Table 1.
Testing for thermal breaks for all kinetic parameters
| Method | Parameter | Davies test | Maximum likelihood | |||
|---|---|---|---|---|---|---|
| Estimated breakpoint (°C) | P-value | Estimated breakpoint (°C) | CI (lower) | CI (upper) | ||
| Radiolabel |
k
catCO2
single point |
26.8 | * | 25.1 | 5.3 | 36.9 |
|
k
catCO2
curve fit |
– | ns | ||||
| k catO2 | – | – | ||||
| K C | – | ns | ||||
| K O | – | ns | ||||
| S C/O | – | ns | ||||
| MIMS | k catCO2 | 25.3 | * | 25.3 | 23.1 | 31.5 |
| k catO2 | 25.3 | * | 25.5 | 24.3 | 32.6 | |
| K C | – | ns | ||||
| K O | – | ns | ||||
| S C/O | 25.4 | * | 25.2 | 15.0 | 27.6 | |
Arrhenius plots were examined using the package ‘segmented’ in R (R Core Team, 2013), which determines the significance of breakpoints in linear models and estimates breakpoint locations as described by Davies (1987). Additionally, breakpoint locations and confidence intervals (CIs, lower and upper) were independently estimated using a maximum likelihood test (Muggeo, 2003, 2008). * indicates a P-value <0.05 for the Davies test and ns is not significant.