A study of constructed soil-membrane diffusivity probes for the determination of gaseous diffusivity coefficients at varying soil volumetric water contents
Open Access
Author:
Turner, Bret Douglas
Area of Honors:
Environmental Resource Management
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Jason Philip Kaye, Thesis Supervisor Robert David Shannon, Thesis Honors Advisor
Keywords:
gas diffusion soil gas soil volumetric water content membrane probe carbon dioxide greenhouse gas
Abstract:
The goal of this project was to evaluate the use of soil-membrane diffusivity probes
(based on the work of Risk et al, 2008) in the determination of the gaseous diffusivity coefficient
for carbon dioxide in soil of varying volumetric water contents. The earth’s soils represent the
largest non-anthropogenic source of greenhouse gas emissions (US EPA, 2013); and it is
therefore vital to understand both the biological and physical processes by which greenhouse
gases escape the soil profile and enter the earth’s atmosphere because of the effect of greenhouse
gases on the earth’s terrestrial and auatic ecosystems CC, 2014). Soil respiration occurs due
to plant and microbial activity within the soil, but gas diffusion is also a physically-based process
relating to soil porosity, water content, tortuosity, and other factors (Luo & Zhou, 2006). In this
study, a probe was tested in laboratory conditions using a LiCor 6200 (LiCor Biosciences,
Lincoln, Nebraska) and soil of varying simulated volumetric water contents. The method of
analysis tested in this paper was found to be a novel way to measure gaseous diffusivity of soil
in-situ, with minimal soil disturbance and less estimation than previous methods. The use of
soil-membrane diffusivity probes warrants further in-field testing and could prove to be valuable
tool for soil research in the future.