PARENT SESSION
PW7 - Biotransformation / Metabolisms / Degradation
Wednesday, 20 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P804) [9-13C]Phenanthrene Fate and Toxicity in Anaerobic Marine Sediments Contaminated with PAHs.
Guthrie-Nichols, Elizabeth*,1, Walker, Angela2, Salloum, Myrna3, Hatcher, Patrick4, 1 North Carolina State University, Raleigh, NC, USA2 University of Tennessee at Chattanooga, Chattanooga, TN, USA3 University of Toronto at Scarborough, Toronto, Ontario, Canada4 The Ohio State University, Columbus, OH, USA
ABSTRACT- The effect of anaerobic conditions on phenanthrene (PHEN) transformation and PHEN association with sedimentary organic matter (SdOM) was evaluated using [9-13C]PHEN. Sediments were collected from sites of varying petroleum hydrocarbon contamination in San Diego Bay, San Diego, CA. Whole sediment microcosms were amended with [9-13C]PHEN (n=1) and PHEN (n=2) for each microcosm set. For each time point, four microcosm sets were prepared. Microcosm sets included: (1) sediment and PHEN only, (2) sediment + Na2SO4 + PHEN, (3) sediment + MoNa2O4+ PHEN, or (4) sediment + HgCl2 + PHEN. Microcosms were incubated under anaerobic conditions (80:20 N2:CO2) for up to 180 days. For each time point, microcosms were acidified to collect evolved CO2, sediments were lipid extracted to quantify remaining PHEN, and sediments were analyzed by stable carbon isotope ratio analyses (IRMS) to determine 13C label association with SdOM. PHEN concentrations in sediments from sites with high PAH contamination was 0% by 150 days. Biological removal of PHEN was associated with sulfate reduction. Minimal PHEN loss was observed in microcosms where sulfate reduction was inhibited with MoNa2O4. PHEN or metabolite sequestration in SdOM was only observed at sediment sites with low PAH contamination. PHEN loss in sediments from sites with low PAH contamination or sediments from both sites amended with Na4SO2 were similar regardless of site location (40%). IRMS indicated some 13C label association with SdOM in sediments with low PAH contamination. Solution 13C NMR analyses of lipid extracts from all sediments suggest dihyrodiol substitution at the C9,C10 positions of PHEN. Toxicity analyses by Whole Sediment Flash Toxicity Assay tests using Vibrio fischeri indicated that sediments remained toxic throughout anaerobic incubations
Key words: 13C phenanthrene, anaerobic sediments, stable isotope carbon ratio analyses, 13C NMR