Term of Award

Summer 2017

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

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

Department

Department of Biology

Committee Chair

Risa A. Cohen

Committee Member 1

John Stone

Committee Member 2

Johanne Lewis

Committee Member 3

Vinoth Sittaramane

Abstract

Silver nanoparticles (AgNPs) are used in 25% of all nano-enabled products and applied for anti-microbial properties. Silver nanoparticles are discharged into aquatic environments through wastewater discharge, runoff, and chemical spills. Once in aquatic environments silver nanoparticles have the potential to harm aquatic organisms. While the fate of silver nanoparticles in lentic systems has been investigated, limited information is available for the fate of silver nanoparticles in flowing environments. The purpose of this study was to compare the fate of AgNPs following a one-time pulsed application simulating a chemical spill, or small repetitive applications simulating effluent discharge, in artificial stream communities containing river water, sediment, periphyton, snails, and fish under realistic environmental conditions. In addition to comparing the fate of AgNPs between application types, the fate of AgNPs were also compared between 35 and 70 µg L-1 concentrations of AgNPs. Water samples were collected on days 0, 7, and 14 to quantify total Ag (TAg) in the water column. Periphyton samples were taken on days 0 and 14, and sediment, snail, and fish samples were taken on day 14 for silver content. Results from this study show that AgNP concentrations applied to streams only affects the fate of AgNPs in sediment where the majority of AgNPs settled and in fish which had limited exposure to AgNPs in the water column. Additionally, application type only affected the fate of AgNPs in periphyton samples of pulsed treated streams where snails and flowing conditions had a longer period of time to reduce Ag adsorption to periphyton compared to repetitively treated streams. In this study, silver nanoparticles rapidly settled in lotic environments placing benthic organisms at risk for Ag accumulation. Furthermore, exposure to 70 µg L-1 and 35 µg L-1 AgNPs concentrations in artificial streams was not toxic to aquatic organisms regardless of application type. This study emphasizes the importance of testing AgNP exposure under environmentally relevant conditions to assess their fate and toxicity in the environment.

Research Data and Supplementary Material

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