scholarly journals Nonvolcanic Carbon Dioxide Emission at Continental Rifts: The Bublak Mofette Area, Western Eger Rift, Czech Republic

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Horst Kämpf ◽  
Alena Sophie Broge ◽  
Pouria Marzban ◽  
Masoud Allahbakhshi ◽  
Tobias Nickschick
Keyword(s):  
Carbon Dioxide Emission ◽  
Closed Chamber ◽  
Gas Flux ◽  
Eger Rift ◽  
Plant Zonation ◽  
Soil Degassing ◽  
Continental Rifts ◽  
Flux Measurements ◽  
Cheb Basin ◽  
Closed Chamber Method

This study presents the results of gas flux measurements of cold, mantle-derived CO2 release at the Bublák mofette field (BMF), located inside of the N-S directed Počátky Plesná fault zone (PPFZ). The PPFZ is presently seismically active, located in the eastern part of the Cheb Basin, western Eger Rift, Central Europe. The goal of the work was to identify the linkage between tectonics and gas flux. The investigated area has a size of 0,43 km2 in which 1.115 locations have been measured. Besides classical soil CO2 gas flux measurements using the closed chamber method (West Systems), drone-based orthophotos were used in combination with knowledge of plant zonation to find zones of high degassing in the agriculturally unused part of the BMF. The highest observed soil CO2 gas flux is 177.926,17 g m-2 d-1, and the lowest is 0,28 g m-2 d-1. Three statistical methods were used for the calculation of the gas flux: arithmetic mean, kriging, and trans-Gaussian kriging. The average CO2 soil degassing of the BMF is 30 t d-1 for an area of 0,43 km2. Since the CO2 soil degassing of the Hartoušov mofette field (HMF) amounts to 23 t d-1 for an area of 0,35 km2, the average dry degassing values of the BMF and HMF are in the same magnitude of order. The amount of CO2 flux from wet mofettes is 3 t d-1 for the BMF and 0,6 t d-1 for the HMF. It was found that the degassing in the BMF and HMF is not in accordance with the pull-apart basin interpretation, based on the direction of degassing as well as topography and sediment fill of the suggested basins. En-echelon faults inside of the PPFZ act as fluid channels to depth (CO2 conduits). These structures inside the PPFZ show beginning faulting and act as tectonic control of CO2 degassing.

Quantifying soil denitrification in situ from depth profiles of 15N labelled denitrification products by diffusion-reaction modelling 

2021 ◽  
Author(s):  
Reinhard Well ◽  
Dominika Lewicka-Szczebak ◽  
Martin Maier ◽  
Amanda Matson
Keyword(s):  
Soil Gas ◽  
Diffusion Reaction ◽  
Flux Method ◽  
Closed Chamber ◽  
Gas Flux ◽  
Depth Profiles ◽  
Chamber Method ◽  
Chamber Measurements ◽  
Closed Chamber Method

<p>Common field methods for measuring soil denitrification in situ include monitoring the accumulation of <sup>15</sup>N labelled N<sub>2</sub> and N<sub>2</sub>O evolved from <sup>15</sup>N labelled soil nitrate pool in soil surface chambers. Bias of denitrification rates derived from chamber measurements results from subsoil diffusion of <sup>15</sup>N labelled denitrification products, but this can be corrected by diffusion modeling (Well et al., 2019). Moreover, precision of the conventional <sup>15</sup>N gas flux method is low due to the high N<sub>2</sub> background of the atmosphere. An alternative to the closed chamber method is to use concentration gradients of soil gas to quantify their fluxes (Maier &  Schack-Kirchner, 2014). Advantages compared to the closed  chamber method include the facts that (i) time consuming work with closed chambers is replaced by easier sampling of soil gas probes, (ii) depth profiles yield not only the surface flux but also information on the depth distribution of gas production and (iii) soil gas concentrations are higher than chamber gas concentration, resulting in better detectability of <sup>15</sup>N-labelled denitrification products. Here we use this approach for the first time to evaluate denitrification rates derived from depth profiles of <sup>15</sup>N labelled N<sub>2</sub> and N<sub>2</sub>O in the field by closed chamber measurements published previously (Lewicka-Szczebak et al., 2020).</p><p>We compared surface fluxes of N<sub>2</sub> and N<sub>2</sub>O from <sup>15</sup>N labelled microplots using the closed chamber method. Diffusion–based soil gas probes (Schack-Kirchner et al., 1993) were used to sample soil air at the end of each closed chamber measurement. A diffusion-reaction model (Maier et al., 2017) will be  used to fit measured and modelled concentrations of <sup>15</sup>N labelled N<sub>2</sub> and N<sub>2</sub>O. Depth-specific values of denitrification rates and the denitrification product ratio will be obtained from best fits of depth profiles and chamber accumulation, taking into account diffusion of labelled denitrification products to the subsoil (Well et al., 2019).</p><p>Depending on the outcome of this evaluation, the gradient method could be used for continuous monitoring of denitrification in the field based on soil gas probe sampling. This could replace or enhance current approaches by improving the detection limit, facilitating sampling and delivering information on depth-specific denitrification.  </p><p>References:</p><p>Lewicka-Szczebak D, Lewicki MP, Well R (2020) N2O isotope approaches for source partitioning of N2O production and estimation of N2O reduction – validation with the 15N gas-flux method in laboratory and field studies. Biogeosciences, <strong>17</strong>, 5513-5537.</p><p>Maier M, Longdoz B, Laemmel T, Schack-Kirchner H, Lang F (2017) 2D profiles of CO2, CH4, N2O and gas diffusivity in a well aerated soil: measurement and Finite Element Modeling. Agricultural and Forest Meteorology, <strong>247</strong>, 21-33.</p><p>Maier M, Schack-Kirchner H (2014) Using the gradient method to determine soil gas flux: A review. Agricultural and Forest Meteorology, <strong>192</strong>, 78-95.</p><p>Schack-Kirchner H, Hildebrand EE, Wilpert KV (1993) Ein konvektionsfreies Sammelsystem für Bodenluft. Zeitschrift Fur Pflanzenernahrung Und Bodenkunde, <strong>156</strong>, 307-310.</p><p>Well R, Maier M, Lewicka-Szczebak D, Koster JR, Ruoss N (2019) Underestimation of denitrification rates from field application of the N-15 gas flux method and its correction by gas diffusion modelling. Biogeosciences, <strong>16</strong>, 2233-2246.</p><p> </p><p> </p>

scholarly journals Calculations of automatic chamber flux measurements of methane and carbon dioxide using short time series of concentrations

2016 ◽  
Vol 13 (4) ◽  
pp. 903-912 ◽  
Author(s):  
Norbert Pirk ◽  
Mikhail Mastepanov ◽  
Frans-Jan W. Parmentier ◽  
Magnus Lund ◽  
Patrick Crill ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Time Series ◽  
High Resolution ◽  
Ecosystem Respiration ◽  
General Applicability ◽  
Closed Chamber ◽  
Gas Flux ◽  
Flux Measurements ◽  
Concentration Changes ◽  
Chamber Measurements

Abstract. The closed chamber technique is widely used to measure the exchange of methane (CH4) and carbon dioxide (CO2) from terrestrial ecosystems. There is, however, large uncertainty about which model should be used to calculate the gas flux from the measured gas concentrations. Due to experimental uncertainties the simple linear regression model (first-order polynomial) is often applied, even though theoretical considerations of the technique suggest the application of other, curvilinear models. High-resolution automatic chamber systems which sample gas concentrations several hundred times per flux measurement make it possible to resolve the curvilinear behavior and study the information imposed by the natural variability of the temporal concentration changes. We used more than 50 000 such flux measurements of CH4 and CO2 from five field sites located in peat-forming wetlands ranging from 56 to 78° N to quantify the typical differences between flux estimates of different models. In addition, we aimed to assess the curvilinearity of the concentration time series and test the general applicability of curvilinear models. Despite significant episodic differences between the calculated flux estimates, the overall differences are generally found to be smaller than the local flux variability on the plot scale. The curvilinear behavior of the gas concentrations within the chamber is strongly influenced by wind-driven chamber leakage, and less so by changing gas concentration gradients in the soil during chamber closure. Such physical processes affect both gas species equally, which makes it possible to isolate biochemical processes affecting the gases differently, such as photosynthesis limitation by chamber headspace CO2 concentrations under high levels of incoming solar radiation. We assess the possibility to exploit this effect for a partitioning of the net CO2 flux into photosynthesis and ecosystem respiration as an example of how high-resolution automatic chamber measurements could be used for purposes beyond the estimation of the net gas flux. This shows that while linear and curvilinear calculation schemes can provide similar net fluxes, only curvilinear models open additional possibilities for high-resolution automatic chamber measurements.

scholarly journals Application of Open-Path FT-IR Spectroscopy to Determine Green House Gas Flux from Farmland-1. Closed-Chamber Method-

2009 ◽  
Vol 93 (5) ◽  
pp. 252-259 ◽  
Author(s):  
Kenji Nakashige ◽  
Masaaki Oikawa ◽  
Takanori Enomoto ◽  
Norio Yoshimura ◽  
Kaoruko Sunaga ◽  
...  
Keyword(s):  
Ir Spectroscopy ◽  
Closed Chamber ◽  
Gas Flux ◽  
Chamber Method ◽  
Green House ◽  
Green House Gas ◽  
Open Path ◽  
Ft Ir ◽  
Closed Chamber Method ◽  
Ft Ir Spectroscopy

scholarly journals Calculations of automatic chamber flux measurements of methane and carbon dioxide using short time series of concentrations

2015 ◽  
Vol 12 (17) ◽  
pp. 14593-14617 ◽  
Author(s):  
N. Pirk ◽  
M. Mastepanov ◽  
F.-J. W. Parmentier ◽  
M. Lund ◽  
P. Crill ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
High Resolution ◽  
Ecosystem Respiration ◽  
Flux Measurement ◽  
Co2 Flux ◽  
Terrestrial Ecosystems ◽  
Closed Chamber ◽  
Gas Flux ◽  
Flux Measurements ◽  
Concentration Changes

Abstract. The closed chamber technique is widely used to measure the exchange of methane (CH4) and carbon dioxide (CO2) from terrestrial ecosystems. There is, however, large uncertainty about which model should be used to calculate the gas flux from the measured gas concentrations. Due to experimental uncertainties the robust linear regression model (first order polynomial) is often applied, even though theoretical considerations of the technique suggest the application of other, curvilinear models. High-resolution automatic chamber systems which sample gas concentrations several hundred times per flux measurement make it possible to resolve the curvilinear behavior and study the information imposed by the natural variability of the temporal concentration changes. We used more than 50 000 such flux measurements of CH4 and CO2 from five field sites located in peat forming wetlands to calculate fluxes with different models. The flux differences from independent linear estimates are generally found to be smaller than the local flux variability on the plot scale. The curvilinear behavior of the gas concentrations within the chamber is strongly influenced by wind driven chamber leakage, and less so by changing gas concentration gradients in the soil during chamber closure. Such physical processes affect both gas species equally, which makes it possible to isolate biochemical processes affecting the gases differently, such as photosynthesis limitation by chamber headspace CO2 concentrations under high levels of incoming solar radiation. We assess the possibility to exploit this effect for a partitioning of the net CO2 flux into photosynthesis and ecosystem respiration and argue that high-resolution automatic chamber measurements could be used for purposes beyond the estimation of the net gas flux.

Seismic structure of the Cheb Basin from high resolution surveying – data quality assessment and first results

2021 ◽  
Author(s):  
Natalia Banasiak ◽  
Florian Bleibinhaus
Keyword(s):  
High Resolution ◽  
Earthquake Activity ◽  
Seismic Structure ◽  
North West ◽  
The North ◽  
Eger Rift ◽  
First Results ◽  
Ground Roll ◽  
Variscan Granites ◽  
Cheb Basin

<p><span><span>In this study we present data and preliminary results from several shallow high-resolution seismic surveys in the Cheb Basin, CR, a small intracontinental basin in the North-West Bohemian Massif, located at the Western end of the Cenozoic Eger Rift. The area is well known for its intense earthquake activity, with the largest instrumentally recorded magnitude of M</span></span><span><sub><span>L</span></sub></span><span><span>=4.6. Macroseismic reports of local seismicity date back to the early 19</span></span><span><sup><span>th</span></sup></span><span><span> century, with magnitudes possibly above 5. Quaternary volcanoes, CO</span></span><span><sub><span>2</span></sub></span><span><span>-rich moffettes, and the swarm-like occurrence of the earthquakes suggest they are being triggered by crustal fluids. In contrast, most focal mechanisms show a dominant strike-slip component, indicative of tectonics. Investigating the role of fluids in triggering those earthquakes is one of the objectives of an ongoing ICDP program.</span></span></p><p><span>We expect high-resolution images of the basin structure to provide additional constraints regarding the importance of tectonic faulting. To that end, we surveyed several up to 3-km-long reflection and refraction profiles in the basin center across the putative Počátky-Plesná Fault, and at its edge, across the basin-bounding Mariánské Lázně Fault. The up to 350-m-thick basin sediments are mostly of Miocene and Quaternary origin, overlying Paleozoic Variscan units and post-Variscan granites. The main reflectors are around 200-400 ms. The data were collected with a 500-m-long split-spread of single geophones at 2 m spacing, and the raw shots are dominated by ground roll. In this presentation, we will show an overview of the field campaigns and present first results.</span></p>

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