Poly-use multi-level sampling system for soil-gas transport analysis in the vadose zone

Area of Science:

• Environmental Science
• Soil Science
• Geochemistry

Background:

• Soil-gas turnover is critical for global greenhouse gas cycling.
• Accurate measurement of soil-gas profiles informs below-ground processes and fluxes.
• Existing methods can be invasive or lack high depth resolution.

Purpose of the Study:

• To develop and validate a versatile multi-level sampling system (PMLS) for soil-gas analysis.
• To enable high-resolution, minimally invasive measurement of soil-gas composition, water content, and temperature.
• To assess the PMLS's utility in quantifying soil-gas transport and greenhouse gas fluxes in situ.

Main Methods:

• Development of a Poly-Use Multi-Level Sampling (PMLS) system using perforated access tubes (ATs).
• Integration of a multi-level sampler for gas extraction and a capacitance probe for water content.
• In situ gas tracer tests and field applications for quantifying methane oxidation and soil-atmosphere fluxes.

Main Results:

• The PMLS demonstrated good agreement with conventional techniques for soil-gas and water-content measurements.
• Gas tracer tests confirmed the PMLS's capability to determine in situ soil-gas diffusion coefficients.
• Field applications successfully quantified atmospheric methane oxidation, yielding results consistent with prior studies.

Conclusions:

• The PMLS is a robust and adaptable tool for detailed investigation of soil-gas dynamics.
• This system offers enhanced methodological options for studying soil-gas transport in the vadose zone.
• The PMLS contributes to a better understanding of greenhouse gas cycling and soil processes.