Fig 3.

Apparent Michaelis-Menten kinetics of nitrate-dependent (A) and nitrite-dependent (B) N₂O production in the presence of acetylene and N₂O consumption (C) in anoxic palsa peat soil microcosms. Squares, circles, and triangles represent microcosms supplemented with nitrate, nitrite, and N₂O, respectively. Closed and open symbols represent 0- to 20-cm and below-20-cm palsa peat soils, respectively. The x axis displays the amount of supplemented (i.e., additional) nitrate, nitrite, or N₂O. Mean values and standard errors of three replicate microcosms are shown. Solid and dashed lines are indicative of 0- to 20-cm and below-20-cm palsa peat soils, respectively. Curves represent Michaelis-Menten fits of the data. Horizontal and vertical lines represent v_max and K_m values, respectively. Letters indicate the following values: (i) nitrate-dependent v_max (a, 2.75; b, 1.4) and K_m (c, 8.1; d, 17.3), (ii) nitrite-dependent v_max (e, 14.6; f, 3.0) and K_m (g, 12.3; h, 39.1), and (iii) N₂O-dependent v_max (i, −17.0; j, −18.9) and K_m (k, 2.5; l, 4.0).