Mobile open dynamic chamber measurement of methane macroseeps in lakes

Abstract. Methane (CH4) seepage; i.e., steady or episodic flow of gaseous hydrocarbons from subsurface reservoirs, has been identified as a significant source of atmospheric CH4. However, radiocarbon data from polar ice cores recently brought into question the magnitude of fossil CH4 seepage naturally occurring. In northern high latitudes, seepage of subsurface CH4 is impeded by permafrost and glaciers, which are under an increasing risk of thawing and melting in a globally warming world, implying the potential release of large stores of CH4 in the future. Resolution of these important questions requires a better constraint and monitoring of actual emissions from seepage areas. The measurement of these seeps is challenging, particularly in aquatic environments, because they involve large and irregular gas flowrates, unevenly distributed both spatially and temporally. Large macroseeps are particularly difficult to measure due to a lack of lightweight, inexpensive methods that can deployed in remote Arctic environments. Here, we report the use of a mobile chamber for measuring emissions at the surface of ice-free lakes subject to intense CH4 macroseepage. Tested in a remote Alaskan lake, the method was validated for the measurement of fossil CH4 emissions of up to 1.08 × 104 g CH4 m-2 d-1 (13.0 L m-2 min-1 of 83.4 % CH4 bubbles), which is within the range of global fossil methane seepage and several orders of magnitude above standard ecological emissions from lakes. In addition, this method allows for low diffusive flux measurements. Thus, the mobile chamber approach presented here covers the entire magnitude range of CH4 emissions currently identified, from those standardly observed in lakes to intense macroseeps, with a single apparatus of moderate cost.

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Technical note: Mobile open dynamic chamber measurement of methane macroseeps in lakes

Hydrology and Earth System Sciences ◽

10.5194/hess-24-6047-2020 ◽

2020 ◽

Vol 24 (12) ◽

pp. 6047-6058

Author(s):

Frederic Thalasso ◽

Katey Walter Anthony ◽

Olya Irzak ◽

Ethan Chaleff ◽

Laughlin Barker ◽

...

Keyword(s):

Gas Flow ◽

Ice Cores ◽

Technical Note ◽

Ch4 Emissions ◽

Methane Seepage ◽

Radiocarbon Data ◽

Flux Measurements ◽

Gaseous Hydrocarbons ◽

Moderate Cost ◽

Warming World

Abstract. Methane (CH4) seepage (i.e., steady or episodic flow of gaseous hydrocarbons from subsurface reservoirs) has been identified as a significant source of atmospheric CH4. However, radiocarbon data from polar ice cores have recently brought into question the magnitude of fossil CH4 seepage naturally occurring. In northern high latitudes, seepage of subsurface CH4 is impeded by permafrost and glaciers, which are under an increasing risk of thawing and melting in a globally warming world, implying the potential release of large stores of CH4 in the future. Resolution of these important questions requires a better constraint and monitoring of actual emissions from seepage areas. The measurement of these seeps is challenging, particularly in aquatic environments, because they involve large and irregular gas flow rates, unevenly distributed both spatially and temporally. Large macroseeps are particularly difficult to measure due to a lack of lightweight, inexpensive methods that can be deployed in remote Arctic environments. Here, we report the use of a mobile chamber for measuring emissions at the surface of ice-free lakes subject to intense CH4 macroseepage. Tested in a remote Alaskan lake, the method was validated for the measurement of fossil CH4 emissions of up to 1.08 × 104 g CH4 m−2 d−1 (13.0 L m−2 min−1 of 83.4 % CH4 bubbles), which is within the range of global fossil methane seepage and several orders of magnitude above standard ecological emissions from lakes. In addition, this method allows for low diffusive flux measurements. Thus, the mobile chamber approach presented here covers the entire magnitude range of CH4 emissions currently identified, from those standardly observed in lakes to intense macroseeps, with a single apparatus of moderate cost.

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EMISSIONS OF NH3, CH4 AND N2O DURING STORAGE AND AFTER APPLICATION OF UNTREATED AND ANAEROBICALLY DIGESTED SLURRY

Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca Agriculture ◽

10.15835/buasvmcn-agr:1425 ◽

1970 ◽

Vol 63 ◽

Author(s):

G. Moitzi ◽

B. Amon ◽

T. Amon ◽

V. Kryvoruchko ◽

C. Wagner-Alt ◽

...

Keyword(s):

Renewable Energy ◽

Anaerobic Digestion ◽

Pig Slurry ◽

Gaseous Emissions ◽

Ch4 Emissions ◽

Dynamic Chamber ◽

Fermentation Tank ◽

Application Techniques ◽

Ch4 And N2o ◽

Anaerobically Digested Slurry

The paper presents the investigations results of the effect of anaerobic digestion on emissions of NH3, N2O and CH4 during storage and after application of slurry. Dairy cattle and pig slurry was stored in concrete tanks (12 m3) over a period of 100 days. Gaseous emissions were collected continuously by a large open dynamic chamber. Gas concentrations (NH3, N2O and CH4) were analysed by high resolution FTIR-spectrometry. After storage, the slurries were surface applied on permanent grassland. NH3 emissions were followed for two days by a large open-dynamic-chamber. N2O and CH4 emissions were quantified with closed chambers until day 20 after application. 65 – 95 % of net total NH3 emissions were lost after slurry application. NH3 abatement will therefore be effective, if low emission application techniques are used. This is especially important when anaerobically digested slurry is applied. More than 90 % of net total CH4 emissions from untreated slurry were lost during slurry storage. Anaerobically digested slurry still emitted methane during storage. These emissions can be totally avoided if the secondary fermentation tank and the slurry store are connected with the gas bearing system of the biogas plant. Then, CH4 produced in these tanks is collected and used as renewable energy source. In conclusion it can be assumed that biogas plants will play a major role in the reduction of greenhouse gas emissions as they generate renewable energy and reduce CH4 emissions during manure storage. Furthermore, anaerobic digestion improves the fertiliser value of animal manures.

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Methane variations on orbital timescales: a transient modeling experiment

Climate of the Past Discussions ◽

10.5194/cpd-7-47-2011 ◽

2011 ◽

Vol 7 (1) ◽

pp. 47-77

Author(s):

T. Y. M. Konijnendijk ◽

S. L. Weber ◽

E. Tuenter ◽

M. van Weele

Keyword(s):

Climate Model ◽

Climate Modeling ◽

Ice Cores ◽

Vegetation Coverage ◽

Ch4 Emissions ◽

Monsoon Area ◽

Two Factors ◽

Modeling Experiment ◽

Global Vegetation ◽

Atmospheric Concentrations

Abstract. Methane (CH4) variations on orbital timescales are often associated with variations in wetland coverage, most notably in the summer monsoon areas of the Northern Hemisphere. Here we test this assumption by simulating orbitally forced variations in global wetland emissions, using a simple wetland distribution and CH4 emissions model that was coupled off-line to a climate model containing atmosphere, ocean and vegetation components. The transient climate modeling simulation extends over the last 650 000 yrs and includes variations in land-ice distribution and greenhouse gases. Tropical temperature and global vegetation are found to be the dominant controls for global CH4 emissions and thus atmospheric concentrations. The relative importance of wetland coverage, vegetation coverage, and emission temperatures depends on the specific climatic zone (boreal, tropics and Indian/Asian monsoon area) and timescale (precession, obliquity and glacial-interglacial timescales). Simulated variations in emissions agree well with those in measured concentrations, both in their time series and spectra. The simulated lags with respect to the orbital forcing also show close agreement with those found in measured data, both on the precession and obliquity timescale. We only find covariance between monsoon precipitation and CH4 concentrations, however we find causal links between atmospheric concentrations and tropical temperatures and global vegetation. The primary importance of these two factors explains the lags found in the CH4 record from ice cores.

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Soil CO2 fluxes and surface microtopography in a mixed hemiboreal forest: space, time and models.

10.5194/egusphere-egu2020-11452 ◽

2020 ◽

Author(s):

Dmitrii Krasnov ◽

Alisa Krasnova ◽

Steffen Noe

Keyword(s):

Tree Species ◽

Environmental Changes ◽

Temporal Distribution ◽

Forest Stand ◽

Tree Species Composition ◽

Surface Microtopography ◽

Dynamic Chamber ◽

Spatial Coverage ◽

Flux Measurements ◽

Flux Estimation

The understanding of biophysical mechanisms influencing the spatial and temporal distribution of CO2 flux is important for predicting the response of forest ecosystem on any environmental changes. It has been shown, that the most important controlling factors responsible for CO2 flux fluctuation from the forest soils are soil moisture, temperature and the type of the forest stand. In our work, we present three years of soil CO2 flux measurements in the hemiboreal forest that is characterized by high spatial heterogeneity of vegetation and soil. Three sample plots that represent the main common tree species (Pinus sylvestris, Picea abies and Betula sp) were chosen to assess the influence of tree species composition on the soil CO2 flux. The chosen sample plots have clear microtopographical structure with depressions, elevations and flat zones. The data were collected from three sample plots according to forest floor microtopography using manual closed dynamic chamber equipped with IRGA sensor (The Vaisala GMP343 probe), humidity and temperature sensors (Vaisala HMP155). Obvious temporal resolution limitation of manual chamber method is compensated by higher spatial coverage.Previous research has indicated that one of the major sources of uncertainties in the flux estimation is the choice of the model for flux calculation. We compared the commonly used models (linear, exponential and HMR) using two available R packages: &#8220;gasflux&#8221; and &#8220;flux&#8221; packages. Additionally, we developed the algorithm that allows for automatically choosing the best model based on widely used criteria (MAE, RAE, AIC, RMSE).The results showed that in most of the cases linear and exponential models performed better. The comparison of sample plot showed that the biggest influence of microtopography was in the birch forest but the moisture had a bigger effect in the pine forest stand.

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Spatial versus Day-To-Day Within-Lake Variability in Tropical Floodplain Lake CH4 Emissions – Developing Optimized Approaches to Representative Flux Measurements

PLoS ONE ◽

10.1371/journal.pone.0123319 ◽

2015 ◽

Vol 10 (4) ◽

pp. e0123319 ◽

Cited By ~ 9

Author(s):

Roberta B. Peixoto ◽

Fausto Machado-Silva ◽

Humberto Marotta ◽

Alex Enrich-Prast ◽

David Bastviken

Keyword(s):

Floodplain Lake ◽

Ch4 Emissions ◽

Flux Measurements ◽

Tropical Floodplain

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Biases in methane chamber measurements in peatlands

International Agrophysics ◽

10.2478/v10247-012-0081-z ◽

2013 ◽

Vol 27 (2) ◽

pp. 159-168 ◽

Cited By ~ 9

Author(s):

R. Juszczak

Keyword(s):

Methane Flux ◽

Dynamic Chamber ◽

Methane Fluxes ◽

Flux Measurements ◽

Underestimation Rate ◽

Methane Measurement ◽

Linear Technique ◽

Chamber Measurements ◽

Calculated Flux

Abstract The paper presents results of CH4 emission measurements at peatland with the application of the dynamic chamber technique. The measurements were conducted in two types of chambers differing in shape, height, volume and technology used to assure their tightness. The study tested how the following factors: 1) forced chamber headspace mixing or its absence, 2) mistakes of the person conducting measurements, 3) improper application of linear technique for calculating CH4 fluxes, and 4) simulated air sampling typical for static chambers, influence the significance of errors and the underestimation rate of CH4 fluxes measured in situ. It was indicated that chamber headspace mixing allows estimating methane fluxes with a smaller error than in the case of measurements conducted without mixing, and CH4 fluxes in such conditions can be 47 to 58% higher (depending on the chamber type) than in a chamber without fans. Using dynamic chambers and a fast analyzer to measure methane fluxes allows shortening the methane measurement process to a few minutes. On the other hand, using static chambers for methane flux measurements may lead to 70% underestimation of the calculated flux.

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Global geological methane emissions: An update of top-down and bottom-up estimates

Elem Sci Anth ◽

10.1525/elementa.383 ◽

2019 ◽

Vol 7 ◽

Cited By ~ 8

Author(s):

Giuseppe Etiope ◽

Stefan Schwietzke

Keyword(s):

Ice Cores ◽

Mud Volcanoes ◽

Polar Ice ◽

Top Down ◽

Bottom Up ◽

Area Distribution ◽

Flux Measurements ◽

Fossil Fuel Industry ◽

Fuel Industry ◽

Volcanic Manifestations

A wide body of literature suggests that geological gas emissions from Earth’s degassing are a major methane (CH4) source to the atmosphere. These emissions are from gas-oil seeps, mud volcanoes, microseepage and submarine seepage in sedimentary (petroleum-bearing) basins, and geothermal and volcanic manifestations. Global bottom-up emission estimates, ranging from 30 to 76 Tg CH4 yr–1, evolved in the last twenty years thanks to the increasing number of flux measurements, and improved knowledge of emission factors and area distribution (activity). Based on recent global grid maps and updated evaluations of mud volcano and microseepage emissions, the global geo-CH4 source is now (bottom-up) estimated to be 45 (27–63) Tg yr–1, i.e., ~8% of total CH4 sources. Top-down verifications, based on independent approaches (including ethane and isotopic observations) from different authors, are consistent with the range of the bottom-up estimate. However, a recent top-down study, based on radiocarbon analyses in polar ice cores, suggests that geological, fossil (14C-free) CH4 emissions about 11,600 years ago were much lower (<15 Tg yr–1, 95% CI) and that this source strength could also be valid today. Here, we show that (i) this geo-CH4 downward revision implies a fossil fuel industry CH4 upward revision of at least 24–35%. (ii) The 95% CI estimates of the recent radiocarbon analysis do not overlap with those of 5 out of 6 other bottom-up and top-down studies (no overlap for the 90% CI estimates). (iii) The contrasting lines of evidence require further discussion, and research opportunities exist to help explain this gap.

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Understanding and modeling the scaling spectrum of climate

10.5194/egusphere-egu2020-262 ◽

2020 ◽

Author(s):

Beatrice Ellerhoff ◽

Kira Rehfeld

Keyword(s):

Surface Temperature ◽

Climate Model ◽

Ice Cores ◽

Power Laws ◽

Temperature Spectrum ◽

Scaling Properties ◽

Background Continuum ◽

Temperature Records ◽

Paleoclimate Records ◽

Warming World

Modeling climate dynamics in a comprehensive way and improving its predictability in a warming world requires a better understanding of climate variability across scales. However, fundamental mechanisms governing variability on long timescales are still poorly understood. The temporal evolution of climate can be inferred from paleoclimate records, such as ice cores or marine sediments. Power spectra serve to quantify changes of variability over time and to identify timescales associated with periodic or quasi-periodic processes. The spectra of surface temperature not only comprise spectral peaks, but also reveal a continuous part. It was shown that the background continuum exhibits a scale break, following different power-laws on monthly to decadal versus millennial to longer periods. It is yet mostly unexplained, how these power-laws arise and whether a coupling between different timescales can be deduced from it. We study these questions by comparing and applying spectral analyses to paleoclimate records and climate model simulations for the Quaternary. The data is used to reconstruct the temperature spectrum on diurnal to astronomical timescales. We extend previous studies by including climate responses, such as &#948;18O and temperature records, and climate forcings, for example, insolation and volcanic forcing. The emergence of scaling in temperature variability is analyzed by successively accessing the background continuum. Higher order spectra test for correlations between forcings and responses. In particular, the bispectrum and bicoherence is computed for statistical processes and evaluated for temperature records in order to study whether the scaling properties are related to energy transfers between different states in time. We elaborate the potential of these methods to reveal dynamical processes governing the continuous spectrum of surface temperature.

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Methane variations on orbital timescales: a transient modeling experiment

Climate of the Past ◽

10.5194/cp-7-635-2011 ◽

2011 ◽

Vol 7 (2) ◽

pp. 635-648 ◽

Cited By ~ 6

Author(s):

T. Y. M. Konijnendijk ◽

S. L. Weber ◽

E. Tuenter ◽

M. van Weele

Keyword(s):

Climate Model ◽

Climate Modeling ◽

Ice Cores ◽

Vegetation Coverage ◽

Ch4 Emissions ◽

Monsoon Area ◽

Two Factors ◽

Modeling Experiment ◽

Global Vegetation ◽

Atmospheric Concentrations

Abstract. Methane (CH4) variations on orbital timescales are often associated with variations in wetland coverage, most notably in the summer monsoon areas of the Northern Hemisphere. Here we test this assumption by simulating orbitally forced variations in global wetland emissions, using a simple wetland distribution and CH4 emissions model that has been run on the output of a climate model (CLIMBER-2) containing atmosphere, ocean and vegetation components. The transient climate modeling simulation extends over the last 650 000 yr and includes variations in land-ice distribution and greenhouse gases. Tropical temperature and global vegetation are found to be the dominant controls for global CH4 emissions and therefore atmospheric concentrations. The relative importance of wetland coverage, vegetation coverage, and emission temperatures depends on the specific climatic zone (boreal, tropics and Indian/Asian monsoon area) and timescale (precession, obliquity and glacial-interglacial timescales). Despite the low spatial resolution of the climate model and crude parameterizations for methane production and release, simulated variations in CH4 emissions agree well with those in measured concentrations, both in their time series and spectra. The simulated lags between emissions and orbital forcing also show close agreement with those found in measured data, both on the precession and obliquity timescale. We find causal links between atmospheric CH4 concentrations and tropical temperatures and global vegetation, but only covariance between monsoon precipitation and CH4 concentrations. The primary importance of the first two factors explains the lags found in the CH4 record from ice cores. Simulation of the dynamical vegetation response to climate variation on orbital timescales would be needed to reduce the uncertainty in these preliminary attributions.

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An automated dynamic chamber system for surface exchange measurement of non-reactive and reactive trace gases of grassland ecosystems

Biogeosciences ◽

10.5194/bg-6-405-2009 ◽

2009 ◽

Vol 6 (3) ◽

pp. 405-429 ◽

Cited By ~ 85

Author(s):

L. Pape ◽

C. Ammann ◽

A. Nyfeler-Brunner ◽

C. Spirig ◽

K. Hens ◽

...

Keyword(s):

Physiological Activity ◽

Trace Gases ◽

Inert Material ◽

Chamber System ◽

Ambient Conditions ◽

Surface Exchange ◽

Grassland Ecosystems ◽

Dynamic Chamber ◽

Flux Measurements ◽

Reactive Trace Gases

Abstract. We present an automated dynamic chamber system which is optimised for continuous unattended flux measurements of multiple non-reactive and reactive trace gases on grassland ecosystems. Main design features of our system are (a) highly transparent chamber walls consisting of chemically inert material, (b) individual purging flow units for each chamber, and (c) a movable lid for automated opening and closing of the chamber. The purging flow rate was chosen high enough to keep the mean residence time of the chamber air below one minute. This guarantees a proven efficient mixing of the chamber volume and a fast equilibration after lid closing. The dynamic chamber system is able to measure emission as well as deposition fluxes of trace gases. For the latter case, the modification of the turbulent transport by the chamber (compared to undisturbed ambient conditions) is quantitatively described by a bulk resistance concept. Beside a detailed description of the design and functioning of the system, results of field applications at two grassland sites are presented. In the first experiment, fluxes of five trace gases (CO2, H2O, NO, NO2, O3) were measured simultaneously on small grassland plots. It showed that the dynamic chamber system is able to detect the characteristic diurnal cycles with a sufficient temporal resolution. The results also demonstrated the importance of considering the chemical source/sink in the chamber due to gas phase reactions for the reactive compounds of the NO-NO2-O3 triad. In a second field experiment, chamber flux measurements of CO2 and methanol were compared to simultaneous independent eddy covariance flux measurements on the field scale. The fluxes obtained with the two methods showed a very good agreement indicating a minimal disturbance of the chambers on the physiological activity of the enclosed vegetation.

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