Table 2.

CH4 oxidation kinetics in three upland forest soils

SoilTreatmentKm(app) (μl liter−1)aVmax(app) (pmol g−1 h−1)First-order rate constant (h−1)b% Inhibition compared toc:Implied inhibition mechanismCurve fit (R2)d
TruePseudoH2OK+
Birch taigaH2O0.007110.994
K2SO4 0.006538.2?0.996
(NH4)2SO4 0.0052626* 19* ?0.992
KCl0.0007889* ?0.772
NH4Cl0.0007290* 7.7?0.771
Temperate hardwoodH2O15.2 (1.3)5,807 (329)0.7050.998
K2SO4 9.8 (0.4)2,662 (584)0.51028* Uncompetitive0.999
(NH4)2SO4 22.4 (1.8)2,870 (157)0.23567* 54* Mixed competitive0.998
KCl7.2 (0.6)786 (30)0.20072* Uncompetitive0.993
NH4Cl25.6 (4.9)1,174 (155)0.08588* 58* Mixed competitive0.991
Temperate pineH2O6.7 (0.9)2,594 (160)0.7150.984
K2SO4 6.1 (0.9)1,591 (98)0.48532* Noncompetitive0.978
(NH4)2SO4 9.8 (1.4)1,699 (123)0.32055* 34* Mixed competitive0.986
KCl8.8 (4.0)573 (123)0.12083* Noncompetitive0.855
NH4Cl10.9 (7.2)515 (176)0.0858829Mixed competitive0.769
  • a The values in parentheses are standard errors.

  • b True first-order rate constants were calculated by linear regression of CH4 oxidation rates against midpoint CH4 concentrations. Pseudo-first-order rate constants were calculated by determining Vmax/Km after Km values were converted to picomoles of CH4 per bottle.

  • c An asterisk indicates that the treatment value was statistically different from the corresponding control value (P ≤ 0.05).

  • d The regression coefficients are linear for the birch taiga soil and nonlinear (Michaelis-Menten curve fit) for the two temperate soils.