Date of Graduation

5-2020

Document Type

Thesis

Degree Name

Bachelor of Science in Agricultural, Food and Life Sciences

Degree Level

Undergraduate

Department

Crop, Soil and Environmental Sciences

Advisor/Mentor

Savin, Mary

Committee Member

Stenken, Julie

Second Committee Member

Wood, Lisa S.

Abstract

The use of phytoremediation in ecological remediation projects has numerous benefits including soil stabilization and nutrient uptake. Recently, microdialysis, a diffusion-based sampling technique commonly used in biomedical research, has been recognized as a candidate for monitoring chemical changes in the rhizosphere. The real-time, in situ data it provides about nutrient diffusion may improve the management and success of restoration projects. Therefore, the objective of this study was to employ the technique of microdialysis in the novel application of quantifying the diffusive flux of inorganic nitrogen compounds in the rhizosphere of native plants of Arkansas. The microdialysis technique was first optimized for the soil setting, which included flow rate determination and experimentation with soil saturation and the addition of prepared and natural spikes. Switchgrass (Panicum virgatum) and Reed canarygrass (Phalaris arundinacea) plants were planted in soil obtained from Lake Keith and maintained in a greenhouse along with a soil control. Two different watering regimes were established and microdialysis samples were collected six times during a 2-week experiment while watering with nitrate-N-rich (5-6 µg/mL) water acquired from Lake Keith. Samples were analyzed for nitrate-N and ammonium-N fluxes using colorimetric assays. Fluxes of nitrate-N in the Reed canarygrass rhizosphere increased throughout the experiment such that they were different from the Switchgrass treatment by the second sampling day and were different from both Switchgrass and the control during the second week of experimentation. Ammonium-N in all samples was below detection limits. Overall, this study revealed that in situ nitrogen sampling can be accomplished successfully using the microdialysis technique and that Switchgrass is a likely candidate for future phytoremediation applications, as shown by temporal nitrate-N distributions and total nitrogen analysis of above- and belowground biomass.

Keywords

Microdialysis; Rhizosphere; Nitrogen; Phytoremediation; Flux; Soil Nutrients

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