Year of Publication

2013

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Agriculture

Department

Plant and Soil Sciences

First Advisor

Dr. Paul M. Bertsch

Second Advisor

Dr. Jason M. Unrine

Abstract

In order to properly evaluate the ecological and human health risks of ZnO Manufactured nanomaterials (MNMs) released to the environment, it is critical to understand the likely transformation products in the wastewater treatment process and in soils receiving biosolids. To address this critical knowledge gap, we examined the transformation reactions of 30 nm ZnO MNMs in single component and multi-component systems, with phosphate and natural organic matter (NOM). We also assessed the influence of nano ZnO transformation on the bioavailability, and toxicity of ZnO transformation products to Triticum aestivum. The data revealed that ZnO MNMs react with phosphate at concentrations expected in wastewater and transform into two distinct morphological/structural phases. A micron scale crystalline zinc phosphate phase (hopeite), and a nano-sized phase that likely consists of a ZnO core with a Zn3(PO4)2 rich shell. Presence of NOM reduces particle aggregation and enhances stability, regardless of the sequence of ligands addition in the aging scenarios. The presence of phosphate and NOM also altered the bioavailability and reduced the toxicity of the ZnO MNMs to Triticum aestivum.

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