Uptake of Gold Nanoparticles in an Algae - Daphnid Food Chain

Author

Matthew Osborne-koch, Clemson UniversityFollow

Date of Award

12-2009

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Environmental Toxicology

Committee Chair/Advisor

Klaine, Steve

Committee Member

Baldwin , William

Committee Member

Lee , Cindy

Abstract

Nanoparticle entry into the environment can result in deleterious effects to exposed organisms, disruption of ecological processes, and accumulation within the wood web. Gold nanoparticles (AuNPs), which are classified as zero-valent metals, are of significant interest due to their use in a variety of applications including electrical, biomedical, catalytic, magnetic, and optical technology. The wide range of uses for AuNPs can be attributed to a combination of the unique physical properties of the element gold (i.e. density, conductivity, stability, etc.) and the diversity of sizes, shapes, and surface compositions that can be achieved through manipulation of AuNP synthesis. While previous studies have suggested that AuNPs can be bioconcentrated and bioaccumulated, these studies do not indicate the effects of AuNPs characteristics on trophic transfer.
The objectives of this study were to 1) quantify the uptake and depuration of 4nm and 18nm gold spheres by D. magna; 2) quantify the uptake of 4nm and 18nm AuNPs by the algae, Selenastrum capricornutum; 3) quantify the bioaccumulation of 4nm and 18nm AuNPs previously incorporated in algae; and 4) determine the bioconcentration factors (BCF) for 4nm and 18nm AuNps in Selenastrum capricornutum and D. magna and the bioaccumulation factors (BAF) for 4nm and 18nm AuNPs in D. magna. Bioconcentration factors for D. magna exposed to 4nm and 18nm AuNPs for 96hr were 6641 and 10207, respectively. Depuration followed first order kinetics for the D. magna exposed to 18 nm AuNPs with a rate of -0.67 ug Au/hr, however the slope for 4nm depuration was not found to be significantly different from 0. Bioconcentration factors for S. capricornutum exposed to 4nm and 18nm AuNPs for 96hr were 79.8 and 146.3, respectively. Bioaccumulation factors for D. magna exposed to 4nm and 18nm AuNPs for 96hr were 3.9 and 7.5, respectively. In conclusion these data indicate that uptake and depuration of AuNPs by D. magna is dependent on particle size with larger AuNPs exhibiting increased depuration and that AuNP depuration is incomplete over the duration of these experiments.