Document Type


Date of Degree

Spring 2010

Degree Name

PhD (Doctor of Philosophy)

Degree In

Civil and Environmental Engineering

First Advisor

Schnoor, Jerald L.

First Committee Member

Parkin, Gene

Second Committee Member

Scherer, Michelle

Third Committee Member

Knudtson, Kevin

Fourth Committee Member

Clayton, Maureen

Fifth Committee Member

Irish, Erin


Poplar (Populus deltoides x nigra DN34) tissue cultures removed 2,4,6-trinitrotoluene (TNT) from an aqueous solution in five days, reducing the toxicity of the solution from highly toxic Microtox® EC value to that of the control. 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) was taken up by the plant tissue cultures more slowly, but toxicity reduction of the solution was evident. The measurement of toxicity reduction of aqueous solutions containing TNT and RDX was performed using a novel methodology developed for use with the Microtox® testing system. Radiolabeled TNT and RDX were used to confirm removal of explosives from hydroponic solutions containing plant tissue cultures and to verify that toxicity did not change in solutions where no plant cultures were present (positive controls). High Performance Liquid Chromatography (HPLC) and Liquid Scintillation Counter (LSC) measurements confirmed removal of TNT and RDX from solutions containing poplar plant tissue cultures and constancy of the plant-free controls. In addition, metabolites were identified in remediated solutions by HPLC, confirming the mechanism by which plants can remediate groundwater, surface water, and soil solutions.

Using an Affymetrix® microarray, poplar trees were exposed to TNT over 48 hours. General patterns, as well as significant downregulated and upregulated genes were studied. We identified several new genes that were implicated in the detoxification and metabolism of TNT by Populus. In particular, our results support the "green liver" model of different gene families being expressed during the time course experiments. This suggests an alignment with Phase I transformation, Phase II conjugation, and Phase III compartmentation processes. Many of the genes identified in this study were related to those significantly expressed in previous Arabidopsis studies, supporting the comparison between these two plants. Gene families represented as significant in this study were glucosyltransferases, glycosyltransferases, cytochromes, and phosphofructokinases. We saw patterns in the areas of respiration, citric acid cycle, shikimatic pathway, and toxic responses.


Ecotoxicology, Phytoremediation, Phytotoxicity, Populus, RDX, TNT


viii, 81 pages


Includes bibliographical references (pages 73-81).


Copyright 2010 Brittany Renee Flokstra

Additional Files

FinalDataTableMay10.xlsx (231 kB)
ANOVAResults.xls (36210 kB)
Schnoor.avp (56681 kB)