Observational constraints on methane emissions from Polish coal mines using a ground-based remote sensing network

Given its abundant coal mining activities, the Upper Silesian Coal Basin (USCB) in southern Poland is one of the largest sources of anthropogenic methane (CH$_{4}$) emissions in Europe. Here, we report on CH$_{4}$emission estimates for coal mine ventilation facilities in the USCB. Our estimates are driven by pairwise upwind–downwind observations of the column-average dry-air mole fractions of CH$_{4}$ (XCH$_{4}$) by a network of four portable, ground-based, sun-viewing Fourier transform spectrometers of the type EM27/SUN operated during the CoMet campaign in May–June 2018. The EM27/SUN instruments were deployed in the four cardinal directions around the USCB approximately 50 km from the center of the basin. We report on six case studies for which we inferred emissions by evaluating the mismatch between the observed downwind enhancements and simulations based on trajectory calculations releasing particles out of the ventilation shafts using the Lagrangian particle dispersion model FLEXPART. The latter was driven by wind fields calculated by WRF (Weather Research and Forecasting model) under assimilation of vertical wind profile measurements of three co-deployed wind lidars. For emission estimation, we use a Phillips–Tikhonov regularization scheme with the L-curve criterion. Diagnosed by the emissions averaging kernels, we find that, depending on the catchment area of the downwind measurements, our ad hoc network can resolve individual facilities or groups of ventilation facilities but that inspecting the emissions averaging kernels is essential to detect correlated estimates. Generally, our instantaneous emission estimates range between 80 and 133 kt CH$_{4}$ a$^{-1}$ for the southeastern part of the USCB and between 414 and 790 kt CH$_{4}$a$^{-1}$ for various larger parts of the basin, suggesting higher emissions than expected from the annual emissions reported by the E-PRTR (European Pollutant Release and Transfer Register). Uncertainties range between 23 % and 36 %, dominated by the error contribution from uncertain wind fields

New contributions of measurements in Europe to the global inventory of the stable isotopic composition of methane

Recent climate change mitigation strategies rely on the reduction of methane (CH4) emissions. Carbon and hydrogen isotope ratio (δ13CCH4 and δ2HCH4) measurements can be used to distinguish sources and thus to understand the CH4 budget better. The CH4 emission estimates by models are sensitive to the isotopic signatures assigned to each source category, so it is important to provide representative estimates of the different CH4 source isotopic signatures worldwide. We present new measurements of isotope signatures of various, mainly anthropogenic, CH4 sources in Europe, which represent a substantial contribution to the global dataset of source isotopic measurements from the literature, especially for δ2HCH4. They improve the definition of δ13CCH4 from waste sources, and demonstrate the use of δ2HCH4 for fossil fuel source attribution. We combined our new measurements with the last published database of CH4 isotopic signatures and with additional literature, and present a new global database. We found that microbial sources are generally well characterised. The large variability in fossil fuel isotopic compositions requires particular care in the choice of weighting criteria for the calculation of a representative global value. The global dataset could be further improved by measurements from African, South American, and Asian countries, and more measurements from pyrogenic sources. We improved the source characterisation of CH4 emissions using stable isotopes and associated uncertainty, to be used in top-down studies. We emphasise that an appropriate use of the database requires the analysis of specific parameters in relation to source type and the region of interest. The final version of the European CH4 isotope database coupled with a global inventory of fossil and non-fossil δ13CCH4 and δ2HCH4 source signature measurements is available at 10.24416/UU01-YP43IN

Caractérisation des émissions de méthane (CH4) en milieu urbain (Paris)

This Ph.D. aimed to measure methane (CH4) mixing ratio, its carbon isotope (δ13CH4) and ethane to methane ratio (C2H6:CH4) of diverse Île-de-France sources using CRDS G2201-i during near-source mobile measurements.Laboratory tests showed good performances of CRDS2201-i, notably a good agreement between δ13CH4 determined using CRDS G2201-i and IRMS. Indeed, precision of CRDS is less good than for IRMS, but it improves with larger CH4 mixing ratio (chapter 2). Possibilities and limitation of using CRDS G2201-i instrument to determine C2H6:CH4 ratio were also verified in laboratory and field conditions. Using CRDS G2201-i to measure C2H6:CH4 ratio is possible when enhancement is higher than 1 ppm above background and dried air is measured, which allows to use only one instrument to measure two proxies of CH4 sources (δ13CH4 and C2H6:CH4 ) (chapter 3).Then, the mobile set-up was adapted for mobile surveys in Paris city. There, three main CH4 sources where found: natural gas leaks, sewage network leaks and venting grid leaks ascribed to leaking furnaces installations. The latest category was discovered during walking measurements and was not described in previous studies. Compared to other cities, mostly surveyed in the U.S., Paris CH4 emissions are relatively small and comparable to cities with modern pipeline system. Comparison with inventories showed that for the energy sector, CH4 emissions are about fifteen times smaller than downscaled AIRPARIF inventories (chapter 4). Finally, at the industrial site scale, δ13CH4 and δDCH4 were determined and contributed to extend the database of isotopic signatures of European CH4 emissions. C2H6:CH4 observed from gas compressor stations are comparable with those in previous studies in other countries. For part of the sites, emission rates were also estimated using a Gaussian model or the tracer dispersion method (chapter 5).Results of this Ph.D. can be used as a base for future mobile, near-source campaigns in IDF region.Le but de cette thèse est de mesurer les concentrations de méthane (CH4), sa signature isotopique en carbone (δ13CH4) et le ratio éthane/méthane (C2H6:CH4) de diverses sources en Île-de-France avec des mesures mobiles proche des sources en utilisant l’instrument CRDS G2201-i.Les tests en laboratoire ont montré que le CRDS G2201-i présentaient de bonnes performances, notamment un bon accord avec les mesures de δ13CH4 par IRMS. En effet, la précision du CRDS est moins élevée que celle de l’IRMS, mais elle s’améliore avec des concentrations plus élevées en méthane (chapitre 2). Les performances et les limites de l’instrument ont été également testées pour la mesure du ratio C2H6:CH4 au laboratoire et sur le terrain. Il est possible d’utiliser le G2201-i quand l’élévation de CH4 au-dessus des valeurs ambiantes est supérieure à 1pmm et que l’air mesuré est séché. Cela permet d’utiliser un seul instrument pour mesurer deux proxies des sources de méthane (δ13CH4 et C2H6:CH4 ) (chapitre 3).Ensuite, la plateforme de mesures mobiles a été adaptées pour des campagnes de mesure dans Paris et sa petite couronne. Là, trois sources de CH4 ont été trouvées: des fuites du réseau de gaz naturel, des fuites du réseau d’assainissement et des fuites au niveau de grilles d’aération associées à des chaudières. Cette dernière catégorie a été découverte lors de mesures à pied et n’était pas décrite précédemment dans la littérature. Par rapport à d’autres villes, en majorité américaine, les émissions parisiennes de CH4 sont relativement faibles et comparables à celles des villes ayant un réseau moderne de distribution de gaz. La comparaison avec les inventaires a montré que pour le secteur de l’énergie, les émissions estimées étaient quinze fois plus faibles que celles de d’AIRPARIF ajustées pour Paris (chapitre 4). Enfin, à l’échelle du site industriel, δ13CH4 et δDCH4 ont été déterminés et contribuent à enrichir la base de données de signatures isotopiques européenne pour CH4. Le ratio C2H6:CH4 mesuré sur les stations de compression de gaz sont comparables à celles observées dans d’autres études dans d’autres pays. Pour certains sites, les émissions sont été également estimées, soit avec un modèle Gaussien soit avec le méthode traceur (chapitre 5).Les résultats de cette thèse peuvent être utilisés comme support pour de futures campagnes de mesures en Île-de-France

Further Cryogenic Separation and Mass Spectrometry Developments: Towards Ambient Air Methane Clumped Isotopes Measurements

The multiply-substituted isotopologues of methane are of significant interest due to their increased ability to distinguish between methane formation and destruction processes, in comparison to singly-substituted isotopologues, as shown previously by Thiagarajan et al.(2022) and Sivan et al.(2022). Methane isotopologues, unlike the isotopologues of carbon dioxide, do not easily transition towards thermodynamic equilibrium in the atmosphere and therefore, ambient air methane isotopologues, offer constraints on the atmospheric methane sources and sinks (Chung and Arnold, 2021). These processes potentially offer new insight into the causes of variation in methane concentrations in the last two decades. We present developments in the separation of the components of air, using a helium-cooled cryostat. Working on both pre-concentrated air mixtures and laboratory created gas mixtures, we extract methane from the contaminants and other atmospheric gases using the cryostat, applicable to a minimum methane concentration of ~1% (Stolper et al., 2015), then we analyse using a TFS Ultra HR-IRMS. We demonstrate that our cryostat separations successfully extract methane and krypton from laboratory gas mixtures containing the components of atmospheric air, without causing methane fractionation. We also present further developments in measuring and calibrating the isotopologues of methane by high-resolution mass spectrometry. We successfully created thermodynamically equilibrated samples of methane in the 250-500oC range using a nickel catalyst and are working on the 1-250oC range using a γ-Al2O3 catalyst (Eldridge et al., 2019). It is essential to have an extensive calibration curve to best constrain the effects of scale compression on the calculated deltas and therefore reduce sources of further error, hence the extension of this calibration range. Further work will add additional reference and sample points to the absolute reference frame created by the equilibrated samples, optimise the cryogenic/gas chromatographic purification methods for more complex gas mixtures, and optimise the IRMS workflow to reduce the necessary air sample sizes

Mapping Urban Methane Sources in Paris, France

International audienceMegacities, with their large and complex infrastructures, are significant sources of methane emissions. To develop a simple, low-cost methodology to quantify these globally important methane sources, this study focuses on mobile measurements of methane (CH 4) and its isotopic composition in Paris. Data collected between September 2018 to March 2019 resulted in 17 days of measurements, which provided spatial distribution of street-level methane mixing ratios, source type identification, and emission quantification. Consequently, 90 potential leaks were detected in Paris sorted into three leak categories: natural gas distribution network emissions (63%), sewage network emissions (33%), and emissions from heating furnaces of buildings (4%). The latter category has not previously been reported in urban methane studies. Accounting for the detectable emissions from the ground, the total estimated CH 4 emission rate of Paris was 5000 L/min (190 t/yr), with the largest contribution from gas leaks (56%). This ranks Paris as a city with medium CH 4 emissions. Two areas of clusters were found, where 22% and 56% of the total potential emissions of Paris were observed. Our findings suggest that the natural gas distribution network, the sewage system, and furnaces of buildings are ideal targets for street-level CH 4 emission reduction efforts for Paris

Observational constraints on methane emissions from Polish coal mines using a ground-based remote sensing network

International audienceGiven its abundant coal mining activities, the Upper Silesian Coal Basin (USCB) in southern Poland is one of the largest sources of anthropogenic methane (CH 4) emissions in Europe. Here, we report on CH 4 emission estimates for coal mine ventilation facilities in the USCB. Our estimates are driven by pairwise upwinddownwind observations of the column-average dry-air mole fractions of CH 4 (XCH 4) by a network of four portable, ground-based, sun-viewing Fourier transform spectrometers of the type EM27/SUN operated during the CoMet campaign in May-June 2018. The EM27/SUN instruments were deployed in the four cardinal directions around the USCB approximately 50 km from the center of the basin. We report on six case studies for which we inferred emissions by evaluating the mismatch between the observed downwind enhancements and simulations based on trajectory calculations releasing particles out of the ventilation shafts using the Lagrangian particle dispersion model FLEXPART. The latter was driven by wind fields calculated by WRF (Weather Research and Forecasting model) under assimilation of vertical wind profile measurements of three co-deployed wind lidars. For emission estimation, we use a Phillips-Tikhonov regularization scheme with the L-curve criterion. Diagnosed by the emissions averaging kernels, we find that, depending on the catchment area of the downwind measurements, our ad hoc network can resolve individual facilities or groups of ventilation facilities but that inspecting the emissions averaging kernels is essential to detect correlated estimates. Generally, our instantaneous emission estimates range between 80 and 133 kt CH 4 a −1 for the southeastern part of the USC

The European methane isotope database coupled with a global inventory of fossil and non-fossil δ13C- and δ2H-CH4 source signature measurements

Stable isotopic composition (13C and 2H) of methane (CH4) emission sources. European Methane Isotope Database, based on measurements carried out during the MEMO2 project (https://h2020-memo2.eu) Methane Isotopic signatures from previous literature, reported by Sherwood et al. (2017, 2021), and in other literature sources. Sherwood, O.A., Schwietzke, S., Arling, V.A., Etiope, G., 2017. Global Inventory of Gas Geochemistry Data from Fossil Fuel, Microbial and Burning Sources, version 2017. Earth Syst. Sci. Data 9, 639–656. https://doi.org/10.5194/essd-9-639-2017 Sherwood, O.A., Schwietzke, S., Lan, X., 2021. Global δ13C-CH4 source signature inventory 2020. Available at: https://doi.org/10.15138/qn55-e01

Efeito da suplementação de linhaça, óleo de canola e vitamina e na dieta sobre a oxidação dos ácidos graxos na gema dos ovos de galinhas poedeiras

To investigate the effect of dietary sources of polyunsaturated fatty acids - canola oil and flaxseed - with different vitamin E supplementation upon the fatty acids oxidation produtcts deposition into the eggs. 288 Babcock laying hens were used. Birds were fed diets containing 6% of canola oil, 20% of flaxseed or a combination of 3% of canola oil and 10% of flaxseed, enriched with 0, 100 or 200 Ul of dl-a-tocopheril acetate, hens were randomly allocated and the experimental design was a 3X3 factorial arrangement. The inclusion of flaxseed into the diet increased the yolk polyunsaturated fatty acids oxidation products, in crude and cooked stored eggs. The concentration of fatty acids oxidation products decrease in crude eggs in all sources of polyunsaturated fatty acids. The cooked eggs without a-tocopherol supplementation in the diet increase the concentration of oxidation products when compared with cooked eggs from diets with 100 or 200UI a-tocopherol in the die

New contributions of measurements in Europe to the global inventory of the stable isotopic composition of methane

International audienceAbstract. Recent climate change mitigation strategies rely on the reduction of methane (CH4) emissions. Carbon and hydrogen isotope ratio (δ13CCH4 and δ2HCH4) measurements can be used to distinguish sources and thus to understand the CH4 budget better. The CH4 emission estimates by models are sensitive to the isotopic signatures assigned to each source category, so it is important to provide representative estimates of the different CH4 source isotopic signatures worldwide. We present new measurements of isotope signatures of various, mainly anthropogenic, CH4 sources in Europe, which represent a substantial contribution to the global dataset of source isotopic measurements from the literature, especially for δ2HCH4. They improve the definition of δ13CCH4 from waste sources, and demonstrate the use of δ2HCH4 for fossil fuel source attribution. We combined our new measurements with the last published database of CH4 isotopic signatures and with additional literature, and present a new global database. We found that microbial sources are generally well characterised. The large variability in fossil fuel isotopic compositions requires particular care in the choice of weighting criteria for the calculation of a representative global value. The global dataset could be further improved by measurements from African, South American, and Asian countries, and more measurements from pyrogenic sources. We improved the source characterisation of CH4 emissions using stable isotopes and associated uncertainty, to be used in top-down studies. We emphasise that an appropriate use of the database requires the analysis of specific parameters in relation to source type and the region of interest. The final version of the European CH4 isotope database coupled with a global inventory of fossil and non-fossil δ13CCH4 and δ2HCH4 source signature measurements is available at https://doi.org/10.24416/UU01-YP43IN (Menoud et al., 2022a)

mamenoud/European_Methane_Isotope_Database

Stable isotope (13C and 2H) data of methane (CH4) emission sources. European Methane Isotope Database, based on measurements carried out during the MEMO2 project (https://h2020-memo2.eu) Methane Isotopic signatures from previous literature, reported by Sherwood et al. (2017, 2021), and in other literature sources. Sherwood, O.A., Schwietzke, S., Arling, V.A., Etiope, G., 2017. Global Inventory of Gas Geochemistry Data from Fossil Fuel, Microbial and Burning Sources, version 2017. Earth Syst. Sci. Data 9, 639–656. https://doi.org/10.5194/essd-9-639-2017 Sherwood, O.A., Schwietzke, S., Lan, X., 2021. Global δ13C-CH4 source signature inventory 2020. Available at: https://doi.org/10.15138/qn55-e01