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Denitrification in San Francisco Bay intertidal sediments

January 1, 1984

The acetylene block technique was employed to study denitrification in intertidal estuarine sediments. Addition of nitrate to sediment slurries stimulated denitrification. During the dry season, sediment-slurry denitrification rates displayed Michaelis-Menten kinetics, and ambient NO3 + NO2 concentrations (≤26 μM) were below the apparent Km (50 μM) for nitrate. During the rainy season, when ambient NO3 + NO2 concentrations were higher (37 to 89 μM), an accurate estimate of the Km could not be obtained. Endogenous denitrification activity was confined to the upper 3 cm of the sediment column. However, the addition of nitrate to deeper sediments demonstrated immediate N2O production, and potential activity existed at all depths sampled (the deepest was 15 cm). Loss of N2O in the presence of C2H2 was sometimes observed during these short-term sediment incubations. Experiments with sediment slurries and washed cell suspensions of a marine pseudomonad confirmed that this N2O loss was caused by incomplete blockage of N2O reductase by C2H2 at low nitrate concentrations. Areal estimates of denitrification (in the absence of added nitrate) ranged from 0.8 to 1.2 μmol of N2 m−2 h−1 (for undisturbed sediments) to 17 to 280 μmol of N2 m−2 h−1 (for shaken sediment slurries).

Publication Year 1984
Title Denitrification in San Francisco Bay intertidal sediments
DOI 10.1128/aem.47.5.1106-1112.1984
Authors Ronald S. Oremland, Cindy Umberger, Charles W. Culbertson, Richard L. Smith
Publication Type Article
Publication Subtype Journal Article
Series Title Applied and Environmental Microbiology
Index ID 70175218
Record Source USGS Publications Warehouse
USGS Organization San Francisco Bay-Delta; Toxic Substances Hydrology Program; Pacific Regional Director's Office