Limiting air bubble formation during X‐ray CT fast scanning of rewetted soils

Résumé fourni par la source

Abstract The microscale distribution of air, water, and solids determines many aspects of soil functionality. There is increasing interest in drying‐rewetting cycles impacts on soil structural dynamics and water redistribution. However, resolving these dynamics over short timescales with X‐ray computed tomography (CT) necessitates high fluxes of X‐rays (over 1E10 photons s −1 mm −2 ), which may cause radiolysis of the water and form air bubbles, leading to artificial soil deformation. This technical note explores the effect of fast scanning using different X‐ray fluxes in millimeter‐scale rewetted soil aggregates. We quantified the evolution of the air, water, and solid phases over 10 min with one 13.2 s scan per minute. Radiolysis of the water can destroy mm‐scale aggregates at fluxes of 2.5E13 photons s −1 mm −2 , but it was removed at 8E10 photons s −1 mm −2 without compromising the quality of the dynamic scans. Dynamic X‐ray CT studies on wet soils should minimize flux to 8E10 photons s −1 mm −2 or under.

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