A Microscale Investigation of Naphthalene Dissolution and Biodegradation

Michelle Anne Sullivan: A Microscale Investigation of Naphthalene Dissolution and Biodegradation (Under the direction of Dr. Frederic K. Pfaender) Biodegradation of PAHs by soil microbes is often hindered because the compounds are not always available to the microorganisms responsible for metabolism. Light microscopy, with digital photography and image analysis, was used to observed naphthalene dissolution. A small scale flow cell containing a naphthalene crystal was viewed at 100x magnification. Abiotic, biotic, and azide-inhibited systems were examined in this experimental system. Changes in the crystal's mass were determined from image analysis, and changes in the aqueous naphthalene's mass were determined with a fluorescence detector. Naphthalene's mass decreased approximately 6 x 10-3 mg/hr, 1.5 x 10-3 mg/hr, and 1.0 x 10-3 mg/hr for abiotic, biotic, and azide-inhibited experiments, respectively. Cellular material around the crystal caused slower dissolution rates for the biotic and azide-inhibited experiments. There was no evidence that bacterial metabolism was occurring in the system. A model was developed which underestimated the dissolution rate by approximately one order of magnitude. Environmental Health Sciences (Grant ES11890). I would like to thank the Pfaender/Aitken lab members for their advice, insight, and friendship. In particular, I would like to acknowledge Dr. Chad Roper, for his thoughts and suggestions that have helped shape this project. Lastly, I would like to thank my committee, Dr.