Identifier

etd-04102017-125358

Degree

Master of Science in Civil Engineering (MSCE)

Department

Civil and Environmental Engineering

Document Type

Thesis

Abstract

Louisiana coastal marshes were heavily impacted by the 2010 Deepwater Horizon oil spill. MC252 oil pollution in coastal marshes lead to the exposure of biota to polycyclic aromatic hydrocarbons (PAHs). PAHs are persistent organic pollutants that can reside and accumulate in marsh biota. The aim of this study was to investigate the uptake mechanisms of PAHs by Spartina alterniflora at heavily oiled Bay Jimmy marsh in Barataria Basin, Louisiana. Study objectives were to quantify and investigate the uptake mechanisms of PAHs in the leaves of Spartina. The plant/air partitioning of PAHs was studied using a fugacity approach to determine their partitioning coefficients. Semipermeable membrane devices (SPMDs) were utilized in a parallel study of the uptake of PAHs from the marsh surface and air. Sampling was between June 2016 and February 2017. A three-step sequential extraction procedure was applied for analysis of PAHs in Spartina leaves. At the field, particulates deposited on Spartina leaves were washed with EDTA solution followed by dichloromethane to dissolve the cuticle. Leaf tissues were extracted by the accelerated solvent extraction method. PAHs in SPMDs were extracted via dialysis with hexane. A laboratory scale fugacity meter was designed to study plant/air partitioning of PAHs. PAHs were quantified in selective ion monitoring mode connected with a mass selective detector. Similar PAHs profiles in Spartina leaf tissues and SPMDs suggested the cycling of PAHs at Bay Jimmy. Naphthalenes accumulated twice more than phenanthrenes in Spartina leaves and SPMDs. PAHs were sequestered in leaf tissues than the cuticle. Statistically significant correlation (p <0.05) of PAHs in plant leaves and SPMDs were as high as 97%. Soil analysis revealed naphthalenes and phenanthrenes to total PAHs fraction of less than 20%. Results indicated that air-leaf-partitioning was the dominant uptake route of PAHs accumulation in Spartina. Lower plant/air partition coefficients of naphthalenes than phenanthrenes from the fugacity experiment suggested the accumulation of lower molecular weight PAHs in greater quantities. Temporal trends revealed seasonal variability of PAHs accumulation in Spartina and SPMDs. This study demonstrated the efficiency of Spartina cuticle measurements as passive samplers for assessing the pace of natural recovery in marsh systems.

Date

2017

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Pardue, John

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