Figure 1.
Schematic overview of major direct and indirect effects of temperature on denitrification.
Figure 2.
Temperature dependence of denitrification and dissolved oxygen concentrations.
Panels show: Denitrification rates at different temperatures in vegetated microcosms (A) and vegetated drainage ditches (B). Dissolved oxygen concentrations at different temperatures in vegetated microcosms (C) and in drainage ditches based on monthly average values (April-July) at 3100 sites for the years 1980–2005 (D). Solid lines show the model predictions based on equation (2) (panels A and B), and equation (3) (panels C and D). Dashed lines represent the temperature dependence of the saturation concentration of oxygen (equation 4).
Figure 3.
Temperature dependence of denitrification rates at constant low dissolved oxygen levels.
Denitrification rates measured in vegetated freshwater microcosms, as compared to the fitted Arrhenius equation (dotted black line; equation 1), the modelled denitrification rates (black line; equations 2–4 with parameters from Table 2), and modelled denitrification with O2 fixed at 1 mg l−1(dashed blue line; equation 2).
Table 1.
Overall temperature effects on denitrification (equation 1) with either temperature dependent or fixed dissolved oxygen levels.
Table 2.
Model parameter values.