CO2 Measurements Research Articles

High central venous pressure amplitude predicts successful defibrillation in a porcine model of cardiac arrest

AimIncreasing venous return during cardiopulmonary resuscitation (CPR) has been shown to improve hemodynamics during CPR and outcomes following cardiac arrest (CA). We hypothesized that a high central venous pressure amplitude (CVP-A), the difference between the maximum and minimum central venous pressure during chest compressions, could serve as a robust predictor of return of spontaneous circulation (ROSC) in addition to traditional measurements of coronary perfusion pressure (CPP) and end-tidal CO2 (etCO2) in a porcine model of CA. MethodsAfter 10 min of ventricular fibrillation, 9 anesthetized and intubated female pigs received mechanical chest compressions with active compression/decompression (ACD) and an impedance threshold device (ITD). CPP, CVP-A and etCO2 were measured continuously. All groups received biphasic defibrillation (200 J) at minute 4 of CPR and were classified into two groups (ROSC, NO ROSC). Mean values were analyzed over 3 min before defibrillation by repeated-measures Analysis of Variance and receiver operating characteristic (ROC). ResultsFive animals out of 9 experienced ROSC. CVP-A showed a statistically significant difference (p = 0.003) between the two groups during 3 min of CPR before defibrillation compared to CPP (p = 0.056) and etCO2 (p = 0.064). Areas-under-the-curve in ROC analysis for CVP-A, CPP and etCO2 were 0.94 (95% Confidence Interval 0.86, 1.00), 0.74 (0.54, 0.95) and 0.78 (0.50, 1.00), respectively. ConclusionIn our study, CVP-A was a potentially useful predictor of successful defibrillation and return of spontaneous circulation. Overall, CVP-A could serve as a marker for prediction of ROSC with increased venous return and thereby monitoring the beneficial effects of ACD and ITD.

PHANGS–JWST First Results: A Global and Moderately Resolved View of Mid-infrared and CO Line Emission from Galaxies at the Start of the JWST Era

We explore the relationship between mid-infrared (mid-IR) and CO rotational line emission from massive star-forming galaxies, which is one of the tightest scalings in the local universe. We assemble a large set of unresolved and moderately (∼1 kpc) spatially resolved measurements of CO (1–0) and CO (2–1) intensity, I CO, and mid-IR intensity, I MIR, at 8, 12, 22, and 24 μm. The I CO versus I MIR relationship is reasonably described by a power law with slopes 0.7–1.2 and normalization I CO ∼ 1 K km s−1 at I MIR ∼ 1 MJy sr−1. Both the slopes and intercepts vary systematically with choice of line and band. The comparison between the relations measured for CO (1–0) and CO (2–1) allow us to infer that , in good agreement with other work. The 8 μm and 12 μm bands, with strong polycyclic aromatic hydrocarbon (PAH) features, show steeper CO versus mid-IR slopes than the 22 and 24 μm, consistent with PAH emission arising not just from CO-bright gas but also from atomic or CO-dark gas. The CO-to-mid-IR ratio correlates with global galaxy stellar mass (M ⋆) and anticorrelates with star formation rate/M ⋆. At ∼1 kpc resolution, the first four PHANGS–JWST targets show CO-to-mid-IR relationships that are quantitatively similar to our larger literature sample, including showing the steep CO-to-mid-IR slopes for the JWST PAH-tracing bands, although we caution that these initial data have a small sample size and span a limited range of intensities.

Dual trace gas detection using a compact two-channel multipass cell with dense and line spot patterns

A highly sensitive dual-gas sensor based on a two-channel multipass cell (MPC) was designed and developed for simultaneous detection of atmospheric methane (CH4) and carbon dioxide (CO2) by using two distributed feedback lasers emitting at 1653 nm and 2004 nm. The nondominated sorting genetic algorithm was applied to intelligently optimize the MPC configuration and accelerate the dual-gas sensor design process. A compact and novel two-channel MPC was used to achieve two optical path lengths of 27.6 m and 2.1 m in a small volume of 233 cm3. Simultaneous measurements of CH4 and CO2 in the atmosphere were performed to demonstrate the stability and robustness of the gas sensor. According to the Allan deviation analysis, the optimal detection precision for CH4 and CO2 was 4.4 ppb at an integration time of 76 s and 437.8 ppb at an integration time of 271 s, respectively. The newly developed dual-gas sensor exhibits superior characteristics of high sensitivity and stability, cost-effectiveness and simple structure, which make it well-suited for multiple trace gas sensing in various applications, including environmental monitoring, safety inspections and clinical diagnosis.

Effect of Surface Characteristics of Graphene Aerogels and Hydrophilicity of Ionic Liquids on the CO2/CH4 Separation Performance of Ionic Liquid/Reduced Graphene Aerogel Composites

Two ionic liquids (ILs) having the same cation with different anions offering opposite hydrophilic/hydrophobic characters, 1-n-butyl-1-methylpyrrolidinium dicyanamide ([BMPyr][DCA]) and 1-n-butyl-1-methylpyrrolidinium hexafluorophosphate ([BMPyr][PF6]), were impregnated onto two different reduced graphene aerogels (rGAs) prepared by the thermal treatment of GAs at 300 and 500 °C to investigate the consequences of the changes in the hydrophilic character of ILs and the reduction temperature of the GAs on the corresponding gas sorption and separation performance of the IL/rGAs. The structural analyses of nanoporous rGAs and IL/rGAs pointed to a change in the quantity of oxygenated functional groups upon thermal treatment and a change in the direct interactions between IL molecules and the host rGA surface upon IL deposition. Single-component CO2 and CH4 sorption measurements were performed for each rGA and IL/rGA composite, and both ideal and mixture CO2/CH4 selectivities were calculated. The samples prepared by reducing the GA at 300 and 500 °C yielded ideal CO2/CH4 selectivities of 3.6 and 18 at 1 mbar and 25 °C, respectively. Among IL/rGA composites, the one prepared at 300 °C displayed a remarkable CO2/CH4 separation performance when combined with the hydrophobic [BMPyr][PF6], offering an ideal selectivity of 450.9 at 1 mbar and 25 °C, whereas the composite prepared with rGA500 yielded a substantially high CO2/CH4 selectivity of 173.5 after the incorporation of the hydrophilic [BMPyr][DCA] at 1 mbar and 25 °C. The ideal CO2/CH4 selectivities of [BMPyr][PF6]/rGA300 and [BMPyr][DCA]/rGA500 surpassed most of the previously reported selectivities of carbon-based materials in the literature. These results demonstrate the broad potential of IL/rGAs in sorption-based gas separations owing to the highly tunable nature of both the structure of IL and the surface characteristics of rGA.

Can Air Quality Gas Sensors Be Used for Emission Monitoring of Small-Scale Local Air Pollution Sources? Pilot Test Evaluation

In recent years we have seen a growing number of applications that use various sensory measurements of physicochemical features. Within the research project “Research on the identification of combustion of unsuitable fuels and systems of self-diagnostics of boilers combustion solid fuels for domestic heating”, the authors tested and evaluated the possible use of an air quality monitoring sensor unit for the measurement of operating parameters of solid fuel burning boilers and stoves. In the Czech Republic, programs to support citizens in the replacement of domestic boilers of poor combustion quality have been subsidized for several years. Unfortunately, no assessment of the impact of subsidies on air quality has been carried out. However, the increased pollutant emissions due to improper use of domestic boilers are supposed to be one of the greatest problems with domestic boilers. Hence, providing users with real-time feedback may lead to changes in combustion conditions and consequently to a reduction in air pollution. We focus on sensory measurements of CO, CO2, NO, and VOCs as compounds that correspond to the operating conditions of the combustion process. The research included sampling, construction of the flue gas dilution duct, and the influence of direct measurement on the service life of the sensors.

UAV-based sampling systems to analyse greenhouse gases and volatile organic compounds encompassing compound-specific stable isotope analysis

Abstract. The study herein reports on the development and testing of sampling systems (and subsequent analytical setups) that were deployed on an unmanned aerial vehicle (UAV) for the purpose of analysing greenhouse gases (GHGs) and volatile organic compounds (VOCs) in the lower atmospheric boundary layer. Two sampling devices, both of which can be mounted to an UAV with a payload capability greater than 1 kg, were tested for respective sampling and analysis of specific GHGs (carbon dioxide, CO2, and methane, CH4) and VOCs (chlorinated ethenes, CEs). The gas analyses included measurements of the molar amounts and the respective stable carbon isotope ratios. In addition to compound calibration in the laboratory, the functionality of the samplers and the UAV-based sampling was tested in the field. Atmospheric air was either flushed through sorbent tubes for VOC sampling or collected and sampled in glass vials for GHG analysis. The measurement setup for the sorbent tubes achieved analyte mass recovery rates of 63 %–100 % (more favourable for lower chlorinated ethenes), when prepared from gaseous or liquid calibration standards, and reached a precision (2σ) better than 0.7 ‰ for δ13C values in the range of 0.35–4.45 nmol. The UAV-equipped samplers were tested over two field sampling campaigns designed to (1) compare manual and UAV-collected samples taken up a vertical profile at a forest site and (2) identify potential emissions of CO2, CH4 or VOC from a former domestic waste dump. The precision of CO2 measurements from whole air samples was ≤7.3 µmol mol−1 and ≤0.3 ‰ for δ13C values and ≤0.03 µmol mol−1 and ≤0.2 ‰ for CH4 working gas standards. The results of the whole air sample analyses for CO2 and CH4 were sufficiently accurate to detect and localise potential landfill gas emissions from a secured former domestic waste dump using level flight. Vertical CO2 profiles from a forest location showed a causally comprehensive pattern in the molar ratios and stable carbon isotope ratios but also the potential falsification of the positional accuracy of a UAV-assisted air sample due to the influence of the rotor downwash. The results demonstrate that the UAV sampling systems presented here represent a viable tool for atmospheric background monitoring, as well as for evaluating and identifying emission sources. By expanding the part of the lower atmosphere that can be practicably sampled over horizontal and vertical axes, the presented UAV-capable sampling systems, which also allow for compound-specific stable isotope analysis (CSIA), may facilitate an improved understanding of surface–atmosphere fluxes of trace gas.

Laser-induced sublimation extraction for centimeter-resolution multi-species greenhouse gas analysis on ice cores

Abstract. Precision, accuracy, and temporal resolution are key to making full use of atmospheric trace gas records in ice cores. These aspects will become especially crucial for ice cores that aim to extend the ice core record to the last 1.5 Myr, i.e., across the Mid-Pleistocene Transition (as currently drilled within the European project Beyond EPICA – Oldest Ice Core (BE-OIC)). The ice from this period is expected to be close to bedrock and, due to glacier flow, extremely thinned with 15 000 years of climate history contained in only 1 m of ice. Accordingly, for a century-scale resolution, the sample vertical extent must be reduced to a few centimeters containing only about 1–2 mL air STP. We present a novel combined system for the extraction and the simultaneous measurement of CO2, CH4, and N2O concentrations, as well as δ13CO2, which achieves a vertical resolution of 1–2 cm (3.5×3.5 cm cross section) with precisions of 0.4 ppm, 3 ppb, 1 ppb, and 0.04 ‰, respectively, in sublimation tests with standard gas over gas-free ice. This is accomplished by employing a directional and continuous laser-induced sublimation followed by analysis of the sample gas by a quantum cascade laser absorption spectrometer (QCLAS). Besides the low sample volume requirements and the vertical resolution capabilities, the described method holds additional advantages over previous methods, including the immunity of the highly specific QCLAS analysis to drilling fluid contamination as well as the non-destructive nature of the spectroscopic gas analysis. The combined extraction and analysis system was extensively tested by sublimating gas-free ice with introduction of a standard gas to determine the accuracy and characterize potential artifacts. Moreover, Antarctic ice samples were measured to confirm the measurement performance, covering the range of variability expected in Pleistocene ice and highlighting the vertical resolution capabilities critical for its application within BE-OIC.

Evaluating the performance of a Picarro G2207-i analyser for high-precision atmospheric O2 measurements

Abstract. Fluxes of oxygen (O2) and carbon dioxide (CO2) in and out of the atmosphere are strongly coupled for terrestrial biospheric exchange processes and fossil fuel combustion but are uncoupled for oceanic air–sea gas exchange. High-precision measurements of both species can therefore provide constraints on the carbon cycle and can be used to quantify fossil fuel CO2 (ffCO2) emission estimates. In the case of O2, however, due to its large atmospheric mole fraction (∼20.9 %) it is very challenging to measure small variations to the degree of precision and accuracy required for these applications. We have tested an atmospheric O2 analyser based on the principle of cavity ring-down spectroscopy (Picarro Inc., model G2207-i), both in the laboratory and at the Weybourne Atmospheric Observatory (WAO) field station in the UK, in comparison to well-established, pre-existing atmospheric O2 and CO2 measurement systems. In laboratory tests analysing dry air in high-pressure cylinders, we found that the best precision was achieved with 30 min averaging and was ±0.5 ppm (∼±2.4 per meg). Also from continuous measurements from a cylinder of dry air, we found the 24 h peak-to-peak range of hourly averaged values to be 1.2 ppm (∼5.8 per meg). These results are close to atmospheric O2 compatibility goals as set by the UN World Meteorological Organization. However, from measurements of ambient air conducted at WAO we found that the built-in water correction of the G2207-i does not sufficiently correct for the influence of water vapour on the O2 mole fraction. When sample air was dried and a 5-hourly baseline correction with a reference gas cylinder was employed, the G2207-i's results showed an average difference from the established O2 analyser of 13.6±7.5 per meg (over 2 weeks of continuous measurements). Over the same period, based on measurements of a so-called “target tank”, analysed for 12 min every 7 h, we calculated a repeatability of ±5.7±5.6 per meg and a compatibility of ±10.0±6.7 per meg for the G2207-i. To further examine the G2207-i's performance in real-world applications we used ambient air measurements of O2 together with concurrent CO2 measurements to calculate ffCO2. Due to the imprecision of the G2207-i, the ffCO2 calculated showed large differences from that calculated from the established measurement system and had a large uncertainty of ±13.0 ppm, which was roughly double that from the established system (±5.8 ppm).

Evaluation of the concordance between hemodynamic variables obtained by Swan-Ganz catheterization and transthoracic echocardiography in patients after coronary revascularization surgery

Introduction: Currently, there is a trend towards non-invasive hemodynamic monitoring guided by echocardiography, however, in our center, in patients undergoing coronary revascularization surgery, invasive hemodynamic monitoring with Swan-Ganz catheter placement continues. Given that hemodynamic monitoring using non-invasive methods has been shown to be feasible, it is therefore expected that the hemodynamic variables obtained by echocardiography are consistent with the variables obtained by Swan-Ganz catheterization in this type of patient. The objective of the study is to evaluate the concordance that exists between the different hemodynamic variables obtained by Swan-Ganz catheterization, with the variables obtained by echocardiography. Methods: Observational, non-interventional, retrospective, cross-sectional and analytical study, non-randomized. Patients admitted to the Coronary Unit after coronary revascularization surgery were selected, who had a Swan-Ganz catheter on admission, all patients underwent measurement of the hemodynamic variables CO, RAP, PASP, PWP and later TTE was performed to obtain the same variables. Finally, the Concordance Correlation Coefficient described by Lin CCC= (A2+B2-C2) ÷(A2+B2+D2) and by the Bland-Altman method was used as a statistical tool. Results: 26 patients were included, with a mean age of 63.8 ± 6.2 years, 69.2% male. For the CO variable, an average absolute difference of 0.77 L/min and a CCC of 0.7334 were obtained; in the analysis of (B-A), an average difference is -0.4149 L/min. For the RAP an average difference of 2.11 mmHg, with a CCC = 0.8595 and in the analysis of B-A an average difference of -1.11 mmHg. For the PASP an average absolute difference of 5.11 mmHg was obtained with a CCC = 0.5444 and in the B-A analysis an average difference of 0.2944 mmHg. For PWP an average absolute difference of 2.78 mmHg with a CCC = 0.3842, in the analysis of B-A an average difference of 2.13 mmHg. When carrying out the analysis of the average differences obtained from each of the variables, with which a P value of 0.293 was obtained for the CO, 0.129 for the RAP, 0.308 for the PASP, and 0.017 for the PWP. Conclusions: A poor strength of agreement was observed for the CCC for each of the variables, however, these are not clinically significant, so they can be considered as interchangeable methods. It is important to mention that the TTE provides other relevant parameters in the management of these patients.

Efficacy of the CO Tracer Technique in Partitioning Biogenic and Anthropogenic Atmospheric CO2 Signals in the Humid Subtropical Eastern Highland Rim City of Cookeville, Tennessee

Accurate accounting of the partition between anthropogenic and biogenic carbon dioxide mixing ratios (CO2Anth and CO2Bio) in urban-based CO2 measurements is key to developing effective emission reduction strategies since such measurements can provide an independent catalogue of local and regional CO2 emission inventories. In an attempt to delineate the contribution of CO2Bio to the overall urban CO2 mixing ratio enhancements, carbon monoxide (CO) was utilized as a tracer, following CO2 and CO mixing ratio measurements using a wavelength-scanned cavity ring-down spectrometer (CRDS). These measurements were performed in Cookeville, TN, (36.1628° N, 85.5016° W), a medium-sized city within the Eastern Highland Rim region of the United States. Between the years 2017 and 2019, the average seasonal wintertime CO2Bio mixing ratios varied between −0.65 ± 3.44 ppm and 0.96 ± 2.66 ppm. During the springtime, the observed CO2Bio signals were largely negative while the CO2Anth values were generally lower than the wintertime values. The contribution of CO from the isoprene oxidation reaction with the hydroxyl radical (OH) (COisoprene) to the overall CO enhancement during the growing season was estimated to be ~17–27 ppb, underscoring the importance of considering the contribution of COisoprene to untangling different CO2Anth and CO2Bio sources and sinks in high isoprene-emitting urban environments.

The Cobalt(II) Oxidotellurate(IV) Hydroxides Co2(TeO3)(OH)2 and Co15(TeO3)14(OH)2

Previously unknown Co2(TeO3)(OH)2 and Co15(TeO3)14(OH)2 were obtained under mild hydrothermal reaction conditions (210 °C, autogenous pressure) from alkaline solutions. Their crystal structures were determined from single-crystal X-ray diffraction data. Co2(TeO3)(OH)2 (Z = 2, P1¯, a = 5.8898(5), b = 5.9508(5), c = 6.8168(5) Å, α = 101.539(2), β = 100.036(2), γ = 104.347(2)°, 2120 independent reflections, 79 parameters, R[F2 > 2σ(F2)] = 0.017) crystallizes in a unique structure comprised of undulating 2∝[Co2(OH)6/3O3/3O2/2O1/1]4− layers. Adjacent layers are linked by TeIV atoms along the [001] stacking direction. Co2(TeO3)(OH)2 is stable up to 450 °C and decomposes under the release of water into Co6Te5O16 and CoO. Magnetic measurements of Co2(TeO3)(OH)2 showed antiferromagnetic ordering at ≈ 70 K. The crystal structure of Co15(TeO3)14(OH)2 (Z = 3, R3¯, a = 11.6453(2), c = 27.3540(5) Å, 3476 independent reflections, 112 parameters, R[F2 > 2σ(F2)] = 0.026) is isotypic with Co15(TeO3)14F2. A quantitative structural comparison revealed that the main structural difference between the two phases is connected with the replacement of F by OH, whereas the remaining part of the three-periodic network defined by [CoO6], [CoO5(OH)], [CoO5] and [TeO3] polyhedra is nearly unaffected. Consequently, the magnetic properties of the two phases are similar, namely being antiferromagnetic at low temperatures.

Development of a Portable and Sensitive CO2 Measurement Device with NDIR Sensor Clusters and Minimizing Water Vapor Impact

Increasing carbon dioxide (CO2) concentrations threaten human production and life. Currently the equipment used for CO2 monitoring is heavy and expensive, without a portable CO2 detector that is inexpensive and resistant to interference. Here we designed a portable CO2 detector based on no-dispersive infrared sensors to measure CO2 concentration. The detector, which has a mass of 1 kg, is powered by a lithium battery with dimensions of 200 mm (length) × 150 mm (width) × 100 mm (height). Considering the fact that field observations are susceptible to humidity, a series of experiments were carried out to reduce the humidity interference on sensor responses at a laboratory. The values of humidity and CO2 variation were used in a regression model analysis to determine a quadratic function with an R2 above 0.94. The detector was compared with a reference analyzer in ambient CO2 measurement during a 7-day field campaign in Hangzhou, China. After humidity correction, the data show better correlation with the reference data, with the R2 0.62–0.97 increasing from 0.62–0.97 compared to before the correction and the value deviation decreasing to less than 3%. Cluster analysis of sensors revealed a reduction in average relative deviation of up to 1.4% as the number of sensors increased.

Organic Carbon Burial in Constructed Ponds in Southern Sweden

Small ponds constructed for nutrient retention, biodiversity conservation or recreation also store large amounts of carbon. The potential role of small ponds for carbon storage and greenhouse gas emissions have been highlighted both in the scientific literature and in management plans. The role of small ponds in the global carbon budget is likely significant, but the potential has not been fully explored. Here we present measurements of yearly sedimentary carbon accumulation and carbon stocks in six small, constructed and restored ponds in southern Sweden. The ponds were constructed or restored during the last 20 years primarily for nutrient retention. The sediment cores span the time from the construction of the ponds until today. The ponds had high carbon accumulation, with mean total carbon stocks in the top 6 cm of sediment of 836 g C m−2 and a yearly mean C accumulation rate of 152 g C m−2 yr−1. The total amount of restored wetlands within the restoration program studied here has a total area of 480 ha, and upscaling the carbon stocks to the whole area of restored ponds and wetlands gave a total carbon stock of 4.013 × 106 kg C in the top 6 cm of the sediments. If considering the potential increase of CO2 and CH4 from the ponds it is likely that the constructed ponds studied here are net carbon sources. We compared our results with published measurements of CO2 and CH4 emissions from small ponds in Sweden. This shows that the CO2 equivalent emissions could be between 1.8 and 37.5 times higher than the sedimentary carbon accumulation. Our data indicate that small constructed ponds are potential net carbon sources. Therefore, we suggest that using small, constructed, or restored ponds as carbon mitigation strategy must be done with caution, and the potential for increased methane emissions must be considered.

Information fusion of stationary, mobile, and wearable consumer-grade sensors to confidently estimate bedroom ventilation rates

This study adds to the body of research investigating ventilation rates measured in residential dwellings. Using open-source Consumer-Grade Sensors (CGS), we measure Carbon Dioxide (CO2) to estimate ventilation rates under one of three conditions: CO2build-up when bedrooms were initially occupied, steady-state CO2 during the latter half of participants’ sleep episodes, and CO2decay after participants wake and vacate their bedroom. We do not ask participants to record their bedroom occupancy, but use information fusion to identify nightly occupied periods by cross-referencing home addresses to GPS measurements provided by their smartphones during sleep episodes identified by Fitbit wearable fitness trackers. We estimate 106 ventilation rates during build-up conditions which ranged from 0.04–1.36 h−1, 242 ventilation rates under steady-state conditions spanning 0.17–2.49 h−1, and 39 ventilation rates from decay conditions over a range of 0.06–1.05 h−1. In addition, we used occupied periods alongside times when GPS confirmed participants were away from home to label Indoor Air Quality (IAQ) data, and to train a Multi-Layer Perceptron (MLP) to classify occupancy based on CO2 and Total Volatile Organic Compound (TVOC) measurements. Using periods classified as occupied with at least 90% confidence, we estimated 116 additional steady-state ventilation rates spanning 0.25–2.49 h−1. Our results are consistent with more traditional and costly sensing approaches, and we conclude that information fusion of CGS is effective in measuring IAQ, detecting occupancy, and estimating ventilation rates.

A 30-year dataset of CO2 in flowing freshwaters in the United States

Increasing atmospheric carbon dioxide (CO2) concentrations have been linked to effects in a wide range of ecosystems and organisms, with negative effects of elevated CO2 documented for marine organisms. Less is known about the dynamics of CO2 in freshwaters, but the potential exists for freshwater organisms to be challenged by elevated CO2. In flowing freshwaters CO2 exhibits more variability than in lakes or the ocean, yet spatiotemporally extensive direct measures of CO2 in freshwater are rare. However, CO2 can be estimated from pH, temperature, and alkalinity—commonly collected water quality metrics. We used data from the National Water Quality Monitoring Council along with the program PHREEQC to estimate CO2 in flowing freshwaters across 35,000 sites spanning the lower 48 US states from 1990 through 2020. Site data for water chemistry measurements were spatially joined with the National Hydrology Dataset. Our resulting dataset, CDFLOW, presents an opportunity for researchers to add CO2 to their datasets for further investigation.

Catalyzed oxidation of nuclear graphite by simulated fission products Sr, Eu, and I

The influence of three fission products Sr, Eu, and I on the oxidation of IG-110 nuclear graphite was studied in the temperature range of 400 to 1000 °C. Sr and Eu were introduced as chlorides, and I was introduced as NaI. The temperature dependence of both CO2 and CO production during the graphite oxidation measured with mass spectroscopy and infrared spectrometry shows that the introduction of these three compounds to graphite significantly decreases the onset temperature for the oxidation of graphite. Among the three compounds, NaI is the most active towards the oxidation reaction, characterized by a significant decrease of the onset temperature from approximately 650 to 400 °C before and after its introduction to graphite. Separate measurements of CO2 and CO concentration at varying temperatures enable the calculation of the activation energy for the formation of CO2 and CO. The activation energies for the oxidation of pure and fission product-impregnated graphite samples decrease in the following order: standard IG-110 graphite, EuCl3-impregnated IG-110, SrCl2-impregnated IG-110, and NaI-impregnated IG-110. This trend indicates that the three compounds catalyze the oxidation of graphite at temperatures relevant to the operation of high-temperature gas-cooled reactors. Furthermore, it is found that the three compounds can also affect the molar ratio of reaction products CO2 and CO, and the rates of the graphite oxidation. At temperatures higher than about 850 °C, the impregnated samples exhibit lower CO2: CO ratios than the pure graphite. Different from EuCl3 and NaI, the introduction of SrCl2 decreases the graphite oxidation rates at temperatures higher than about 770 °C. Their catalytic mechanism can be understood based on a redox cycle of the intermediate active species, promoting the dissociation of molecular oxygen and transfer to the carbon.

Assessment of CO2 enrichment mechanism in integrated coal gasification fuel cell combined cycle system with carbon capture

The present research proposes an innovative multi-physics coupled model of different configurations of an integrated coal gasification fuel cell combined cycle (IGFC) system employing Solid Oxide Electrolytic Cell (SOEC) for CO2 capture. Full-system simulation is carried out to examine efficiency. The model incorporates a Solid Oxide Fuel Cell (SOFC), a SOEC, a gas turbine (GT), and multiple recirculation loops operated by two ejectors. The results reveal that compared with traditional power plants, the proposed IGFC system equipped with SOEC can reduce CO2 emission by almost 80%, and operates environmentally beneficial. The efficiency of the system varies greatly depending on the design parameters implemented. The CO2 enrichment phenomenon by SOFC and capture measures of CO2 by SOEC are simultaneously analyzed. In addition, parametric analysis is performed to evaluate the coupling influence of multiple operating parameters on the IGFC system. Recirculation ratios of 0.75 with four times recirculations are found to be the optimal conditions for both SOFC fuel electrode and SOEC air electrode aimed at getting to the highest power generation efficiency and total CO2 capture rate of the system. After systematic optimization of the design parameters, the electrical efficiency and CO2 capture rate of the proposed system could achieve 68.47% and 87.88%, respectively, which are about 20% and 60% greater than those of traditional power plants. Furthermore, after optimizing the control strategy, the fuel utilization rate of the system increases from 63.09% to 83.40%.

Vast ecosystem disturbance in a warming climate may jeopardize our climate goal of reducing CO2: a case study for megafires in the Australian ‘black summer’

A warming climate is one of the most important driving forces of intensified wildfires globally. The unprecedented wildfires broke out in the Australian ‘Black Summer’ (November 2019–February 2020), which released massive heat, gases, and particles into the atmosphere. The total carbon dioxide (CO2) emissions from wildfires were estimated at ∼963 million tons by using a top-down approach based on direct satellite measurements of CO2 and fire radiative power. The fire emissions have led to an approximately 50–80 folds increase in total CO2 emission in Australia compared with the similar seasons of 2014–2019. The excess CO2 from wildfires has offset almost half of the global anthropogenic CO2 emission reductions due to the Corona Virus Disease 2019 in 2020. When the wildfires were intense in December 2019, they caused a 1.48 watts per square meter additional positive radiative forcing above the monthly average in Australia and the vicinity. Our findings demonstrate that vast ecosystem disturbance in a warming climate can strongly influence the global carbon cycle and hamper our climate goal of reducing CO2.

DYNAMICS OF CO2 EMISSION AND DISPERSION FROM TWO SUGARCANE MILLS IN THE GUAYAS BASIN

Sugarcane (Saccharum spp.) is a C4 plant widely cultivated for the production of sugar, energy, and other derivatives. Sugarcane fixes a certain amount of carbon in the biomass but emits variable amounts of carbon dioxide (CO2) into the atmosphere, depending on the technologies used in both field and industrial processes. This study quantified and described the spatial and temporal dispersion of CO2 emissions generated during the sugarcane harvest period by the San Carlos and Valdez sugarcane mills, in Guayas, Ecuador. Measurements of CO2 were carried out using a 3M's portable gas analyzer model Monitor 3M-EVM-7, which provides digital readings without requiring any additional procedure. Samples were taken every two weeks during the milling period (June to December). Sampling was carried out at distances of approximately 280, 500, 1000, and 3000 m from the central chimney of the factories. Locations were eventually georeferenced to allow for possible associations to infer spatial and temporal patterns and distributions. The effects associated with dispersion patterns of greenhouse gases released from the industrial chimneys as well as wind direction and speed were considered. The results show that CO2 emitted by the industrial sugarcane process did not impact surface-level measurements due to natural dispersion, although it decreased with distance. There was a high, negative, and significant correlation between CO2 concentrations and temperature; and a high, direct, and significant correlation with dew point. CO2 concentrations were inversely correlated with distances from the factory chimneys.

Analysis of seed viability through respiration metabolism using CO2 sensors and internet of things (IoT) system

The respiration metabolism is an indicator of seed viability. The respiration process can be measured through the production of CO2 during the seed germination process. The respiration process can be measured through the production of CO2 during the seed germination process. This study aims to create a CO2 measuring device that can measure in real-time using a CO2 sensor and an IoT system. The study consisted of two experiments. The first experiment was to create a seed respiration measuring device using a CO2 sensor and an IoT system. The second experiment was to validate. The first experiment’s results were that a device can detect carbon dioxide levels automatically in the measurement range from 400 ppm to 5000 ppm. The device had online data storage through a database that can be monitored using the IoT system and is equipped with backup data storage using an SD card to avoid data loss in the cloud due to internet connection failure. The second experiment used a randomized complete block design. The treatment consisted of six levels of soybean seed viability (94.8%, 92.4%, 90.4%, 88.4%, 66.0%, 40.8% based on germination test). The results showed that the CO2 measurement could differentiate the viability of seeds.