Changes In CO2 Research Articles

Asian monsoonal temperature and environmental changes since the penultimate deglaciation as revealed by alkenones and alkanes in sediments from the northern South China Sea

A new alkenone sea surface temperature (SST) record from the South China Sea (SCS) over the last 170 ka has been reported here. Our analysis of magnetic susceptibility and AMS 14C dating on the top portion of the core suggests that this record dates to the Marine Isotope Stage (MIS) 6. As indicated in Termination I and II, SST changes are correlated with clear glacial/interglacial cycles and likely dominated by atmospheric CO2 and Western Pacific Warm Pool temperature changes. But the two Terminations were different in magnitude. In Termination I, the minimum and maximum SSTs are 24.5 °C and 27.5 °C, respectively, showing a smaller rise (3 °C) than in Termination II (24–28.3 °C). The n-alkane indices, such as average chain length (ACL) and carbon preference index (CPI), exhibited high/low values during glacial/interglacial periods, and possible more arid climate during MIS 6 than MIS 2. During Termination II, the maximum surface warming in the SCS is accompanied by a progressive lag of approximately 7000 years in relation to maximum summer insolation until Termination I, when they are nearly synchronous. According to the study, SSTs are continuously changing and are influenced by solar insolation, global ice volume changes, and ocean–atmosphere interactions across hemispheres.

The Effects of Halogen (Cl, Br) Decorating on the Gas Adsorption Behaviors of the Pristine Black Phosphorene: A First-Principles Study

As a novel two-dimensional (2D) material, black phosphorene (BP) finds wide applications in gas adsorption and detection devices due to its distinctive optical, thermoelectric, and surface properties. However, numerous studies have demonstrated that BP exhibits strong selectivity towards gas adsorption and displays significant affinity towards gas molecules containing the element N, thereby greatly impeding its utilization in gas detection. To partially compensate for this deficiency, this study investigates the impact of halogen atom decoration on the adsorption behavior of BP towards CO2, H2O, and O2 molecules. Furthermore, a comparison is made between the variations in gas adsorption energy with and without decorated halogen atoms. The results showed that the adsorbates of CO2, H2O, and O2 molecules and halogen atoms (Cl, Br) adsorbed at the top (T) site of BP was much stronger than those at the bridge (B) and the hollow (H) sites of the P-P bond of BP, owing to their low adsorption energies. After the t position of BP is modified by the halogen (Cl, Br) atom, the optimal adsorption of CO2 changes from −0.85 eV to −1.70 eV (Cl) and −1.64 eV (Br), and the optimal adsorption of H2O changes from −0.72 eV to −1.48 eV (Cl) and −1.23 eV (Br), respectively. The adsorption properties were significantly enhanced. That is to say, the gas adsorption properties of BP have been largely improved by halogen Cl (Br) atoms decorating.

Nitrogen niche partitioning between tropical legumes and grasses conditionally weakens under elevated CO2

Abstract Plant community biodiversity can be maintained, at least partially, by shifts in species interactions between facilitation and competition for resources as environmental conditions change. These interactions also drive ecosystem functioning, including productivity, and can promote over‐yielding‐ an ecosystem service prioritized in agro‐ecosystems, such as pastures, that occurs when multiple species together are more productive than the component species alone. Importantly, species interactions that can result in over‐yielding may shift in response to rising CO2 concentrations and changes in resource availability, and the consequences these shifts have on production is uncertain especially in the context of tropical mixed‐species grasslands. We examined the relative performance of two species pairs of tropical pasture grasses and legumes growing in monoculture and mixtures in a glasshouse experiment manipulating CO2. We investigated how over‐yielding can arise from nitrogen (N) niche partitioning and biotic facilitation using stable isotopes to differentiate soil N from biological N fixation (BNF) within N acquisition into above‐ground biomass for these two‐species mixtures. We found that N niche partitioning in species‐level use of soil N versus BNF drove species interactions in mixtures. Importantly partitioning and overyielding were generally reduced under elevated CO2. However, this finding was mixture‐dependent based on biomass of dominant species in mixtures and the strength of selection effects for the dominant species. This study demonstrates that rising atmospheric CO2 may alter niche partitioning between co‐occurring species, with negative implications for the over‐yielding benefits predicted for legume‐grass mixtures in working landscapes with tropical species. Furthermore, these changes in inter‐species interactions may have consequences for grassland composition that are not yet considered in larger‐scale projections for impacts of climate change and species distributions. Read the free Plain Language Summary for this article on the Journal blog.

Real-time blood gas analysis using pH, PO2 and PCO2 multifunctional fluorescent capillary sensing system

Real-time blood gas analysis is of great significance in disease diagnosis and treatment. Here we have developed a pH, PO2 and PCO2 multifunctional fluorescent capillary sensing system. The pH, O2 and CO2 fluorescent indicators with same excitation wavelength are fixed into a single capillary tube. The sensing system possesses sensitive fluorescence response to pH, O2 and CO2, and the changes of pH, O2 and CO2 in buffer, in vitro, and in vivo can be detected simultaneously by measuring the fluorescence signals of sensor probe. The PO2, PCO2 and pH of rabbits in four disease models were assessed efficiently by the sensing system, exhibiting similar variation trend with the results by blood gas analyzer. Studies in living rabbit display the reasonable and favorable feasibility of capillary sensing system in real-time arterial blood gas analysis. Overall, the multifunctional fluorescent capillary sensing system exhibits significant potential in real-time arterial blood gas analysis and clinical application of disease diagnosis.

The Response Characteristics of Pore Volume and Specific Surface Area of Different Phases of Carbon Dioxide Injection into Anthracite Coal Pores

After the coal sample reacts with CO2, the porosity and pore volume change. Compared with dry raw coal sample, the porosity of coal after CO2 adsorption is increased. With the increase of CO2 injection pressure, the porosity of coal will gradually increase, especially when CO2 enters the supercritical phase. In terms of pore capacity of coal samples, CO2 adsorption time, CO2 adsorption pressure and CO2-H2O treatment do not show obvious regularity in the changes of pore capacity of coal samples, but in general, the increase of CO2 adsorption pressure and CO2-H2O treatment have a positive effect on the increase of pore capacity of coal samples, especially ScCO2-H2O. The mesoporous pore capacity increased by 137.1%. In terms of macro pore volume of coal sample, the change of macro pore volume after CO2 adsorption is more regular. Extending CO2 adsorption time, increasing CO2 adsorption pressure and CO2-H2O treatment all have positive effects on the increase of macro pore volume of coal sample. Under 8MPaScCO2-H2O, macro pore volume reaches a maximum of 0.016462ml/g. The increase also reached 130.4 percent. On the mesoporous specific surface area of coal sample, increasing CO2 adsorption pressure, prolongating CO2 adsorption time and CO2-H2O treatment can increase the mesoporous specific surface area of the sample. The mesoporous specific surface area of the sample at 8 MPa ScCO2-H2O is 0.631 m2/g, which reaches the maximum in this experiment, with an increase of 334.27%.

Fish gill chemosensing: knowledge gaps and inconsistencies.

In this review, we explore the inconsistencies in the data and gaps in our knowledge that exist in what is currently known regarding gill chemosensors which drive the cardiorespiratory reflexes in fish. Although putative serotonergic neuroepithelial cells (NEC) dominate the literature, it is clear that other neurotransmitters are involved (adrenaline, noradrenaline, acetylcholine, purines, and dopamine). And although we assume that these agents act on neurons synapsing with the NECs or in the afferent or efferent limbs of the paths between chemosensors and central integration sites, this process remains elusive and may explain current discrepancies or species differences in the literature. To date it has been impossible to link the distribution of NECs to species sensitivity to different stimuli or fish lifestyles and while the gills have been shown to be the primary sensing site for respiratory gases, the location (gills, oro-branchial cavity or elsewhere) and orientation (external/water or internal/blood sensing) of the NECs are highly variable between species of water and air breathing fish. Much of what has been described so far comes from studies of hypoxic responses in fish, however, changes in CO2, ammonia and lactate have all been shown to elicit cardio-respiratory responses and all have been suggested to arise from stimulation of gill NECs. Our view of the role of NECs is broadening as we begin to understand the polymodal nature of these cells. We begin by presenting the fundamental picture of gill chemosensing that has developed, followed by some key unanswered questions about gill chemosensing in general.

Landscape evolution in the southern Transantarctic Mountains during the early Miocene (c. 20–17 Ma) and evidence for a highly dynamic East Antarctic Ice Sheet margin from the southernmost volcanoes in the world (87°S)

Observations of ice sheet stability in Antarctica in the past, during significantly warmer climatic periods than today, are hampered by a paucity of continental outcrops but they are essential if we are to test and more fully understand established concepts of ice sheet growth and decay and robustly predict Earth's future during rapid global warming. In this paper we use the unique terrestrial record preserved in the three most southerly volcanoes on Earth to reconstruct Antarctica's environmental landscape in the Transantarctic Mountains for three time slices (at 20.1, 19.31 and c. 17 Ma). We demonstrate that the East Antarctic Ice Sheet margin was highly dynamic and fluctuated greatly during the Early Miocene. The period included a much-reduced ice cover that left the southern Transantarctic Mountains virtually ice-free, although a few tidewater glaciers reached the shores of the Early Miocene Ross Sea (Sheridan Bluff; 20.1 Ma); and a substantially thicker, much more voluminous ice mass (represented by volcanism at Mount Early; 19.31 Ma). An intermediate stage of ice retreat is also indicated (at c. 17 Ma), when the East Antarctic Ice Sheet had again withdrawn to behind the Transantarctic Mountains. It is represented by a subglacial volcanic centre identified remotely by aerogeophysics and sampled only as glacial erratics. The associated ice cover at c. 17 Ma had a relatively low surface elevation but it was confluent with thin ice domes that covered the adjacent mountains. Although the ice margin probably did not extend down to the Ross Sea coast, several glaciers fed icebergs into the Ross Sea. The large ice sheet indicated by the Mount Early volcanic centre is the only known physical record of a significant glacial event that took place at 19.31 ± 0.32 Ma (‘Mount Early glacial’). The records examined at the other two volcanic sites correspond to eruptions during periods of substantially reduced ice in Antarctica, of which that at 20.1 ± 0.4 Ma is the most remarkable (‘Sheridan Bluff interglacial’). The causes of the extreme variations in ice sheet thickness and extent indicated are uncertain but they occurred during a period of rapidly fluctuating atmospheric CO2 compositions. Although Milankovitch astronomical forcing probably also played a significant part, the results suggest that the East Antarctic Ice Sheet was highly susceptible to comparatively slight changes in CO2 during the warm Early Miocene.

Data-based modeling of cerebral hemodynamics quantifies impairment of cerebral blood flow regulation in type-2 diabetes

We studied the regulation dynamics of cerebral blood velocity (CBv) at middle cerebral arteries (MCA) in response to spontaneous changes of arterial blood pressure (ABP), termed dynamic cerebral autoregulation (dCA), and end-tidal CO2 as proxy for blood CO2 tension, termed dynamic vasomotor reactivity (DVR), by analyzing time-series data collected at supine rest from 36 patients with Type-2 Diabetes Mellitus (T2DM) and 22 age/sex-matched non-diabetic controls without arterial hypertension. Our analysis employed a robust dynamic modeling methodology that utilizes Principal Dynamic Modes (PDM) to estimate subject-specific dynamic transformations of spontaneous changes in ABP and end-tidal CO2 (viewed as two “inputs”) into changes of CBv at MCA measured via Transcranial Doppler ultrasound (viewed as the “output”). The quantitative results of PDM analysis indicate significant alterations in T2DM of both DVR and dCA in terms of two specific PDM contributions that rise to significance (p < 0.05). Our results further suggest that the observed DVR and dCA alterations may be due to reduction of cholinergic activity (based on previously published results from cholinergic blockade data) that may disturb the sympatho-vagal balance in T2DM. Combination of these two model-based “physio-markers” differentiated T2DM patients from controls (p = 0.0007), indicating diabetes-related alteration of cerebrovascular regulation, with possible diagnostic implications.

Mutual inhibition effects of elevated CO2 and climate change on global forest GPP

The impact of CO2 fertilization on enhancing global forest gross primary productivity (GPP) is acknowledged, but its interaction with climate factors—air temperature (Tem), precipitation (Pre), vapor pressure deficit (VPD), and radiation (Rad)—remains unclear. In this study, global forest GPP trends from 1982 to 2018 were examined using BEPS, NIRv, FLUXCOM, and revised EC-LUE datasets, with interannual trends of 5.618 (p < 0.01), 5.831 (p < 0.01), 0.227, and 6.566 g C m−2 yr−1 (p < 0.01), respectively. Elevated CO2 was identified as the primary driver of GPP trends, with the dominant area ranging from 51.11% to 90.37% across different GPP datasets. In the NIRv and revised EC-LUE datasets, the positive impact of CO2 on GPP showed a decrease of 0.222 g C m−2 yr−1, while the negative impact of Rad increased by 0.007 g C m−2 yr−1. An inhibitory relationship was found between the actual effects of elevated CO2 and climate change on GPP in most forest types. At lower latitudes, Tem primarily constrained CO2 fertilization, while at higher latitudes, VPD emerged as the key limiting factor. This was mainly attributed to the potential trade-off or competition between elevated CO2 and climate change in influencing GPP, with strategic resource allocation varying across different forest ecosystems. This study highlights the significant inhibitory effects of elevated CO2 and climate change on global forest GPP, providing insights into the dynamic responses of forest ecosystems to changing environments.

Broadleaf afforestation impacts on terrestrial hydrology insignificant compared to climate change in Great Britain

Abstract. Widespread afforestation has been proposed internationally to reduce atmospheric carbon dioxide; however, the specific hydrological consequences and benefits of such large-scale afforestation (e.g. natural flood management) are poorly understood. We use a high-resolution land surface model, the Joint UK Land Environment Simulator (JULES), with realistic potential afforestation scenarios to quantify possible hydrological change across Great Britain in both present and projected climate. We assess whether proposed afforestation produces significantly different regional responses across regions; whether hydrological fluxes, stores and events are significantly altered by afforestation relative to climate; and how future hydrological processes may be altered up to 2050. Additionally, this enables determination of the relative sensitivity of land surface process representation in JULES compared to climate changes. For these three aims we run simulations using (i) past climate with proposed land cover changes and known floods and drought events; (ii) past climate with independent changes in precipitation, temperature, and CO2; and (iii) a potential future climate (2020–2050). We find the proposed scale of afforestation is unlikely to significantly alter regional hydrology; however, it can noticeably decrease low flows whilst not reducing high flows. The afforestation levels minimally impact hydrological processes compared to changes in precipitation, temperature, and CO2. Warming average temperatures (+3 °C) decreases streamflow, while rising precipitation (130 %) and CO2 (600 ppm) increase streamflow. Changes in high flow are generated because of evaporative parameterizations, whereas low flows are controlled by runoff model parameterizations. In this study, land surface parameters within a land surface model do not substantially alter hydrological processes when compared to climate.

ЗАКОНОМЕРНОСТИ ИЗМЕНЕНИЯ КОНЦЕНТРАЦИЙ CO2 И CH4 ПО РЕЗУЛЬТАТАМ ИЗМЕРЕНИЙ В ПРИЗЕМНОМ СЛОЕ АТМОСФЕРЫ ГОРОДСКОЙ И ЗАГОРОДНОЙ ТЕРРИТОРИИ В 2021-2022 ГОДАХ

The patterns and factors of changes in CO2 and CH4 concentrations in the surface atmosphere of an urbanized and suburban environment were analyzed based on the results of the synchronous measurements in Yekaterinburg and the Kourovka Astronomical Observatory (KAO) in September 2021–August 2022. On average, the maximum levels of CO2 in Yekaterinburg (443.2 ppm) were shown to be higher than in KAO (432.4 ppm) and were reached in January. The minima, on the contrary, were lower in the city than in the suburban area (405.4 ppm in July in Yekaterinburg against 412.7 ppm in September in KAO). Enhanced CO2 levels in the warm season in KAO were caused by very high nighttime concentrations (up to 500 ppm), which was not observed in the surface urban atmosphere. For CH4, the seasonal dynamics in the city and in KAO was similar: the maximum levels were reached in January (2.154 and 2.076 ppm), and the minima were registered in June (1.998 and 1.971 ppm). The mutual influence of the territories under consideration was assessed to be moderate. The results of the study can be used to develop a technology for assessing the carbon balances on a regional scale, which is the main task of the Carbon Supersites program in the Urals.

Atmospheric oxygenation as a potential trigger for climate cooling

Secular changes in atmospheric CO2 and consequent global climate variations, are commonly attributed to global outgassing and the efficiency of silicate weathering, which may have been linked to mountain formation, land/arc distribution, and plant colonization through geological time. Although oxidative weathering has been shown to exert a significant role in the propagation of weathering fronts through the oxidation of Fe-bearing minerals, the influence of atmospheric O2 concentration (pO2) on silicate weathering, CO2 consumption, and global climate has not been thoroughly evaluated. This study presents a numerical model aimed at estimating the effects of pO2 on the climate, considering the influence of pO2 on the regolith thickness and thus weathering duration of granitic domains. Our model simulations reveal that an increase in weathering efficiency, through deeper penetration of the oxidative weathering front in the granitic regolith, would independently introduce a steady-state climate cooling of up to ∼8 °C, in step with one-order of magnitude rise in pO2. This temperature change may have repeatedly initiated the runaway ice-albedo feedback, leading to global glacial events (e.g., Neoproterozoic Snowball Earth). Increasing granitic weathering efficiency caused by a substantial pO2 increase may also have contributed to the development of icehouse climate during the Phanerozoic.

Earth system responses to carbon dioxide removal as exemplified by ocean alkalinity enhancement: tradeoffs and lags

Carbon dioxide removal (CDR) is discussed for offsetting residual greenhouse gas emissions or even reversing climate change. All emissions scenarios of the Intergovernmental Panel on Climate Change that meet the ‘well below 2 °C’ warming target of the Paris Agreement include CDR. Ocean alkalinity enhancement (OAE) may be one possible CDR where the carbon uptake of the ocean is increased by artificial alkalinity addition. Here, we investigate the effect of OAE on modelled carbon reservoirs and fluxes in two observationally-constrained large perturbed parameter ensembles. OAE is assumed to be technically successful and deployed as an additional CDR in the SSP5-3.4 temperature overshoot scenario. Tradeoffs involving feedbacks with atmospheric CO2 result in a low efficiency of an alkalinity-driven atmospheric CO2 reduction of −0.35 [−0.37 to −0.33] mol C per mol alkalinity addition (skill-weighted mean and 68% c.i.). The realized atmospheric CO2 reduction, and correspondingly the efficiency, is more than two times smaller than the direct alkalinity-driven enhancement of ocean uptake. The alkalinity-driven ocean carbon uptake is partly offset by the release of carbon from the land biosphere and a reduced ocean carbon sink in response to lowered atmospheric CO2 under OAE. In a second step we use the Bern3D-LPX model in CO2 peak-decline simulations to address hysteresis and temporal lags of surface air temperature change (ΔSAT) in an idealized scenario where ΔSAT increases to ~2 °C and then declines to ~1.5 °C as result of CDR. ΔSAT lags the decline in CO2-forcing by 18 [14–22] years, depending close to linearly on the equilibrium climate sensitivity of the respective ensemble member. These tradeoffs and lags are an inherent feature of the Earth system response to changes in atmospheric CO2 and will therefore be equally important for other CDR methods.

Stable isotope evidence for long-term stability of large-scale hydroclimate in the Neogene North American Great Plains

Abstract. The Great Plains of North America host a stark climatic gradient, separating the humid and well-watered eastern US from the semi-arid and arid western US, and this gradient shapes the region's water availability, its ecosystems, and its economies. This climatic boundary is largely set by the influence of two competing atmospheric circulation systems that meet over the Great Plains – the wintertime westerlies bring dominantly dry air that gives way to moist, southerly air transported by the Great Plains low-level jet in the warmer months. Climate model simulations suggest that, as CO2 rises, this low-level jet will strengthen, leading to greater precipitation in the spring but less in the summer and, thus, no change in mean annual precipitation. Combined with rising temperatures that will increase potential evapotranspiration, semi-arid conditions will shift eastward, with potentially large consequences for the ecosystems and inhabitants of the Great Plains. We examine how hydroclimate in the Great Plains varied in the past in response to warmer global climate by studying the paleoclimate record within the Ogallala Formation, which underlies nearly the entire Great Plains and provides a spatially resolved record of hydroclimate during the globally warmer late Miocene. We use the stable isotopes of oxygen (δ18O) as preserved in authigenic carbonates hosted within the abundant paleosol and fluvial successions that comprise the Ogallala Formation as a record of past hydroclimate. Today, and coincident with the modern aridity gradient, there is a sharp meteoric water δ18O gradient with high (−6 ‰ to 0 ‰) δ18O in the southern Great Plains and low (−12 ‰ to −18 ‰) δ18O in the northern plains. We find that the spatial pattern of reconstructed late Miocene precipitation δ18O is indistinguishable from the spatial pattern of modern meteoric water δ18O. We use a recently developed vapor transport model to demonstrate that this δ18O spatial pattern requires air mass mixing over the Great Plains between dry westerly and moist southerly air masses in the late Miocene – consistent with today. Our results suggest that the spatial extents of these two atmospheric circulation systems have been largely unchanged since the late Miocene and any strengthening of the Great Plains low-level jet in response to warming has been isotopically masked by proportional increases in westerly moisture delivery. Our results hold implications for the sensitivity of Great Plains climate to changes in global temperature and CO2 and also for our understanding of the processes that drove Ogallala Formation deposition in the late Miocene.

A Novel Perspective on Enhancing Photocatalytic Performance through the Synergistic Effect of Nd Single Atoms and Heterostructures.

There are few reports on lanthanide single atom modified catalysts, as the role of the 4f levels in photocatalysis is difficult to explain clearly. Here, the synergistic effect of 4f levels of Nd and heterostructures is studied by combining steady-state, transient, and ultrafast spectral analysis techniques with DFT theoretical calculations based on the construction of Nd single atom modified black phosphorus/g-C3N4 (BP/CN) heterojunctions. As expected, the generation rates of CO and CH4 of the optimized heterostructure are 7.44 and 6.85 times higher than those of CN, and 8.43 and 9.65 times higher than those of BP, respectively. The Nd single atoms can not only cause surface reconstruction and regulate the active sites of BP, but also accelerate charge separation and transfer, further suppressing the recombination of electron-hole pairs. The electrons can transfer from g-C3N4:Nd to BP:Nd, with a transfer time of ≈11.4ps, while the radiation recombination time of electron-hole pairs of g-C3N4 is ≈26.13 µs, indicating that the construction of heterojunctions promotes charge transfer. The 2P1/2/2G9/2/4G7/2/2H11/2/4F7/2→4I9/2 emissions from Nd3+ can also be absorbed by heterostructures, which improves the utilization of light. The energy change of the key rate measurement step CO2 *→COOH* decreases through Nd single atom modification.

Perspectives on embryo maturation and seed quality in a global climate change scenario.

Global climate change has already brought noticeable alterations to multiple regions of our planet, including increased CO2 concentrations and changes in temperature. Several important steps of plant growth and development, such as embryogenesis, can be affected by such environmental changes; for instance, they affect how stored nutrients are used during early stages of seed germination during the transition from heterotrophic to autotrophic metabolism-a critical period for the seedling's survival. In this article, we briefly describe relevant processes that occur during embryo maturation and account for nutrient accumulation, which are sensitive to environmental change. Most of the nutrients stored in the seed during its development-including carbohydrates, lipids, and proteins, depending on the species-accumulate during the seed maturation stage. It is also known that iron, a key micronutrient for various electron transfer processes in plant cells, accumulates during embryo maturation. The existing literature indicates that climate change can not only affect the quality of the seed, in terms of total nutritional content, but also affect seed production. We discuss the potential effects of temperature and CO2 increases from an embryo-autonomous point of view, in an attempt to separate the effects on the parent plant from those on the embryo.

Assessing the impact of global carbon dioxide changes on atmospheric fluctuations in Iran through satellite data analysis

ABSTRACT Atmospheric Carbon Dioxide (CO2), a significant greenhouse gas, drives climate change, influencing temperature, rainfall, and the hydrologic cycle. This alters precipitation patterns, intensifies storms, and changes drought frequency and timing of floods, impacting ecosystems, agriculture, water resources, and societies globally. Understanding how global CO2 fluctuations impact regional atmospheric CO2 levels can inform mitigation strategies and Facilitate water resources management. The study investigates how global CO2 fluctuations affect atmospheric CO2 concentrations (XCO2) in Iran from 2015 to 2020, aiming to inform mitigation strategies against climate change. XCO2 data OCO-2 satellite and CO2 surface flux data from the Copernicus Atmosphere Monitoring Service (CAMS) were analyzed. Over the 6 years, XCO2 in Iran increased steadily by 12.66 ppm, mirroring global rises. However, Iran's CO2 surface flux decreased, with slight increases in anthropogenic emissions but decreased natural and total fluxes. Monthly patterns of XCO2 and surface flux exhibited variations, with XCO2 reaching its zenith in spring and dipping to its lowest point during summer, while surface flux peaked during the summer months. The results reveal a significant discrepancy between Iran's surface CO2 flux and atmospheric XCO2 trends. While Iran's anthropogenic emissions increased barely from 2015–2020, its natural and total CO2 fluxes decreased. However, XCO2 increased steadily over this period, indicating the dominant impact of global rather than local factors on Iran's XCO2. Curbing worldwide greenhouse gas output is imperative to disrupt the current trajectory of climate change. Reporting CO2 levels can inform climate mitigation plans, reducing emissions to combat global warming and minimize global impacts on the hydrologic cycle.

Experimental testing and mechanism investigation of amine-functionalized layered vermiculite for CO2 capture

Solid amine adsorbents have attracted significant attention due to their low energy consumption, high selectivity, and environmental friendliness, positioning them as the most promising technology for CO2 capture. However, current adsorbent carrier materials commonly encounter challenges such as expensive costs and inadequate stability. In this study, acid-activated expanded vermiculite carrier (AEV) with a large pore volume and hierarchical pore structure was prepared. Subsequently, a series of functionalized polyethyleneimine (PEI) adsorbents were synthesized and employed in CO2 capture experiments to investigate the impact of PEI loading and temperature on adsorption characteristics. The results showed that the acid-modified expanded vermiculite with a large pore volume structure significantly increased amine loading, while the layered structure network promoted amine dispersion. Under the conditions of 50 wt% PEI loading, the CO2 capture capacity of AEV reached 3.29 mmol/L at 75 ℃. Furthermore, density functional theory was utilized to calculate the adsorption energy and Gibbs free energy change of CO2 and polyethyleneimine molecules. The HOMO and LUMO distributions of CO2 molecules with different polyethyleneimine chains were determined using frontier orbital theory, combined with infrared spectroscopy results confirming the conversion of CO2 into carbamate. Additionally, AEV-PEI50 adsorbent exhibited good stability during 8 cycles of the adsorption process. The obtained results demonstrate that the utilization of layered mesoporous scaffolds offers notable benefits in terms of efficient CO2 capture.

E-Nose for Piston Ring and Cylinder Block Condition Detection of Motorcycle Engine Based on MyRIO LabVIEW Programming

This study has created a system capable of identifying the condition of the piston ring and cylinder block of a 4-stroke motorcycle engine using petrol or similar through exhaust emissions. Multisensory gas, sensitive to changes in CO, CO2, NOx, and HC gas elements and compounds, is installed as an input to the exhaust channel and integrated using LabVIEW programming on the NI myRIO module. Multisensory data is processed using the FFT and the backpropagation method to classify whether the piston rings and engine cylinder block are in good or damaged condition. Tests have been carried out on motorbikes with piston rings and engine cylinder blocks that are in good, damaged, or unknown condition. During the test, the target error value for motorcycles with piston rings and engine cylinder blocks in good or damaged condition is less than 1%. The system can distinguish the condition of the piston ring and cylinder block of a motorcycle engine that is 100% optimal and 100% damaged with an error of 0% compared to the compression test method, and the maximum error is 20% Compared to the technician's manual method. Ten motorcycles were randomly tested in unknown conditions; 50% were in good condition, and 50% were damaged. For further development, an electronic nose system can detect engine combustion conditions and damage to cylinder rings and 4-stroke motorbike engine blocks based on exhaust emissions.

Soil dependence of biochar composts in mitigating greenhouse gas emissions: An overlooked biophysical mechanism

Biochar-manure co-compost (BM) has garnered considerable attention as a promising soil amendment for improving nutrient retention and mitigating the emission of greenhouse gases (GHGs). However, its efficacy often varies largely from one soil to another. By comparing soil CO2 and N2O effluxes, solution chemistry, enzyme activities, and the abundances of N-cycle genes between BM and manure compost (M) across three soils of different texture classes through microcosm incubations, we aimed to develop biophysical mechanics to untangle the soil-dependent efficacy of BM in mediating soil carbon and nitrogen transformation processes. Compared to M addition, BM addition significantly reduced soil CO2 and N2O emissions, but its effectiveness was soil texture-dependent, being strongest for CO2 and N2O in fine-textured clay loam and coarse-textured sand, respectively. Such soil texture-dependent effects of BM versus M were also observed in soil enzyme activities and gene copy numbers of ammonia-oxidizing bacteria and denitrifiers. Our datasets suggest that BM interacted strongly with soil texture to modulate the pore scale-based diffusion of oxygen, thereby creating divergence in the aeration status among soils. Sequentially, soil phenol oxidase activity was greater in BM than in M under more aerobic conditions but no difference between BM and M in oxygen-limited soils. The balance between oxygen depletion due to microbial respiration of organic amendments and oxygen diffusion through soil/biochar pores also shaped the activities of nitrifying and denitrifying prokaryotes differently between coarse- and fine-textured soils. This logic model well-explained the magnitude of change in soil-dependent CO2 and N2O emissions from organic amendments. The knowledge gained in this work will likely have profound practical ramifications for optimizing BM efficacy in mitigating the GHGs emission.