Date of Award:

5-2016

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Civil and Environmental Engineering

Committee Chair(s)

Joan E. McLean

Committee

Joan E. McLean

Committee

Anne J. Anderson

Committee

David W. Britt

Committee

David K. Stevens

Abstract

Copper oxide nanoparticles (CuO NPs) are extremely small particles (less than 1 nm in one or more dimension, or one billionth (10-9) of a meter) used in a diverse range of industries. They have been shown to travel through water systems, and like pharmaceuticals, can end up in wastewater treatment plants and then be land applied as biosolids, where crops are grown for animal consumption, potentially leading to food chain accumulation.

Cu is an essential micronutrient for plants, but is phytotoxic at higher concentrations. CuO NPs present an increasingly real environmental threat to agriculture in soils treated with biosolids, in addition to aquatic systems.

To understand this interaction, wheat was grown in sand amended with various levels of CuO NPs for 10 days. Compared to the control, roots of wheat grown with nanoparticles were dose-­‐dependently shorter. Analysis of the shoot tissue showed that micronutrients, calcium, magnesium, manganese and iron (Fe) as well as potassium were lower, while Cu was higher in CuO NP-treated wheat.

Additionally, higher levels of root exudates, citrate and Fe uptake molecule deoxymugineic acid, were found at higher CuO NP doses. These negatively charged molecules at neutral pH bind to Cu2+, dissolving more Cu into solution compared to a solution without plants. Our studies show that increasing amounts of Cu in solution,
driven by complexes formed by root exudates, may be in part responsible for the toxicity of CuO NPs.

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