Non-invasive imaging of CO2 and O2 concentration reveals hotspots of root respiration 

2021 ◽  
Author(s):  
Sarah Bereswill ◽  
Nicole Rudolph-Mohr ◽  
Sascha E. Oswald
Keyword(s):  
Soil Moisture ◽  
Root System ◽  
Root Respiration ◽  
Pore Space ◽  
Gas Diffusion ◽  
Cluster Roots ◽  
Spatial And Temporal Variability ◽  
In Situ Observation ◽  
Imaging Method ◽  
Non Invasive

<p>Root respiration constitutes a major contribution to the CO<sub>2</sub> efflux from vegetated soils. Amongst temperature, soil moisture is a key environmental variable determining respiration in soils, because it affects the amount of oxygen available for respiration as well as the CO<sub>2</sub> gas transport within the soil pore space.</p><p>Non-invasive imaging techniques facilitate the in situ observation of the complex respiration patterns in the rhizosphere. We applied planar optodes (80x100 mm²) to map the CO<sub>2</sub> and O<sub>2</sub> concentration in the rhizosphere of white lupine plants (<em>Lupinus albus</em>) grown in slab-shaped glass rhizotrons (150x150x15 mm³) in sandy soil under P-deficient conditions. Respiration was measured daily for 19 days after planting at constant soil moisture content as well as during a drying-rewetting experiment, during which soil volumetric water content varied between 0.1 and 0.3 cm³ cm<sup>-3</sup>.</p><p>During their development, the plants exhibited a heterogeneous spatial pattern of root respiration; the highest CO<sub>2</sub>-concentrations were measured at the root tips and along younger parts of the root system. Heterogeneity in CO<sub>2</sub> and O<sub>2</sub> patterns was most pronounced in the drying-rewetting experiment: Distinct hotspots of CO<sub>2</sub>-release and oxygen consumption emerged 30 to 60 minutes after watering. The hotspot-regions correlated with the location of cluster roots growing close to the optodes, where up to three times increased CO<sub>2</sub> concentrations occurred. Overall CO<sub>2</sub> concentrations in the bulk soil increased as CO<sub>2</sub> accumulated over time as gas diffusion in the wet soil was limited.</p><p>Our results highlight the strong spatial and temporal variability of root respiration throughout the growth and development of the root system, and particularly in response to an increase in soil moisture. Further experiments aim to combine CO<sub>2</sub> and O<sub>2</sub> optode measurements with neutron computed laminography, a tomographic imaging method suited to capture the 3D root system architecture of plants grown in laterally extended rhizotrons in order to link root respiration to root branching order, diameter and functional type.</p>

Novel 3D imaging of root systems grown in slab-shaped rhizotrons

2020 ◽  
Author(s):  
Sarah Bereswill ◽  
Nicole Rudolph-Mohr ◽  
Christian Tötzke ◽  
Nikolay Kardjilov ◽  
André Hilger ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Root System ◽  
3D Imaging ◽  
Neutron Radiography ◽  
Root Systems ◽  
Root System Architecture ◽  
Moisture Distribution ◽  
Ph Gradients ◽  
Non Invasive ◽  
Soil Moisture Distribution

<p>Complex plant-soil interactions can be visualized and quantified by combined application of different non-invasive imaging techniques. Oxygen, carbon dioxide and pH gradients in the rhizosphere can be observed with fluorescent planar optodes, while neutron radiography detects small-scale heterogeneities in soil moisture and its dynamics. Respiration and exudation rates can vary between roots of different types, such as primary and lateral roots, as well as along single roots among the same plant. The 3D root system architecture is therefore a key information when studying rhizosphere processes. It can be captured in detail with neutron tomography, but so far only for plants grown in small, cylindrical containers.</p><p>Combined non-invasive imaging of biogeochemical dynamics, soil moisture distribution and 3D root system architecture is a technical challenge. Thin, slab-shaped rhizotrons with relatively large vertical and lateral extension are well suited for optical fluorescence imaging, allowing for spatially extended observation of biogeochemical patterns. This rhizotron geometry is, however, unfavorable for standard 3D tomography due to reconstruction artefacts triggered by insufficient neutron transmission when the long side of the sample is aligned parallel to the beam direction.</p><p>We therefore applied neutron laminography, a method where the rotational axis is tilted, to measure the root systems of maize and lupine plants grown in slab-shaped glass rhizotrons (length = 150 mm, width = 150 mm, depth = 15 mm) in 3D. In parallel, we investigated rhizosphere oxygen dynamics and pH value via fluorescence imaging and assessed soil moisture distribution with neutron radiography.</p><p>Neutron laminography enabled the 3D reconstruction of the root systems with a nominal spatial resolution of 100 µm/pixel. Reconstruction quality strongly depended on root-soil contrast and hence soil moisture level. After reconstruction of the root system and co-registration with the fluorescence images, first results indicate that observed oxygen concentrations and pH gradients depend on root type and individual distance of the roots from the planar optode.</p><p>In conclusion, neutron laminography is a novel 3D imaging method for root-soil systems grown in slab-shaped rhizotrons. The method allows for determining the precise 3D position of individual roots within the rhizotron and can be combined with 2D imaging approaches. Following experiments will address X-ray laminography as a possible attractive further application.</p>

scholarly journals POS1388 ULTRASOUND FOR PANNICULITIS

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 977.1-977
Author(s):  
A. Potapova ◽  
O. Egorova ◽  
O. Alekseeva ◽  
A. Volkov ◽  
S. Radenska-Lopovok
Keyword(s):  
Dynamic Range ◽  
Subcutaneous Fat ◽  
Diagnostic Value ◽  
High Energy ◽  
Contralateral Side ◽  
Imaging Method ◽  
Non Invasive ◽  
M 12

Background:Ultrasound (US) is a non-invasive and safe imaging method that allows in vivo differentiation of the morphological structures of subcutaneous fat (SCF) tissue in in normal and pathology.Objectives:Reveal features of ultrasound changes in SCF in panniculitis (Pn).Methods:57 patients (f – 45, m - 12) aged 18 - 67 years with an initial diagnosis of erythema nodosum and a disease duration of 3.6 ± 1.4 years were examined. In addition to the general clinical examination, a computed tomography of the chest organs and a pathomorphological examination of a skin biopsy from the site of the node were performed. Ultrasound was performed on a MyLabTwice apparatus (ESAOTE, Italy) using a multi-frequency linear transducer (10-18 MHz) with the PD technique, the parameters of which were adapted for recording low-speed flows (PRF 300-600 Hz, low filter, dynamic range - 20-40 dB), the presence of vascularization was assessed not only in the affected area, but also on the contralateral side using high-energy Doppler.Results:33 patients were diagnosed with septal Pn (SPn), 24 - lobular Pn (LPn). In all cases, the diagnosis was verified by histological examination. Ultrasound made it possible to assess the thickness, echoicity and vascularization of the SCF. In 35 patients, significant thickening of the SCF was revealed (as compared to the contralateral side), of which in 14 cases with SPn, in 21 - with LPn. Significant diffuse thickening of the SCF with the contralateral side was observed in 18 patients, incl. in 12 (66%) patients with LPn. Limited thickening was more typical for SPn (73%). A significant increase in the echoicity of the SCF was noted in all forms of Pn. A “lobular” echo pattern with an anechogenic environment was observed in 25 patients, of which 18 (72%) had LPn. An increase in vascularization compared to the contralateral side was recorded in 30 cases (SPn-17, LPn-13).Conclusion:The obtained preliminary results indicate the important role of ultrasound in assessing the depth and prevalence of the inflammatory process at Pn. To clarify the diagnostic value of this method, further studies are needed on a larger sample of patients.Disclosure of Interests:None declared

Predicted Liquid Water Saturation in Unstructured Pore Networks Based on PEMFC GDL Porosity Profiles

2010 ◽  
Author(s):  
J. Hinebaugh ◽  
Z. Fishman ◽  
A. Bazylak
Keyword(s):  
Liquid Water ◽  
Water Saturation ◽  
Pore Space ◽  
Polymer Electrolyte Membrane ◽  
Gas Diffusion ◽  
Pore Network Model ◽  
High Porosity ◽  
Pore Networks ◽  
Electrolyte Membrane ◽  
Capillary Pressures

An unstructured, two-dimensional pore network model is employed to describe the effect of through-plane porosity profiles on liquid water saturation within the gas diffusion layer (GDL) of the polymer electrolyte membrane fuel cell. Random fibre placements are based on the porosity profiles of six commercially available GDL materials recently obtained through x-ray computed tomography experiments. The pore space is characterized with a Voronoi diagram, and invasion percolation-based simulations are performed. It is shown that water tends to accumulate in regions of relatively high porosity due to the lower associated capillary pressures. It is predicted that GDLs tailored to have smooth porosity profiles will have fewer pockets of high saturation levels within the bulk of the material.

scholarly journals Biological and physical influences on soil <sup>14</sup>CO<sub>2</sub> seasonal dynamics in a temperate hardwood forest

2013 ◽  
Vol 10 (12) ◽  
pp. 7999-8012 ◽  
Author(s):  
C. L. Phillips ◽  
K. J. McFarlane ◽  
D. Risk ◽  
A. R. Desai
Keyword(s):  
Soil Moisture ◽  
Soil Carbon ◽  
Root Respiration ◽  
Late Summer ◽  
Co2 Production ◽  
Forest Site ◽  
Surprising Result ◽  
Sampling Campaign ◽  
Microbial Turnover ◽  
High Frequency Sampling

Abstract. While radiocarbon (14C) abundances in standing stocks of soil carbon have been used to evaluate rates of soil carbon turnover on timescales of several years to centuries, soil-respired 14CO2 measurements are an important tool for identifying more immediate responses to disturbance and climate change. Soil Δ14CO2 data, however, are often temporally sparse and could be interpreted better with more context for typical seasonal ranges and trends. We report on a semi-high-frequency sampling campaign to distinguish physical and biological drivers of soil Δ14CO2 at a temperate forest site in northern Wisconsin, USA. We sampled 14CO2 profiles every three weeks during snow-free months through 2012 in three intact plots and one trenched plot that excluded roots. Respired Δ14CO2 declined through the summer in intact plots, shifting from an older C composition that contained more bomb 14C to a younger composition more closely resembling present 14C levels in the atmosphere. In the trenched plot, respired Δ14CO2 was variable but remained comparatively higher than in intact plots, reflecting older bomb-enriched 14C sources. Although respired Δ14CO2 from intact plots correlated with soil moisture, related analyses did not support a clear cause-and-effect relationship with moisture. The initial decrease in Δ14CO2 from spring to midsummer could be explained by increases in 14C-deplete root respiration; however, Δ14CO2 continued to decline in late summer after root activity decreased. We also investigated whether soil moisture impacted vertical partitioning of CO2 production, but found this had little effect on respired Δ14CO2 because CO2 contained modern bomb C at depth, even in the trenched plot. This surprising result contrasted with decades to centuries-old pre-bomb CO2 produced in lab incubations of the same soils. Our results suggest that root-derived C and other recent C sources had dominant impacts on respired Δ14CO2 in situ, even at depth. We propose that Δ14CO2 may have declined through late summer in intact plots because of continued microbial turnover of root-derived C, following declines in root respiration. Our results agree with other studies showing declines in the 14C content of soil respiration over the growing season, and suggest inputs of new photosynthates through roots are an important driver.

scholarly journals First evaluation of SMOS L2 soil moisture products using in situ observation data of MAVEX on the Mongolian Plateau in 2010 and 2011

2013 ◽  
Vol 7 (2) ◽  
pp. 30-35 ◽  
Author(s):  
Ichirow Kaihotsu ◽  
Keiji Imaoka ◽  
Hideyuki Fujii ◽  
Dambaravjaa Oyunbaatar ◽  
Tsutomu Yamanaka ◽  
...  
Keyword(s):  
Soil Moisture ◽  
In Situ Observation ◽  
Observation Data ◽  
Mongolian Plateau

scholarly journals Spatial and temporal variation of methane emissions in drained eutrophic peat agro-ecosystems: drainage ditches as emission hotspots

2008 ◽  
Vol 5 (2) ◽  
pp. 1237-1261 ◽  
Author(s):  
A. P. Schrier-Uijl ◽  
E. M. Veenendaal ◽  
P. A. Leffelaar ◽  
J. C. van Huissteden ◽  
F. Berendse
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Table ◽  
Soil Moisture Content ◽  
Explanatory Variable ◽  
Spatial And Temporal Variation ◽  
Spatial And Temporal Variability ◽  
Ch4 Emissions ◽  
Intensively Managed ◽  
Moisture Conditions

Abstract. Our research investigates the spatial and temporal variability of methane (CH4) emissions in two drained eutrophic peat areas (one intensively managed and the other less intensively managed) and the correlation between CH4 emissions and soil temperature, air temperature, soil moisture content and water table. We stratified the landscape into landscape elements that represent different conditions in terms of topography and therefore differ in moisture conditions. There was great spatial variability in the fluxes in both areas; the ditches and ditch edges (together 27% of the landscape) were methane hotspots whereas the dry fields had the smallest fluxes. In the intensively managed site the fluxes were significantly higher by comparison with the less intensively managed site. In all the landscape element elements the best explanatory variable for CH4 emission was temperature. Neither soil moisture content nor water table correlated significantly with CH4 emissions, except in April, where soil moisture was the best explanatory variable.

A general approach for analytically upscaling the exact root water uptake equations despite heterogeneous soil moisture at the soil-root interface

2021 ◽  
Author(s):  
Martin Bouda ◽  
Jan Vanderborght ◽  
Mathieu Javaux
Keyword(s):  
Soil Moisture ◽  
Exact Solutions ◽  
Root System ◽  
Water Uptake ◽  
Grid Cell ◽  
Earth System ◽  
Water Flows ◽  
Heterogeneous Soil ◽  
Soil Moisture Heterogeneity ◽  
Earth System Models

&lt;p&gt;Recent advances in scaling up water flows on root system networks hold promise for improving predictions of water uptake at large scales. These developments are particularly timely, as persistent difficulties in getting Earth system models to accurately represent soil-root water flows, especially under drying or heterogeneous soil moisture conditions, are now a major obstacle describing the water limitation of terrestrial fluxes.&lt;/p&gt;&lt;p&gt;One recently developed upscaling formalism has been shown to be both free of discretisation error in flow predictions regardless of scale and with computational cost linearly diminishing with the number of soil subdomains considered. What has been missing from this approach, however, is a proven method to apply it generally &amp;#8211; i.e. to an arbitrary root system architecture discretised on an arbitrary grid.&lt;/p&gt;&lt;p&gt;The work presented here demonstrates a general algorithm that can be applied to a wide range of root system architectures (the only assumption being that only one lateral root originates at one point along a parent root) discretised on a grid consisting of a series of soil layers of variable thickness, as is common in Earth system models. It is further shown theoretically that both of these restrictions can in principle be relaxed and that this approach can in principle be extended to conditions of soil moisture heterogeneity &amp;#8211; i.e. situations where each root segment in a soil grid cell faces a different water potential at the soil-root interface.&lt;/p&gt;&lt;p&gt;This work represents both a practical advance bringing broad applicability to this upscaling approach and a major theoretical advance as exact solutions for water uptake under conditions of soil moisture heterogeneity within grid cells were previously unknown. While obtaining exact solutions despite heterogeneity within the grid cell requires a way of finding the overall mean soil water potential faced by the plant, this advance nevertheless points to possible directions of future research for overcoming the major hurdle of soil moisture heterogeneity.&lt;/p&gt;

Measurement Tools for Non-Invasive Monitoring of the Plants Growth Conditions by Using Hyperspectral Imaging Methods: a Review

2021 ◽  
Vol 2 (43) ◽  
pp. 54-61
Author(s):  
Dmitriy A. Burynin ◽  
◽  
Aleksandr A. Smirnov
Keyword(s):  
Hyperspectral Imaging ◽  
Physiological State ◽  
Effective Means ◽  
Research Problem ◽  
High Spectral Resolution ◽  
Research Purpose ◽  
Imaging Method ◽  
Invasive Monitoring ◽  
Imaging Methods ◽  
Non Invasive

Portable spectroradiometers and hyperspectral cameras are increasingly being used to quickly assess the physiological state of plants. The operation of these devices is based on the registration of reflection or reflection and transmission spectra. (Research purpose) The research purpose is in analyzing the technical means and methods of non-invasive monitoring of the plant state based on the registration of the reflection spectra of leaves. (Materials and methods) The article presents a review of the work on the application of hyperspectral imaging methods. Authors classified and analyzed materials on spectroscopic radiometers and hyperspectral cameras, and outlined the prospects for implementation. Authors applied the methods of a systematic approach to the research problem. (Results and discussion) Hyperspectral imaging methods serve as an effective means of monitoring plants. It is possible to determine the pigment composition of plants, lack of nutrition, and detect biotic stress through hyperspectral imaging. The article presents methods of application of portable spectroradiometers and hyperspectral cameras. With the help of these devices it is possible to carry out measurements with high spectral resolution. The difficulty of accurately detecting the content of pigments in the leaves lies in the mutual overlap of the areas of light absorption by them. The main drawback of spectroradiometers is that they measure only at one point on a single sheet. The article presents the difficulties encountered in interpreting the results obtained by the hyperspectral camera. The background reflectivity of the soil, the geometry of the vegetation cover, and the uneven lighting can make errors in the measurements. (Conclusions) The article presents the disadvantages of the hyperspectral imaging method when using only the reflection spectrum. In order to increase the accuracy of the determination of pigments and stresses of various origins, it is necessary to develop a portable device that combines the methods of recording reflection and fluorescence.

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