INHIBITION OF METHANE OXIDATION BY AMMONIUM IN THE SURFACE-LAYER OF ALITTORAL SEDIMENT

Citation
U. Bosse et al., INHIBITION OF METHANE OXIDATION BY AMMONIUM IN THE SURFACE-LAYER OF ALITTORAL SEDIMENT, FEMS microbiology, ecology, 13(2), 1993, pp. 123-134
Citations number
49
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
ISSN journal
0168-6496
Volume
13
Issue
2
Year of publication
1993
Pages
123 - 134
Database
ISI
SICI code
0168-6496(1993)13:2<123:IOMOBA>2.0.ZU;2-L
Abstract
The diffusive flux of CH4 from the sediment into the water was measure d in intact sediment cores taken from the littoral of Lake Constance. CH4 fluxes were measured under oxic and anoxic conditions. Emissions u nder anoxic conditions were used to estimate the potential diffusive f lux. The results showed that about 79% of the CH4 diffusing upwards wa s oxidized at the sediment surface. Kinetic measurements of CH4 oxidat ion in diluted surface sediment gave V-max = 1.2 mu mol CH4 ml(sed)(-1 )h(-1). This was high enough to explain the oxidation rates calculated from the flux measurements. NH4+ was added to the water overlaying th e sediment cores to measure its influence on CH4 oxidation. This treat ment resulted in increased concentrations of pore water NH4+ which wer e measured with a NH4+ microelectrode. Pore water NH4+ concentrations of < 4 mM had no effect on CH4 oxidation while concentrations between 4 and 10 mM NH4+ reduced the CH4 oxidation rates by about 30%. Measure ment of CH4 oxidation rates in diluted surface sediment gave similar r esults. At CH4 concentrations of 21 mu M, the CH4 oxidation rate decre ased at NH4+ concentrations greater than or equal to 4 mM, and was com pletely inhibited at NH4+ concentrations > 20 mM. Measurements of pote ntial NH4+ oxidation rates were below the detection limit of 0.5 nmol NO2- produced ml(sed)(-1)h(-1). Thus, the NH4+ oxidizing activity was about 3 magnitudes lower than the CH4 oxidizing activity, and it is un likely that NH4+ oxidizers are important for CH4 oxidation in this lit toral sediment.