Date of Award

Fall 2006

Project Type

Dissertation

Program or Major

Civil Engineering

Degree Name

Doctor of Philosophy

First Advisor

Tom Ballestero

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants in estuarine environments, but little is known about the distribution and fate of PAHs in wetland sediments and plants. The effect of PAHs on common salt marsh plants, and the PAH distribution within the plants, sediment, and atmosphere were evaluated to determine if PAHs were transported from the sediment into the plants, and if the PAHs affected plant growth. Four salt marsh plant species, Spartina alterniflora, Phragmites australis, Solidago sempervirens and Distichlis spicata were grown in pots of PAH contaminated sediment containing mean total PAH concentrations of 355 mg/kg (ppm). During the growing season, the plant height, aboveground biomass, percent survival and percent flowering were measured. After approximately three months, the plants were harvested, cleaned, and analyzed for PAHs. PAH compounds were detected in all of the samples, but the highest concentrations were found in samples of the contaminated sediment. The root sample concentrations were generally about one order of magnitude lower than that of the sediment, and were strongly correlated with the concentration in the sediment in which they were grown. The concentrations in foliage were low (<1.8 mg/kg total PAHs), did not correlate with sediment concentration, and decreased for the higher molecular weight compounds. Concentrations in plants grown in contaminated sediment were higher for most of the compounds, but were not linearly related to sediment concentrations. These data suggest that both atmospheric deposition and sediment concentrations are factors in PAH contamination of foliage.

All of the plants were impacted by the contaminated sediment to some degree. The Distichlis were the most affected, and did not survive at the highest concentrations, although Distichlis grown at a lower mean concentration (200 mg/kg) survived, and appeared healthy. Solidago and Phragmites grown in contaminated sediment were shorter than the control plants, and produced less above ground biomass. The Spartina showed the least impact, and grew well in the contaminated sediment, although the plants were smaller than the controls.

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