scholarly journals Methane (CH<sub>4</sub>) sources in Krakow, Poland: insights from isotope analysis

2021 ◽  
Vol 21 (17) ◽  
pp. 13167-13185
Author(s):  
Malika Menoud ◽  
Carina van der Veen ◽  
Jaroslaw Necki ◽  
Jakub Bartyzel ◽  
Barbara Szénási ◽  
...  
Keyword(s):  
Time Series ◽  
Isotopic Composition ◽  
Transport Model ◽  
Ambient Air ◽  
Coal Extraction ◽  
Night Time ◽  
Isotopic Signatures ◽  
Ch4 Emissions ◽  
Gas Leaks ◽  
Pollution Events

Abstract. Methane (CH4) emissions from human activities are a threat to the resilience of our current climate system. The stable isotopic composition of methane (δ13C and δ2H) allows us to distinguish between the different CH4 origins. A significant part of the European CH4 emissions, 3.6 % in 2018, comes from coal extraction in Poland, the Upper Silesian Coal Basin (USCB) being the main hotspot. Measurements of CH4 mole fraction (χ(CH4)), δ13C, and δ2H in CH4 in ambient air were performed continuously during 6 months in 2018 and 2019 at Krakow, Poland, in the east of the USCB. In addition, air samples were collected during parallel mobile campaigns, from multiple CH4 sources in the footprint area of the continuous measurements. The resulting isotopic signatures from sampled plumes allowed us to distinguish between natural gas leaks, coal mine fugitive emissions, landfill and sewage, and ruminants. The use of δ2H in CH4 is crucial to distinguish the fossil fuel emissions in the case of Krakow because their relatively depleted δ13C values overlap with the ones of microbial sources. The observed χ(CH4) time series showed regular daily night-time accumulations, sometimes combined with irregular pollution events during the day. The isotopic signatures of each peak were obtained using the Keeling plot method and generally fall in the range of thermogenic CH4 formation – with δ13C between −59.3 ‰ and −37.4 ‰ Vienna Pee Dee Belemnite (V-PDB) and δ2H between −291 ‰ and −137 ‰ Vienna Standard Mean Ocean Water (V-SMOW). They compare well with the signatures measured for gas leaks in Krakow and USCB mines. The CHIMERE transport model was used to compute the CH4 and isotopic composition time series in Krakow, based on two emission inventories. The magnitude of the pollution events is generally underestimated in the model, which suggests that emission rates in the inventories are too low. The simulated isotopic source signatures, obtained with Keeling plots on each simulated peak, indicate that a higher contribution from fuel combustion sources in the EDGAR v5.0 inventory would lead to a better agreement than when using CAMS-REG-GHG v4.2 (Copernicus Atmosphere Monitoring Service REGional inventory for Air Pollutants and GreenHouse Gases). The isotopic mismatches between model and observations are mainly caused by uncertainties in the assigned isotopic signatures for each source category and the way they are classified in the inventory. These uncertainties are larger for emissions close to the study site, which are more heterogenous than the ones advected from the USCB coal mines. Our isotope approach proves to be very sensitive in this region, thus helping to evaluate emission estimates.

scholarly journals Measurement report: Methane (CH<sub>4</sub>) sources in Krakow, Poland: insights from isotope analysis

2021 ◽  
Author(s):  
Malika Menoud ◽  
Carina van der Veen ◽  
Jaroslaw Necki ◽  
Jakub Bartyzel ◽  
Barbara Szénási ◽  
...  
Keyword(s):  
Time Series ◽  
Isotopic Composition ◽  
Transport Model ◽  
Isotope Analysis ◽  
Ambient Air ◽  
Coal Extraction ◽  
Night Time ◽  
Isotopic Signatures ◽  
Ch4 Emissions ◽  
Gas Leaks

Abstract. Methane (CH4) emissions from human activities are a threat to the resilience of our current climate system, and to the adherence of the Paris Agreement goals. The stable isotopic composition of methane (δ13C and δ2H) allows to distinguish between the different CH4 origins. A significant part of the European CH4 emissions, 3.6 % in 2018, comes from coal extraction in Poland; the Upper Silesian Coal Basin (USCB) being the main hotspot. Measurements of CH4 mole fraction (χ(CH4)), δ13C and δ2H in CH4 in ambient air were performed continuously during 6 months in 2018 and 2019 at Krakow, Poland, 50 km east of the USCB. In addition, air samples were collected during parallel mobile campaigns, from multiple CH4 sources in the footprint area of the continuous measurements. The resulting isotopic signatures from sampled plumes allowed us to distinguish between natural gas leaks, coal mine fugitive emissions, landfill and sewage, and ruminants. The use of δ2H in CH4 is crucial to distinguish the fossil fuel emissions in the case of Krakow, because their relatively depleted δ13C values overlap with the ones of microbial sources. The observed χ(CH4) time series showed regular daily night-time accumulations, sometimes combined with irregular pollution events during the day. The isotopic signatures of each peak were obtained using the Keeling plot method, and generally fall in the range of thermogenic CH4 formation – with δ13C between −55.3 and −39.4 ‰ V-PDB, and δ2H between −285 and −124 ‰ V-SMOW. They compare well with the signatures measured for gas leaks in Krakow and USCB mines. The CHIMERE transport model was used to compute the CH4 and isotopic composition time series in Krakow, based on two emission inventories. The χ(CH4) are generally under-estimated in the model. The simulated isotopic source signatures, obtained with Keeling plots on each simulated peak using the EDGAR v5.0 inventory, indicate that a higher contribution from fuel combustion sources in EDGAR would lead to a better agreement. The isotopic mismatches between model and observations are mainly caused by uncertainties in the assigned isotopic signatures for each source category, and the way they are classified in the inventory. These uncertainties are larger for emissions close to the study site, which are more heterogenous than the ones advected from the USCB coal mines. Our isotope approach proves to be very sensitive in this region, thus helping to evaluate emission estimates.

Isotopic characterisation of methane emissions from Krakow, Poland

2021 ◽  
Author(s):  
Malika Menoud ◽  
Carina van der Veen ◽  
Jaroslaw Necki ◽  
Mila Stanisavljevic ◽  
Barbara Szenási ◽  
...  
Keyword(s):  
Time Series ◽  
Transport Model ◽  
Ambient Air ◽  
Night Time ◽  
Isotopic Signatures ◽  
Upper Silesian Coal Basin ◽  
Source Category ◽  
Footprint Area ◽  
Gas Leaks ◽  
Pollution Events

&lt;p&gt;Methane (CH&lt;sub&gt;4&lt;/sub&gt;) emissions from human activities are a threat to the resilience of our current climate, and to the adherence of the Paris Agreement goals. The stable isotopic composition of methane (&amp;#948;&lt;sup&gt;13&lt;/sup&gt;C and &amp;#948;&lt;sup&gt;2&lt;/sup&gt;H) allows to distinguish between the different CH&lt;sub&gt;4&lt;/sub&gt; origins. A significant part of the European CH&lt;sub&gt;4&lt;/sub&gt; emissions, 10 % in 2016, comes from the Upper Silesian Coal Basin (USCB).&amp;#160;&lt;/p&gt;&lt;p&gt;Measurements of CH&lt;sub&gt;4&lt;/sub&gt; mole fraction (&amp;#967;(CH&lt;sub&gt;4&lt;/sub&gt;)), &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C and &amp;#948;&lt;sup&gt;2&lt;/sup&gt;H&amp;#160;in CH&lt;sub&gt;4&lt;/sub&gt; in ambient air were performed continuously during 6 months in 2018 and 2019 at Krakow, Poland. In addition, CH&lt;sub&gt;4&lt;/sub&gt; samples were collected during parallel mobile campaigns, from multiple CH&lt;sub&gt;4&lt;/sub&gt; sources in the footprint area of continuous measurements. The resulting isotopic signatures from natural gas leaks, coal mine fugitive emissions, landfill and sewage, and ruminant emissions were statistically different. The use of &amp;#948;&lt;sup&gt;2&lt;/sup&gt;H in CH&lt;sub&gt;4&lt;/sub&gt; is crucial to distinguish the fossil fuel emissions in the case of Krakow, because their relatively depleted &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C values overlap with the ones of microbial sources. The observed &amp;#967;(CH&lt;sub&gt;4&lt;/sub&gt;) time series showed a regular daily night-time accumulations, sometimes combined with irregular pollution events during the day. The isotopic signatures of each peak were obtained using the Keeling plot method, and generally fall in the range of thermogenic CH&lt;sub&gt;4&lt;/sub&gt; formation, with &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C between -55.3 and -39.4 &amp;#8240; V-PDB, and &amp;#948;&lt;sup&gt;2&lt;/sup&gt;H between -285 and -124&amp;#160;&amp;#8240;&amp;#160;V-SMOW. They compare well with the signatures measured for gas leaks in Krakow and USCB mines.&amp;#160;&lt;/p&gt;&lt;p&gt;The CHIMERE transport model was used to compute the CH&lt;sub&gt;4&lt;/sub&gt; time series at the study location, based on two emission inventories. The &amp;#967;(CH&lt;sub&gt;4&lt;/sub&gt;) are generally under-estimated in the model. The isotopic signatures of all pollution events over the entire time periods were extracted from Keeling plots applied on each peaks, for both observed and modelled time series using the EDGAR v5.0 inventory. The results indicate that a higher contribution from fuel combustion sources in the inventory would lead to a better agreement. The isotopic mismatches between model and observations are mainly caused by uncertainties in the assigned isotopic signatures for each source category, and how they are classified in the inventory. These uncertainties are larger for emissions close to the study site, which are more heterogenous than the ones advected from the USCB coal mines. Our isotope approach proves here to be very sensitive in this region, thus helping to improve emission estimates.&lt;/p&gt;

scholarly journals Measuring and modelling the isotopic composition of soil respiration: insights from a grassland tracer experiment

2011 ◽  
Vol 8 (5) ◽  
pp. 1333-1350 ◽  
Author(s):  
U. Gamnitzer ◽  
A. B. Moyes ◽  
D. R. Bowling ◽  
H. Schnyder
Keyword(s):  
Steady State ◽  
Isotopic Composition ◽  
Transport Model ◽  
Tracer Experiment ◽  
Atmospheric Co2 ◽  
Soil Co2 ◽  
Soil Air ◽  
Co2 Transport ◽  
Atmosphere System

Abstract. The carbon isotopic composition (δ13C) of CO2 efflux (δ13Cefflux) from soil is generally interpreted to represent the actual isotopic composition of the respiratory source (δ13CRs). However, soils contain a large CO2 pool in air-filled pores. This pool receives CO2 from belowground respiration and exchanges CO2 with the atmosphere (via diffusion and advection) and the soil liquid phase (via dissolution). Natural or artificial modification of δ13C of atmospheric CO2 (δ13Catm) or δ13CRs causes isotopic disequilibria in the soil-atmosphere system. Such disequilibria generate divergence of δ13Cefflux from δ13CRs (termed "disequilibrium effect"). Here, we use a soil CO2 transport model and data from a 13CO2/12CO2 tracer experiment to quantify the disequilibrium between δ13Cefflux and δ13CRs in ecosystem respiration. The model accounted for diffusion of CO2 in soil air, advection of soil air, dissolution of CO2 in soil water, and belowground and aboveground respiration of both 12CO2 and 13CO2 isotopologues. The tracer data were obtained in a grassland ecosystem exposed to a δ13Catm of −46.9 ‰ during daytime for 2 weeks. Nighttime δ13Cefflux from the ecosystem was estimated with three independent methods: a laboratory-based cuvette system, in-situ steady-state open chambers, and in-situ closed chambers. Earlier work has shown that the δ13Cefflux measurements of the laboratory-based and steady-state systems were consistent, and likely reflected δ13CRs. Conversely, the δ13Cefflux measured using the closed chamber technique differed from these by −11.2 ‰. Most of this disequilibrium effect (9.5 ‰) was predicted by the CO2 transport model. Isotopic disequilibria in the soil-chamber system were introduced by changing δ13Catm in the chamber headspace at the onset of the measurements. When dissolution was excluded, the simulated disequilibrium effect was only 3.6 ‰. Dissolution delayed the isotopic equilibration between soil CO2 and the atmosphere, as the storage capacity for labelled CO2 in water-filled soil pores was 18 times that of soil air. These mechanisms are potentially relevant for many studies of δ13CRs in soils and ecosystems, including FACE experiments and chamber studies in natural conditions. Isotopic disequilibria in the soil-atmosphere system may result from temporal variation in δ13CRs or diurnal changes in the mole fraction and δ13C of atmospheric CO2. Dissolution effects are most important under alkaline conditions.

Imputing missing data in non-renewable empower time series from night-time lights observations

2018 ◽  
Vol 84 ◽  
pp. 106-118 ◽  
Author(s):  
Laura Neri ◽  
Luca Coscieme ◽  
Biagio F. Giannetti ◽  
Federico M. Pulselli
Keyword(s):  
Time Series ◽  
Missing Data ◽  
Night Time

scholarly journals In-situ observations of the isotopic composition of methane at the Cabauw tall tower site

2016 ◽  
Author(s):  
Thomas Röckmann ◽  
Simon Eyer ◽  
Carina van der Veen ◽  
Maria E. Popa ◽  
Béla Tuzson ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
High Precision ◽  
Temporal Resolution ◽  
Isotope Ratio ◽  
Mesoscale Model ◽  
Ambient Air ◽  
Model Calculations ◽  
Dual Isotope ◽  
Methane Budget

Abstract. High precision analyses of the isotopic composition of methane in ambient air can potentially be used to discriminate between different source categories. Due to the complexity of isotope ratio measurements, such analyses have generally been performed in the laboratory on air samples collected in the field. This poses a limitation on the temporal resolution at which the isotopic composition can be monitored with reasonable logistical effort. Here we present the performance of a dual isotope ratio mass spectrometric system (IRMS) and a quantum cascade laser absorption spectroscopy (QCLAS) based technique for in-situ analysis of the isotopic composition of methane under field conditions. Both systems were deployed at the Cabauw experimental site for atmospheric research (CESAR) in the Netherlands and performed in-situ, high-frequency (approx. hourly) measurements for a period of more than 5 months. The IRMS and QCLAS instruments were in excellent agreement with a slight systematic offset of +(0.05 ± 0.03) ‰ for δ13C and –(3.6 ± 0.4) ‰ for δD. This was corrected for, yielding a combined dataset with more than 2500 measurements of both δ13C and δD. The high precision and temporal resolution dataset does not only reveal the overwhelming contribution of isotopically depleted agricultural CH4 emissions from ruminants at the Cabauw site, but also allows the identification of specific events with elevated contributions from more enriched sources such as natural gas and landfills. The final dataset was compared to model calculations using the global model TM5 and the mesoscale model FLEXPART-COSMO. The results of both models agree better with the measurements when the TNO-MACC emission inventory is used in the models than when the EDGAR inventory is used. This suggests that high-resolution isotope measurements have the potential to further constrain the methane budget, when they are performed at multiple sites that are representative for the entire European domain.

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