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opencc-zeroJan 2023View details →

Influence of sedimentary environment evolution on fingerprint characteristics of methane isotopes: A case study from Hangzhou Bay

To better understand the depositional constraints on the fingerprint characteristics of methane isotopes, we present a set of carbon/hydrogen isotopic data for CH4, CO2, pore water, carbonates, and total organic carbon (TOC) along a 70-m sedimentary core from Hangzhou Bay, China. The sedimentary facies (Units I, II, and III from upper to bottom) suggested depositional environments of the present estuary, shallow marine, and floodplain-estuary. The values of δDCH4 displayed similar trends with those of δDH2O and Cl- concentrations along the depth profiles. The values of δ13CCH4 generally synchronously changed with those of δ13CCO2. The variation trends of δ13CCH4 and δ13CCO2 were the same with δ13Ccarbonate from 10 m to 70 m depth but decoupled above 10 m. Calculations suggested that about 86% of methane was produced through the CO2 reduction pathway. In this pathway, the hydrogen in CH4 is from ambient water, while the carbon is from dissolved inorganic carbon. In our study, the low δDCH4 below 44.5 m corresponded to low δDH2O and low salinity during the cold and low-sea-level period. The values of δ13CCH4 in Units II and III were correlated with the δ13Ccarbonates, which is related to the sedimentary processes. But decoupling of low values of δ13CCH4 and δ13CCO2 from δ13Ccarbonates in Unit I may be related to preferential microbial consumption of labile compounds with light carbon isotopic compositions, such as lipids. In short, the variations of the stable carbon and hydrogen isotopic compositions of CH4 were largely related to sedimentary processes.

opencc-by-4.0Jan 2023View details →

Methane Fluxes and 13C-CH4 from a Northern Temperate Peatland

This dataset contains methane (CH4) emissions and their 13C isotope composition (δ13C-CH4) measured using the static flux chamber method in a poor fen in New Hampshire, USA. Measurements were collected weekly (CH4 emissions) to bi-weekly (δ13C-CH4) from flux collars with varying microtopgraphy (hummock, lawn, and wet) from May to August 2020 and 2021. Datasets includes metadata of water table depth, peat and air temperature, and precipitation collected alongside flux meausurements. Each data file contains a "README" tab with a guide for variable units and descriptions.

opencc-by-4.0Nov 2022View details →

Methane emissions of ditches of boreal forestry-drained peatlands

Six datasets regarding our study on methane emissions of ditches of boreal forestry-drained peatlands of Finland: Dataset 1: Accepted methane fluxes analysed via manual chamber technique from ditches of 21 boreal forestry-drained peatland study areas located in Finland. Dataset 2: Temperature within ditches of 3 boreal forestry-drained peatlands (Ränskälänkorpi, Lettosuo and Paroninkorpi) studied in 2021.  Dataset 3: Relative water table level (relative to the level in the beginning of June 2021) in ditches of 3 boreal forestry-drained peatlands (Ränskälänkorpi, Lettosuo and Paroninkorpi) studied in 2021.  Dataset 4: Yearly methane emission factors calculated for different types of ditches in the study areas. Dataset 5: Tested random forest models' variables and their mean decrease in accuracy, and models' error rates in classifying boreal peatland forest ditches into moss-covered and moss-free categories. Dataset 6: Tested random forest models (as zipped .RData files) to classify boreal peatland forest ditches into moss-covered and moss-free categories.

opencc-zeroFeb 2023View details →

Methane and carbon dioxide cumulative amounts data for: Algal amendment enhances biogenic methane production from coals of different thermal maturity

The addition of small amounts of algal biomass to stimulate methane production in coal seams is a promising low carbon renewable coalbed methane enhancement technique. However, little is known about how the addition of algal biomass amendment affects methane production from coals of different thermal maturity. Here, we show that biogenic methane can be produced from five coals ranging in rank from lignite to low-volatile bituminous using a coal-derived microbial consortium in batch microcosms with and without algal amendment. The addition of 0.1 g/L algal biomass resulted in maximum methane production rates up to 37 days earlier and decreased the time required to reach maximum methane production by 17–19 days when compared to unamended, analogous microcosms. Cumulative methane production and methane production rate were generally highest in low rank, subbituminous coals, but no clear association between increasing vitrinite reflectance and decreasing methane production could be determined. Microbial community analysis revealed that archaeal populations were correlated with methane production rate (p=0.01), vitrinite reflectance (p=0.03), percent volatile matter (p=0.03), and fixed carbon (p=0.02), all of which are related to coal rank and composition. Sequences indicative of the acetoclastic methanogenic genus Methanosaeta dominated low rank coal microcosms. Amended treatments that had increased methane production relative to unamended analogs had high relative abundances of the hydrogenotrophic methanogenic genus Methanobacterium and the bacterial family Pseudomonadaceae. These results suggest that algal amendment may shift coal-derived microbial communities towards coal-degrading bacteria and CO2-reducing methanogens. These results have broad implications for understanding subsurface carbon cycling in coal beds and the adoption of low carbon renewable microbially enhanced coalbed methane techniques across a diverse range of coal geology.

opencc-zeroMar 2023View details →

Data for: Intercomparison of commercial analyzers for atmospheric ethane and methane observations

Methane (CH4) is a strong greenhouse gas that has become the focus of climate mitigation policies in recent years. Ethane / methane ratios can be used to identify and partition the different sources of methane, especially in areas with natural gas mixed with biogenic methane emissions, such as cities. We assessed the precision, accuracy, and selectivity of three commercially available laser-based analyzers that have been marketed as measuring instantaneous dry mole fractions of methane and ethane in ambient air. The Aerodyne SuperDUAL instrument performed best of the three instruments but it requires expertise to operate and space for the large footprint. The Aeris Mira Ultra LDS analyzer also performed well for the price point and small footprint but required characterization of the water vapor dependence of reported concentrations and careful setup for use. The Picarro G2210-i precisely measured methane but it did not detect the 10 ppbv increases in ambient ethane detected by the other two instruments when sampling a plume of incompletely combusted natural gas. For long-term tower deployments or those with large mobile laboratories, the Aerodyne SuperDUAL provides the best precision for methane and ethane. For smaller mobile platforms, the Aeris MIRA is a more compact analyzer, and with careful use, can quantify thermogenic methane sources to sufficient precision for short term deployments in urban or oil and gas areas. We weighed the advantages of each instrument, including size, power requirement, ease of use on mobile platforms, and expertise needed to operate the instrument, and we recommend the Aerodyne SuperDUAL or the Aeris MIRA Ultra LDS depending on the situation.

opencc-by-4.0Mar 2023View details →

Enhanced methane emissions driven by glacial retreat in the high Arctic

Methane concentration data of proglacial groundwater springs supporting the publication 'Enhanced methane emissions driven by glacial retreat in the high Arctic.' The data also includes icing depth and area measurements. In addition, we include fjord surface methane concentrations adjacent to marine-terminating glaciers.

Quantifying the effects sizes of common controls on methane emissions from an ombrotrophic peat bog

Northern wetlands and bogs are a large source of biogenic methane (CH4) to the atmosphere and shape climate. There is then substantial interest in quantifying the effect sizes of controls on bog CH4 emissions. Yet quantification is complicated because wetland emissions are, like the controls that regulate them, spatially and temporarily heterogeneous within individual wetland systems. To account for this heterogeneity, we established 55 measurement plots in a sampling design that had extensive spatial, and repeated temporal, coverage over one ombrotrophic bog. This coverage allowed us to robustly estimate the effect sizes of known environmental controls on CH4 emissions such as temperature, water table depth (WTD), and plant functional composition. As expected, 89% of the cumulative measured flux came from 16% of the plots, with consistently high CH4 emissions over two consecutive growing seasons. Soil temperature exhibited the strongest control on emissions, while WTD and vegetation composition had much smaller relative effects compared to temperature. Interestingly, at high temperatures, WTD was a strong determinant of whether a plot had high vs. lower emissions. Despite temperature's large effect size, the controls we measured only explained ~29% of the variance in CH4 fluxes. Overall, our data confirm observations from other wetlands that CH4 emissions are highly variable at local scales, and yet our data also reveal that effect sizes can be quantified robustly within this heterogeneity. Highly-replicated, local designs may therefore be useful for generating data that can serve to help refine wetland CH4 emissions uncertainties.

Fencing farm dams to exclude livestock halves methane emissions and improves water quality

Agricultural practices have created tens of millions of small artificial water bodies ("farm dams" or "agricultural ponds") to provide water for domestic livestock worldwide. Among freshwater ecosystems, farm dams have some of the highest greenhouse gas (GHG) emissions per m2 due to fertilizer and manure run-off boosting methane production – an extremely potent GHG. However, management strategies to mitigate the substantial emissions from millions of farm dams remain unexplored. We tested the hypothesis that installing fences to exclude livestock could reduce nutrients, improve water quality, and lower aquatic GHG emissions. We established a large-scale experiment spanning 400 km across south-eastern Australia where we compared unfenced (N = 33) and fenced farm dams (N = 31) within 17 livestock farms. Fenced farm dams recorded 32% less dissolved nitrogen, 39% less dissolved phosphorus, 22% more dissolved oxygen, and produced 56% less diffusive methane emissions than unfenced dams. We found no effect of farm dam management on diffusive carbon dioxide emissions and on the organic carbon in the soil. Dissolved oxygen was the most important variable explaining changes in carbon fluxes across dams, whereby doubling dissolved oxygen from 5 to 10 mg L-1 led to a 74% decrease in methane fluxes, a 124% decrease in carbon dioxide fluxes, and a 96% decrease in CO2-eq (CH4 + CO2) fluxes. Dams with very high dissolved oxygen (>10 mg L-1) showed a switch from positive to negative CO2-eq. (CO2 + CH4) fluxes (i.e., negative radiative balance), indicating a positive contribution to reducing atmospheric warming. Our results demonstrate that simple management actions can dramatically improve water quality and decrease methane emissions while contributing to more productive and sustainable farming.

Global methane and nitrous oxide emissions from inland waters and estuaries

Inland waters (rivers, reservoirs, lakes, ponds, streams) and estuaries are globally significant emitters of methane (CH4) and nitrous oxide (N2O) to the atmosphere, while global estimates of these emissions have been hampered due to the lack of a worldwide comprehensive dataset with the collection of complete CH4and N2O flux components. Here, we synthesize 2,997 in-situ flux or concentration measurements of CH4 and N2O from 277 peer-reviewed publications to explore the role of inland waters and estuaries in shaping climate change. We estimate that inland waters including rivers, reservoirs, lakes, and streams together release 95.18 Tg CH4 yr-1 (ebullition plus diffusion) and 1.48 Tg N2O yr-1 (diffusion) to the atmosphere, yielding an overall CO2-equivalent emission total of 3.06 Pg CO2 yr-1, representing roughly 60% of CO2 emissions (5.13 Pg CO2 yr-1) from these four inland aquatic systems, among which lakes act as the largest emitter for both CH4and N2O. Ebullition is noticed as a dominant flux component of CH4, contributing up to 62–84% of total CH4fluxes across all inland waters. Chamber-derived CH4 emission rates are significantly greater than those determined by diffusion model-based methods for commonly capturing both diffusive and ebullitive fluxes. Water dissolved oxygen (DO) showed as a dominant factor among all variables to influence both CH4(diffusive and ebullitive) and N2O fluxes from inland waters. Our study reveals a major oversight in regional and global CH4budgets from inland waters, caused by neglect of the dominant role of ebullition pathways in those emissions. The indirect N2O EF5 values established in this study generally suggest a downward revision is required in current IPCC default EF5 values for inland waters and estuaries. Our findings further indicate that a comprehensive understanding of the magnitude and patterns of CH4 and N2O emissions from inland waters and estuaries is essential in defining how these aquatic systems will shape our climate.

opencc-by-4.0Apr 2023View details →

Evaluation of the stratospheric contribution to the inter-annual variabilities of tropospheric methane growth rates

Input invariant emission inventory, OH field and the stratospheric loss field in fixed-budget simulation

Comparison between ozone column depths and methane lifetimes computed by 1-D and 3-D models at different atmospheric O2 Levels

Recently, Cooke et al. (2022) used a 3-D coupled chemistry-climate model (WACCM6) to calculate ozone column depths at varied atmospheric O2 levels. They argued that previous 1-D photochemical model studies, e.g., Segura et al. (2003), may have overestimated the ozone column depth at low pO2, and hence also overestimated the lifetime of methane. We have compared new simulations from an updated version of the Segura et al. model with those from WACCM6, together with some results from another 1-D and 3-D model. The discrepancy in ozone column depths is likely due to multiple interacting parameters, including lower boundary conditions, vertical and meridional transport rates, and different chemical mechanisms, especially the treatment of O2 photolysis in the Schumann-Runge (SR) bands (175-205 nm). The discrepancy in tropospheric OH concentrations and methane lifetime between WACCM6 and the 1-D model at low pO2 is reduced when absorption from CO2 and H2O in this wavelength region is included in WACCM6. Including scattering in the SR bands may further reduce this difference. Resolving these issues can be accomplished by developing an accurate parameterization for O2 photolysis in the SR bands and then repeating these calculations in the various models. Work is already underway to this end.

opencc-zeroMay 2023View details →

Data for: Coupled anaerobic methane oxidation and metal reduction in soil under elevated CO2

Continued current emissions of carbon dioxide (CO2) and methane (CH4) by human activities will increase global atmospheric CO2 and CH4 concentrations and surface temperature significantly. Fields of paddy rice, the most important form of anthropogenic wetlands, account for about 9% of anthropogenic sources of CH4. Elevated atmospheric CO2 may enhance CH4 production in rice paddies, potentially reinforcing the increase in atmospheric CH4. However, what is not known is whether and how elevated CO2 influences CH4 consumption under anoxic soil conditions in rice paddies, as the net emission of CH4 is a balance of methanogenesis and methanotrophy. In this study, we used a long-term free-air CO2 enrichment experiment to examine the impact of elevated CO2 on the transformation of CH4 in a paddy rice agroecosystem. We demonstrate that elevated CO2 substantially increased anaerobic oxidation of methane (AOM) coupled to manganese and/or iron oxides reduction in the calcareous paddy soil. We further show that elevated CO2 may stimulate the growth and metabolism of Candidatus Methanoperedens nitroreducens, which is actively involved in catalyzing AOM when coupled to metal reduction, mainly through enhancing the availability of soil CH4. These findings suggest that a thorough evaluation of climate-carbon cycle feedbacks may need to consider the coupling of methane and metal cycles in natural and agricultural wetlands under future climate change scenarios.

opencc-by-4.0May 2023View details →

Data for "biochar-composting substantially reduces methane and air pollutant emissions from dairy manure"

Dataset showing: 1) Weekly compost NH4 concentrations 2) Weekly compost NO3 concentrations 3) Weekly compost C, N, O, H 4) Weekly compost pH and EC 5) Daily compost temperature 6) Weekly compost moisture 7) Weekly compost porosity 8) Final compost CEC 9) Final compost germination indexes 10) AP3 integrated assessment model results 11) Daily compost gas fluxes

opencc-by-4.0Jun 2023View details →

Decreasing seasonal cycle amplitude of methane in the northern high latitudes being driven by lower latitude changes in emissions and transport

This dataset contains the smoothed and detrended time series of methane from the TOMCAT regional tagged tracer simulations between 1995-2020 at 22 NOAA surface observation sites. Each file contains the Site Code and the latitude and longitude of of each observation site. The regional file contains the region code of each regional tagged tracer. More information on the TOMCAT simulation and the Site Codes and Region Codes can be found at: https://doi.org/10.5194/egusphere-2023-132, 2023

opencc-by-4.0Jun 2023View details →

Data for Radiation and temperature drive diurnal variation of aerobic methane emissions from Scots pine canopy

Aerobic methane emissions from plant foliage may play an important role in the global methane cycle, but their size and the underlying source processes remain poorly understood. Here, we quantify methane fluxes from the shoots Scots pine trees, a dominant tree species in boreal forests,  identify source processes and environmental drivers, and evaluate the potential of leaf emissions to constrain methane emissions at the ecosystem-level eddy covariance flux measurements. We show that shoot-level measurements conducted in forest, garden, or greenhouse settings; on mature trees and saplings; manually and with an automated CO2 -, temperature-, and water-controlled chamber system; and with multiple methane analysers  all resulted in comparable daytime flux rates  (0.094±0.035 to 0.241±0.090 nmol CH4 g-1 foliar dw h-1). We find that methane emissions from Scots pine shoots exhibit a pronounced diurnal cycle that closely follows photosynthetically active radiation (PAR) and is further modulated by temperature. These diurnal patterns indicate that methane production is associated with diurnal cycle of sunlight, suggesting that methane is either a byproduct of photosynthesis-associated biochemical reactions (e.g. the methionine cycle) or produced through non-enzymatic photochemical reactions in plant biomass. Moreover, we identified a light-dependent component in stand-level methane fluxes, which showed an order-of-magnitude agreement with shoot-level measurements (0.968±0.031 nmol CH4 g-1 h-1), and which provides an upper limit to shoot methane emissions.

opencc-by-4.0Jun 2023View details →

Subsurface redox interactions regulate ebullitive methane flux in heterogeneous Mississippi River deltaic wetland

This dataset is model outputs archive from a model study about  'Subsurface redox interactions regulate ebullitive methane flux in heterogeneous Mississippi River deltaic wetland' (manuscript is Under Review). Plotting scripts are also included in this data file. There are four model results. 'Ebull' model output are ebullition flux, 'Jswi' model output are diffusion flux across soil-water interface, and 'Methane' files are porewater concentration results in each soil layers, and 'LtranR' model outputs for redox species exchange rates across different soil layers. The model source codes can be found at <a href="https://zenodo.org/record/8084441">https://zenodo.org/record/8084441</a> and <a href="https://zenodo.org/record/8087566">https://zenodo.org/record/8087566</a>.

opencc-by-4.0Jul 2023View details →

Modelling results for the paper "The impact of methane leakage on the role of natural gas in the European energy transition"

This data file represents the modelling results of the paper "The impact of methane leakage on the role of natural gas in the European energy transition" that is accepted to Nature Communications.

opencc-zeroJul 2023View details →

Great Plains grassland methane dynamics

The grassland biome is an important sink for CH4, a major greenhouse gas. There is considerable uncertainty in the grassland CH4 sink capacity due to diverse environmental gradients in which grasslands occur, and many environmental conditions can affect abiotic (e.g., CH4 diffusivity into soils) and biotic (e.g., methanotrophy) factors that determine spatial and temporal CH4 dynamics. We investigated the relative importance of a soil's gas diffusivity vs. net methanotroph activity in 22 field plots in seven sites distributed across the US Great Plains by making ca. bi-weekly measures during the growing seasons over three years. We quantified net methanotroph activity and diffusivity by using an approach combining a gas tracer, chamber headspace measurements, and a mathematical model. At each plot, we also measured environmental characteristics, including water-filled pore space (WFPS), soil temperature and inorganic nitrogen contents, and examined the relative importance of these for controlling diffusivity and net methanotroph activity. At most of the plots across the seven sites, CH4 uptake rates were consistently greatest when WFPS was intermediate at the plot level. Our results show that variation in net methanotroph activity was more important than diffusivity in explaining temporal variations in net CH4 uptake, but the two factors were equally important for driving spatial variation across the seven sites. Water-filled pore space was a significant predictor for diffusivity only in plots with sandy soils. Water-filled pore space was the most important control on net methanotroph activity, with net methanotroph activity showing a parabolic response to WFPS (concave down), and the shape of this response differed significantly among sites. Moreover, we found that the WFPS level at peak net methanotroph activity was strongly correlated with mean annual precipitation of the site. These results suggest that local precipitation regime determines unique sensitivity of CH4 uptake rates to soil moisture. Our findings indicate that grassland CH4 uptake may be predicted using local soil water conditions. More variable soil moisture, potentially induced through predicted future extremes of rainfall and drought, could reduce grassland CH4 sink capacity in the future.

opencc-by-4.0Aug 2023View details →

Information regarding the particulate methane monooxygenase enzyme of known methanotrophs

A collection of information with regard to the particulate methane monooxygenase (pmmo) enzyme of known methanotrophs which was extracted from NCBI is published in this database.