Speaker
Description
The availability of key soil nutrients, including nitrogen, phosphorus, and sulfur, is strongly governed by soil redox conditions, making redox dynamics a key determinant of both agricultural productivity and environmental sustainability. These redox conditions are directly linked to oxygen concentrations in porewater, which are highly dynamic and fluctuate significantly over millimeter-scale distances. In cultivated soils, various land management practices alter the soil pore structure, directly influencing oxygen transport and distribution, which subsequently govern coupled physicochemical and biological processes. This study examines the relationship between the porous medium structure and water saturation in influencing pore-scale oxygen distribution and redox potential. These interactions were investigated using two-dimensional microfluidic soil-on-chip reactors, enabling high-resolution observation of oxygen dynamics across diverse porous medium structures under drainage conditions. To ensure that oxygen dynamics were governed solely by pore-space transport, the microfluidic devices were fabricated using gas-impermeable NOA-81, thereby eliminating oxygen leakage through the solid phase. The microfluidic devices are equipped with oxygen-sensitive fluorescent sensors, allowing for high-resolution, real-time visualization of oxygen concentrations within pore spaces. By varying pore structural complexity and water distribution in controlled experiments, we aim to quantify the relationships between pore geometry, water saturation, and distribution, as well as oxygen dynamics. Preliminary results comparing two porous media with distinct correlation lengths indicate that structural connectivity has a significant impact on water distribution during drainage. In structures with a higher correlation length, the liquid phase organized into large clusters with a lower surface-to-volume ratio. In contrast, media with lower correlation lengths exhibited smaller, more dispersed clusters with a higher surface-to-volume ratio. These spatial patterns directly govern the distribution of oxygen concentrations, where the center of larger clusters maintains significantly lower oxygen concentrations, whereas smaller clusters exhibit more uniform, well-oxygenated conditions.
| Country | Israel |
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