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Date of Award

Spring 2025

Document Type

Masters Thesis

Department or Program Affiliation

Environmental Sciences

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Montaño, Manuel D.

Second Advisor

Bunn, Rebecca

Third Advisor

Messer, Tiffany

Abstract

Nanopesticides offer potential environmental benefits in agriculture, but their impact on downstream wetlands remain understudied. This study was guided by two hypotheses: (1) nano-enabled pesticides would alter nitrogen and phosphate availability, through interactions with plant-associated microbial communities; and (2) copper-based nanofungicides would inhibit microbial degradation of nano-imidacloprid, resulting in lower concentrations of degradation byproducts such as IMI-desnitro compared to bulk formulations. We evaluated the behavior of nano-enabled copper and neonicotinoid (imidacloprid) pesticides in outdoor wetland mesocosms by measuring pesticide persistence, degradation byproducts, and changes in nutrient concentrations. Treatments included nano-copper hydroxide (Kocide 3000), nano-imidacloprid (Viloprid), and conventional imidacloprid, applied individually and in combination to vegetated mesocosms established with native wetland species (Eleocharis palustris, Schoenoplectus pungens, and Carex obnupta). Water samples were collected and analyzed for nitrate-N, phosphate-P, dissolved organic carbon (DOC), copper, and imidacloprid along with its degradation products. Parent imidacloprid was not detected in the nano-imidacloprid (NI) treatment, while low concentrations of IMI-desnitro were found primarily in the bulk imidacloprid treatment. Copper concentrations showed no significant differences between the Kocide-only (Cu) and Kocide + nano-imidacloprid (CUNI) treatments. Greater total copper concentrations relative to dissolved indicated a rapid absorption of copper to the mesocosm sediment particles. Nutrient data, particularly nitrate and phosphate, were highly variable across treatments, while dissolved organic carbon showed an increase throughout the experiments, with no differences seen between treatments. Overall, these results demonstrate that there are some differences in the chemical cycling of nutrients in wetlands upon exposure to nano-pesticides, indicating the need for future research.

Type

Text

Keywords

nanopesticides, mesocosms, imidacloprid, degradation, copper, wetlands

Publisher

Western Washington University

OCLC Number

1523106678

Subject – LCSH

Imidacloprid--Environmental aspects; Neonicotinoids--Environmental aspects; Fungicides; Biodegradation; Nanostructured materials; Experimental ecology--Washington (State)--Padilla Bay National Estuarine Research Reserve; Ecological risk assessment

Geographic Coverage

Padilla Bay National Estuarine Research Reserve (Wash.)

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

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