Carbon Mass Research Articles

Evolution of solid residue composition during inert and oxidative biomass torrefaction

Biomass torrefaction is a thermochemical pretreatment that can be used to improve biomass properties, contributing to the energy densification of biomass or increasing its grindability, burning and gasification characteristics, porous structure, etc. While it is typically carried out under inert conditions, oxygen-lean torrefaction of biomass can reduce the process cost and complexity. This work proposes a novel extended 2-step kinetics mechanism capable of accurately predicting the evolution of the chemical composition of torrefied biomass. The model parameters are obtained from data collected from an extensive experimental campaign in which the chemical composition of torrefied biomass was measured at different temperatures, residence times, and oxygen fractions. The carbon mass fraction of the torrefied products was found to increase by up to 50 % under severe inert torrefaction conditions, i.e., high temperatures and long residence times, whereas the hydrogen fraction decreased. In the presence of oxygen during torrefaction, the carbon and hydrogen contents in the solid residue decrease compared with those produced under inert torrefaction. The extended 2-step model can also be used to determine the high heating value and energy densification of the torrefied biomass, with the latter ranging from 1 to 1.4 for the operating conditions tested.

Greenhouse gas emission from prescribed fires is influenced by vegetation types in West African Savannas

Greenhouse gas (GHG) emissions from prescribed fires are poorly investigated, resulting in a high uncertainty in GHG budgets. Using, a carbon mass balance approach and experimental prescribed fires in 80 plots, this study assessed carbon emissions and established emission factors (EFs) for carbon dioxides (CO2), carbon monoxide (CO), and methane (CH4) across climate zones and vegetation types. In grass and shrub savannas, fires could burn intensely due to the lower moisture content and continuous spatial distribution of biomass fuel, causing greater carbon emissions with 1.61 ± 0.13 t C ha−1 and 1.01 ± 0.13 t C ha−1, respectively. Despite their low carbon emissions, tree savannas (1658.17 ± 11.13 g kg−1) and woodlands (1629.94 ± 12.23 g kg−1) have the highest EFs, which can be attribute to the high carbon content of biomass fuel in these vegetation types. Vegetation types and their interaction with climate zones have a substantial impact on carbon emissions and carbon species EFs, and should therefore be considered in assessing GHG emissions from fires. The findings from this study provide a useful basis for improving the national measurement, reporting, and verification of GHG emissions and for improving the measurement of the global balance of GHG emissions from fires.

Closing the geologic carbon cycle

Estimates of sedimentary organic carbon burial fluxes based on inventory and isotope mass balance methods have been divergent. A new calculation of the isotope mass balance using a revised assessment of the inputs to the ocean-atmosphere system resolves the apparent discrepancy. Inputs include weathering of carbonate and old kerogen, geogenic methane oxidation, and volcanic and metamorphic degassing. Volcanic and metamorphic degassing comprise ≈23% of the total C input. Inputs from isotopically light OCpetro and CH4-geo drive the mean δ13C of the input to =-8.0 ± 1.9‰, notably lower than the commonly assumed volcanic degassing value. The isotope mass balance model yields a modern burial flux =15.9 ± 6.6 Tmol y-1. The impact of the mid-Miocene Climatic Optimum isotope anomaly is an integrated excess deposition ≈ 4.3 × 106 Tmol between 18 and 11 Ma, which is both longer and larger than estimates for the total degassing by the Columbia River Basalt eruptions, implying a complex carbon system response to large eruptive events. Monte Carlo evaluation finds that late Cenozoic net growth of the carbonate reservoir is very likely while net growth of the Corg reservoir is less certain but more likely than not. At present, subduction does not appear to keep up with net sedimentation and the overall masses of sedimentary carbonate and organic carbon are likely increasing. Growth in the sedimentary Corg reservoir implies oxidation of the surface environment and likely increases in atmospheric pO2.

Variations of black carbon, particulate matter and nitrogen oxides mass concentrations in urban environment with respect to winter heating period and meteorological conditions

The atmospheric concentrations of particulate pollution are of great scientific concern due to their impact on both human health and environment. This study aimed to investigate the concentration of black carbon (BC), particulate matter with an aerodynamic diameter of less than 10 micrometres (PM10) and nitrogen oxides (NOx) at an urban background environment throughout the year, and understand the impact of winter heating and meteorology on its concentration level. The campaign covered heating and non-heating periods, from 1 June 2021 to 31 May 2022. During the heating period, the mass concentrations of BC, PM10 and NOx were 1.17, 24.9 and 19.4 µg m–3, respectively. The analysis revealed that the mass concentrations of BC and NOx were 1.9 and 1.4 times greater during the heating period, respectively, compared to the non-heating period. In contrast, PM10 remained almost constant during the heating (19.4 µg m–3) and non-heating periods (20.0 µg m–3). Throughout the year, the BC mass concentration was dominated by BCFF (71.2%) originating from fossil fuel combustion with a maximum (8.43 µg m–3) during the heating period. Moreover, wind speed presented a weak negative correlation with BC (r = –0.40), PM10 (r = –0.19) and NOx (r = –0.40) during the heating period.

Multi-site comparison and source apportionment of equivalent Black Carbon mass concentrations (eBC) in United States: Southern California Basin and Rochester, New York,

Spatial and temporal variability of equivalent black carbon (eBC) mass concentrations were studied using Aethalometers (AE33 and AE21) at 10 sites, including 5 urban and 5 near-road across the south coast of California and New York-Rochester. Statistical methods were applied to perform intra-urban and multi-site comparisons. Given that nominal eBC values provided by the Aethalometer were significantly overestimated, eBC concentrations were corrected using an appropriate multiple-scattering enhancement correction factor (C0) to accurately calculate light absorption. Annual and seasonal variations highlighted the significant contributions of traffic emissions to eBC mass concentrations at all sites. Source apportionment using the Aethalometer approach demonstrated that fuel combustion—primarily from gasoline and diesel vehicles— accounted for up to 80% of eBC emissions. Emission sources were found to be largely region specific. Our findings suggest that the implementation of restrictive regulations aimed at reducing gasoline and diesel vehicle emissions, such as California's Tier 3 (SULEV, 2015) and New York (2017), has led to a higher proportion of cleaner, emission-controlled vehicles in the South Coast Air Basin compared to Rochester. However, the effects of these measures may require more time to be fully observed in traffic-polluted areas across the US.

Characteristics and hydrocarbon accumulation model of Paleogene whole petroleum system in western depression of Qaidam Basin, NW China

Based on the oil and gas exploration in western depression of the Qaidam Basin, NW China, combined with the geochemical, seismic, logging and drilling data, the basic geological conditions, oil and gas distribution characteristics, reservoir-forming dynamics, and hydrocarbon accumulation model of the Paleogene whole petroleum system (WPS) in the western depression of the Qaidam Basin are systematically studied. A globally unique ultra-thick mountain-style WPS is found in the western depression of the Qaidam Basin. Around the source rocks of the upper member of the Paleogene Lower Ganchaigou Formation, the structural reservoir, lithological reservoir, shale oil and shale gas are laterally distributed in an orderly manner and vertically overlapped from the edge to the central part of the lake basin. The Paleogene WPS in the western depression of the Qaidam Basin is believed unique in three aspects. First, the source rocks with low organic matter abundance are characterized by low carbon and rich hydrogen, showing a strong hydrocarbon generating capacity per unit mass of organic carbon. Second, the saline lake basinal deposits are ultra-thick, with mixed deposits dominating the center of the depression, and strong vertical and lateral heterogeneity of lithofacies and storage spaces. Third, the strong transformation induced by strike-slip compression during the Himalayan resulted in the heterogeneous enrichment of oil and gas in the mountain-style WPS. As a result of the coordinated evolution of source-reservoir-caprock assemblage and conducting system, the Paleogene WPS has the characteristics of “whole process” hydrocarbon generation of source rocks which are low-carbon and hydrogen-rich, “whole depression” ultra-thick reservoir sedimentation, “all direction” hydrocarbon adjustment by strike-slip compressional fault, and “whole succession” distribution of conventional and unconventional oil and gas. Due to the severe Himalayan tectonic movement, the western depression of the Qaidam Basin evolved from depression to uplift. Shale oil is widely distributed in the central lacustrine basin. In the sedimentary system deeper than 2 000 m, oil and gas are continuous in the laminated limy-dolomites within the source rocks and the alga limestones neighboring the source kitchen, with intercrystalline pores, lamina fractures in dolomites and fault-dissolution bodies serving as the effective storage space. All these findings are helpful to supplement and expand the WPS theory in the continental lake basins in China, and provide theoretical guidance and technical support for oil and gas exploration in the Qaidam Basin.

Synthesis, Characterization, Biological Evaluation, DFT, and Molecular Docking Study of a Co(II) Complex Derived from ON Donor Bidentate Schiff Base Ligand

AbstractThe utilization of biologically active metal complexes in medicine is gaining recognition as an alternative approach to traditional biologically active organic molecules, which often exhibit undesirable side effects. This study focuses on the synthesis and characterization of a Co(II) complex derived from the (E)‐2‐((2‐hydroxybenzylidene)amino)‐5‐methylbenzonitrile ligand system (HL) and cobalt(II) acetate tetrahydrate in a dichloromethane/methanol solution. A comprehensive characterization strategy was employed, involving proton and carbon nuclear magnetic resonance, infrared, electronic spectra, PXRD, SEM‐EDX, and mass spectroscopies, as well as elemental analysis (CHN and Co), TGA, and molar conductance, to confirm the chemical structures of the ligand and its complex. The infrared spectral data revealed the ligand as a bidentate ligand, chelating the Co(II) ion through the oxygen and nitrogen atoms of the phenolate and imine groups. Additionally, PXRD and SEM analyses indicated crystalline and amorphous properties for the ligand and complex, respectively. Assessment of antimicrobial potential using a modified disc diffusion method, with streptomycin as the positive control, demonstrated the complex's enhanced antibacterial activity compared to the ligand against all tested bacteria, showing a concentration‐dependent response. Similarly, antioxidant studies revealed promising results, with the complex exhibiting superior DPPH radical scavenging activity (IC50 values: ligand 64.5 μg.mL−1, complex 43.1 μg.mL−1). Theoretical analysis through DFT calculations and molecular docking provided insights into the electronic properties and binding affinity of the ligand and complex, supporting the experimental findings and affirming the biological activities exhibited by the compounds. Overall, this research showcases the synthesis, characterization, and biological evaluation of a promising Co(II) complex, highlighting its potential as an effective antimicrobial and antioxidant agent.

Adsorption Capacity and Efficiency of Composite Thin Sheet Made of Chitosan-Activated Carbon on The Adsorption of Methylene Blue

Abstract Methylene blue (MB) is a waste dye produced by textile industries. One way to reduce MB in polluting the environment is using MB adsorbent materials, such as chitosan (CS)-based composites. This research aims to investigate the adsorption capacity and efficiency of chitosan-activated carbon composites (CS-AC), which are in the form of thin sheets, on MB adsorption. The composite was made by manually mixing the chitosan and activated carbon, and then the mixture was poured into a dish and dried at around 50 °C until a dry, thin sheet was formed. The composites were prepared with varying activated carbon mass concentrations (25%, 50%, 75%, and 100% of chitosan mass). The MB adsorption measurements were carried out using UV-Vis spectroscopy. Adsorption capacity and adsorption efficiency increase with increasing activated carbon content, and the composite containing activated carbon mass 100% of chitosan mass shows the highest values, namely 11.51 mg/g and 95.93%, respectively. Furthermore, the values of adsorption capacity and adsorption efficiency are also influenced by the initial MB concentration and mass of the adsorbent. The adsorption capacity increases with increasing initial MB concentration but decreases with increasing adsorbent mass. Adsorption efficiency increases with increasing initial MB concentration and adsorbent mass.

Peat profile database from peatlands in Canada.

Peatlands cover approximately 12% of the Canadian landscape and play an important role in the carbon cycle through their centennial- to millennial-scale storage of carbon under waterlogged and anoxic conditions. In recognizing the potential of these ecosystems as natural climate solutions and therefore the need to include them in national greenhouse gas inventories, the Canadian Model for Peatlands module (CaMP v. 2.0) was developed by the Canadian Forest Service. Model parameterization included compiling peat profiles across Canada to calibrate peat decomposition rates from different peatland types, to define typical bulk density profiles, and to describe the hydrological (i.e., water table) response of peatlands to climatic changes. A total of 1217 sites were included in the dataset from published and unpublished sources. The CORESITES table contains site location and summary data for each profile, as well as an estimate of total carbon mass per unit area (in megagrams of C per hectare). Total carbon mass per unit area at each location was calculated using bulk density and carbon content through each profile. The PROFILES table contains data for depth (in centimeters), bulk density (in grams per cubic meter), ash and carbon content (in percentage), and material descriptions for contiguous samples through each peat profile. Data gaps for bulk density and C content were filled using interpolation, regression trees, and assigned values based on material description and/or soil classification to allow for the estimation of total carbon mass per unit area. A subset of the sites (N = 374) also have pH and pore water trace-elemental geochemistry data and are found in the WATER table. The REFERENCES table contains the full citation of each source of the data and is linked to each core location through the SOURCEDATA table. The LOOKUP table defines codes in the database that required more space that what was sufficient in the metadata tables. The data can be accessed on Open Government Canada and will be useful for future work on carbon stock mapping and ecosystem modeling. All metadata and data are provided © Her Majesty the Queen in Right of Canada, 2023 and information contained in this publication may be reproduced for personal or public noncommercial purposes with attribution, whereas commercial reproduction and distribution are prohibited except with written permission from NRCan; complete details are noted in the Supporting Information file Metadata S1 (see Class III.B.3: Copyright restrictions).

ADSORPTION OF TEXTILE DYE ACID GREEN 42 (AG42) ON ACTIVATED CARBON FROM CHICKEN EGGSHELLS (CAC30)

The present work is a contribution to the valorization of chicken eggshells, an abundant waste product in Cote dIvoire, as a credible alternative to commercial activated carbon.Chemicalactivation of the precursorwascarriedoutwith30%phosphoricacidfor24h of contactin a ratio of 200 g of material to 100 mL of acid, and calcined at 600°C for 1h. The surface of the activated carbon obtained was studied using the BET (Brunauer-Emmett and Teller) method, which consists in establishing the adsorption isotherm for nitrogen N2. The results reveal a specific surface area of 5.42 m2.g-1, 65.68% of micropores and a pHzc of 7.40. Chemical characteristics determined by Boehms method indicate the basic nature of the surface. The elemental composition is dominated by oxygen(50.53%),calcium(30.78%)andcarbon(11.33%).The experiments demonstrated that the removalof AG42by adsorption on CAC30 is influenced by contact time, activated carbon mass, solution pH, and initial concentration and temperature of the dye aqueous solution. Adsorption kinetics followed the pseudo-second-order model and the isotherm is described by the Langmuir model. The thermodynamic study revealed the spontaneous (ΔG < 0) and exothermic (ΔH < 0) nature of dye adsorption, with a well-organized distribution of dye molecules at the adsorption sites (∆S°< 0).

Making Activator Materials Active Carbon From Wedi Skin Salak (Salacca edulis Reinw) With ZnCl2 Activator as Adsorbent to Reduce Fenol Content

Making Activator Materials Active Carbon From Wedi Skin Salak (Salacca edulis Reinw) With ZnCl2 Activator as Adsorbent to Reduce Fenol Content. Wedi salak skin in Bojonegoro as an activated carbon material can provide an alternative for activated carbon manufacturing materials by utilizing environmentally friendly natural materials. The wedi salak skin is modified by treatment in the sun, in the roast, and in the oven in the manufacture of activated carbon which is then activated with ZnCl2 and then tested the adsorbs power of this salak skin activated carbon against phenol reduction. The adsorbent material that reduces the concentration of phenol the most is the roasted adsorbent material with a final phenol concentration of 2.15 mg/L so that the concentration of phenol absorbed is 297.85 mg/L at a mass of 1.5 g. The results of the analysis show that each variation of the activated carbon variation can reduce the concentration of phenol. The results obtained from this study are the type of activated carbon material whose highest absorption efficiency is the type of activated carbon material roasted at 99.28% with a mass of activated carbon of 1.5 g. Based on the results of the analysis, it can be seen that each variation of the type of activated carbon material will experience a decrease in concentration as the mass of the adsorbent increases. The greater the mass of the adsorbent, the adsorption ability will also increase. Each type of activated carbon material also experienced an increase in percent removal along with an increase in adsorbent mass. The results of research on the effect of activated carbon mass, also show that the adsorption capacity value decreases with increasing adsorbent mass. In this research data, the largest capacitance value was 112.87 mg/g at the smallest mass of 0.5g. The decrease in adsorption capacity is caused by the active side of the adsorbent that has not all bonded with the adsorbate.

Coarse-Grained Molecular Dynamics Simulation of Ionomer-Mediated Carbon Cluster Bonding in Polymer Electrolyte Fuel Cell Catalyst Layers

This study examines the impact of ionomer to carbon mass ratio and the number of platinum particle clusters on the structural dynamics and organization of Pt-C-Nafion catalyst layers during the evaporation process. Using Coarse-Grained Molecular Dynamics (CGMD) simulations, we analyzed the center of mass position and ionomer coverage on Pt surface. The results show that a higher ionic polymer to carbon mass ratio (0.6) increases lateral mobility and short-range ordering along with the coverage of the Pt surface with ionomers, whereas increasing the number of Pt particle clusters (from 1 to 4 ) enhances lateral diffusion as well as leading to more difficult adsorption of ionomers. These findings highlight the importance of optimizing these parameters to obtain a homogeneous and stable catalyst layer, which is critical for fuel cell performance. Future work will include tuning the Pt/C mass ratio, hydrophilicity, and IC ratio in conjunction with energy and force analyses to further understand the effect of Nafion on Pt/C clusters.

Comparative analysis of winter composite-PM2.5 in Central Indo Gangetic Plain cities: Combined organic and inorganic source apportionment and characterization, with a focus on the photochemical age effect on secondary organic aerosol formation

To gain insights into air quality dynamics, a high-end instrument such as High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) alongside an Aethalometer was used to measure the Composite PM2.5 (C-PM2.5) in Lucknow and Kanpur during winter. It encompasses non-refractive PM2.5 (NR-PM2.5) and Black Carbon (BC) mass concentrations. Significant variation was noted in average C-PM2.5 concentrations at both sites, as 168.8 ± 61.3 μg m−3 in Lucknow and 90.7 ± 25.7 μg m−3 in Kanpur. Organics emerged as the predominant component, constituting ∼55%–65% of the C-PM2.5 mass, followed by inorganics (24% and 30%) and BC (20% and 8%). The present study employs Positive Matrix Factorization (PMF) on combined organic and inorganic source apportionment, resolving eight and seven source factors at Lucknow and Kanpur, respectively. Both sites exhibit significant contributions from solid-fuel combustion organic aerosol (SFC-OA), with ∼11% in Lucknow and 8% in Kanpur. However, SFC-OA mass concentration in Lucknow, at 24.67 μg m-³, is nearly double that in Kanpur (12.05 μg m-³). This was likely due to domestic coal burning in the nearby households, unregulated open burning, and burning of garbage on roadsides. The study shows that both sites were affected by oxidized biomass burning OA (O-BBOA) emissions, with increased concentration during the night due to dark oxidation by NO3 radicals. The diurnal variation of secondary organic aerosols (SOA), such as O-BBOA and semi-volatile oxygenated OA (SVOOA), shows increasing concentration during daytime hours. Therefore, the photochemical aging (ta) role in SOA formation was analyzed, and it was revealed that the formation might primarily be driven by photochemical oxidation. Additionally, two inorganic-rich factors, sulfate and nitrate-related OA (SO4-OA and NO3-OA) at both sites and additional ammonium chloride-related OA (NH4Cl-OA) resolved at Lucknow. Our study shows that NO3-OA and SO4-OA formation was dominated by aqueous phase processes due to high relative humidity and decline in concentration with increasing ta (ta > 30 h) during winter.

The timing and duration of large-scale carbon release in the Early Jurassic

The Toarcian oceanic anoxic event (T-OAE, ca. 183 Ma) in the Early Jurassic was one of the most significant warming events of the Phanerozoic, associated with large-scale carbon emissions, mass extinction, and perturbations to hydrology and ocean chemistry. However, the age and duration of this hyperthermal have long been uncertain, hindering our understanding of the timing and pace of carbon release and the associated environmental and biotic changes. We present high-precision radioisotopic dates bracketing a biostratigraphically constrained record of the T-OAE in Japan. Our geochronology reveals an unexpectedly short T-OAE duration of ∼300 k.y. and a temporal coincidence with Ferrar large igneous province (LIP) magmatism. Our dates refute previous work linking the T-OAE to the earlier Karoo LIP, which was coincident with an earlier carbon cycle perturbation at the Pliensbachian−Toarcian boundary. Our results suggest both events were driven by extremely rapid (perhaps sub-millennial scale) thermogenic carbon degassing during LIP sill intrusion.

Plastic litter is a part of the carbon cycle in an urban river: Microplastic and macroplastic accumulate with organic matter in floating debris rafts.

Watershed models of plastic export from rivers to oceans have large uncertainties, and improvements require direct measurements of riverine macroplastic (>5mm) and microplastic (<5mm). Also, plastic represents allochthonous carbon inputs to rivers but is rarely measured as carbon mass. We quantified plastic and organic matter within floating debris rafts and open water in an urban river. Macroplastics only occurred in debris rafts. Microplastics had higher concentrations in debris rafts relative to open water. Across sites, organic matter was positively correlated with microplastics and macroplastics. Last, carbon in plastic was 40% of the carbon mass in coarse particulate organic matter in debris rafts. Floating plastic litter accumulates with particulate organic matter in debris rafts. Plastic is an overlooked and ecological meaningful component of carbon standing stocks in urban rivers. Results will inform improved carbon budget calculation in rivers and watershed models of plastic export. PRACTITIONER POINTS: Plastic particles floating on the surface of an urban river accumulate in debris rafts compared to open water in terms of count and mass. Abundance and composition of plastic particles in debris rafts were distinct from those in open water areas. Plastic litter as units of carbon mass was in the same order of magnitude as carbon mass in course particulate organic matter. Plastic litter moves in similar ways to naturally occurring organic particles and should be measured as a part of the riverine carbon cycle.

Fabrication and in-plane compressive collapse of CFRP honeycomb metamaterials

A pin-slot positioning method was proposed to fabricate carbon fiber reinforced polymer (CFRP) metamaterials of hexagonal and zero Poisson’s ratio semi-re-entrant honeycombs with the same mass of monolayer continuous twill-woven carbon fiber/epoxy prepregs. The in-plane compressive collapse of CFRP honeycombs was explored through experiments and finite element (FE) simulations. Furthermore, analytical models were developed to predict the modulus and initial collapse stress of the hexagonal and semi-re-entrant honeycombs. Good agreement is achieved between analytical predictions, FE simulations and experimental results. It is shown that the initial collapse of CFRP honeycombs is by the bending of cell walls. Once initial collapse has been attained, both hexagonal and semi-re-entrant honeycombs have a stress softening. The collapse and failure modes of CFRP honeycombs strongly depend on cellular configurations and loading directions.

Origin of the Ca-phosphate inclusions in Ivory Coast and Australasian Muong-Nong-type tektites

Tektites are reduced (Fe2+) glasses formed by the quenching of molten material ejected from Earth’s surface as a result of a hypervelocity impact. The vast majority of tektites are usually homogeneous glasses, but rare samples containing mineral inclusions can provide insights about the source material, sample thermal history, and tektite formation process. Tektites from two distinct strewn fields presenting Ca-phosphate inclusions detected from anomalous magnetic susceptibility were studied: one sample from the Ivory Coast tektite (ICT) field ejected at 1.07 Ma from the Bosumtwi crater (10.5 km in size) in Ghana and two Muong Nong type samples from the Australasian tektite field (MN-AAT) ejected at 0.79 Ma from a crater possibly situated in southeast Asia. In ICT, Ca-phosphate inclusions are systematically embedded in lechatelierite (SiO2 glass). In MN-AAT Ca-phosphate are either embedded in lechatelierite or in Fe-rich glass forming schlieren. Multiscale petrographic characterization using correlative microscopy associating scanning electron microscopy, microprobe and, transmission electron microscopy reveals that rounded inclusions in ivoirite are composed of acicular Ca-phosphates (merrillite) embedded in an amorphous P-rich glass. In MN-AAT, inclusions consist mostly of single droplets of Fe-Mg rich Ca-phosphate (structurally related to apatite), but few droplets often forming an emulsion texture show a complex assemblage of apatite, magnetite, pyroxene, and spinel growing from a Pt-rich nucleus. Diffusion profile around lechatelierite domains reveals maximum temperatures greater than 2200–2400 °C in the impact plume of the Australasian tektite and the Ivory coast tektite. Heating time is of the order of seconds-tens of seconds rather than minutes as previously suggested (20 s for MN-AAT and 5 s for ICT). The number, the density, and the fact that inclusions are entirely crystallized in MN-AAT support relatively slow cooling rates (<200 °C/h), in comparison with the faster cooling rates (>2000 °C/h) indicated by the precipitation of amorphous P-rich glass in ICT. In both impact events, ejecta that had been heated to high temperatures did not remain in the vapor plume for an extended period of time and landed rapidly (within tens of seconds) at a relatively high temperature (>1000 °C) on the Earth’s surface.Phosphate inclusions systematically embedded in lechatelierite in ICT provide clues about the source material. It suggests that the parent material for these silica-rich inclusions is not conventional detrital quartz. Rather, parts of lechatelierite domains may be inherited from a biogenic source that could be consistent with tropical soil (source of the phosphor) and its biomass (silica of plant origin). The reduction process that tektites record during their formation may be explained by superficial material since forests can contain a sizable mass of carbon that can reduce iron in tektites and produce platinoid-rich metallic nuclei and the Fe3+/ΣFe gradient recorded by the dendritic spinels.

A multiproxy approach for the feeding ecology of Late Miocene ground sloths from the southwestern Amazonia, Upper Solimões Formation, Brazil

A rich assemblage of fossil sloths is recognized in the southwestern Brazilian Amazon, Upper Solimões Formation (Acre Basin), and represents some of the most diverse Folivora fauna from the Late Miocene of tropical South America. Here, we have used a multiproxy approach using carbon (δ13Csc) and oxygen (δ18Osc) isotope compositions of bioapatite structural carbonate, stereomicrowear, ecomorphological indices (relative muzzle width, RMW and occlusal surface area, OSA), and body mass estimates in order to suggest the habitats and diet of the mylodontids (Octodontobradys puruensis, Urumacotherium campbelli, Pseudoprepotherium venezuelanum and Mylodontinae gen. et. sp. nov.) and the nothrotheriid (cf. Mionothropus) ground sloths from localities along the banks at the Purus and Acre rivers in Amazonas and Acre states. The isotopic results (δ13Csc = −13.2 ± 1.2 ‰; δ18Osc = +24.7 ± 0.8 ‰) indicated a consistently C3 plant diet in open-canopy woodland and closed-canopy forest habitats during warm conditions across the Tortonian ages (∼10 and 8.5 Myr). U. campbelli (Urumacotherium sp., bm: 605 kg; Niterói Site) and cf. Mionothropus (bm: 163 kg; Acre 5 Site) possibly had specialized browsing habits (folivorous/frugivorous), due to the few coarse scars in relatively polished tooth surfaces and elongate skull with narrow muzzle, respectively. Both taxa, as also P. venezuelanum (bm: 733 kg; Niterói Site), showed a low OSA values suggesting limited oral food processing offset by higher fermentation capacity and/or lower metabolic requirements. Efficient capacity for oral food processing and a generalized browsing habit with consumption of high intrinsic toughness and abrasiveness items were inferred for O. puruensis (bm: 526 kg; Talismã Site), resembling the pattern observed for the Pleistocene megathere Eremotherium laurillardi from the southwestern Amazon (Acre State). A non-selective browser diet was also supported for the Mylodontinae gen. et. sp. nov. specimen from Cavalcante Site; its similar dentary morphology to the bulk-feeder taxa implies that this individual could occasionally eat C3 herbaceous/grasses.

Environmental fiscal policy and carbon emissions in Turkey: evidence from cointegration and causality analysis with structural breaks

Environmental degradation, a critical issue in academic literature, arises from multiple factors including increased carbon emissions, urbanization, industrialization, mass production, and extensive use of non-renewable energy sources. These factors notably impact sustainable economic growth and environmental quality. Globally, efforts are directed towards optimizing carbon emissions to minimize their adverse effects. This necessitates effective environmental policies. This study examines the effectiveness of Turkey's environmental policy using cointegration and causality tests that account for structural breaks. The analysis utilizes data from 1990 to 2020, the most comprehensive dataset for Turkey to date. Findings indicate that Turkey's environmental policy is effective in reducing carbon emissions, highlighting a need for policy reassessment.

Numerical investigation of the physical-thermal-chemical behaviours of particles during coal combustion and desulfurization processes in a CFB combustor

The desulfurization process has been practised for the clean utilization of coal in chemical engineering fields, yet the physical, thermal, and chemical characteristics of particles are still lacking understanding. In this work, a comprehensive numerical model based on the Eulerian-Lagrangian framework was established to study the particle behaviours during coal combustion and desulfurization processes in a pilot-scale circulating fluidized bed (CFB) combustor. After model validation, the effects of several crucial operation parameters (e.g., excess air ratio, calcium to sulphur ratio, and calcium oxide size) on particle behaviours are illuminated. The results show that density-induced segregation causes coal particles to accumulate in the upper part of the riser. The sand, coal, and CaO particles have time-averaged Reynolds numbers of 15, 6.5, and 0.5, respectively. The particle temperature is higher in areas with lower solid concentrations. Increasing excess air ratio (ϕg) decreases the temperature of sand particles but elevates that of coal and CaO particles. The average particle heat transfer coefficients (HTCs) for sand, coal, and CaO particles are 205 W/m2·K, 172 W/m2·K, and 275 W/m2·K, respectively. With the increase in ϕg, the HTC of sand particles increases but that of CaO particles remains unchanged, additionally, the mass of coal particles decreases and the mass of carbon in coal particles decreases along with the riser. The influence of the Ca/S ratio and CaO size on the axial distribution of coal particle mass and carbon mass fraction is negligible. For each particle species, the axial dispersion coefficient (Dz) is two orders of magnitude greater than the radial ones (Dx, Dy), indicating that the vertical introduction of the fluidizing gas dominates the dense gas-solid flow in the riser.