Zonal Profiles of Jupiter's Tropospheric Abundances from Near-Infrared Juno JIRAM Spectroscopy

<p>The polar orbit of the Juno spacecraft provides an unprecedented view of Jupiter's atmosphere as it passes above the cloud tops every 53 days. The spectrum in the near infrared is dominated by reflected sunlight from aerosols (both condensate clouds and hazes) in the troposphere, as well as absorptions by the molecular species present. In addition, thermal emission longward of 4.5 µm provides access to the gaseous composition and aerosols below the top-most clouds.  Of particular importance in shaping the spectra are ammonia, phosphine and water, in addition to minor contributions from species such as arsine, germane and carbon monoxide. These regions also include emissions by ionospheric H<sub>3</sub><sup>+</sup>. Here, we produce meridionally averaged zonal profiles from the Juno-JIRAM observations obtained during PJ3, which provide almost complete latitude coverage. To analyse the observations, we use the radiative transfer and retrieval code NEMESIS (Irwin et al., 2008), which has been updated to cover this wavelength with the latest line-data from HITRAN. Our aim is to analyse both the reflected-sunlight region (2-4 µm) and the thermal emission region (4-5 µm) simultaneously for the first time, building on the work of Grassi et al. (2019) and Grassi et al. (2020).  We investigate the appropriate set of aerosol and haze layers, starting with NH4SH at 1.3 bars, NH3 and 0.7 bars and two grey hazes: one in the troposphere and one in the stratosphere.  The optical properties of these aerosols are tested to find the optimal cloud structure to reproduce the full JIRAM spectrum. From the retrievals of the zonally-averaged spectra we investigate whether spatial variations of tropospheric composition are truly required to fit the data, comparing gaseous contrasts to the expected circulation patterns associated with Jupiter’s belts and zones.</p>

Striking repercussions of the Australian "Black Summer" bushfires on the stratospheric composition and dynamical circulation

<p>Wildfire-driven pyro-convection (PyroCb) is capable of lofting combustion products into the stratosphere, polluting it with smoke aerosols at hemispheric and yearly scales. This realization has emerged after the record-breaking British Columbia PyroCb event in August 2017 that approached moderate volcanic eruptions in terms of stratospheric aerosol load perturbation. The Australian “Black Summer” bushfires in 2019/20 have surpassed the previous record by a factor of 3 and rivaled the strongest volcanic eruptions in the XXI century. Here we exploit a synergy of various satellite observations, ECMWF meteorological analysis and radiative transfer modeling to quantify the perturbation of stratospheric particulate and gaseous composition, dynamical circulation and radiative balance caused by the Australian New Year’s PyroCb outbreak. One of the most striking repercussions of this event was the generation of several persistent anticyclonic vortices that provided confinement to the PyroCb plumes and preserved them from rapid dilution in the environment. The most intense vortex measured 1000 km in diameter, persisted in the stratosphere for over 13 weeks and lifted a confined bubble of combustion gases, aerosols and moisture to 35 km altitude. It was accompanied by a synoptic-scale ozone hole with the total column reduction by about 30%. The startling consequences of the Australian event provide new insights into climate-altering potential of the wildfires, that have increased in frequency and strength over the recent years.</p>

The Potential of Generating Electrical Energy from Digester Carbon Waste Sources at Erwat Wastewater Treatment Facilities, South Africa

Biogas, a renewable energy source, is generated from biomass under anaerobic treatment. Anaerobic treatment of biomass occurs within a vessel – also known as a digester – that is fully sealed off from air and usually has naturally occurring bacteria to allow digestion and the production of biogas. The objective of this study was to investigate the potential of generating electrical energy from digester carbon waste sources. A GIZ/WEC model was utilized together with other WWTPa-based parameters to calculate the potential electricity that could be generated daily in two plants (Vlakplaats and Waterval), and the size of combined heat and power (CHP) suitable for the WWTPs was also identified. In terms of gaseous composition, four components were found in the biogas with CH4 and CO2 being the main constituents, having concentrations between 30%-38% and 62%-70% for CO2 and CH4, respectively. The electricity generated was on average 3 861 kWeh/day for the Vlakplaats plant and 21 777 kWeh/day for Waterval. Overall, the generation of electricity through the use of biogas is achievable, primarily when the amount of biogas produced on a daily basis reaches or exceeds the estimated biogas usage. The results obtained from this analysis showed estimate efficacy and consistency in the amount of electricity that can be generated.

Recent Advances in Packaging and Edible Coating for Shelf Life Enhancement in Fruit Crops

In today’s competitive world, packaging and edible coating play a significant part in producing usefulness user affable products for marketing. Due to several drawbacks of conventional packaging materials (wooden boxes, gunny bags, pallet, pallet bins, Wire-Bound Crates etc.) new technologies of polymeric films (LDPE, HDPE, Shrink film, Cling film) are adopted. By use of polymeric film (non perforated) modified atmosphere is obtain within the package, which subsequently helps to enhance shelf life of fruits. Application of thin layers of edible coating onto fruit surface helps to modify inner environment of fruit which causes similar effect to the modified atmospheric storage. This technological strategies are helpful to retard water loss, reduces skin damage caused by friction, changes in gaseous composition, moisture content, volatile aromas, and transport of solutes from the fruits overly enhance cosmetic appearance, decreasing ripening process and rise shelf life of fruits.

High pressure serpentinization and abiotic methanogenesis in metaperidotite from the Appalachian subduction, northern Vermont

<p>Serpentinization is the process of hydroxylation of olivine-rich ultramafic rocks to produce minerals such as serpentine, brucite, magnetite, and may release H<sub>2</sub>. The hydrogen produced through serpentinization reactions can be involved in abiotic reaction pathways leading to the genesis of abiotic light hydrocarbons such as methane (CH<sub>4</sub>). Examples of this phenomenon exist at the seafloor, such as at the serpentinite-hosted Lost City hydrothermal field, and on land in ophiolites at relatively shallow depths. However, the possibility for serpentinization to occur at greater depths, especially in subduction zones, raises new questions on the genesis of abiotic hydrocarbons at convergent margin and its impact on the deep carbon cycle. High-pressure ultramafic bodies exhumed in metamorphic belts can provide insights on the mechanisms of high-pressure serpentinization in subduction zones and on the chemistry of the resulting fluids. This study focuses on the ultramafic Belvidere Mountain complex belonging to the Appalachian belt of northern Vermont, USA. Microstructures show overgrowth of olivine by delicate antigorite crystals, suggesting olivine serpentinization at high-temperature consistent with the subduction evolution of the Belvidere Mountain complex.  Fluid inclusion trails cross-cutting the primary olivine relicts  suggest their formation during the antigorite serpentinization event. MicroRaman spectroscopy on the fluid inclusions reveals a CH<sub>4</sub>-rich gaseous composition, with trace of N<sub>2</sub>, NH<sub>3</sub> and S-H compound. Moreover, the precipitation of daughter minerals of lizardite and brucite in the fluid inclusions indicate the initial presence of H<sub>2</sub>O in the fluid. Secondary olivine is observed at the rim of pseudomorphosed primary pyroxenes (bastite), and has higher forsterite (Fo<sub>95</sub>) content with respect to the primary olivine (Fo<sub>92</sub>), suggesting either a syn-serpentinization olivine precipitation in the subduction zone, or a successive partial dehydration of the antigorite during metamorphism. Decreasing oxygen fugacity during serpentinization and related abiotic reduction of carbon at high-pressure conditions is proposed at the origin of methane in the fluid inclusions. This potentially places the Belvidere Mountain complex as an example of deep serpentinization related to high-pressure genesis of abiotic methane.</p>

Microbial role in N2O-NO2 production and CH4 oxidation under active hypogenic settings

<p>The hydrothermal caves linked to active faulting have subterranean atmospheres with a distinctive gaseous composition containing deep endogenous gases, such as carbon dioxide, methane and nitrogen oxides (NOx). Ascending fluids through associated near-surface hydrothermal processes can mobilize endogenous gases into the Critical Zone and, ultimately, to the lower troposphere.<br>Nitrogen oxides are polluting gases and can have adverse effects on human health, especially inhaled NO2. They also catalyse ozone (O3) production in the lower layers of the atmosphere and the greenhouse effect, when they react with volatile organic compounds. The largest source of NOx emissions is anthropogenic. The rest is produced naturally by microbial processes in soil and water, by lightning, volcanic activity, storms, etc. Production of N2O and NO2 is associated with soil and other active-geothermal ecosystems, far less is known about the sources and sinks of these gases within subterranean locations. Here, we report high N2O and NO2 concentrations detected along a hypogenic system associated with an active faulting (Vapour Cave, southern Spain), which enables direct gas exchange with the low-atmosphere. These anomalous concentrations of N2O and, NO2 are about ten and five times higher than the typical atmospheric background, respectively.<br>Gaseous composition analyses of subterranean atmosphere were conducted by high precision field-deployable CRDS and FTIR spectrometers for measuring in situ the target tracer gases (NO2, N2O, CH4, CO2) and δ13C of both carbon-GHGs. DNA extraction, sequencing and phylogenetic analyses were conducted to characterize the microbial community of cave sediments. The results showed that N2O and NO2 emission depends on the activity of nitrification by ammonia oxidizing microorganisms (such as members of the family Nitrosomonadaceae and phylum Thaumarchaeota) and/or as a result of incomplete denitrification by heterotrophic denitrifying bacteria (such as Bacillus, Acinetobacter and Cupriavidus) from this hydrothermal and hypoxic ecosystem.<br>On the other hand, CH4 concentrations and δ13CH4 vary along the cave (with the deep), in deepest cave locations CH4 values are higher with lighter δ13C values in comparison with the more superficial areas, which indicates a deep endogenous origin of methane. However, in areas near the entrance we observe lower concentrations of methane and heavier δ13C values (CH4<1 ppm and δ13C close to −30‰), as a result of methane oxidation by denitrifying methanotrophs of the NC10 phylum during gas migration from the deepest areas to the surface.</p><p>These new findings reveal the sourcing of these nitrogenous gases into the upper vadose zone of a hypogenic/geothermal ecosystem, and its potential release to the lower troposphere. A better understanding of biogeochemical processes controlling the production of nitrogenous gases in subterranean environments will be useful to identify and characterize new possible<br>sources, reservoirs and sinks of greenhouse gases (CO2, CH4, N2O and NOx) in order to calculate more accurately the budgets and for the design of new mitigation strategies of these gases.</p>

Plant sulphur metabolism is stimulated by photorespiration

Intense efforts have been devoted to describe the biochemical pathway of plant sulphur (S) assimilation from sulphate. However, essential information on metabolic regulation of S assimilation is still lacking, such as possible interactions between S assimilation, photosynthesis and photorespiration. In particular, does S assimilation scale with photosynthesis thus ensuring sufficient S provision for amino acids synthesis? This lack of knowledge is problematic because optimization of photosynthesis is a common target of crop breeding and furthermore, photosynthesis is stimulated by the inexorable increase in atmospheric CO2. Here, we used high-resolution 33S and 13C tracing technology with NMR and LC-MS to access direct measurement of metabolic fluxes in S assimilation, when photosynthesis and photorespiration are varied via the gaseous composition of the atmosphere (CO2, O2). We show that S assimilation is stimulated by photorespiratory metabolism and therefore, large photosynthetic fluxes appear to be detrimental to plant cell sulphur nutrition.

Geochemical Fingerprinting of Rising Deep Endogenous Gases in an Active Hypogenic Karst System

The hydrothermal caves linked to active faulting can potentially harbour subterranean atmospheres with a distinctive gaseous composition with deep endogenous gases, such as carbon dioxide (CO2) and methane (CH4). In this study, we provide insight into the sourcing, mixing, and biogeochemical processes involved in the dynamic of deep endogenous gas formation in an exceptionally dynamic hypogenic karst system (Vapour Cave, southern Spain) associated with active faulting. The cave environment is characterized by a prevailing combination of rising warm air with large CO2 outgassing (>1%) and highly diluted CH4 with an endogenous origin. The δ13CCO2 data, which ranges from −4.5 to −7.5‰, point to a mantle-rooted CO2 that is likely generated by the thermal decarbonation of underlying marine carbonates, combined with degassing from CO2-rich groundwater. A pooled analysis of δ13CCO2 data from exterior, cave, and soil indicates that the upwelling of geogenic CO2 has a clear influence on soil air, which further suggests a potential for the release of CO2 along fractured carbonates. CH4 molar fractions and their δD and δ13C values (ranging from −77 to −48‰ and from −52 to −30‰, respectively) suggest that the methane reaching Vapour Cave is the remnant of a larger source of CH4, which was likely generated by microbial reduction of carbonates. This CH4 has been affected by a postgenetic microbial oxidation, such that the gas samples have changed in both molecular and isotopic composition after formation and during migration through the cave environment. Yet, in the deepest cave locations (i.e., 30 m below the surface), measured concentration values of deep endogenous CH4 are higher than in atmospheric with lighter δ13C values with respect to those found in the local atmosphere, which indicates that Vapour Cave may occasionally act as a net source of CH4 to the open atmosphere.