Date of Award

12-7-2023

Publication Type

Thesis

Degree Name

M.Sc.

Department

Earth and Environmental Sciences

Keywords

Microplastic;Rhizosphere;Roots

Supervisor

Cameron Proctor

Rights

info:eu-repo/semantics/openAccess

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

Biosolid fertilizer use causes the input of microplastics into the rhizosphere where they may interfere with root interactions with the soil and microbial community and thereby hinder plant acquisition of nutrients and water. However, it is unclear what microplastic concentration or types affect plant root system and when these impacts manifest. Using the rhizobox method, soybeans were grown in soil was dosed with microplastic mimics (PET sheets and PP beads at 2,000 and 15,000 particles / kg dry soil) and biosolids. A time-series analysis was conducted on plant root traits using non-destructive imaging with an Epson 12000xl scanner of the entire plant root system on a weekly basis until maturity. Microplastic concentration was positively correlated with total soybean biomass and the ratio of above to belowground biomass was statistically different relative to the control at the highest microplastic concentration (Tukey HSD p1mm) revealed higher portions of the total root length were thinner roots and that the root systems of the microplastic treatments grew at a faster rate until saturation whereas the control continually grew. Linear regression predicting root length based on week number suggested that 0-5mm roots grew at a rate of 811.8mm per week in the control versus 1,186.7 and 1,593mm for PET at 2,000 and 15,000 particles/kg dry soil respectively. Overall, microplastics increased the root biomass, root surface area, and duration of contact which overall increase the interface between roots and soil.

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