Based in part on the author's thesis (Ph.D.--ETH Zürich, 1996). / Includes bibliographical references and index.

Thesis (M. Sc.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 49-71).

Thesis (Ph.D.)--Hong Kong Baptist University, 2006. / Adviser: Ming Hung Wong. Includes bibliographical references.

Thesis (Ph. D.)--University of Toronto, 2004. / Adviser: Frank Wania. Includes bibliographical references (p. 154-163).

Univ., Diss.--Hamburg, 2006. / Literaturverz. S. [123] - 129.

Thesis (M.S.)--Villanova University, 2008. / Chemistry Dept. Includes bibliographical references.

Thesis (M.S.)--Villanova University, 2009. / Chemistry Dept. Includes bibliographical references.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Extreme flooding of rivers may contribute to increased loading of persistent organic pollutants (POPs) to the Great Lakes, the Mississippi river, and other large lakes and surface waters downstream of industrial and urban areas. This study examines the fate of POPs that were mobilized during heavy flooding of the Cedar River and the small urban city of Cedar Rapids, Iowa during the summer of 2008. This study focuses polychlorinated biphenyls (PCBs). We hypothesize that these PCBs were mobilized by the flood water and that residues remained in the soils and sediments of the residential areas of the city. To test our hypothesis, soil samples were collected from ~200 of residential locations in the downtown Cedar Rapids area and analyzed for the three compound groups. Samples were extracted using an accelerated solvent extraction (ASE 300), and analyzed using GC/ECD, GC/MSD and GC/MS/MS.

DDT, an extremely widely used organochlorine pesticide, was banned in most developed countries more than 30 years ago. However, DDT residues, including 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (DDE), still persist in the environment and have been identified as priority pollutants due to their toxicity and their ability to bioaccumulate and biomagnify in the food chain. In particular, DDE was long believed to be &quotenon-biodegradable&quote, however some microorganisms have now been isolated that are able to metabolise DDE in pure culture. Terrabacter sp. strain DDE-1 was enriched from a DDT-contaminated agricultural soil from the Canterbury plains and is able to metabolise DDE to 4-chlorobenzoic acid when induced with biphenyl. The primary objective of this study was to identify the gene(s) responsible for Terrabacter sp. strain DDE-1�s ability to metabolise DDE and, in particular, to investigate the hypothesis that DDE-1 degrades DDE cometabolically via a biphenyl degradation pathway. Catabolism of biphenyl by strain DDE-1 was demonstrated, and a biphenyl degradation (bph) gene cluster containing bphDA1A2A3A4BCST genes was identified. The bphDA1A2A3A4BC genes are predicted to encode a biphenyl degradation upper pathway for the degradation of biphenyl to benzoate and cis-2-hydroxypenta-2,4-dienoate and the bphST genes are predicted to encode a two-component signal transduction system involved in regulation of biphenyl catabolism. The bph gene cluster was found to be located on a linear plasmid, designated pBPH1. A plasmid-cured strain (MJ-2) was unable to catabolise both biphenyl and DDE, supporting the hypothesis that strain DDE-1 degrades DDE cometabolically via the biphenyl degradation pathway. Furthermore, preliminary evidence from DDE overlayer agar plate assays suggested that Pseudomonas aeruginosa carrying the strain DDE-1 bphA1A2A3A4BC genes is able to catabolise DDE when grown in the presence of biphenyl. A second objective of this study was to characterise pBPH1. The complete 84,054-bp sequence of the plasmid was determined. Annotation of the DNA sequence data revealed seventy-six ORFs predicted to encode proteins, four pseudogenes, and ten gene fragments. Putative functions were assigned to forty-two of the ORF and pseudogenes. Besides biphenyl catabolism, the major functional classes of the predicted proteins were transposition, regulation, heavy metal transport/resistance, and plasmid maintenance and replication. It was shown that pBPH1 has the terminal structural features of an actinomycete invertron, including terminal proteins and terminal inverted repeats (TIRs). This is the first report detailing the nucleotide sequence and characterisation of a (linear) plasmid from the genus Terrabacter.