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(62-04) The Role of Molecular Structure in Determining Polycyclic Aromatic Hydrocarbon Biodegradation Rates. Peters, Catherine1, Wammer, Kristine*,1, 1 Princeton University, Princeton, NJ ABSTRACT- Polycyclic aromatic hydrocarbons (PAHs) are common environmental pollutants that are of concern because they are suspected carcinogens. One of the major fates of PAHs in the environment is aerobic biodegradation by microorganisms. To be able to predict the behavior of PAHs in the environment and effectively design treatment schemes, it is necessary to have reliable estimates of the rates of these biodegradation reactions. Despite the chemical similarity of PAHs, their observed biodegradation rates in the environment vary over orders of magnitude. Physical and chemical processes (e.g. desorption from soil grains, dissolution from organic liquid phases) affecting compound bioavailability to a microorganism are not part of the actual biodegradation reaction but may control or influence the observed biodegradation rates. In this work, laboratory experiments were designed to estimate biodegradation rates independent of such bioavailability constraints by controlling for or measuring any potentially rate-limiting physical processes. These experiments were performed for more than 20 PAHs. It was found that when bioavailability constraints are removed much of the variation seen for PAH biodegradation rates in the environment disappears. The variations that do exist were examined to look for correlations between molecular structural features and biodegradation rates. The results of these explorations will be presented and the implications for the potential of developing a quantitative structure activity relationship (QSAR) and deducing the rate-limiting steps in the biodegradation process will be discussed. Key words: polycyclic aromatic hydrocarbons, biodegradation, QSAR |
