title: Effect of temperature on consecutive denitrification reactions in brookston clay and fox sandy loam.
abstract: The kinetics of several steps in the microbial denitrification process in Brookston clay and Fox sandy loam, two soils common to Southwestern Ontario, were studied in the temperature range of 5 to 25 degrees C. The extent of chemical denitrification was also determined in otherwise identical but sterilized soils at temperatures up to 80 degrees C. A gas flow system was used in which soil gases were continuously removed from anaerobic soil columns by argon carrier gas. Net steady-state rates of NO and N(2)O production, rates of loss of NO(3), and production and loss of NO(2) were measured over periods of up to 5 days. Arrhenius activation energies for the zero-order process NO(3) --> NO(2) were calculated to be 50 +/- 9 kJ mol for Brookston clay and 55 +/- 13 kJ mol for Fox sandy loam. The overall reaction, NO(2) --> NO (chemodenitrification), in both sterile soils was accurately first order with respect to NO(2); the activation energy was 70 +/- 2.8 kJ mol in Brookston clay and 79 +/- 1.2 kJ mol in the sandy loam, and the preexponential factors were (2.3 +/- 1.2) x 10 and (5.7 +/- 1.2) x 10 min, respectively.
authors.affiliation: Department of Chemistry, University of Windsor, Windsor, Ontario N9B 3P4, and Agriculture Canada, Research Station, Harrow, Ontario NOR IGO, Canada.
authors.forename: D J
authors.initials: DJ
authors.lastname: McKenney
authors.forename: G P
authors.initials: GP
authors.lastname: Johnson
authors.forename: W I
authors.initials: WI
authors.lastname: Findlay