Date of Award

2015

Document Type

Open Access Thesis

Department

Marine Science

Sub-Department

College of Arts and Sciences

First Advisor

James L. Pinckney

Abstract

Nanoparticles are known to be entering the environment and are shown to have adverse effects on aquatic organisms (Fabrega et.al. 2011, Lapresta-Fernandez et.al. 2012, Matranga and Corsi 2012, Moore 2006). The purpose of this study was to quantify the uptake of AgNPs by two estuarine organisms and determine the associated toxic effects of accumulation. There are multiple procedures for nanoparticle (NP) synthesis that involve various core and surface materials, which result in various characteristics such as size, shape, and surface coating. In this study silver nanoparticles (AgNPs) were synthesized by a chemical reduction of silver salts and characterized in stock solution and saltwater algal growth media (L1-Si) using a multi-methodological approach. Dynamic light scattering (DLS) and ultraviolet visible spectrometry (UV-vis) NP characterization resulted in an average size of 11.2 nm for citrate coated AgNPs (cit-AgNPs) and 17.6 nm for polyvinylpyrrolidone (pvp) coated AgNPs (pvp-AgNPs). Transmission electron microscopy (TEM) determined NP size of 14.0 ± 1.7 nm and 14.8 ± 5.7 nm (mean ± 1 s.d.), for cit-AgNPs and pvp-AgNPs respectively. DLS and dissolution analysis showed that cit-AgNPs aggregated in the saltwater media, while pvp-AgNPs remained mono-dispersed in the media as indicated by a polydispersity index (pdi) value of 0.2-0.4.

When exposed to the concentrations of 50-100 ppb, cell abundance of Prorocentrum minimum decreased, with observed LC50 values of 61.9 ppb (cit-AgNPs) and 59.1 ppb (pvp-AgNPs). Crassostrea virginica exposures showed concentration and tissue dependent responses for silver (Ag) accumulation, with a direct relationship between exposure concentration and Ag accumulation. Lipid peroxidation assays indicated a significant difference from the control in the 15 and 50 ppb exposures for cit-AgNP and AgNO3 treatments and no toxic effect was observed in the 1 and 10 ppb exposures of all treatments. Examining AgNP toxicity on the level of a primary producer and primary consumer are extremely important in that these trophic levels are the base of multiple food webs in the marine and estuarine environment. An inhibition of abundance decreases the population size of the exposed or affected species.

Rights

© 2015, Shelby Victoria Butz

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