Abstract

Degradability of organic matter (OM) in soil depends on its spatial location in the soil matrix. A recent breakthrough in 3D-localization of OM combined dual-energy X-ray CT-scanning with OsO 4 staining of OM. The necessity for synchrotron-based µCT and the use of highly toxic OsO 4 severely limit applications in soil biological experiments. Here, we evaluated the potential of alternative staining agents (silver nitrate, phosphomolybdenic acid (PMA), lead nitrate, lead acetate) to selectively enhance X-ray attenuation and contrast of OM in CT volumes of soils containing specific mineral soil particle fractions, obtained via lab-based X-ray µCT. In comparison with OsO 4, administration of Ag + and Pb 2+ resulted in insufficient contrast enhancement of OM versus fine silt (< 20 µm) or clay (< 2 µm) mineral particles. The perfusion procedure used in this work induced changes in soil structure. In contrast, PMA staining resulted in a selective increase of OM’s attenuation contrast, which was comparable to OsO 4. However, OM discrimination from other soil phases remained a challenge. Further development of segmentation algorithms accounting for grey value patterns and shape of stained particulate OM may enable its automated identification. If successful in undisturbed soils, PMA staining may form an alternative to OsO 4 in non-synchrotron based POM detection.

Original languageEnglish
Article number370
Pages (from-to)1-11
Number of pages11
JournalScientific Reports
Volume11
Issue number1
DOIs
Publication statusPublished - Dec 2021

Bibliographical note

Funding Information:
This research received funding from the Research Foundation Flanders (FWO)—project 3G042613 ‘Soil 3-D architecture and protection of soil organic matter: combining X-ray CT and biological approaches’. The special research fund of the Ghent University (BOF-UGent) is acknowledged for the financial support of the UGCT Centre of Expertise (BOF.EXP.2017.0007). We thank Sophie Schepens, Luc Deboosere, Tina Coddens, Anne-Mie Terryn and Matthieu Schatteman for their skillful lab assistance.

Publisher Copyright:
© 2021, The Author(s).

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