title: Dissolved oxygen saturation controls PAH biodegradation in freshwater estuary sediments.
abstract: Polycyclic aromatic hydrocarbons (PAHs) are common contaminants in terrestrial and aquatic environments and can represent a significant constituent of the carbon pool in coastal sediments. We report here the results of an 18-month seasonal study of PAH biodegradation and heterotrophic bacterial production and their controlling biogeochemical factors from 186 sediment samples taken in a tidally influenced freshwater estuary. For each sampling event, measurements were averaged from 25-45 stations covering approximately 250 km(2). There was a clear relationship between bacterial production and ambient temperature, but none between production and bottom water dissolved oxygen (DO) % saturation or PAH concentrations. In contrast with other studies, we found no effect of temperature on the biodegradation of naphthalene, phenanthrene, or fluoranthene. PAH mineralization correlated with bottom water DO saturation above 70% (r(2) > 0.99). These results suggest that the proportional utilization of PAH carbon to natural organic carbon is as much as three orders of magnitude higher during cooler months, when water temperatures are lower and DO % saturation is higher. Infusion of cooler, well-oxygenated water to the water column overlying contaminated sediments during the summer months may stimulate PAH metabolism preferentially over non-PAH organic matter.
authors.affiliation: Code 6114, U.S. Naval Research Laboratory, 4555 Overlook Ave, Washington, DC 20375, USA. tboyd@ccf.nrl.navy.mil
authors.forename: T J
authors.initials: TJ
authors.lastname: Boyd
authors.forename: M T
authors.initials: MT
authors.lastname: Montgomery
authors.forename: J K
authors.initials: JK
authors.lastname: Steele
authors.forename: J W
authors.initials: JW
authors.lastname: Pohlman
authors.forename: S R
authors.initials: SR
authors.lastname: Reatherford
authors.forename: B J
authors.initials: BJ
authors.lastname: Spargo
authors.forename: D C
authors.initials: DC
authors.lastname: Smith
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019015:Geologic Sediments / Q000382:microbiology*; D010100:Oxygen / Q000032:analysis*; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism*; D012044:Regression Analysis; D045483:Rivers / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D010100:Oxygen