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Potential of combined neutron and X-ray imaging to quantify local carbon contents in soil

Koestel, John and Fukumasu, Jumpei and Larsbo, Mats and Herrmann, Anke and Ariyathilaka, Pawala and Magdysyuk, Oxana V. and Burca, Genoveva (2022). Potential of combined neutron and X-ray imaging to quantify local carbon contents in soil. European Journal of Soil Science. 73 :1 , e13178
[Research article]

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Abstract

In this study, we investigated the potential and limitations of using joint X-ray and time-of-flight (TOF) neutron imaging for mapping the 3-dimensional organic carbon distribution in soil. This approach is viable because neutron and X-ray beams have complementary attenuation properties. Soil minerals consist to a large part of silicon and aluminium, and elements that are relatively translucent to neutrons but attenuate X-rays. In contrast, attenuation of neutrons is strong for hydrogen, which is abundant in soil organic matter (SOM), while hydrogen barely attenuates X-rays. In theory, TOF neutron imaging does further more allow the imaging of Bragg edges, which correspond to d-spacings in minerals. This could help to distinguish between SOM and clay minerals, the mineral group in soil that is most strongly associated with hydrogen atoms. We collected TOF neutron image data at the IMAT beamline at the ISIS facility and synchrotron X-ray image data at the I12 beamline at the Diamond Light source, both located within the Rutherford Appleton Laboratory, Harwell, UK. The white beam (the full energy spectrum) neutron image clearly showed variations in neutron attenuation within soil aggregates at approximately constant X-ray attenuations. This indicates a constant bulk density with varying organic matter and/or clay content. Unfortunately, the combination of TOF neutron and X-ray imaging was not suited to allow for a distinction between SOM and clay minerals at the voxel scale. While such a distinction is possible in theory, it is prevented by technical limitations. One of the main reasons is that the neutron frequencies available at modern neutron sources are too large to capture the main d-spacings of clay minerals. As a result, inference to voxel scale SOM concentrations is presently not feasible. Future improved neutron sources and advanced detector designs will eventually overcome the technical problems encountered here. On the positive side, combined X-ray and TOF neutron imaging demonstrated abilities to identify quartz grains and to distinguish between plastics and plant seeds. Highlights Full understanding of biogeochemical processes requires three-dimensional (3-D) maps of organic matter in soil (SOM). This study investigates a novel method to map voxel-scale SOM contents with 3-D resolution. The method is based a combination of X-ray and time-of-flight neutron tomography. At present, technical limitations prevent distinguishing between SOM and clay mineral contents. More advanced neutron sources are required to overcome the encountered technical obstacles.

Authors/Creators:Koestel, John and Fukumasu, Jumpei and Larsbo, Mats and Herrmann, Anke and Ariyathilaka, Pawala and Magdysyuk, Oxana V. and Burca, Genoveva
Title:Potential of combined neutron and X-ray imaging to quantify local carbon contents in soil
Series Name/Journal:European Journal of Soil Science
Year of publishing :2022
Volume:73
Number:1
Article number:e13178
Number of Pages:19
Publisher:WILEY
ISSN:1351-0754
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution-Noncommercial 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Soil Science
Keywords:correlative imaging, neutron imaging, soil organic matter, soil structure, X-ray imaging
URN:NBN:urn:nbn:se:slu:epsilon-p-114462
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-114462
Additional ID:
Type of IDID
DOI10.1111/ejss.13178
Web of Science (WoS)000716519300001
ID Code:27306
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Dept. of Soil and Environment
(S) > Dept. of Soil and Environment
Deposited By: SLUpub Connector
Deposited On:14 Mar 2022 11:26
Metadata Last Modified:14 Mar 2022 11:31

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