Measurement of nitrous oxide reductase activity in aquatic sediments

Journal Article · Wed Jan 01 00:00:00 EST 1986 · Appl. Environ. Microbiol.; (United States)

OSTI ID:5099073

Miller, L G; Oremland, R S; Paulsen, S

Denitrification in aquatic sediments was measured by an N/sub 2/O reductase assay. Sediments consumed small added quantities of N/sub 2/O over short periods (a few hours). In experiments with sediment slurries, N/sub 2/O reductase activity was inhibited by 0/sub 2/, C/sub 2/H/sub 2/, heat treatment, and by high levels of nitrate (1 mM) or sulfide (10 mM). However, ambient levels of nitrate (<100 ..mu..M) did not influence activity, and moderate levels (about 150 ..mu..M) induced only a short lag before reductase activity began. Moderate levels of sulfide (<1 mM) had no effect on N/sub 2/O reductase activity. Nitrous oxide reductase displayed Michaelis-Menten kinetics in sediments from freshwater, estuarine, and alkaline-saline environments. An in situ assay was devised in which a solution of N/sub 2/O was injected into sealed glass cores containing intact sediment. Two estimates of net rates of denitrification in San Francisco Bay under approximated in situ conditions were 0.009 and 0.041 mmol of N/sub 2/O per m/sup 2/ per h. Addition of chlorate to inhibit denitrification in these intact-core experiments (to estimate gross rates of N/sub 2/O consumption) resulted in approximately a 14% upward revision of estimates of net rates. These results were comparable to an in situ estimate of 0.022 mmol of N/sub 2/O per m/sup 2/ per h made with the acetylene block assay.

• Research Organization: Geological Survey, Menlo Park, CA
• OSTI ID: 5099073
• Journal Information: Appl. Environ. Microbiol.; (United States), Vol. 51:1
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
NITROUS OXIDE
BIODEGRADATION
OXIDOREDUCTASES
ENZYME ACTIVITY
SEDIMENTS
DENITRIFICATION
ACETYLENE
BIOLOGICAL EFFECTS
EXPERIMENTAL DATA
HYPERTHERMIA
NITRATES
OXYGEN
SULFIDES
ALKYNES
BODY TEMPERATURE
CHALCOGENIDES
CHEMICAL REACTIONS
DATA
DECOMPOSITION
ELEMENTS
ENZYMES
HYDROCARBONS
INFORMATION
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
SULFUR COMPOUNDS
520200* - Environment
Aquatic- Chemicals Monitoring &amp; Transport- (-1989)