scholarly journals Increasing measurement throughput of methane emission from rice paddies with a modified closed-chamber method

2021 ◽  
Vol 77 (2) ◽  
pp. 160-165
Author(s):  
Takeshi TOKIDA
Keyword(s):  
Methane Emission ◽  
Rice Paddies ◽  
Closed Chamber ◽  
Chamber Method ◽  
Closed Chamber Method

scholarly journals Appropriate chamber deployment time for separate quantification of CH4 emissions via plant and ebullition from rice paddies using a modified closed-chamber method

2021 ◽  
Author(s):  
Masako KAJIURA ◽  
Takeshi TOKIDA
Keyword(s):  
Time Windows ◽  
Flux Measurement ◽  
Minimum Time ◽  
High Time Resolution ◽  
Rice Paddies ◽  
Concentration Data ◽  
Closed Chamber ◽  
Time Length ◽  
Chamber Method ◽  
Closed Chamber Method

Abstract A modified closed-chamber method for estimating total, plant-mediated, and bubbling (ebullition) emissions of CH4 from rice paddies has been developed to use high-time-resolution CH4 concentration data (~ 1 Hz) obtained by a spectroscopic mobile gas analyzer. Here we aimed at determining an appropriate minimum time length of chamber closure for accurate flux measurement by investigating 3255 datasets obtained from a 2-year field survey. To investigate the minimum time length for each chamber measurement, we generated a series of datasets from each measurement: by setting the hypothetical termination time of the chamber closure ahead in 1-min intervals, we obtained various chamber CH4 concentration time series with different durations of chamber closure, and separately estimated CH4 emissions via rice plants and bubbling from each. The estimated flux was sensitive to time length with short closure times, but became less sensitive with longer closure. We defined the minimum time length at which the difference in estimated flux between adjacent time windows was small enough (< 10% of plant-mediated emission). The estimated minimum time length differed from one measurement to another, but 10 min was sufficient for > 99% of cases. Detailed analysis showed a positive correlation between minimum time length and frequency of bubbling events; the time length needed to be longer as bubbling events became more frequent. From this relationship, we computed the appropriate chamber-duration time as a function of bubbling frequency. In the absence of ebullition, 4–5 min was sufficient, but as the bubbling frequency increased to 2.5 times per minute 15–20 min was necessary for accurate pathway-dependent flux measurements.

Experimental Study of Radon Exhalation Rate in Uranium-Like Rock Based on Closed Chamber Method

2018 ◽  
Author(s):  
Fuliang Jiang ◽  
Xiaoli Wang ◽  
Shuai Zhang ◽  
Xiangyang Li ◽  
Changshou Hong
Keyword(s):  
Diffusion Length ◽  
Underground Mining ◽  
Similarity Theory ◽  
Radon Exhalation Rate ◽  
Exhalation Rate ◽  
Closed Chamber ◽  
Radon Exhalation ◽  
Chamber Method ◽  
Diffusion Phenomena ◽  
Closed Chamber Method

The closed chamber method is widely used in measuring radon exhalation rate, which can avoid the error caused by the leakage and anti-diffusion phenomena. Firstly, considering the actual situation that uranium ore is difficult to obtain and have a high radioactivity, the uranium-like rock was made according to the similarity theory. Secondly, the diffusion length and intrinsic radon exhalation rate were obtained by using the closed chamber method. Thirdly, the theoretical values of radon exhalation rate made by uranium-like ore block were calculated, compared with the measured values. This study shows that the uranium-like rock block made by the best mass ratio is helpful for the subsequent experiment, and the error between the theoretical calculation and the measured value is no more than 9.14%. This indicates it is reliable to estimate radon exhalation rate by diffusion length and intrinsic radon exhalation rate and can also provide a foundation for rapidly gaining radon exhalation rate of the same type material by the closed chamber method. This study can further promote the study of the radon exhalation rate under the complex physical conditions and then better guide the protection work of radon radiation in underground mining.

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

&lt;p&gt;Common field methods for measuring soil denitrification in situ include monitoring the accumulation of &lt;sup&gt;15&lt;/sup&gt;N labelled N&lt;sub&gt;2&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O evolved from &lt;sup&gt;15&lt;/sup&gt;N labelled soil nitrate pool in soil surface chambers. Bias of denitrification rates derived from chamber measurements results from subsoil diffusion of &lt;sup&gt;15&lt;/sup&gt;N labelled denitrification products, but this can be corrected by diffusion modeling (Well et al., 2019). Moreover, precision of the conventional &lt;sup&gt;15&lt;/sup&gt;N gas flux method is low due to the high N&lt;sub&gt;2&lt;/sub&gt; background of the atmosphere. An alternative to the closed chamber method is to use concentration gradients of soil gas to quantify their fluxes (Maier &amp;&amp;#160; Schack-Kirchner, 2014). Advantages compared to the closed &amp;#160;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 &lt;sup&gt;15&lt;/sup&gt;N-labelled denitrification products. Here we use this approach for the first time to evaluate denitrification rates derived from depth profiles of &lt;sup&gt;15&lt;/sup&gt;N labelled N&lt;sub&gt;2&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O in the field by closed chamber measurements published previously (Lewicka-Szczebak et al., 2020).&lt;/p&gt;&lt;p&gt;We compared surface fluxes of N&lt;sub&gt;2&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O from &lt;sup&gt;15&lt;/sup&gt;N labelled microplots using the closed chamber method. Diffusion&amp;#8211;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 &amp;#160;used to fit measured and modelled concentrations of &lt;sup&gt;15&lt;/sup&gt;N labelled N&lt;sub&gt;2&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;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).&lt;/p&gt;&lt;p&gt;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. &amp;#160;&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Lewicka-Szczebak D, Lewicki MP, Well R (2020) N2O isotope approaches for source partitioning of N2O production and estimation of N2O reduction &amp;#8211; validation with the 15N gas-flux method in laboratory and field studies. Biogeosciences, &lt;strong&gt;17&lt;/strong&gt;, 5513-5537.&lt;/p&gt;&lt;p&gt;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, &lt;strong&gt;247&lt;/strong&gt;, 21-33.&lt;/p&gt;&lt;p&gt;Maier M, Schack-Kirchner H (2014) Using the gradient method to determine soil gas flux: A review. Agricultural and Forest Meteorology, &lt;strong&gt;192&lt;/strong&gt;, 78-95.&lt;/p&gt;&lt;p&gt;Schack-Kirchner H, Hildebrand EE, Wilpert KV (1993) Ein konvektionsfreies Sammelsystem f&amp;#252;r Bodenluft. Zeitschrift Fur Pflanzenernahrung Und Bodenkunde, &lt;strong&gt;156&lt;/strong&gt;, 307-310.&lt;/p&gt;&lt;p&gt;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, &lt;strong&gt;16&lt;/strong&gt;, 2233-2246.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals CO2 fluxes in subtropical dryland soils-a comparison of the gradient and the closed-chamber method

2016 ◽  
Vol 181 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Jona Luther-Mosebach ◽  
Kira Kalinski ◽  
Alexander Gröngröft ◽  
Annette Eschenbach
Keyword(s):  
Co2 Fluxes ◽  
Closed Chamber ◽  
Chamber Method ◽  
Closed Chamber Method

Methane Fluxes in Cold Season: Assessment by Closed Chamber Method

2016 ◽  
Vol 49 (2) ◽  
pp. 205-212
Author(s):  
A. V. Smagin ◽  
N. A. Shnyrev ◽  
N. B. Sadovnikova
Keyword(s):  
Cold Season ◽  
Closed Chamber ◽  
Chamber Method ◽  
Methane Fluxes ◽  
Closed Chamber Method

scholarly journals Net ecosystem CO<sub>2</sub> exchange measurements by the closed chamber method and the eddy covariance technique and their dependence on atmospheric conditions – a case study

2013 ◽  
Vol 6 (5) ◽  
pp. 8783-8805 ◽  
Author(s):  
M. Riederer ◽  
A. Serafimovich ◽  
T. Foken
Keyword(s):  
Carbon Dioxide ◽  
Eddy Covariance ◽  
Net Ecosystem Exchange ◽  
Carbon Dioxide Flux ◽  
Atmospheric Conditions ◽  
Closed Chamber ◽  
Carbon Dioxide Fluxes ◽  
Chamber Method ◽  
Eddy Covariance Technique ◽  
Closed Chamber Method

Abstract. Carbon dioxide flux measurements in ecosystem sciences are mostly conducted by eddy covariance technique or the closed chamber method. Also some comparisons have been performed. But there is a lack of detailed assessment of present differences and uncertainties. To determine underlying processes, a ten-day, side-by-side measurement of the net ecosystem exchange with both techniques was evaluated with regard to various atmospheric conditions during the diurnal cycle. It was found that, depending on the particular atmospheric condition, the chamber carbon dioxide flux was either: (i) equal to the carbon dioxide flux measured by the reference method eddy covariance, by day with well developed atmospheric turbulence, (ii) higher, in the afternoon in times of oasis effect, (iii) lower, predominantly at night while large coherent structure fluxes or high wind velocities prevailed, or, (iv) showed less variation in the flux pattern, at night while stable stratification was present. Due to lower chamber carbon dioxide fluxes at night, when respiration forms the net ecosystem exchange, and higher chamber carbon dioxide fluxes in the afternoon, when the ecosystem is still a net carbon sink, there are two complementary aspects resulting in an overestimation of the ecosystem sink capacity by the chamber of 40% in this study.

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