagnant lid regime and calculating the outgassed atmospheric compositions and radial extents. The volatile chemical speciation model was extended to include also the sulphur species (H2S, S2 and SO2) and for simulating the real gas behaviour. At the moment the simulations of the C-O-H-S system are only for a limited range of temperature and pressure, and the model needs further improvements for being employed in global outgassing simulations. In conclusion, the thesis includes a detailed description of the developed volatile chemical speciation models showing both their points of weakness and their versatility for investigating the volatile composition of outgassed atmospheres at different planet evolutionary stages.Um die Entstehung und Entwicklung von Atmosphären terrestrischer Planeten zu verstehen, ist es von zentraler Bedeutung das Verhalten und die Charakteristiken freiwerdender volatiler Stoffe bei vulkanischen Ausgasungsprozessen zu untersuchen. In dieser Dissertation wird mittels numerischer Simulierung der Weg vulkanischer Gase von ihrer gebundenen Form im Mantel bis hin zu ihrer freien Form in der Atmosphäre zurückverfolgt und deren Zusammensetzung analysiert. Die Promotionsarbeit ist im Rahmen des Transregio Sonderforschungsbereiches 170 (SFB TRR 170) ”Late accretion onto terrestrial planets” angefertigt worden, wodurch Möglichkeiten zu Kollaborationen mit weiteren Gruppen und Instituten innerhalb des Projektes genutzt werden konnten. Das Ziel dieser Arbeit ist die Entwicklung eines numerischen Modells zur Bestimmung der Gaszusammensetzung, die während der Frühgeschichte und Evolution der Erde durch vulkanische Prozesse ausgegast wurde. Im Zentrum steht dabei das Modell zur chemischen Speziierung von volatilen Elementen, das die Zusammensetzung des Gases innerhalb des C-O-H Systems simuliert. Es wurde mittels der Massenbilanzierungs- und Gleichgewichtsmethode entworfen (French, 1966; Holloway, 1981; Holland, 1984; Huizenga, 2005; Fegley, 2013; Gaillard and Scaillet, 2014; Schaefer and Fegley, 2017) und berücksichtigt die wichtigsten Faktoren, die die Ausgasungsprozesse silikatischer Schmelzen beeinflussen, nämlich Druck, Temperatur und Redox-Zustand. Die volatile chemische Speziierung wird unter Berücksichtigung des chemischen Gleichgewichts mit der silikatischen Schmelze unter der Annahme von idealem Gasverhalten berechnet. Der Redox-Zustands des Systems wird sowohl für reduzierende als auch oxidierende Bedingungen durch die in der Petrologie üblichen Mineralpuffer reproduziert (Holloway et al., 1992). Die Ergebnisse dieser Arbeit zeigen, dass die Zusammensetzung der ausgegasten Verbindungen hauptsächlich durch den Redox-Zustand des Magmas bestimmt wird. In reduzierenden Bedingungen (QIF und IW Puffer) wird hauptsächlich H2 und CO frei, während in oxidierenden Bedingungen (NiNiO und QFM Puffer) überwiegend H2O und CO2 ausgast. Um die Ausgasungsprozesse global zu untersuchen, wurde das volatile Speziierungs-Modell mit weiteren Modellen zur Reproduktion verschiedener Mantelkonvektionsregime (Noack and Breuer, 2013; Noack et al., 2014, 2017) und deren zugehörigen ausgegasten Atmosphären (Dorn et al., 2018) kombiniert. Durch die Verbindung der Modelle lässt sich das Ausgasen unter verschiedenen Umwelteinflüssen und Bedingungen untersuchen. In Guimond et al. (2021) wurde die Entwicklung der Ausgasung während der Magma Ocean Phase der frühen Erdgeschichte untersucht. Katyal et al. (2020) haben weiterhin, unter der Berücksichtigung eines globalen Magma Ozeans, die Zusammensetzung der ausgegasten Atmosphäre, den H2 Verlust und die infrarot Emission sowie Transmission simuliert. In Ortenzi et al. (2020) wurden hingegen die Ausgasungsprozesse für terrestrische Planeten im ’Stagnant Lid Regime’ simuliert sowie die Zusammensetzung und die radiale Ausdehnung der Atmosphäre berechnet. Des Weiteren wurde das volatile Speziierungs-Modell um Schwefel Verbindungen (H2S, S2 und SO2) und das Verhalten von realen Gasen erweitert. Zum gegenwärtigen Zeitpunkt sind die Simulationen des C-O-H-S Systems jedoch durch limitierte Druck- und Temperaturbereiche beschränkt und benötigen Verbesserungen, um für die globalen Ausgasungssimulationen verwendet werden zu können. Zusammengefasst beinhaltet diese Dissertation eine detaillierte Beschreibung des entwickelten Gas-Speziierungs-Modell, wobei sowohl die Schwächen als auch die Vielseitigkeit der Methode zur Untersuchung der Zusammensetzung ausgegaster Atmosphären während verschiedener planetarer Entwicklungsstufen aufgezeigt werden

Explorative Data Analysis Methods: Application to Laser-Induced Breakdown Spectroscopy Field Data Measured on the Island of Vulcano, Italy

One of the strengths of laser-induced breakdown spectroscopy (LIBS) is that a large amount of data can be measured relatively easily in a short time, which makes LIBS interesting in many areas, from geomaterial analysis with portable handheld instruments to applications for the exploration of planetary surfaces. Statistical methods, therefore, play an important role in analyzing the data to detect not only individual compositions but also trends and correlations. In this study, we apply two approaches to explore the LIBS data of geomaterials measured with a handheld device at different locations on the Aeolian island of Vulcano, Italy. First, we use the established method, principal component analysis (PCA), and second we adopt the principle of the interesting features finder (IFF), which was recently proposed for the analysis of LIBS imaging data. With this method it is possible to identify spectra that contain emission lines of minor and trace elements that often remain undetected with variance based methods, such as PCA. We could not detect any spectra with IFF that were not detected with PCA when applying both methods to our LIBS field data. The reason for this may be the nature of our field data, which are subject to more experimental changes than data measured in laboratory settings, such as LIBS imaging data, for which the IFF was introduced first. In conclusion, however, we found that the two approaches complement each other well, making the exploration of the data more intuitive, straightforward, and efficient

Field investigation of volcanic deposits on Vulcano, Italy using a handheld laser-induced breakdown spectroscopy instrument

International audienceLaser-induced breakdown spectroscopy (LIBS) is an important analytical technique in a variety of fields ranging from in-situ terrestrial geological field investigations to robotic exploration missions of extraterrestrial bodies such as Mars. In this study, the performance of a commercial handheld LIBS instrument was evaluated during an international summer school in 2019 that focused on the exploration of extreme environments on Earth and in space. Several sites on the Eolian island Vulcano (Italy) were investigated with different spectroscopic methods including LIBS. We focus here on the exploration of one particular outcrop with LIBS, where layered and colored ash deposits were observed. Furthermore, a laboratory study was performed to investigate and validate the effect of varying distance of the instrument to the sample. Unsupervised principal component analysis (PCA) for data exploration showed that elemental variations between the layers of the outcrop can be observed with the LIBS data from the handheld instrument. This was further confirmed by a layer-by-layer analysis of elemental correlations and depositional trends. Geologically relevant major elements such as Si, Al, Ca, Fe, K, Mg, and Na could be identified but also minor and trace elements such as F, Li, Mn, and Sr. Our results also show that the effects of varying distances of the instrument to the sample are critical for the quality of the data acquired and hence pose significant challenges to the analysis and interpretation. We propose a dedicated data pre-processing approach, which includes the masking of emission lines of Ar from the locally induced Ar atmosphere, as a possible solution to overcome this challenge. Overall, this study provides a better understanding of the performance and limitations of a handheld LIBS instrument, particularly in the context of future terrestrial and planetary field investigations

Field investigation of volcanic deposits on Vulcano, Italy using a handheld laser-induced breakdown spectroscopy instrument

International audienceLaser-induced breakdown spectroscopy (LIBS) is an important analytical technique in a variety of fields ranging from in-situ terrestrial geological field investigations to robotic exploration missions of extraterrestrial bodies such as Mars. In this study, the performance of a commercial handheld LIBS instrument was evaluated during an international summer school in 2019 that focused on the exploration of extreme environments on Earth and in space. Several sites on the Eolian island Vulcano (Italy) were investigated with different spectroscopic methods including LIBS. We focus here on the exploration of one particular outcrop with LIBS, where layered and colored ash deposits were observed. Furthermore, a laboratory study was performed to investigate and validate the effect of varying distance of the instrument to the sample. Unsupervised principal component analysis (PCA) for data exploration showed that elemental variations between the layers of the outcrop can be observed with the LIBS data from the handheld instrument. This was further confirmed by a layer-by-layer analysis of elemental correlations and depositional trends. Geologically relevant major elements such as Si, Al, Ca, Fe, K, Mg, and Na could be identified but also minor and trace elements such as F, Li, Mn, and Sr. Our results also show that the effects of varying distances of the instrument to the sample are critical for the quality of the data acquired and hence pose significant challenges to the analysis and interpretation. We propose a dedicated data pre-processing approach, which includes the masking of emission lines of Ar from the locally induced Ar atmosphere, as a possible solution to overcome this challenge. Overall, this study provides a better understanding of the performance and limitations of a handheld LIBS instrument, particularly in the context of future terrestrial and planetary field investigations