Date of Award

8-2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Committee Member

Dr. Christrophe Darnault, Committee Chair

Committee Member

Dr. Brian Powell

Committee Member

Dr. Stephen Moysey

Committee Member

Dr. Lawrence Murdoch

Abstract

The rhizosphere is the region of soil directly impacted by a plants roots, both physically (root growth) and chemically (water and nutrient uptake via organic compounds). The chemical components exuded by a plants roots can be lumped into two categories; mucilage and exudates. Mucilage effects on flow have been widely studied, though the independent effects of exudates have not. The objective of this research is to investigate the effects of plant root exudates on the infiltration processes through a porous media. This is done by (1) characterizing the solid-liquid and liquid-gas interfaces of the exudate solutions used for the flow experiments, and (2) conduct 2-Dimensional light transmission method infiltration flow experiments. For the interfacial characterization citrate generally was the most effective exudate at reducing the contact angle,19% and 29% reduction, and surface tensions, 6.5% and 3% reduction, at both concentrations respectively. In the flow experiments, saturation overshoot was seen in the control, citrate, and tannic acid at both concentrations. Additionally, for the higher concentration exudate solutions greater horizontal saturation dispersion is seen along the edges of the finger pathways, as compared to the low concentration systems. Interfacial characterization of the exudate solutions determined that unnaturally high concentrations of exudates do not have a significant increased effect on the wettability when compared to the effects seen by natural concentrations. Ultimately, the 2- Dimensional light transmission method tank experiments illustrated additional significant differences between the varying exudate solutions through their vertical and horizontal water saturation profiles, then were otherwise unseen through the interfacial characterization. 2- Dimensional light transmission methodologies are a novel tool for visualizing the subsurface flow environment, and allow for insights to be made, that may otherwise remain unseen.

Share

COinS