CO2 Concentration Research Articles

Stabilising CO2 concentration as a channel for global disaster risk mitigation

We investigate the influence of anthropogenic CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {CO}_2$$\\end{document} concentration fluctuations on the likelihood of climate-related disasters. We calibrate annual incidence rates against global disasters and CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {CO}_2$$\\end{document} growth spanning from 1960 to 2022 based on a dynamic panel logit model. We also study the sensitivity of disaster incidence to stochastic carbon dynamics consistent with IPCC-projected climate outcomes for 2100. The key insight is that present and lagged CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {CO}_2$$\\end{document} growth contains valuable information about the likelihood of future disaster events. We further show that lowering carbon stock uncertainty by dampening the persistence or the variability of CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {CO}_2$$\\end{document} concentration has a first-order impact on mitigating expected disaster risk.

Atmospheric CO2 column concentration over Iran: Emissions, GOSAT satellite observations, and WRF-GHG model simulations

Regarding global warming and climate change, carbon dioxide (CO2) is one of the most important greenhouse gases. Simulating CO2 gas at hourly/weekly time intervals and desired vertical resolution is challenging due to the coarse horizontal resolution of global models. In this study, both column-averaged CO2 mixing ratio (XCO2) and vertical cross sections of CO2 mixing ratio were simulated by the Weather Research and Forecast Green House gas (WRF-GHG) model at spatial resolutions of 30 and 10 km for the Middle East region as the first domain, and Iran as the second domain. Simulations consider the primary CO2 sources (anthropogenic, biogenic, fire, and oceanic) and the Copernicus Atmosphere Monitoring Service (CAMS) dataset. XCO2 retrieved from GOSAT satellite observations was employed to evaluate the simulation results of the column-averaged CO2 concentrations in February and August 2010. The evaluations showed that the spatiotemporal variability of meteorological variables was well simulated by WRF-GHG with correlation coefficients r of 0.86–0.92, 0.67–0.75, and 0.76–0.82 for temperature, wind, and relative humidity, respectively, during February and August 2010. The evaluations also indicated that the WRF-GHG simulations outperformed the global model TM3, with mean bias error values of − 0.79 and 0.45 PPMV for WRF-GHG in February and August, respectively. The percentage contribution of net CO2 emissions from human activities in Iran was calculated as (38.33 % and 23.70 %) of the total emissions, respectively, with values of 4.4 and 0.85 kg/km2 in each month. The net emissions contributions of biogenic, fire, and oceanic sources were evaluated in February and August, with biogenic emissions contributing (31.901 % and 27.66 %), biogenic absorption contributing (24.07 % and 46.63 %), fire emissions contributing (5.7 % and 2.064 %), and oceanic emissions contributing (3.23 × 10−6 % and 2.23 × 10−6 %). Large-scale circulations and biogenic activity are responsible for the major features of the spatial and seasonal distribution of CO2 in the area. In February, column mixing ratios are higher in more northern latitudes; in August, they are higher to the south. Furthermore, the simulated vertical cross sections show high CO2 mixing ratios in the mid-lower troposphere and northerly/northeasterly advection in February; the vertical profile is inverted in August with high concentrations in the lower stratosphere associated with southwesterly advection. However, the interaction between the synoptic and sub-synoptic features with the topography determines the precise dispersion and distribution of CO2. Despite the negligible emissions in central and eastern Iran, these factors play an important role in the observed concentrations in February and August. In August, the areas between the 120-day low-level monsoon flow of Sistan in eastern Iran, and the westerlies over western/southwestern Iran and the Zagros Mountain range, interact with the heat-low in the Iranian plains and with the Arabian subtropical high. In February, the dominant winds in western Asia were west winds, with the main source of pollution coming from the northeastern regions flowing towards central and eastern Iran. The equatorward displacement of the polar jet stream and the passage of low-pressure systems from the west in winter cause a temporary reduction in CO2 concentrations.

High-performance multiphase Sm-Co-B alloys with coercivities up to 6.71 MA·m−1

SmCo4B-based alloys with high magnetocrystalline anisotropy are expected to be used as raw materials or constituent phases for new permanent magnets. In this work, we develop Sm(Co, Fe, Ni)4B alloys with excellent hard magnetic properties by tuning the contents of Fe, Co, and Ni. The addition of Fe enhances the amorphous formation ability of the as-spun ribbons, whereas Ni addition improves the structural stability of the crystalline phases. During annealing, the amorphous phase crystallizes into different Sm-Co-B phases in stages. A high coercivity of 5.68–6.71 MA·m−1 is obtained in the annealed SmCo4–x–yFexNiyB (x = 1.0–2.0, y = 0.8–1.0) ribbons composed of platelet-shaped and equiaxed grains in comparison with the coercivity of 2.89–5.18 MA·m−1 in the x = 1.0–1.2 and y = 0–0.8 ribbons with equiaxed grains. Here, we show the strong correlations between the microstructure and magnetic properties and provide insights for the future development of high-performance SmCo4B-based magnets.

Elevated CO2 alters antibiotic resistome in soil amended with sulfamethazine via chemical-organic fertilization

Rising antimicrobial resistance (AMR) is an enormous challenge for global healthcare systems. The effects of elevated CO2 (eCO2) on AMR are poorly characterized. Using a free-air CO2 enrichment system and high-throughput qPCR arrays, we investigated the response of soil antibiotic resistome and bacterial communities to eCO2 (ambient+200ppm) in soils amended with sulfamethazine (SMZ) at 0.1 and 1mgkg-1 via chemical-organic fertilizer (COL, COH). Results showed that under ambient condition, COH significantly enhanced the diversity of high-risk antibiotic resistance genes (ARGs), relative abundance of low risk ARGs, unassessed ARGs and total ARGs compared to COL. Nevertheless, eCO2 mitigated the effects of COH, with no significant difference found between COL and COH on the above high risk, low risk, unassessed and total ARGs. Meanwhile, eCO2 decreased the relative abundance of spcN, ermA, olec, oprD, sulA-olP, tetB, tetT and vanXD in COL, and alleviated the enrichment of pikR2, ampC, lunC, oprD and pncA caused by the application of SMZ at 1mgkg-1. Correlation and network analysis illustrated that changes of certain bacteria biomarkers and horizontal gene transfer of integrase gene were associated with the altered response of ARGs abundance to eCO2. This study adds knowledge of the potential risk of antibiotic resistance in agricultural exposure scenarios under increasing CO2 concentration.

Molybdenum isotopic evidence for linked changes in North Pacific Intermediate Water and subtropical Northwest Pacific redox conditions over the last 200 k.y

Through biological productivity and ocean-atmosphere CO2 exchange, North Pacific mid-depth ventilation has the potential to regulate regional climate over glacial timescales. Nevertheless, the subtropical Northwest Pacific currently lacks continuous long redox records that would enable us to evaluate this process. In this instance, we present δ98/95Mo and redox-sensitive trace element data derived from Okinawa Trough sediments to reconstruct redox conditions and assess their possible significance in regulating atmospheric CO2 in the subtropical Northwest Pacific over the last 200 k.y. Enhanced oxic conditions induced by a strengthened Kuroshio Current during Marine Isotope Stage (MIS) 1 suggest the presence of enhanced deep water ventilation and upwelling in the Okinawa Trough, which likely contributed to high atmospheric CO2 concentrations during interglacial periods. The Okinawa Trough may have been oxic and served as a regional net carbon sink during MIS2 and MIS6, due to glacial North Pacific Intermediate Water (GNPIW) and a weak Kuroshio Current. During interglacials, high productivity brought on by the stronger East Asian Summer Monsoon (EASM) leads to an increase in organic matter burial and oxygen consumption. This substantial positive excursion in δ98/95Mo values during MIS4 and early MIS3 can be linked to the anaerobic oxidation of methane (AOM) and the release of methane-rich fluids from methane hydrate decomposition. Our findings highlight potential links between higher upwelling, GNPIW expansion, and the underlying processes regulating the atmospheric CO2 budget in the subtropical North Pacific during the late Quaternary.

Selective oxidation of emerging contaminants by high-valent cobalt(IV)-Oxo species: Constructing high-spin Co(III) sites in Fenton-like system

In this study, a novel strategy for selectively generating Co(IV)=O species during peroxymonosulfate (PMS) activation was proposed, utilizing an optimized Co4Cu1-layered double hydroxide (LDH) material with low-coordination and high-spin-state Co sites. The incorporation of Cu(II), influenced by the Jahn-Teller effect, altered the geometry and coordination at Co(III) sites, optimizing the filling of Co 3d orbitals. The Co4Cu1-LDH/PMS system demonstrated exceptional catalytic activity for degrading emerging contaminants (ECs) across various water matrices, with a high concentration of Co(IV)=O generation. Continuous flow experiments showed an average 97.51 % degradation over 10 hours, indicating significant practical potential. Mechanistically, enhanced performance was attributed to a single electron transfer process and optimized orbital configurations for oxygen ligands at Co(III) sites. This study offers both theoretical insights and practical guidance for developing efficient catalysts targeting Co(IV)=O species in Fenton-like systems.

In Situ Phase Transformation-Enabled Metal-Organic Frameworks for Efficient CO2 Electroreduction to Multicarbon Products in Strong Acidic Media.

The electrochemical CO2 reduction reaction (CO2RR) has been acknowledged as a promising strategy to relieve carbon emissions by converting CO2 to essential chemicals. Despite significant progresses that have been made in neutral and alkaline media, the implementation of CO2RR in acidic conditions remains challenging due to the harsh conditions, especially in producing high-value multicarbon products. Here, we report that Cu-btca (btca = benzotriazole-5-carboxylic acid) metal-organic framework (MOF) nanostructures can act as a stable catalyst for the CO2RR in an acidic environment. The Cu-btca MOF undergoes phase transformation and morphology evolution during electrolysis, forming a stable porous Cu-btca MOF network. The resultant MOF network exhibits excellent selectivity toward ethylene and multicarbon products with Faradaic efficiencies of 51.2% and 81.9%, respectively, in a strong acidic electrolyte with a flow cell at 300 mA/cm2. Mechanism studies uncover that the Cu-btca MOF network can limit the proton reduction to suppress hydrogen evolution and maintain high local *CO concentration to promote CO2RR. Theoretical calculations suggest that two adjacent Cu sites in the Cu-btca MOF provide a favorable microenvironment for carbon-carbon coupling, facilitating the multicarbon production. This work reveals that rational structure control of MOFs can enable highly selective and efficient CO2 electroreduction to multicarbon products in strong acidic conditions toward practical applications.

Analysis of carbon sink efficiency of trees based on gas photoacoustic spectroscopy detection

Carbon sinks are natural or man-made systems that absorb and store carbon dioxide (CO2) or other greenhouse gases, thereby helping to reduce greenhouse gas concentrations in the atmosphere, and they play an irreplaceable role in the restoration of the ecological environment. Among the current methods for analyzing the carbon sink efficiency of trees, the accuracy and reliability of remote sensing technology are not high. The carbon isotope method cannot guarantee real-time performance, which also greatly affects the development of the carbon trading industry. A gas absorption to laser pulses can excite an acoustic waves, and the gas content can be measured by detecting the size of the wave, which is called photoacoustic(PA) detection technology. In this work, several trees were used as the research object, and an all-optical multi-component PA spectrometer was used to detect the concentration of feature gases in the air nearby the trees. The volume content of C2H2, CO2 and CH4 respectively is detected out, and the volume content of the three gases varies with the trees. Based on the idea of carbon source and generalized carbon source, the three gases can be used to estimate trees’ capacity for sinking carbon sources or mediating ability to carbon source emissions.

Spatio-temporal variability and trends of air pollutants in the Metropolitan Area of Curitiba

Monitoring air pollutants over time is essential for identifying and addressing trends, which may help improve air quality management and safeguard public health. This study investigates the spatio-temporal variability of air quality in the Metropolitan Area of Curitiba (MAC), Brazil, focusing on six pollutants (SO2, NO2, NOx, O3, CO, and PM10) measured at eight monitoring stations from 2003 to 2017. We conducted statistical analyses, including diurnal cycles, seasonal variability, spatio-temporal correlations, conditional bivariate probability functions, Theil-Sen trend analysis, and comparison with national quality standards (NAQS) and World Health Organization (WHO) guidelines. The analyses revealed large variations in pollutant concentrations across the study area. For instance, stations strongly impacted by industrial emissions presented the highest mean annual SO2 (20–28 μg/m3) and PM10 (32–34 μg/m3) concentrations, while those mostly impacted by traffic showed elevated NO2 (31–39 μg/m3), NOx (63–86 μg/m3) and CO (0.6–0.8 mg/m3) concentrations. The two residential stations recorded the highest O3 concentrations (annual mean of 30–32 μg/m3). Seasonal and diurnal patterns varied by pollutant, with winter experiencing higher concentrations and O3 peaking in spring. SO2 concentrations presented no clear seasonal or diurnal cycle patterns, and showed the highest spatial variability. Significant decreasing annual trends were observed for SO2 (−5.9%), NO2 (−2.6%), NOx (−2.6%), CO (−5.4%), and PM10 (−3.7%), which suggests the success of emission reduction programs implemented in the road transportation and industrial sectors. However, O3 concentrations increased at most stations (+3.3%/yr), likely due to reduced NOx emissions, increased emissions of volatile organic compounds from on-road transport biofuels, and regional O3 transport. Although exceedances of NAQS decreased over time, concentrations of most pollutants remained above WHO guidelines, except for CO. These results highlight the importance of targeted emission control strategies for both industrial and vehicular sources to improve local air quality and inform future policy decisions.

Investigation on steam co-gasification of torrefied biomass and coal: Thermal behavior, reactivity, product characteristic and synergy

The steam gasification of rice straw torrefied at 200–300 °C and its co-gasification with coal were examined in this study. The effect of torrefaction temperature on thermal behavior, reactivity, product characteristic, and synergy were investigated. The results showed that torrefaction temperature influenced the pyrolysis and char gasification stages by shifting them to higher temperature ranges. As torrefaction temperature increased, the H2 content increased while the CO and CH4 contents decreased, with H2/CO molar ratio increasing from 1.8 to 2.4. The total gas yield also increased from 0.95 to 1.30 Nm3/kg, especially with a large increase up to 27.4 %. As for the co-gasification, stages of biomass pyrolysis and coal pyrolysis overlapped at torrefaction temperature of 300 °C. The pyrolysis reactivity decreased while the char gasification reactivity increased with the torrefaction temperature increasing. The H2/CO molar ratio decreased slightly from 3.55 to 3.40, while the total gas yield increased from 1.87 to 1.96 Nm3/kg as well as the cold gas efficiency from 75 % to 77 %. The strongest synergistic effect on the reactivity occurred at torrefaction temperature of 250 °C. The increased torrefaction temperature enhanced the synergistic effect on the total gas yield but weakened it on the H2 yield.

Comprehensive study on co-pyrolysis mechanisms of sewage sludge and low rank coal under rapid/slow heating conditions

Co-pyrolysis of sewage sludge (SS) and low rank bituminous coal (BC) was considered as an effective technology in realising the co-resource utilization and disposal of municipal waste. The current work focused on the co-pyrolysis characteristics and synergistic mechanisms under rapid/slow heating conditions, with experimental and analytical methods of the thermogravimetric-mass spectrometry (TG-MS), gas chromatography (GC), and Fourier transform infrared spectroscopy (FTIR). The results showed that the heating rate and mixing ratio of SS and BC caused different yields of the co-pyrolysis products. The gas products performed different releasing rules with the effect of mixing ratio of SS and BC, and the different stages during the slow pyrolysis were defined in terms of weight loss and product release. Under the rapid heating condition, the gas product yield in the experiment was found to be consistently higher than the theoretical yield, regardless of the mixing ratio. The addition of SS in the mixtures would increase the yield content of CO2 and high calorific gases (C2H2, C2H4, C2H6) and reduce H2, CO, and CH4. The intensities and widths of the absorption peaks of functional groups such as O-H, C-H, C=O and C=C in the char decreased. The morphology, pore structure, and particle size distribution of the pyrolyzed samples were compared and analysed. Kinetic analysis was carried out according to different stages of slow pyrolysis. Finally, the synergistic effect and mechanism of the co-pyrolysis were comprehensively compared and revealed under slow/rapid heating conditions.

Reactive carbon capture using saline water: evaluation of prospective sources, processes, and products.

Reactive carbon capture (RCC) processes involve the capture of carbon dioxide (CO2) and conversion to a value-added product using a single sorbent/reaction medium. Not only can RCC processes generate valuable byproducts that can reduce the cost of carbon capture, but RCC tends to have lower energy demand than processes involving the transfer of CO2 between the mediums used for capture and subsequent reactions. Saline water has been proposed as a potential medium for RCC due to it's relative abundance and low cost. Additionally, the composition and chemistry of many saline water sources: (1) elevates the CO2 content (as compared to atmospheric concentrations), (2) provides various cations that can form valuable products with CO2, and (3) enhances the kinetics of chemical reactions used to convert CO2 to stable byproducts. In addition to established industrial processes for converting CO2 into inert or valuable byproducts, we found 20 new processes and technologies that have been developed specifically to capture and convert CO2 using saline water. Both preexisting and emerging processes can be broadly classified as electrochemical or chemical titration processes. When assessing the potential viability of applying any of these processes for large scale carbon capture, several factors must be considered, such as the net carbon footprint of the process, the market size, location of customers and value of the end product, the energy demand and chemical costs of the process, and any other environmental impacts. The feasability of many emerging saline-based RCC processes is difficult to determine, as many technologies were tested using synthetic saline waters and/or concentrated CO2 sources. Notwithstanding the early stage of development of many saline-based RCC technologies, the major limitation to implementation of this approach to carbon capture is the mismatch in the scale of the markets for products of saline-based RCC and the scale of carbon capture needed to meet climate goals. However, because the products of many of the processes reviewed here are stable and non-hazardous, these technologies may also be used for carbon sequestration efforts where the products are managed as waste, in which case the carbon capture potential of these technologies can surpass the market-imposed limitations on RCC. Thus, the potential benefits of saline water-based RCC identified in this review encourage further study and development of these technologies.

Numerical simulation and experimental study of hydrogen production from chili straw waste gasification using Aspen Plus

Biomass gasification is a promising method for hydrogen production. This study systematically models the gasification of chili straw waste (CSW) using the Aspen Plus simulator, focusing on the effects of gasification agents—steam, air, and oxygen—and sensitivity analyses of key parameters. Results show that under optimal steam gasification conditions, with a temperature of 700 °C and atmospheric pressure, hydrogen concentration reached 59.61%, while the lower heating value (LHV) decreased to 6.65 MJ/m3 due to CO reduction. In air gasification, increasing air input reduced hydrogen and CO concentrations by 18.5% and 26.6%, respectively, while LHV dropped by 52.5%. Oxygen-enriched gasification significantly improved hydrogen and CO concentrations, increasing LHV by 129.4% as the oxygen fraction rose. Sensitivity analysis revealed that optimal hydrogen production in air-steam gasification occurred with a low equivalence ratio of 0.18, moderate temperature around 700 °C, and atmospheric pressure. These findings highlight the critical role of temperature, pressure, and gasifying agents in optimizing hydrogen production, providing a basis for improving the efficiency of biomass gasification systems.

Characterizing the Impacts of 2024 Total Solar Eclipse Using New York State Mesonet Data.

On 8 April 2024, a rare total solar eclipse (TSE) passed over western New York State (NYS), the first since 1925 and the last one until 2079. The NYS Mesonet (NYSM) consisting of 126 weather stations with 55 on the totality path provides unprecedented surface, profile, and flux data and camera images during the TSE. Here we use NYSM observations to characterize the TSE's impacts at the surface, in the planetary boundary layer (PBL), and on surface fluxes and CO2 concentrations. The TSE-induced peak surface cooling occurs 17min after the totality and is 2.8°C on average with a maximum of 6.8°C. It results in night-like surface inversion, calm winds, and reduced vertical motion and mixing, leading to the shallowing of the PBL and its moistening. Surface sensible, latent and ground heat fluxes all decrease whereas near-surface CO2 concentration rises as photosynthesis slows down.

Carbon farming for climate change mitigation and ecosystem services – Potentials and influencing factors

Carbon Farming (CF) decreases atmospheric CO2 concentrations by increasing carbon stocks in soils and biomass. In addition to mitigating climate change, CF measures provide co-benefits through the supply of additional ecosystem services (ES). Integrating such benefits into a comprehensive assessment may increase the attractiveness of CF measures, increase adoption rates, and ultimately benefit climate and ecosystems. However, site-specific and measure-specific characteristics influence the impacts of CF measures. A comprehensive overview over CF impacts is lacking. We therefore analyzed six CF measures on cropland in the European temperate zone: (1) cover cropping, (2) introducing legumes or semi-perennial crops into crop rotations, (3) conversion to short rotation coppice, (4) agroforestry, (5) afforestation of marginal cropland, and (6) partial rewetting of drained organic soils. Through a structured literature review, we derived on-site climate change mitigation potentials, impacts on the supply of ES, and economic trade-offs, as well as influencing factors causing spatial heterogeneities. Our results show that the climate change mitigation potential varies strongly between and within CF measures. All measures can boost the supply of regulating ecosystem services, while trade-offs exist mainly with provisioning services and economic returns. Spatially heterogeneous effects in ES supply depend on local ES demand. As proof of concept, we mapped expected beneficial ES effects from 4 selected ES positively impacted by the measure (4) agroforestry in a GIS environment for Germany, as well as opportunity costs as an economic trade-off. The results suggest that strong co-benefits can be expected in areas where opportunity costs are high. Moreover, the CF measures with the highest climate change mitigation potential also imply the highest systemic change of the farm system. This constitutes a strong economic hurdle to implementation. We argue that payments for ES are needed to incentivize CF adoption and harness the beneficial effects on climate and ecosystems. Our findings provide a comprehensive view on the effect of CF measures and may support effective European climate change mitigation policy.

Origin of fluids in the Araró-Simirao geothermal system, Central Mexico

The Araró-Simirao geothermal system is located in the eastern part of Cuitzeo Lake in Michoacán, Mexico. It is a liquid-dominated convective system featuring a high salinity, rapid discharge, and heat loss derived into a self-sealing process. The reservoir temperature is higher than 200 °C, associated with a fracture zone linked to the Araró-Simirao fault. Samples of thermal fluids (water and gases) were collected from springs, wells, a mud pool, and runoff water in the study area. The waters had temperatures ranging from 31 °C and 76 °C and near-neutral pH values. Three hydrogeochemical facies types were identified, Na+- Cl−, Ca2+-Na+ - HCO3−, and Na+ -HCO3−, associated with deep thermal water, groundwater, and recently infiltrated water, respectively.According to the stable isotopes systematics, a binary mixture of thermal water and groundwater was calculated at a proportion from 61 % to 80 % of the thermal component. In the mud pool sample, the chemical composition of bubbling gas is CO2-dominated, with a mostly magmatic origin according to the Rc/Ra (5.19), CO2/3He (4.12 × 109) ratios, and the isotopic composition of δ13C(CO2) (−8 ‰). The gases dissolved in waters are characterized by higher N2 and CO2 concentrations compared to the other gases, representing possible mixing processes between an end-member enriched in CO2 and the chemical composition of air-saturated water. Regarding helium isotopes, the gases are the result of mixing origins between crustal, atmospheric, and mantellic helium, and 3 groups were identified: 1) high contribution of mantle helium ranging from 21 to 66 % up to (Mud pool, LS07 and LS07A) 2) high contribution of crustal helium (LSA-02, LSA-08A, Araró) ranging from 55 to 80 % and 3) high contribution of atmospheric helium of 84 % (LSA-08). The δ13C(CO2) results show a primary interaction with magmatic environments and a slightly sedimentary origin. The origin of CO2, MORB-type, as well as other gases, may be similar to that in Los Azufres. However, these gases reach the surface through different vertical paths, resulting in varying fluid compositions. In the study area, the Araró-Simirao and Huigo faults would act as zones for these gas ascents from the degassing source (magma) at depth.According to the estimates of the magma aging model, the age of the mud pool sample is estimated to be 2.7 × 106 ± 1.2 × 106 years, which is younger than the andesitic basement rocks. Additionally, there is evidence of a more recent 3He input in the sample. However, the Los Azufres geothermal system has a 3He input from rocks that are even younger (1.5 × 105 years). This suggests that Los Azufres may have a more recent 3He input than Araro-Simirao.

Acclimation of barley plants to elevated CO2 concentration and high light intensity does not increase their protection against drought, heat, and their combination

Plants face fluctuations in environmental conditions throughout their life cycles. Some of these conditions, such as CO2 concentration and increasing temperature, are closely linked to ongoing climate change. These conditions not only affect plant growth and development but also modify the response to sudden exposure to stressors through morphological, physiological, and biochemical acclimation. Understanding these responses is therefore important for defining adaptation strategies for future crop production. In this study, we tested the acclimation effect of light intensity (low, high) and CO2 concentration (low, ambient, elevated) on barley plants and its implications for subsequent responses to drought, heat, and their combination. The acclimation to the growth conditions induced numerous changes both in plant morphology and physiology. The whole-plant leaf area was stimulated by increasing light intensity and CO2 concentration. That led to increased whole-plant transpiration despite the trend of stomatal conductance was the opposite in comparison to leaf area. The increased whole-plant transpiration then increased the sensitivity of barley plants to the stress treatments. Similarly, the stimulatory effect of high light intensity on antioxidative capacity was not sufficient to improve barley performance under the stress treatments. The presented results show that for physiological or biochemical indicators of stress tolerance to be realistically used to evaluate the expected response to stress conditions, they must be related to the morphology of the whole plant, which influences both the severity of stress and the quantitative role of resistance mechanisms.

Effects of sugarcane cultivation in the carbon dioxide dynamics in tropical headwater streams

São Paulo state is the largest sugarcane cultivation area in Brazil and is the largest sugarcane producer in the world. However, the impact of sugarcane cultivation on carbon dynamics in tropical stream ecosystems remains poorly understood. We investigated CO2 emissions and concentrations in streams draining sugarcane fields and native vegetation catchments to elucidate the influence of sugarcane cultivation on CO2 dynamics in streams. Contrary to our hypothesis, streams from native vegetation catchments exhibited greater CO2 emissions and concentrations than those from draining sugarcane fields. This result can be attributed to the soil respiration, which are higher in native vegetation catchments due to higher organic matter inputs. Our findings underscore the significant role of tropical vegetation dynamics in shaping carbon dynamics in freshwater ecosystems and the connections between terrestrial and aquatic ecosystems in headwaters. Additionally, we observed higher CO2 emissions during the summer, attributable to increased temperatures, streamflow, and terrestrial organic matter inputs in soils and streams. The variables influencing CO2 concentrations were pH, conductivity, season, and methane concentration, highlighting the complex interplay of environmental factors. Future research should address critical gaps, including the effects of soil texture and liming on CO2 dynamics, and the quantification of the contributions of methane oxidation to CO2 emissions. Understanding these factors is vital for assessing the impact of sugarcane cultivation on freshwater carbon cycles, particularly in regions such as Brazil, which is a major contributor to global sugarcane production.

Solid-State Electrochemical Carbon Dioxide Capture by Conductive Metal-Organic Framework Incorporating Nickel Bis(diimine) Units.

This paper presents the first implementation of electrically conductive metal-organic framework (MOF) Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 (Ni3(HITP)2) integrated with nickel bis(diimine) (Ni-BDI) units for efficient solid-state electrochemical carbon dioxide (CO2) capture. The electrochemical cell assembled using Ni3(HITP)2 as working electrodes can reversibly capture and release CO2 through potential control. A high-capacity utilization of 96% and a Faraday efficiency of 98% have been achieved. The material also exhibits excellent electrochemical stability with its capacity maintained during 50 capture-release cycles and resistance to general interferences, including O2, H2O, NO2, and SO2. Capacity utilization of up to 35% is obtained at CO2 concentrations as low as 1%. The capture of CO2 at concentrations ranging from 1% to 100% requires exceptionally low energy consumption of only 30.5-72.4 kJ mol-1. Studies combining spectroscopic experiments and computational approaches reveal that the CO2 capture and release mechanism involves reversible carbamate formation on the N atom of the Ni-BDI unit in the MOF upon its one-electron redox reaction.

Three-dimensional numerical simulation of coal and papermaking trash co-combustion in a circulating fluidized bed

Circulating fluidized bed (CFB) combustion is a important method of waste treatment with the benefits of harmlessness, recycling, and energy recovery. Using the existing co-firing CFB boiler to dispose of waste can reduce investment in boilers and environmental protection equipment. However, there is currently limited research available on the co-combustion of coal and waste (especially for papermaking trash), and the mechanism of pollutant emissions during unit operation remains unclear. In this work, the co-combustion of coal and papermaking trash in a three-dimensional industrial-scale CFB are investigated by using the Dense Discrete Phase Model (DDPM) method. Both homogeneous reactions (such as fuel particle pyrolysis, combustion, and surface reaction) and non-homogeneous reactions (such as gas combustion and pollutant generation) are considered. The co-combustion characteristics are comprehensively analyzed in terms of gas distribution, chemical reaction rates, and bed temperature under various operating conditions, including fuel mixing ratio, secondary air arrangement, and excess air coefficient. The results are obtained by comparing the distribution profile along the height. By reducing the mixing ratio of papermaking trash, the excess air coefficient, and adjusting the secondary air arrangement in the lower region, an expanding, reducing atmosphere is observed in the vicinity of the fuel feeding point. This, in turn, leads to an increase in CO concentration and a decrease in NO emissions, which is attributable to the interplay of gas distribution, chemical reaction rates, and bed temperature. A reduction in NO gas emissions was achieved by adjusting the secondary air arrangement and the excess air coefficient. Overall, this work provides valuable insights into the co-combustion characteristics of coal and papermaking trash in an industrial-scale circulating fluidized bed boilers.