ARTICLE | doi:10.20944/preprints202305.0782.v1
Subject: Environmental And Earth Sciences, Remote Sensing Keywords: Hyperspectral IR Sounding, Methane, CH4 Concentration, AIRS, CrIS, CH4 Trends
Online: 11 May 2023 (04:26:45 CEST)
Methane (CH4) is the second most significant contributor to climate change after carbon dioxide (CO2), accounting for approximately 20% of the contributions from all the well-mixed greenhouse gases. Understanding the spatiotemporal distributions, and the relevant long-term trends are crucial to identifying the sources, sinks, and impacts on climate. Hyperspectral thermal infrared (TIR) sounders, including the Atmospheric Infrared Sounder (AIRS), the Cross-track Infrared Sounder (CrIS), and the Infrared Atmospheric Sounding Interferometer (IASI), have been used to measure global CH4 concentrations since 2002. This study analyzed nearly twenty years of data from AIRS and CrIS and confirmed a significant increase in CH4 concentrations in the mid-upper troposphere (around 400 hPa) from 2003 to 2020, with a total increase of approximately 85 ppb, representing a +4.8% increase in 18 years. The rate of increase was derived using global satellite TIR measurements is consistent with in-situ measurements, indicating a steady increase starting in 2007 and became stronger in 2014. The study also compared CH4 concentrations derived from the AIRS and CrIS against ground-based measurements from NOAA Global Monitoring Laboratory (GML) and found phase shifts in the seasonal cycles in the middle to high latitudes in the northern hemisphere, which is attributed to the influence of stratospheric CH4 that varies at different latitudes. These findings provide insights into the global budget of atmospheric composition and the understanding of satellite measurement sensitivity of CH4.
ARTICLE | doi:10.20944/preprints202206.0184.v1
Subject: Environmental And Earth Sciences, Geochemistry And Petrology Keywords: Over mature shale gas; Magnitude of isotope reversal; CH4 polymerization; CH4 cracking; Mud gas
Online: 13 June 2022 (10:41:14 CEST)
Exploration practices have proven that over mature shale gas exhibits a feature of carbon isotope reversal. The geochemical statistics indicate that the wetness (C2-C5/C1-C5) of shale gas with carbon isotope reversal is less than 1.8%. In addition, the magnitude of carbon isotope reversal (δ13C1- δ13C2) for the over mature shale gas presents a parabolic variation with decreasing wetness. δ13C1-δ13C2 increases with decreasing wetness within a wetness range of 0.9% ~1.8% and then decreases with decreasing wetness at wetness < 0.9%. The CH4 cracking experiment demonstrates that CH4 polymerization occurring in the early stage of CH4 cracking is an important factor involved in isotope reversal of over mature shale gas. Moreover, δ13C1- δ13C2 decreases with an increase in experimental temperature prior to CH4 substantial cracking. The values of δ13C1 and δ13C2 tend to equalize during CH4 substantial cracking. The δ13C1-δ13C2 of mud gas present at different depths during shale gas drilling in Sichuan Basin increases initially, then decreases with further increase in the depth and finally tends to zero, with only a trace hydrocarbon gas being detectable. Statistical data suggests that the shale gas production in Sichuan Basin decreases with the decreasing δ13C1-δ13C2 value and wetness. Thus, δ13C1-δ13C2 and wetness could potentially serve as useful criteria to screen CH4 cracking degree and to determine the largest depth of natural gas exploration. Great care should be taken during shale gas exploration in deeper layers, with wetness and δ13C1-δ13C2 less than 0.2% and 1%, respectively, since very low wetness (<0.2%) and δ13C1-δ13C2 (<1%) might be indicative of CH4 substantial cracking in a geological setting.
ARTICLE | doi:10.20944/preprints202306.1292.v1
Subject: Chemistry And Materials Science, Physical Chemistry Keywords: polythiophene; ZnO; CO2 reduction; photocatalysis; CH4
Online: 19 June 2023 (05:03:57 CEST)
In today's society, mankind is confronted with two major problems: the energy crisis and the greenhouse effect. The artificial photosynthesis can use solar energy to convert greenhouse gas CO2 into high-value compounds, which is an ideal solution to alleviate the energy crisis and solve the problem of global warming. The combination of ZnO and polythiophenes (PTh) can make up for each other's drawbacks, thus improving the photoresponse behavior and separation efficiency of photogenerated carriers. PTh layer can transfer photogenerated electrons to ZnO, thereby extending the lifetime of photogenerated charges. The production rate of CH4 from photoreduction of CO2 with ZnO/PTh10 is 4.3 times that of pure ZnO, and the selectivity of CH4 is increased from 70.2% to 92.2%. The conductive PTh can absorb photons to induce π–π* transition, the photogenerated electrons can transfer from LUMO to the conduction band (CB) of ZnO, thus more electrons involve in the reduction of CO2.
COMMUNICATION | doi:10.20944/preprints202304.0717.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: cattle; CH4; rumen fermentation; hydrogen; nitrocompounds
Online: 21 April 2023 (10:20:30 CEST)
The objective of this study was to investigate the effects of ethyl nitroacetate, ethyl 2-nitropropionate and 3-nitropropionic acid on ruminal production of CH4, H2, volatile fatty acids (VFAs) and on dry matter digestibility of ground alfalfa under in vitro conditions. In vitro incubations were conducted as consecutive batch cultures. Total gas and amounts of methane produced by ruminal microbes were decreased by all nitrocompounds (P < 0.05). Total production of VFAs was significantly reduced for all the nitrocompounds (P < 0.05) except for NPA. DM disappearance was not affected (P >0.05) by treatment.
ARTICLE | doi:10.20944/preprints201812.0215.v1
Subject: Chemistry And Materials Science, Inorganic And Nuclear Chemistry Keywords: CH4, CeO2, Dry reforming, MgO, Ni, TiO2
Online: 18 December 2018 (10:19:37 CET)
This study investigated dry reforming of methane with combined catalysts supported on γ-Al2O3 support doped with 3.0 wt. % TiO2. The physicochemical properties of all the catalysts were determined by inductively-coupled plasma/mass spectrometry metal analysis, nitrogen physisorption, X-ray diffraction, temperature programmed reduction/desorption, thermogravimetric analysis, and scanning electron microscopy. The addition of CeO2 and MgO to Ni strengthened the interaction between the Ni and the support. The catalytic activity results indicated that the CeO2 and MgO addition to Ni did not do much in retarding carbon deposition, but they improved the activity of the catalysts. Among the tested catalysts, it was found that the catalyst with the composition of 5.0 wt % NiO-10.0 wt % CeO2/3.0 wt %TiO2-γ-Al2O3 resulted in the highest CH4 and CO2 conversion with H2/CO mole ratio close to unity. The optimum reaction conditions in terms of reactant conversion and H2/CO mole ratio were achieved by varying space velocity and CO2/CH4 mole ratio.
ARTICLE | doi:10.20944/preprints201807.0489.v1
Subject: Chemistry And Materials Science, Physical Chemistry Keywords: CO2 adsorption, CH4 adsorption, biomass, activated carbon.
Online: 25 July 2018 (15:29:22 CEST)
The aim of the present study is to provide new insights into the CO2 and CH4 adsorption using a set of biomass-based activated carbons obtained by physical and chemical activation of olive-stones. The adsorption behavior is analyzed by means of pure gas adsorption isotherms up to 3.2 MPa at two temperatures (303.15 and 323.15 K).The influence of the activation method on the adsorption uptake is studied in terms of both textural properties and surface chemistry. For three activated carbons the CO2 adsorption was more important than that of CH4. The chemically activation resulted in higher BET surface area and micropore volume that lead to higher adsorption for both CO2 and CH4. For methane the presence of mesopores seems to facilitate the access of the gas molecules into the micropores while for carbon dioxide, the presence of oxygen groups enhanced the adsorption capacity.
ARTICLE | doi:10.20944/preprints202307.1353.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: Reforming; CH4; hydrogen production; adsorption; hydrogen storage; MgH2-12Ni
Online: 19 July 2023 (13:00:53 CEST)
A new study for CH4 reforming to hydrogen and hydrogen storage was performed using magnesium-based alloy. MgH2-12Ni (with the composition of 88 wt% MgH2 + 12 wt% Ni) was prepared in a planetary ball mill by milling in hydrogen atmosphere (reaction-involved milling). X-ray diffraction (XRD) analyses were performed for the samples after reaction-involved milling and after reactions with CH4. The variation of adsorbed or desorbed gas with time was measured by a Sieverts’ type high-pressure apparatus at 773 K. The microstructures of the powders were observed using scanning transmission microscope (STEM) with energy-dispersive X-ray spectroscopy (EDS). The synthesized samples were also characterized using Fourier Transform Infrared (FT-IR) spectroscopy. XRD pattern of MgH2-12Ni after reaction with CH4 of 12 bar at 773 K and decomposition under 1.0 bar at 773 K exhibited phases of MgH2 and Mg2NiH4. This shows that reforming of CH4 was occurred, hydrogen produced after reforming of CH4 was then adsorbed on the particles, and hydrides were formed during cooling to room temperature. Ni and Mg2Ni formed during heating up to 773 K are believed to have brought about catalytic effects for reforming CH4. MgH2-12Ni adsorbed 0.8 wt% reformed CH4 within 1 min in a reaction with CH4 of 12 bar at 773 K and then desorbed 0.8 wt% reformed CH4 (hydrogen-containing mixture) within 1 min under 1 bar at 773 K. Attenuated total reflectance FT-IR spectroscopy (ATR-FTIR) spectra of MgH2-12Ni after reactions under 12 bar CH4 at 723 K and 773 K showed peaks of C-H bending, C=C stretching, O-H stretching, O-H bending, and C-O stretching.
ARTICLE | doi:10.20944/preprints202309.0082.v1
Subject: Physical Sciences, Other Keywords: CO2; CH4; CO; Bivariate polar diagram; weather conditions; Lamto; Côte d’Ivoire
Online: 5 September 2023 (10:26:05 CEST)
CO2, CH4 and CO are the most critical atmospheric gases in terms of their impact on the radiative system, air quality and health. This work provides information on the direction of source areas and potential sources of emissions and shows many aspects of these gases by a statistical analysis using bivariate polar diagrams and local weather conditions (e.g., temperature, wind speed and wind direction) recorded at the Lamto station (LTO, 6°31N and 5°02W) in Côte d’Ivoire over the 2014-2018 period. The results show that the main regions contributing to the high concentrations of CH4 (> 1925 ppb) and CO2 (> 420 ppm) in the GSS, GSP, PSS and PSP seasons are the North and Northwest sectors of Lamto. In these directions, CH4 and CO2 concentrations are associated with wind speeds less than 6 m.s-1, due to the influences of local sources as emissions resulting from the degradation of organic matter submerged during the impoundment of the Taabo dam, and/nor human activities linked to the practice of intensive agriculture. In addition, the high concentrations of CO (> 350 ppb) are observed in GSS in the North, North-West, North-East and East sectors for wind speeds less than or equal to 9 m.s-1, due to the influences of both local and distant sources. The correlation coefficients between CH4 and CO, and between CH4 and CO2 are positive and significant in all sectors. However, those calculated between CO2 and CO have showed both low and high values in all seasons.
ARTICLE | doi:10.20944/preprints202011.0220.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: canopy; CH4; CO2; dehesas; diversity-interaction model; N2O; plant functional types
Online: 5 November 2020 (17:53:12 CET)
Iberian holm oak meadows are savannah-like ecosystems that result from traditional silvo pastoral practices. However, such traditional uses are declining, driving changes in the typical tree – open grassland structure of these systems. Yet, there are no studies integrating the whole ecosystem — including the arboreal and the herbaceous layer — as drivers of greenhouse gas (GHG: CO2, CH4 and N2O) dynamics. Here we aim at integrating the influence of tree canopies and interactions among plant functional types (PFT: grasses, forbs, and legumes) of the herbaceous layer as GHG exchange drivers. For that purpose, we performed chamber based GHG surveys in plots dominated by representative canopy types of Iberian holm oak meadows, including Quercus species and Pinus pinea stands, the last a common tree plantation replacing traditional stands; and unravelled GHG drivers through a diversity interaction model approach. Our results show that the tree – open grassland structure especially drove CO2 and N2O fluxes, with higher emissions under the canopy than in the open grassland. Emissions under P. pinea canopies being higher than those under Quercus species. In addition, the inclusion of diversity and compositional terms of the herbaceous layer improve the explained variability, legumes enhancing CO2 uptake and N2O emissions. Changes in the tree cover and tree species composition, in combination with changes in the structure and composition of the herbaceous layer, will imply deep changes in the GHG exchange of Iberian holm oak meadows. These results may provide some guidelines to perform better management strategies of this vast but vulnerable ecosystem.
ARTICLE | doi:10.20944/preprints201909.0250.v1
Subject: Chemistry And Materials Science, Chemical Engineering Keywords: ch4 temperature-programmed reduction; methane combustion; pd/zro2 catalyst; reduction; calcination
Online: 21 September 2019 (09:36:45 CEST)
The improvement of the methane combustion activity was observed in cyclic temperature-programmed and isothermal reactions over Pd/ZrO2 catalysts by simple reduction/re-oxidation treatment. The catalytic activity increased during the initial stages of isothermal reaction, and the light-off temperature was lowered as the number of cycles increased in the cyclic temperature-programmed reaction. To reveal the origin of activation, variations in the reduction properties after the activation period were carefully investigated through CH4 temperature-programmed reduction (TPR) measurements. From the CH4-TPR results, it was confirmed that the reduction temperature decreased significantly after activation. The observation of the CH4-TPR peak at relatively low temperatures is directly proportional to the catalytic activity of CH4 combustion. It was therefore concluded that repeated reduction/re-oxidation occurred in the reactant stream, and this phenomenon allowed the combustion reaction to proceed more easily at lower temperatures.
ARTICLE | doi:10.20944/preprints202103.0634.v1
Subject: Physical Sciences, Acoustics Keywords: MGEM; pin-anodes; Low-Mass WIMP; Axions; Quarks; TPC; SD-interactions; H2; CF4; CH4; TMAE
Online: 25 March 2021 (15:21:06 CET)
Gas electron multipliers (GEMs) with wire (WGEMs) or metal electrodes (MGEMs), which don’t use any plastic insulators between electrodes are created. The chambers containing MGEMs (WGEMs) with pin-anodes are proposed as detectors for searching of spin-dependent interactions between Dark Matter (DM) particles and gases with nonzero-spin nuclei (H2, D2, 3He, 21Ne, CF4, CH4, etc.). In this paper, we present a review of such chambers. For investigation of the gas mixtures Ne+10%H2, H2 (D2) +3ppmTMAE, the chamber containing WGEM with pin-anode detection system was constructed. In this paper we present the results of an experimental study of these gaseous mixtures exited by an α - source. Mixture of Ar + 40 ppm C2H4 and mixture 50% Xe + 50%CF4 have been investigated. The spatial distributions of photoelectron clouds produced by primary scintillations on α- and β-particle tracks, as well as the distributions of photoelectron clouds due to photons from avalanches at the pin-anode, have been measured for the first time. In our experiments as another filling of the chambers for search of low-mas WIMP (<10 GeV/c2), solar neutrino and solar axions with spin-dependent interaction we propose to use the mixtures: D2 + 3ppmTMAE, 3He + 3%CH4, 21Ne + 10%H2, at pressure 10-17 bar. And in our experiment with liquid gases is used the mixtures with 19F (LAr + CF4, LXe + CF4) and mixture LCH4 + 40ppm TMAE. The time projection chamber (TPC) with the mixture D2 + 3ppmTMAE filling allow to search of spin-dependent interactions of solar axions and deuterium. As well as we present the detecting systems for search of narrow pp-resonances (quarks) in accelerators experiments.
Subject: Environmental And Earth Sciences, Environmental Science Keywords: agricultural soils; carbon dioxide (CO2), energy; forests; methane (CH4), nitrous oxide (N2O), nutrient leaching; peat; traffic
Online: 6 November 2020 (17:19:26 CET)
rdinary people and political leaders must know the sources of greenhouse gas emissions and their effect on global climate change before they have ability to make decisions to reduce emissions and increase sinks of these gases. These people must, however, understand where greenhouse gas emissions are formed and how reductions can be made: they must understand where carbon dioxide sinks are and how to preserve or increase these sinks. North Savo is the example used in this work to describe the present emissions and sinks. There are proposals on what should and could be done to reduce greenhouse gas emissions caused by traffic, heating, forests and agriculture. There are possibilities of reducing emissions of greenhouse gases in traffic and heating in spite of the fact that the province has a low population density with long distances between homes and workplaces and schools, and a cold climate. We believe that research will also find solutions for reducing greenhouse gases and protecting waters, which are used for recreational purposes and for raw water of drinking water in many places. Luckily forests cover large areas of North Savo and their growth is an important carbon dioxide sink. In addition, forest soils serve as a valuable storage of carbon. Besides carbon dioxide emissions, emissions of nitrous oxide and methane must also be considered since they are more potent greenhouse gases than carbon dioxide and land use can thus influence these gas emissions.
ARTICLE | doi:10.20944/preprints202312.0195.v1
Subject: Physical Sciences, Optics And Photonics Keywords: KrF laser pulse compression; stimulated Brillouin and Raman scattering in SF6 and CH4; theory of soliton-like pulse compression.
Online: 4 December 2023 (15:14:24 CET)
Nonlinear compression of narrow-band (Δ ≈ 0.2 cm-1) 20 ns KrF laser pulses in SF6 at 10 atm and CH4 at 50 atm pressure was studied. Both SBS and SRS optically phase conjugated backward reflected radiation was registered with energy reflectivity 10−14% in SF6 and CH4. In SF6 SBS pulses gradually shortened from 10 ns to 2−3 ns with pumping decrease to the SBS threshold ~ 10 mJ, while the SRS pulse had the shortest length of 30−60 ps for the maximal pumping of 120 mJ and broadened near the SRS threshold of ~30 mJ. For the SRS pulse energy ~ 2 mJ peak power 5×107 W was tenfold higher than the pump power. The theoretical model predicted a soliton-like SRS pulse compression to a temporal length of the order of vibrational relaxation time. There was no pulse compression of backward SBS and SRS radiation in CH4, while in the forward direction SRS pulses shortened to 3−4 ns at reduced pumping.
ARTICLE | doi:10.20944/preprints202310.0090.v1
Subject: Environmental And Earth Sciences, Geochemistry And Petrology Keywords: CO2; CH4; δ13С in wood; tree-ring; Pinus sylvestris; iWUE; ci/ca; temperature; precipitation; evapotranspiration; cloud fraction; Tatarstan Republic; Russia
Online: 3 October 2023 (09:20:36 CEST)
Human-caused anthropogenic greenhouse emissions impact climate globally. In this pilot study, we aim to reveal the impact of oil and gas emissions from local oil deposits in the regime of their natural degradation and development and eco-physiological changes of pine forests in Tatarstan Republic, Russia over the past century. We performed stable carbon isotope analysis in pine tree rings (13Cptrw) to reveal the impact of oil and gas emissions from the giant oil field reservoirs located in Leninogorsk region (UVRT) and the natural reserve site in Raifa. Our results show decreasing 13Cptrw at UVRT in 1943 when oil extraction was started, and in 1970, when it reached the maximum production. We found that 13Cptrw from UVRT indicates on developing unfavourable drier conditions and suppressed tree growth caused by both human-induced oil and deposit infrastructure and natural processes compared to undisturbed Raifa. The 13Cptrw from Raifa is more negative compared to UVRT, which can be explained by higher forest sensitivity to human-induced impact. From an ecophysiological point of view decreasing intercellular to ambient CO2 concentration at the leaf level and increasing intrinsic water use efficiency along with decreasing tree-ring width at UVRT (1970-2021) indicate on development of drought conditions.
ARTICLE | doi:10.20944/preprints202103.0493.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: California Air Resources Board; carbon trading; Climate Action Reserve; eddy covariance; forest carbon protocols; forest carbon supply chain; Green New Deal; Howland Forest; net ecosystem exchange; social cost of CO2, CH4, N2O
Online: 19 March 2021 (08:23:11 CET)
Forest carbon sequestration is a widely accepted natural climate solution, however, methods to determine net carbon offsets are limited to commercial carbon proxies and CO2 eddy covariance research. Non-CO2 greenhouse gases (GHG) (e.g., CH4, N2O) receive less attention in the context of forests, in part, due to emphasis on CO2 and the operational requirements and cost for three-gas eddy covariance platforms. In this study, Howland forest flux tower (CO2, CH4) and soil flux data (CO2, CH4, N2O), representing net emission reductions, are linked to their respective social costs to estimate commercial revenue if sold as a GHG social cost forest offset product (GHG-SCF). Estimated annual revenue for GHG-SCF products, applicable to realization of a Green New Deal, range from 120,000 covering the site area of 557 acres in 2021, to 12,000,000 for extrapolation to 40,000 acres in 2040, assuming a 3% discount rate. The Howland Forest CO2 flux record for two adjacent towers is compared to California Air Resources Board forest carbon proxy data for compliance sequestration offsets, the only project site where these approaches overlap. Overcrediting, incomplete carbon accounting with annual errors of up to 2,256%, inadequate third-party verification, and limited application to non-CO2 GHG’s are established. In contrast, direct measurement of one or more GHG’s offers new forest products and revenue incentives to restore and conserve forests worldwide.