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Oxygen Consumption and Denitrification Kinetics in Soil
Author(s) -
Cho C. M.
Publication year - 1982
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1982.03615995004600040018x
Subject(s) - denitrification , oxygen , environmental science , consumption (sociology) , kinetics , environmental chemistry , soil science , chemistry , nitrogen , social science , physics , quantum mechanics , sociology , organic chemistry
Oxygen consumption and CO 2 , N 2 O, and N 2 production from a slurry of a slightly acidic soil incubated in a closed container with several different concentrations of NO ‐ 3 were investigated using a mass spectrometer. Under unshaken conditions, the rates of O 2 consumption and CO 2 production changed with time. Nitrous oxide and N 2 gases were produced even though there was ample O 2 in the atmosphere above the stagnant water. Under these conditions the rates of O 2 consumption and N 2 O, N 2 , and CO 2 production were controlled by the kind and rate of supply of electron acceptors to the sites of denitrification. When well shaken, the rate of O 2 consumption was constant. The CO 2 production rate had two distinctive values. The rate of CO 2 production when O 2 was still in the system was greater than the value obtained after O 2 in the system was all depleted. Nitrous oxide started to appear only when O 2 was completely consumed. Under the shaken conditions, the measured rates of O 2 consumption, CO 2 , and N 2 O production were independent of NO ‐ 3 concentration; however, the average life and the maximum concentration of N 2 O were directly related to initial NO ‐ 3 concentration. It is useful to define a parameter, denitrification intensity (DNI), which is proportional to the potential maximum rate of electron production for a soil with constant microbial activity under fixed temperature. Determination of the DNI must be made when the rate of electron acceptor (NO ‐ 3 or NO ‐ 2 ) supply is not limiting the reaction. Under these conditions, the inhibition of conversion of N 2 O to N 2 results in the rate of N 2 O‐N production which is greater than the rate of production of the sum of N 2 O‐N and N 2 ‐N without inhibition. If the rate of supply of electron acceptors (NO ‐ 3 or NO ‐ 2 ) is smaller than DNI, a parameter, gaseous nitrogen production rate (GNPR), the magnitude of which is unaffected by the inhibition of conversion of N 2 O to N 2 , characterizes the denitrification process.